Back-contact cell and photovoltaic module

Abstract

The present application relates to the technical field of photovoltaics. Disclosed are a back-contact cell and a photovoltaic module, configured to reduce the risk of leakage current between a first doped semiconductor layer and a second doped semiconductor layer. The back-contact cell comprises: a semiconductor substrate, a first doped semiconductor layer, and a second doped semiconductor layer. In the direction from a first surface to a second surface, the surface of a spacing region is recessed inward relative to the surface of a first region, so as to form a groove structure. The first doped semiconductor layer is at least partially disposed on the first region. The second doped semiconductor layer is disposed on a second region. The second doped semiconductor layer and the first doped semiconductor layer have opposite conductivity types. In the extending direction of the spacing region, the first doped semiconductor layer comprises a first boundary close to the spacing region. In the width direction of the spacing region, the first boundary comprises a first sub-boundary located within the first region and a second sub-boundary which extends from the first region to above the groove structure and is located above the groove structure.

Description

Back contact batteries and photovoltaic modules Technical Field

[0001] This application relates to the field of photovoltaic technology, and more particularly to a back contact battery and a photovoltaic module. Background Technology

[0002] Back-contact solar cells are solar cells with no electrodes on the light-facing side, and both the positive and negative electrodes are located on the back-facing side of the cell. This reduces the shading of the cells by the electrodes, increases the short-circuit current, and improves the energy conversion efficiency of the cells.

[0003] However, in existing back-contact batteries, there is an isolation structure between the first and second doped semiconductor layers with opposite conductivity types on the back side. The actual efficiency of the battery is affected by the specific isolation structure, and the efficiency of current batteries still needs to be improved. Summary of the Invention

[0004] The purpose of this application is to provide a back-contact battery and a photovoltaic module for improving the efficiency of the back-contact battery.

[0005] To achieve the above objectives, in a first aspect, this application provides a back contact battery, comprising: a semiconductor substrate, a first doped semiconductor layer, and a second doped semiconductor layer. The semiconductor substrate includes a first surface and a second surface opposite to each other. The first surface includes alternating first and second regions, and a gap region located between the first and second regions. Along the direction from the first surface to the second surface, the surface of the gap region is recessed inward relative to the surface of the first region to form a groove structure. The first doped semiconductor layer is at least partially disposed on the first region. The second doped semiconductor layer is disposed on the second region. The second doped semiconductor layer and the first doped semiconductor layer have opposite conductivity types. Wherein, along the extension direction of the gap region, the first doped semiconductor layer includes a first boundary adjacent to the gap region. Along the width direction of the gap region, the first boundary includes a first sub-boundary located within the first region, and a second sub-boundary extending from the first region to above the groove structure and located above the groove structure.

[0006] When the back contact battery is in operation, the first and second doped semiconductor layers can effectively shunt and collect charge carriers, facilitating the formation of photocurrent. Secondly, the spacer region between the first and second regions separates the first and second doped semiconductor layers, reducing the risk of leakage between them. Furthermore, along the width of the spacer region, the first boundary of the first doped semiconductor layer includes not only a second sub-boundary extending from the first region to above the groove structure, but also a portion of the first doped semiconductor layer corresponding to the second sub-boundary suspended above the groove structure. This facilitates the reflection of some light emitted from the first surface of the semiconductor substrate back to the semiconductor substrate for reuse, improving the light utilization rate of the back contact battery. Additionally, the first boundary of the first doped semiconductor layer also includes a first sub-boundary located within the first region and away from the groove structure. The portion of the first doped semiconductor layer corresponding to the first sub-boundary is recessed within the first region relative to the first sidewall of the groove structure (the sidewall of the groove structure closest to the first region), increasing the distance between the first and second doped semiconductor layers and further reducing the risk of leakage between them. Compared to existing back contact batteries where each part of the first boundary is suspended above the groove structure, the back contact battery provided in this application has a lower leakage risk and carrier recombination rate. Furthermore, compared to batteries where each part of the first boundary is recessed into the first region, the back contact battery provided in this application has higher light utilization, thus improving the working performance of the back contact battery.

[0007] As one possible implementation, along the extension direction of the interval region, within a unit length, the total length of the first sub-boundary located within the first region is greater than the total length of the second sub-boundary located above the groove structure.

[0008] Understandably, the distance between the portion of the first doped semiconductor layer corresponding to the second sub-boundary and the second doped semiconductor layer is greater than that between the portion of the first doped semiconductor layer corresponding to the first sub-boundary and the second doped semiconductor layer. Therefore, when the total length of the first sub-boundary within the first region is greater than the total length of the second sub-boundary above the groove structure, the portion of the first boundary of the first doped semiconductor layer with a larger distance from the second doped semiconductor layer accounts for a higher proportion. This is beneficial for further reducing the leakage risk between the first and second doped semiconductor layers and reducing the carrier recombination rate of the back contact battery.

[0009] As one possible implementation, the first boundary of the first doped semiconductor layer near the spacer region has an alternating concave-convex structure, which includes concave boundaries and convex boundaries.

[0010] As one possible implementation, the first sub-boundary includes at least a partially concave boundary, and the second sub-boundary includes at least a partially convex boundary. In this case, the first sub-boundary of the first doped semiconductor layer disposed in the first region is opposite to at least a partially concave boundary in the alternating concave-convex structure, and the second sub-boundary of the first doped semiconductor layer disposed above the groove structure is opposite to at least a partially convex boundary in the alternating concave-convex structure. This is beneficial for better matching the fluctuation changes of the alternating concave-convex structure presented by the first boundary with the portion of the first doped semiconductor layer that is recessed into the first region and the portion of the first doped semiconductor layer that is suspended above the groove structure. This can reduce the increase in etching amount of the semiconductor substrate required to make the first boundary of the first doped semiconductor layer simultaneously have a first sub-boundary and a second sub-boundary, which is beneficial for increasing the light absorption area of ​​the semiconductor substrate and improving the conversion efficiency of the back contact cell.

[0011] As one possible implementation, the first sub-boundary includes at least a partially concave boundary and at least a partially convex boundary; or, the second sub-boundary includes at least a partially concave boundary and at least a partially convex boundary. This helps to reduce the manufacturing difficulty of back contact batteries and improve their yield.

[0012] As one possible implementation, along the extension direction of the interval region, the total length of adjacent convex and concave boundaries in the alternating concave-convex structure can be greater than or equal to 0.05 μm and less than or equal to 10 μm. In this case, the total length of adjacent convex and concave boundaries in the alternating concave-convex structure has a large selectable range, which is beneficial to improving the applicability of the back contact battery provided in this application in different application scenarios.

[0013] As one possible implementation, along the extension direction of the spacing region, the distance W1 between adjacent concave boundaries or adjacent convex boundaries is greater than or equal to 1 μm and less than or equal to 15 μm. In this case, the total length of adjacent convex and concave boundaries in the alternating concave-convex structure has a large selectable range, which is beneficial to improving the applicability of the back contact battery provided in this application in different application scenarios.

[0014] As one possible implementation, along the width direction of the interval region, the extension width W2 of the first sub-boundary within the first region is less than or equal to 8 μm.

[0015] The extension width W2 of the first sub-boundary in the first region is within the aforementioned range, which helps to prevent the area ratio of the first doped semiconductor layer in the first region from being too small due to the excessive extension width W2 of the first sub-boundary in the first region. This helps to enable the first doped semiconductor layer to have a higher field passivation effect and carrier collection capability, thereby further improving the working performance of the back contact battery.

[0016] As one possible implementation, the extension width W3 of the second sub-boundary above the groove structure along the width direction of the interval region is less than or equal to 10 μm.

[0017] The extension width W3 of the second sub-boundary above the groove structure is within the above range, which helps to prevent the minimum spacing between the first doped semiconductor layer and the second doped semiconductor layer from being too small due to the extension width W3 of the second sub-boundary above the groove structure being too large, thereby further reducing the risk of leakage between the back contact cells.

[0018] As one possible implementation, the groove structure has a first sidewall near the first region along the width direction of the spacing region. Along the width direction of the spacing region, the first region includes a platform region near the first sidewall, the platform region including a platform surface substantially perpendicular to the thickness direction of the semiconductor substrate.

[0019] The plateau region includes a plateau surface that is approximately perpendicular to the thickness direction of the semiconductor substrate. In this case, the surface of the portion of the first region of the semiconductor substrate not directly covered by the first doped semiconductor layer (i.e., the plateau region) is relatively flat, which helps reduce the number of surface defects in the plateau region and decrease the carrier recombination rate. Furthermore, this plateau surface has high light reflectivity, which helps reduce the probability of light escaping from the plateau region within the semiconductor substrate, thereby improving the light utilization efficiency of the back-contact battery.

[0020] As one possible implementation, the platform area also includes a second sidewall that is away from the first sidewall and continuous with the platform surface. The second sidewall is disposed perpendicular to the platform surface, or the second sidewall is disposed at an angle relative to the platform surface.

[0021] The platform region also includes a second sidewall that is continuous with the platform surface, indicating that along the direction from the first surface to the second surface, the platform surface is recessed into the semiconductor substrate relative to the surface of the region in the first region that is directly covered by the first doped semiconductor layer. This can reduce the height variation between the bottom surface of the groove structure and the surface of the region with a larger height in the first region, which is beneficial to the formation quality and coverage of the surface passivation layer at the junction of the first region and the spacer region, and reduces the carrier recombination rate at the junction of the first region and the spacer region.

[0022] As one possible implementation, a portion of the sidewalls of the first doped semiconductor layer are aligned with the second sidewalls of at least one adjacent platform region; or, at least one first sub-boundary within the first region extends above the platform surface.

[0023] When a portion of the sidewall of the first doped semiconductor layer aligns with a second sidewall of at least one adjacent platform region, the distance between this portion of the sidewall of the first doped semiconductor layer and the second doped semiconductor layer is relatively large, which helps to further reduce the risk of leakage between them. However, when at least one first sub-boundary located within the first region extends above the platform surface, although the distance between this portion of the first boundary and the second doped semiconductor layer is relatively small, the portion of the first doped semiconductor layer corresponding to this portion of the first boundary can reflect some of the light emitted from the platform surface, allowing some light to re-enter the semiconductor substrate, further improving the light utilization rate of the back contact cell.

[0024] As one possible implementation, the angle between the second sidewall and the platform surface is greater than or equal to 30° and less than or equal to 150°. In this case, when the angle between the second sidewall and the platform surface is within the above range, the size of the angle is relatively large, which can reduce the process difficulty of forming the platform area.

[0025] As one possible implementation, along the extension direction of the interval region, the area ratio between the platform surfaces of two adjacent platform regions is greater than or equal to 1.05 and less than or equal to 50. In this case, the platform surfaces of different platform regions can be the same or different, and relatively large differences between the different platform surfaces are allowed to reduce the manufacturing difficulty of the platform regions.

[0026] As one possible implementation, the height of the second sidewall is greater than or equal to 0.05 μm and less than or equal to 8 μm along the thickness direction of the semiconductor substrate.

[0027] When the above technical solution is adopted, the height of the second sidewall is within the aforementioned range. This helps prevent a large height difference between the bottom surface of the groove structure and the surface of the higher region in the first region due to a small second sidewall height. This further improves the passivation effect of the surface passivation layer at the junction of the first region and the spacer region. Additionally, it prevents a large etching amount in the semiconductor substrate corresponding to the platform region due to a large second sidewall height. This allows the semiconductor substrate to have a larger light absorption depth in the platform region, improving the light utilization rate of the semiconductor substrate and further enhancing the conversion efficiency of the back contact cell.

[0028] As one possible implementation, the back contact battery also includes an island-shaped passivation structure disposed on the platform region, with the island-shaped passivation structure spaced apart from the first doped semiconductor layer.

[0029] Island-shaped passivation structures possess passivation capabilities, enabling the passivation of the surface of regions on semiconductor substrates where island-shaped passivation structures are formed. This reduces the number of defects on the surface of these regions and lowers the carrier recombination rate. Furthermore, the height difference between the island-shaped passivation structure and the plateau region allows the side and / or top surfaces of the island-shaped passivation structure to reflect incident light from one side of the first face of the back contact cell. This alters the transmission path of the incident light (e.g., by increasing the reflection path), facilitating the refraction of more incident light into the cell, increasing the incident light absorption ratio, and improving the bifaciality of the back contact cell.

[0030] As one possible implementation, at least one island passivation structure includes a doped semiconductor passivation portion; and / or, at least one island passivation structure includes an interface passivation portion.

[0031] The island-shaped passivation structure can be formed by at least two types of passivation components that offer good performance and are compatible with battery manufacturing processes: doped semiconductor passivation portions and interface passivation portions. This not only provides excellent passivation performance but also improves the yield of the back contact battery. Furthermore, since doped semiconductor passivation portions and interface passivation portions are also materials used in manufacturing back contact batteries, the island-shaped passivation structure can be fabricated simultaneously with the corresponding structure in the back contact battery, improving manufacturing efficiency and simplifying the manufacturing process.

[0032] As one possible implementation, the material and conductivity type of the doped semiconductor passivation portion are the same as those of one of the first doped semiconductor layer and the second doped semiconductor layer.

[0033] When adopting the above technical solution, taking the example where the material and conductivity type of the doped semiconductor passivation portion included in the island passivation structure are the same as those of the second doped semiconductor layer, the island passivation structure can be manufactured simultaneously with the manufacturing of the second doped semiconductor layer, thereby improving the manufacturing efficiency of the back contact battery and simplifying the manufacturing process of the back contact battery.

[0034] As one possible implementation, the back contact battery further includes a first interface passivation layer disposed between the semiconductor substrate and the first doped semiconductor layer, and a second interface passivation layer disposed between the semiconductor substrate and the second doped semiconductor layer. The material of the interface passivation portion is the same as the material of the first interface passivation layer or the second interface passivation layer. The application principle of the beneficial effect in this case can refer to the application principle of the beneficial effect described above, where the material and conductivity type of the doped semiconductor passivation portion are the same as the material and conductivity type of one of the first doped semiconductor layer and the second doped semiconductor layer, respectively, and will not be repeated here.

[0035] As one possible implementation, the first doped semiconductor layer is a P-type doped semiconductor layer; and / or, the first doped semiconductor layer is an emitter doped layer.

[0036] As one possible implementation, the first side is the back side, the interval region has a first boundary region adjacent to the first region, the interval region has a second boundary region adjacent to the second region, and the first boundary region and / or the second boundary region has one or more pits.

[0037] When the above technical solution is adopted, the first boundary region of the spacer region adjacent to the first region and / or the second boundary region of the spacer region adjacent to the second region have one or more pits. The presence of pits can improve the light trapping effect of the back contact battery, improve the light absorption rate and utilization rate of the back contact battery, thereby improving the photoelectric conversion efficiency.

[0038] As one possible implementation, the pit includes a closed pit and / or a non-closed pit, wherein the side of the closed pit is surrounded by the semiconductor substrate to form a closed structure, and the side of the non-closed pit is partially surrounded by the semiconductor substrate to form a non-closed structure.

[0039] With the above technical solution, various situations regarding the pits can exist. For example, closed pits and non-closed pits can be used alone or in combination. For example, in some cases, a boundary region has only one type of pit, either closed or non-closed; in some cases, a boundary region includes both closed and non-closed pits; in some cases, a boundary region has only closed pits, while another boundary region adjacent to it in the same interval has only non-closed pits; in some cases, a boundary region includes both closed and non-closed pits, while another boundary region adjacent to it in the same interval has only non-closed pits; in some cases, a boundary region includes both closed and non-closed pits, while another boundary region adjacent to it in the same interval includes both closed and non-closed pits; and so on. Whether the pit is closed or not, and the opening direction of the pit, will change the light path, thus ultimately affecting the light-trapping effect. Combining different types of pits or different opening directions of different pits can improve the light trapping effect of back contact batteries, enhance the light absorption rate and utilization rate of back contact batteries, and thus improve photoelectric conversion efficiency.

[0040] As one possible implementation, the semiconductor substrate has prisms surrounding the sides forming the closed recess and / or the non-closed recess.

[0041] The presence of prisms within the pit increases the number of reflections and absorption rate of light within the pit, preventing light from being directly reflected away from the pit from the sides. This improves the light trapping effect of the back contact battery, enhances its light absorption and utilization rate, and thus improves the photoelectric conversion efficiency.

[0042] As one possible implementation, at least one of the prisms of the closed recess is joined to form at least one joint seam, and / or at least one of the prisms of the non-closed recess is joined to form at least one joint seam.

[0043] Since the ridges of the pits meet to form at least one seam, the larger the number of seams, the more uneven the inner surface of the pit is. This can increase the number of reflections and absorption rate of light in the pit, prevent light from being directly reflected away from the pit from the side, improve the light trapping effect of the back contact battery, and enhance the light absorption rate and utilization rate of the back contact battery, thereby improving the photoelectric conversion efficiency.

[0044] As one possible implementation, the first boundary region has at least the closed recess; and / or the second boundary region has at least the non-closed recess.

[0045] At least the closed pits in the first boundary region and at least the open pits in the second boundary region can be used individually or in combination to improve the light trapping effect of the back contact battery in different opening directions of the pits, thereby improving the light absorption rate and utilization rate of the back contact battery and thus improving the photoelectric conversion efficiency.

[0046] As one possible implementation, one or both of the first boundary region and the second boundary region have the closed recess and the non-closed recess.

[0047] At least the closed and unclosed pits in the first boundary region and at least the closed and unclosed pits in the second boundary region can be used individually or in combination to improve the light trapping effect of the back contact battery in different opening directions of the pits, thereby improving the light absorption rate and utilization rate of the back contact battery and thus improving the photoelectric conversion efficiency.

[0048] As one possible implementation, the number of closed pits in the first boundary region is greater than the number of closed pits in the second boundary region; and / or the number of open pits in the second boundary region is greater than the number of open pits in the first boundary region.

[0049] By increasing the number of closed pits in the first boundary region to be greater than the number of closed pits in the second boundary region, and / or increasing the number of open pits in the second boundary region to be greater than the number of open pits in the first boundary region, for example, when the first region is a P region and the second region is an N region, the light trapping effect of the back contact battery can be improved, the light absorption rate and utilization rate of the back contact battery can be increased, thereby improving the photoelectric conversion efficiency.

[0050] As one possible implementation, at least part of the recess has an extended brim of a corresponding doped semiconductor layer above it, and / or at least part of the recess has an exposed portion near the top that is not covered by the corresponding doped semiconductor layer.

[0051] The brim can reflect light reaching it to the recess below, the recess in another boundary area, or the semiconductor substrate to increase light absorption and utilization. The exposed part can directly increase the light absorption and utilization of the semiconductor substrate. By using different combinations of the brim, exposed part, and recess, the light trapping effect of the back contact battery can be improved, the light absorption and utilization of the back contact battery can be increased, thereby improving the photoelectric conversion efficiency.

[0052] As one possible implementation, at least a portion of the pit in the first boundary region has an extended brim of a first doped semiconductor layer above it, and / or at least a portion of the pit in the second boundary region has an exposed portion near the top that is not covered by a second doped semiconductor layer.

[0053] The brim of the first boundary region can reflect the light reaching it to the recess below, the recess of the second boundary region, or the semiconductor substrate to increase the light absorption rate and utilization rate. The exposed part of the second boundary region can directly increase the light absorption rate and utilization rate of the semiconductor substrate. By using different combinations of the brim, the exposed part, and the recess, the light trapping effect of the back contact battery can be improved, the light absorption rate and utilization rate of the back contact battery can be increased, thereby improving the photoelectric conversion efficiency.

[0054] As one possible implementation, the thickness of the semiconductor substrate in the first region is greater than the thickness of the semiconductor substrate in the second region.

[0055] Due to the thickness difference between the semiconductor substrates in the first and second regions, light reaching the pits in the first or second boundary regions may be reflected to the pits or semiconductor substrates in the other boundary region, rather than being directly reflected away from the gap. This can improve the light trapping effect of the back contact battery, increase the light absorption rate and utilization rate of the back contact battery, and thus improve the photoelectric conversion efficiency.

[0056] As one possible implementation, the first doped semiconductor layer has an extension, and / or the second doped semiconductor layer has an extension, at least one of the first doped semiconductor layer and the second doped semiconductor layer overlaps with another doped semiconductor layer of the first doped semiconductor layer and the second doped semiconductor layer through its extension, the first boundary region further includes a first position where the spacing region is adjacent to the extension, or the second boundary region further includes a second position where the spacing region is adjacent to the extension.

[0057] By locally electrically connecting the first and second doped semiconductors with opposite conductivity types through the extension (also known as electrical connection), the risk of hot spots on the back contact battery can be reduced to a certain extent while having little impact on the working efficiency of the back contact battery in the positive voltage region. This can achieve the effect of preventing hot spots and improve the burn-out resistance of the back contact battery.

[0058] As one possible implementation, the total number of closed recesses at at least one corner of the first position or the second position is not less than the total number of non-closed recesses at the at least one corner.

[0059] While achieving the effect of preventing hot spots, by setting an appropriate number of closed or open pits at the first or second position, the light trapping effect of the back contact battery can also be improved, the light absorption rate and utilization rate of the back contact battery can be increased, thereby improving the photoelectric conversion efficiency.

[0060] As one possible implementation, the first boundary region includes a first sub-boundary region extending 50 μm from the edge of the first region away from the interval region toward the first region, and the second boundary region includes a second sub-boundary region extending 50 μm from the edge of the second region away from the interval region toward the second region, and the first sub-boundary region and / or the second sub-boundary region have one or more of the pits.

[0061] Since the location of the pits in the first boundary region, the second boundary region, and the corresponding boundary regions is not limited to the sidewalls of the semiconductor substrate, the range of the pits is expanded, which can improve the light trapping effect of the back contact battery, improve the light absorption rate and utilization rate of the back contact battery, and thus improve the photoelectric conversion efficiency.

[0062] As one possible implementation, the sidewalls of the semiconductor substrate in the first boundary region and / or the second boundary region have a wavy, undulating structure in a direction perpendicular to the extension direction of the spacing region, and the closed recess is located at a protruding position of the undulating structure, or the non-closed recess is located at a recessed position of the undulating structure.

[0063] Different combinations of undulating structures and pits on the sidewalls of a semiconductor substrate can further improve the light trapping effect of the sidewalls, enhance the light absorption and utilization rate of the back contact cell, and thus improve the photoelectric conversion efficiency.

[0064] As one possible implementation, in the first sub-boundary region and / or the second sub-boundary region, the pits in the first sub-boundary region and / or the second sub-boundary region that are closer to the interval region have a larger diameter than the pits in the first sub-boundary region and the second sub-boundary region that are farther away from the interval region.

[0065] By making the pits at different locations have different diameters, the adverse effects of the pits on the first or second region can be reduced. At the same time, the light trapping effect of the back contact battery can be improved, the light absorption rate and utilization rate of the back contact battery can be increased, thereby improving the photoelectric conversion efficiency.

[0066] As one possible implementation, the first doped semiconductor layer is a P-type doped semiconductor layer and the second doped semiconductor layer is an N-type doped semiconductor layer.

[0067] By appropriately setting the first and second regions and the conductivity type of the corresponding doped semiconductor layers, the light trapping effect of the back contact cell can be further improved compared to other conductivity types, thereby increasing the light absorption rate and utilization rate of the back contact cell and thus improving the photoelectric conversion efficiency.

[0068] As one possible implementation, the back contact battery includes an island-shaped passivation structure disposed on the side of the first doped semiconductor layer and / or the second doped semiconductor layer away from the semiconductor substrate, and / or the island-shaped passivation structure is disposed between the first doped semiconductor layer and / or the second doped semiconductor layer and the semiconductor substrate.

[0069] When the back contact cell is in operation, the first and second doped semiconductor layers can effectively shunt and collect charge carriers, which is beneficial for the formation of photocurrent. The island-shaped passivation structure set in the back contact cell has two functions: firstly, it can passivate the surface of the region where the island-shaped passivation structure is formed, reducing the number of defects on the surface of the region and reducing the carrier recombination rate; secondly, it can change the transmission path of incident light (such as increasing the reflection path of incident light), which is conducive to more incident light being refracted into the cell, increasing the incident light absorption ratio, and improving the bifaciality of the back contact cell. Taking the island-shaped passivation structure disposed on the side of the first doped semiconductor layer away from the semiconductor substrate as an example: The island-shaped passivation structure has a passivation function and can strengthen the passivation of the surface of the area where the island-shaped passivation structure is formed; In addition, the island-shaped passivation structure is not part of the first doped semiconductor layer. It is an additional passivation structure disposed on the side of the first doped semiconductor layer away from the semiconductor substrate and has an island-shaped shape. There may be a certain height difference between the island-shaped passivation structure and the side of the first doped semiconductor layer away from the semiconductor substrate, or there may be a difference in material between the island-shaped passivation structure and the first doped semiconductor layer. This allows the island-shaped passivation structure to reflect or refract incident light on the first side of the back contact battery, change the transmission path of the incident light (such as increasing the reflection path of the incident light), which is beneficial for more incident light to be refracted into the battery, improve the incident light absorption ratio, and improve the bifaciality of the back contact battery.

[0070] Furthermore, the beneficial effects of island-shaped passivation structures disposed on the side of the second doped semiconductor layer away from the semiconductor substrate, and between the first and / or second doped semiconductor layers and the semiconductor substrate, are based on the same principle as those of island-shaped passivation structures disposed on the side of the first doped semiconductor layer away from the semiconductor substrate, and will not be repeated here. It should be noted that when the island-shaped passivation structure is disposed on the side of the second doped semiconductor layer away from the semiconductor substrate, the island-shaped passivation structure is not part of the second doped semiconductor layer; it is an additional passivation structure disposed outside the second doped semiconductor layer. When the island-shaped passivation structure is disposed between the first doped semiconductor layer and the semiconductor substrate, the island-shaped passivation structure belongs neither to the first doped semiconductor layer nor to the semiconductor substrate; it is an additional passivation structure disposed outside the first doped semiconductor layer and the semiconductor substrate. When the island-shaped passivation structure is disposed between the second doped semiconductor layer and the semiconductor substrate, the island-shaped passivation structure belongs neither to the second doped semiconductor layer nor to the semiconductor substrate; it is an additional passivation structure disposed outside the second doped semiconductor layer and the semiconductor substrate.

[0071] As one possible implementation, at least one island-shaped passivation structure includes a plurality of non-adjacent and clustered passivation portions; and / or, different regions of at least one island-shaped passivation structure are continuously distributed, and the surface of the island-shaped passivation structure has an undulating morphology.

[0072] When an island-like passivation structure comprises multiple non-adjacent, aggregated passivation portions, it is beneficial to increase the specific surface area of ​​a single island-like passivation structure, increase the light absorption area of ​​a single island-like passivation structure, enhance the light-trapping effect of the island-like passivation structure, and further improve the incident light absorption ratio and the bifaciality of the back contact battery. The application principle of the beneficial effects when at least one island-like passivation structure has continuously distributed different regions and its surface has an undulating morphology can refer to the application principle of the beneficial effects of an island-like passivation structure comprising multiple non-adjacent, aggregated passivation portions described above. Secondly, another example of the morphology of the island-like passivation structure can be provided, improving the applicability of the back contact battery provided in this application under different application scenarios and reducing the manufacturing difficulty of the back contact battery. It should be noted that the back contact battery provided in this application can simultaneously contain island-like passivation structures comprising multiple non-adjacent, aggregated passivation portions, and island-like passivation structures with continuously distributed different regions and an undulating surface morphology.

[0073] As one possible implementation, the edges of the island-shaped passivation structure are irregularly shaped. This allows the island-shaped passivation structure to have side surfaces arranged in different directions, enabling the reflection or refraction of light incident from different directions. This facilitates the refraction of more incident light into the battery, further improving the incident light absorption ratio and the bifaciality of the back-contact battery. It should be noted that when the island-shaped passivation structure comprises multiple non-adjacent, clustered passivation portions, the edge of the island-shaped passivation structure refers to the edge of the area occupied by the collectively distributed, non-adjacent, clustered passivation portions. When different regions of the island-shaped passivation structure are continuously distributed, the edge of the island-shaped passivation structure refers to the edge enclosed by the continuously distributed different regions.

[0074] As one possible implementation, at least some of the island-shaped passivation structures are regularly distributed. The distribution pattern can be set according to the interaction characteristics between the incident light and the island-shaped passivation structures, allowing for the regular reflection or refraction of incident light from the first side of the back contact battery. This, combined with the irregular light-trapping effect of the island-shaped passivation structures themselves, maximizes the utilization of the incident light and further improves the light-trapping effect of the island-shaped passivation structures. Alternatively, the presence of island-shaped passivation structures between the first and / or second doped semiconductor layers and the semiconductor substrate results in a higher light-trapping effect on the side of the first and / or second doped semiconductor layers facing away from the semiconductor substrate, reducing light blocking effects and further improving the incident light absorption ratio and the bifaciality of the back contact battery. In practical applications, the regular distribution of which island-shaped passivation structures in the back contact battery is determined based on the light-trapping requirements of different areas on the back side of the battery; no specific limitations are made here. It can be that the different island-shaped passivation structures disposed on the side of the first doped semiconductor layer and / or the second doped semiconductor layer away from the semiconductor substrate are regularly distributed, or it can be that the different island-shaped passivation structures disposed between the first doped semiconductor layer and / or the second doped semiconductor layer and the semiconductor substrate are regularly distributed, or it can be that all the island-shaped passivation structures included in the back contact battery are regularly distributed.

[0075] As one possible implementation, the spacing between two adjacent island passivation structures is greater than or equal to 40 μm and less than or equal to 300 μm.

[0076] The spacing between two adjacent island passivation structures is set within the aforementioned range. This prevents excessive density of island passivation structures on the semiconductor substrate due to a small spacing, which could negatively impact the formation quality of the first and / or second doped semiconductor layers on the island passivation structures. Alternatively, when the island passivation structure includes a doped semiconductor passivation portion, and the doped semiconductor passivation portion has an opposite conductivity type to its adjacent first or second doped semiconductor layer, this prevents a high risk of leakage between the island passivation structure and the first or second doped semiconductor layer due to a small spacing. By controlling the spacing between two adjacent island passivation structures, the density of the island passivation structures is controlled, ensuring that the carrier recombination rate remains within a controllable range. Furthermore, this spacing also prevents poor light trapping on the first side of the back contact battery due to a large spacing, which helps to achieve a higher incident light absorption ratio on the first side, further improving the bifaciality of the back contact battery. It should be noted that the spacing between two adjacent island passivation structures refers to the minimum distance between the edges of the two adjacent island passivation structures.

[0077] As one possible implementation, both the first doped semiconductor layer and the second doped semiconductor layer include strip-shaped doped regions; the strip-shaped doped regions in the first doped semiconductor layer and the strip-shaped doped regions in the second doped semiconductor layer extend along a first direction and are alternately distributed along a second direction; the first direction is different from the second direction; the spacing between two adjacent island passivation structures along the first direction is smaller than the spacing between two adjacent island passivation structures along the second direction.

[0078] It is understandable that the length of the strip-shaped doped region is greater than its width. The light-trapping requirement along the length direction (i.e., the first direction) of the strip-shaped doped region is greater than the light-trapping requirement along the width direction (i.e., the second direction). Therefore, the spacing of the island passivation structures along the first direction and the second direction is different, which can satisfy the different light-trapping requirements along the first direction and the second direction respectively. This makes the adjacent island passivation structures along the first direction have a higher light-trapping effect, further improving the bifaciality of the back contact cell.

[0079] As one possible implementation, at least one island passivation structure includes a doped semiconductor passivation portion; and / or, at least one island passivation structure includes an interface passivation portion; and / or, at least one island passivation structure includes a doped semiconductor passivation portion and a doped silicon glass portion disposed on the side of the doped semiconductor passivation portion away from the semiconductor substrate.

[0080] Island-shaped passivation structures can be formed from at least three types of passivation components that offer good performance and are compatible with battery manufacturing processes: doped semiconductor passivation portions, interface passivation portions, and doped silicon glass portions. This not only provides excellent passivation performance but also improves the yield of back contact batteries. Different materials exhibit varying properties in light absorption, reflection, and refraction; combining different materials can alter the optical path and enhance light utilization. Furthermore, doped semiconductor passivation portions, interface passivation portions, and doped silicon glass portions are also materials used in back contact battery manufacturing. In this case, the island-shaped passivation structure can be fabricated simultaneously with the corresponding structure in the back contact battery, improving manufacturing efficiency and simplifying the back contact battery manufacturing process.

[0081] As one possible implementation, in at least one island-shaped passivation structure disposed on the side of the first doped semiconductor layer facing away from the semiconductor substrate, or in at least one island-shaped passivation structure disposed between the first doped semiconductor layer and the semiconductor substrate, the material and conductivity type of the doped semiconductor passivation portion are the same as the material and conductivity type of the second doped semiconductor layer, respectively. And / or, in at least one island-shaped passivation structure disposed on the side of the second doped semiconductor layer facing away from the semiconductor substrate, or in at least one island-shaped passivation structure disposed between the second doped semiconductor layer and the semiconductor substrate, the material and conductivity type of the doped semiconductor passivation portion are the same as the material and conductivity type of the first doped semiconductor layer, respectively.

[0082] Taking the example of an island-shaped passivation structure adjacent to the first doped semiconductor layer, where the material and conductivity type of the doped semiconductor passivation portion are the same as those of the second doped semiconductor layer, the following explanation is provided: The island-shaped passivation structure adjacent to the first doped semiconductor layer can be manufactured simultaneously with the second doped semiconductor layer, improving the manufacturing efficiency of the back contact battery and simplifying the manufacturing process. The application principle of this beneficial effect—where the material and conductivity type of the doped semiconductor passivation portion of the island-shaped passivation structure adjacent to the second doped semiconductor layer are the same as those of the first doped semiconductor layer—can be referred to the previous text and will not be repeated here.

[0083] As one possible implementation, the back contact battery further includes a first interface passivation layer disposed between the semiconductor substrate and the first doped semiconductor layer, and a second interface passivation layer disposed between the semiconductor substrate and the second doped semiconductor layer. Specifically, in at least one island-shaped passivation structure disposed on the side of the first doped semiconductor layer facing away from the semiconductor substrate, or in at least one island-shaped passivation structure disposed between the first doped semiconductor layer and the semiconductor substrate, the material of the interface passivation portion is the same as the material of the second interface passivation layer; and / or, in at least one island-shaped passivation structure disposed on the side of the second doped semiconductor layer facing away from the semiconductor substrate, or in at least one island-shaped passivation structure disposed between the second doped semiconductor layer and the semiconductor substrate, the material of the interface passivation portion is the same as the material of the first interface passivation layer. The application principle of the beneficial effect in this case can refer to the application principle of the beneficial effect described above in at least one island-shaped passivation structure disposed on the side of the first doped semiconductor layer facing away from the semiconductor substrate, or in at least one island-shaped passivation structure disposed between the first doped semiconductor layer and the semiconductor substrate, where the material and conductivity type of the doped semiconductor passivation portion are the same as the material and conductivity type of the second doped semiconductor layer, respectively, and will not be repeated here.

[0084] As one possible implementation, the back contact battery further includes a first doped silicon glass layer disposed on the side of the first doped semiconductor layer facing away from the semiconductor substrate, and a second doped silicon glass layer disposed on the side of the second doped semiconductor layer facing away from the semiconductor substrate. The first doped silicon glass layer has the same conductivity type as the first doped semiconductor layer. The second doped silicon glass layer has the same conductivity type as the second doped semiconductor layer. Specifically, in at least one island-shaped passivation structure disposed on the side of the first doped semiconductor layer facing away from the semiconductor substrate, or in at least one island-shaped passivation structure disposed between the first doped semiconductor layer and the semiconductor substrate, the material and conductivity type of the doped silicon glass portion are the same as the material of the second doped silicon glass layer; and / or, in at least one island-shaped passivation structure disposed on the side of the second doped semiconductor layer facing away from the semiconductor substrate, or in at least one island-shaped passivation structure disposed between the second doped semiconductor layer and the semiconductor substrate, the material and conductivity type of the doped silicon glass portion are the same as the material and conductivity type of the first doped silicon glass layer. The application principle of the beneficial effect in this case can refer to the application principle of the beneficial effect described above in at least one island passivation structure disposed on the side of the first doped semiconductor layer away from the semiconductor substrate, or in at least one island passivation structure disposed between the first doped semiconductor layer and the semiconductor substrate, where the material and conductivity type of the doped semiconductor passivation portion are the same as the material and conductivity type of the second doped semiconductor layer, and will not be repeated here.

[0085] As one possible implementation, the island-shaped passivation structure disposed on the first region is located on the side of the first doped semiconductor layer facing away from the semiconductor substrate, and the island-shaped passivation structure disposed on the second region is disposed between the second doped semiconductor layer and the semiconductor substrate. Alternatively, the island-shaped passivation structure disposed on the first region is located between the first doped semiconductor layer and the semiconductor substrate, and the island-shaped passivation structure disposed on the second region is located on the side of the second doped semiconductor layer facing away from the semiconductor substrate.

[0086] The first and second doped semiconductor layers of the back contact battery are formed on local areas of the first surface in different operational steps. Furthermore, the patterned first and second doped semiconductor layers are obtained by selectively etching the entire layer of doped semiconductors. Therefore, taking as an example an island-shaped passivation structure located on the side of the first doped semiconductor layer away from the semiconductor substrate in the first region, and an island-shaped passivation structure located between the second doped semiconductor layer and the semiconductor substrate in the second region: In this case, the first doped semiconductor layer can be manufactured first, and the island-shaped passivation structure located between the second doped semiconductor layer and the semiconductor substrate can be manufactured based on the portion of the doped semiconductor material of the first doped semiconductor layer located in the second region. Simultaneously, after forming the first doped semiconductor layer and the island-shaped passivation structure in the second region, the second doped semiconductor layer can be manufactured, and the island-shaped passivation structure located on the side of the first doped semiconductor layer away from the semiconductor substrate can be manufactured based on the portion of the doped semiconductor material of the second doped semiconductor layer located in the first region. This improves the manufacturing efficiency of the back contact battery and simplifies the manufacturing process.

[0087] As one possible implementation, the area occupied by at least one island-shaped passivation structure is greater than or equal to 1 μm. 2 and less than or equal to 100μm 2 .

[0088] Having at least one island passivation structure occupying an area within the aforementioned range helps prevent the passivation effect of the island passivation structure from being too small, and also prevents the light-trapping effect of the island passivation structure itself or the improvement it provides from being too small. This helps to achieve a higher bifaciality for the back contact battery. Furthermore, it prevents the formation quality of the first doped semiconductor layer and / or the second doped semiconductor layer formed on the island passivation structure from being too large. Alternatively, when the island passivation structure includes a doped semiconductor passivation portion, and the doped semiconductor passivation portion has an opposite conductivity type to its adjacent first or second doped semiconductor layer, it can prevent an increase in the risk of battery leakage due to an excessively large island passivation structure, reduce the carrier recombination rate, and improve the operating performance of the back contact battery.

[0089] As one possible implementation, the groove structure has a first sidewall near the first region and a third sidewall near the second region. The second doped semiconductor layer has a second boundary near the spacing region. An island-shaped passivation structure is disposed on the semiconductor substrate. At least one island-shaped passivation structure is at least partially located between the first boundary and the first sidewall; and / or, at least one island-shaped passivation structure is at least partially located between the second boundary and the third sidewall.

[0090] When the back-contact battery is in operation, the first and second doped semiconductor layers can effectively shunt and collect charge carriers, facilitating the formation of photocurrent. The island-shaped passivation structure has a passivation function, passivating the surface of the region on the semiconductor substrate where the island-shaped passivation structure is formed, reducing the number of defects on the surface and lowering the carrier recombination rate. Furthermore, the island-shaped passivation structure can alter the transmission path of incident light (e.g., increasing the reflection path of incident light), allowing more incident light to be refracted into the battery, increasing the incident light absorption ratio, and improving the bifaciality of the back-contact battery. The island-shaped passivation structure is not part of the semiconductor substrate; it is an additional passivation structure formed on the semiconductor substrate in an island shape. Taking at least one island-shaped passivation structure located at least partially between the first boundary and the first sidewall as an example: the island-shaped passivation structure is away from the surface of the semiconductor substrate, and there may be a certain height difference between it and the local surface of the semiconductor substrate located between the first boundary and the first sidewall. Alternatively, the island-shaped passivation structure and the semiconductor substrate may have material differences, which allows the island-shaped passivation structure to reflect or refract incident light on one side of the first surface of the back contact battery, changing the transmission path of the incident light (such as increasing the reflection path of the incident light), which is beneficial for more incident light to be refracted into the battery, increasing the incident light absorption ratio, and increasing the bifaciality of the back contact battery.

[0091] As one possible implementation, an island-shaped passivation structure is provided between at least one first sub-boundary and the first sidewall. And / or, the second boundary has a third sub-boundary located within the second region and spaced apart from the third sidewall along the width direction of the interval region, and an island-shaped passivation structure is provided between at least one third sub-boundary and the third sidewall.

[0092] Taking a first sub-boundary located within a first region and spaced apart from the first sidewall of the groove structure along the width direction of the interval region as an example: When the first boundary also includes the first sub-boundary, along the width direction of the interval region, there is not only an interval region between the portion of the first doped semiconductor layer corresponding to the first sub-boundary and the second doped semiconductor layer, but also, because the first sub-boundary is spaced apart from the first sidewall of the groove structure, in other words, the portion of the first doped semiconductor layer corresponding to the first sub-boundary is recessed into the first region relative to the first sidewall of the groove structure. Therefore, the distance between the first doped semiconductor layer and the second doped semiconductor layer can be increased, further reducing the risk of leakage between them. In addition, the island passivation structure is disposed on the portion of the first region that is not directly covered by the first doped semiconductor layer. This can reduce the impact of the island passivation structure on the quality and precision requirements of forming conductive electrodes on the first doped semiconductor layer. At the same time, the island passivation structure can passivate the local surfaces in the first region of the semiconductor substrate that have a large number of surface defects and high passivation requirements, which is beneficial to reducing the carrier recombination rate of the local surface and improving the conversion efficiency of the back contact battery. The second boundary has a third sub-boundary located within the second region and distributed at intervals with the third sidewall along the width direction of the interval region. At least one third sub-boundary and the third sidewall are provided with an island-shaped passivation structure. The function and effect of the island-shaped passivation structure are the same as those of the island-shaped passivation structure of the first sub-boundary, and will not be repeated here.

[0093] As one possible implementation, the portion of the first region near the first sidewall and not directly covered by the first doped semiconductor layer is a plateau region, and / or, the portion of the second region near the third sidewall and not directly covered by the second doped semiconductor layer is a plateau region. The plateau region includes a plateau surface that is substantially parallel to the first surface. At least one island-shaped passivation structure is disposed on the plateau surface included in the plateau region.

[0094] The platform region includes a platform surface that is approximately parallel to the first surface. At this time, the surface of the portion of the first region of the semiconductor substrate that is not directly covered by the first doped semiconductor layer and / or the portion of the second region that is not directly covered by the second doped semiconductor layer (i.e., the platform region) is relatively flat. On the one hand, as a transition region between the first region or the second region and the spacer region, it can effectively reduce the risk of leakage current. Moreover, by setting island-shaped passivation structures in at least a portion of the platform region, the surface of the platform region with island-shaped passivation structures can be passivated, reducing the number of defects on the surface of the region and reducing the carrier recombination rate. On the other hand, the platform surface of the platform region increases the light absorption area, promotes the diversification of light absorption surface morphology, and by setting island-shaped passivation structures in at least a portion of the platform region, the island-shaped passivation structures enhance light absorption, thereby comprehensively improving the light utilization rate of the back contact battery.

[0095] As one possible implementation, along the width direction of the interval region, the width of the platform surface included in at least one platform region is less than or equal to 1 μm.

[0096] Taking the portion of the first region near the first sidewall that is not directly covered by the first doped semiconductor layer as an example, it can be understood that the wider the platform surface included in the platform region, the larger the distance between the portion of the first doped semiconductor layer corresponding to the platform region and the spacing region, and the smaller the area ratio of the first doped semiconductor layer in the first region. Therefore, when the width of the platform surface included in at least one platform region is within the above range, it is beneficial to improve the bifaciality and passivation effect of the back contact cell through the island-like passivation structure, while allowing the first doped semiconductor layer to have a larger area ratio in the first region. This is beneficial for the first doped semiconductor layer to have a higher field passivation effect and carrier collection capability, and thus for the back contact cell to have a higher conversion efficiency. The portion of the second region near the third sidewall that is not directly covered by the second doped semiconductor layer is a platform region, and the effect of at least one platform region having a platform surface width of less than or equal to 1 μm is the same as the effect of the platform region in the first region having a platform surface width of less than or equal to 1 μm, and will not be repeated here.

[0097] As one possible implementation, if the first region has a platform area, at least one platform area further includes a second sidewall that is remote from the first sidewall and continuous with the platform surface. And / or, if the second region has a platform area, at least one platform area further includes a second sidewall that is remote from the third sidewall and continuous with the platform surface. The second sidewall is either perpendicular to the platform surface or inclined relative to the platform surface.

[0098] Taking a first region having a plateau region, and the plateau region also including a second sidewall, as an example: the plateau region also includes a second sidewall continuous with the plateau surface, indicating that along the direction from the first surface to the second surface, the plateau surface is recessed into the semiconductor substrate relative to the surface of the region in the first region directly covered by the first doped semiconductor layer. This can reduce the height difference between the bottom surface of the groove structure and the surface of the region with greater height in the first region, which is beneficial to the formation quality and coverage of the surface passivation layer at the junction of the first region and the spacer region, reduces the carrier recombination rate at the junction of the first region and the spacer region, enhances the diversity of light absorption surface morphology, and improves the light utilization rate of the back contact cell. The application principle of the beneficial effects of the second region having a plateau region and the plateau region also including a second sidewall can be referred to the application principle of the beneficial effects of the first region having a plateau region and the plateau region also including a second sidewall mentioned above, and will not be repeated here.

[0099] As one possible implementation, at least one island-shaped passivation structure extends from the platform surface to at least a portion of the second sidewall. In this case, it is advantageous to increase the passivation contact area of ​​the island-shaped passivation structure on one side of the first surface, thereby improving the passivation effect of the island-shaped passivation structure. Furthermore, it is also possible to increase the surface area of ​​the island-shaped passivation structure on the side facing away from the semiconductor substrate, which is beneficial for enhancing the light-trapping effect of the first surface on which the island-shaped passivation structure is provided.

[0100] As one possible implementation, the height of the second sidewall is greater than or equal to 0.05 μm and less than or equal to 8 μm along the thickness direction of the semiconductor substrate.

[0101] The height of the second sidewall, within the aforementioned range, helps prevent a large height variation between the bottom surface of the groove structure and the surface of the area with greater height in the first region (and / or the second region) due to a smaller height of the second sidewall. This further enhances the passivation effect of the surface passivation layer at the junction of the first region and the spacer region, and / or at the junction of the second region and the spacer region. Additionally, it prevents a large etching amount in the semiconductor substrate corresponding to the platform region due to a larger height of the third sidewall. This allows for a greater light absorption depth in the semiconductor substrate corresponding to the platform region, improving the light utilization rate of the semiconductor substrate and further enhancing the conversion efficiency of the back contact cell.

[0102] As one possible implementation, when the first region has a plateau region, a portion of the first boundary also extends above the platform surface included in the plateau region, and the first doped semiconductor layer and the island-shaped passivation structure are distributed at intervals. And / or, when the second region has a plateau region, a portion of the second boundary also extends above the platform surface included in the plateau region, and the second doped semiconductor layer and the island-shaped passivation structure are distributed at intervals.

[0103] Taking a first region with a platform area, where a portion of the first boundary extends above the platform surface included in the platform area, as an example: Although the distance between this portion of the first boundary and the second doped semiconductor layer is relatively small, the portion of the first doped semiconductor layer corresponding to this portion of the first boundary can reflect some of the light emitted from the platform surface and / or reflected from the outer surface of the island passivation structure, allowing some light to re-enter the semiconductor substrate, further improving the light utilization rate of the back contact battery. Furthermore, the alternating distribution of the first doped semiconductor layer and the island passivation structure facilitates light transmission between the outer surface of the island passivation structure and the inner surface of the portion of the first doped semiconductor layer extending above the platform surface. This alters the transmission path of the incident light, allowing more incident light to refract into the battery, increasing the incident light absorption ratio, and further improving the bifaciality of the back contact battery. Moreover, when the island passivation structure includes a doped semiconductor passivation portion with a conductivity type opposite to that of the first doped semiconductor layer, the alternating distribution of the first doped semiconductor layer and the island passivation structure also helps reduce the leakage risk between them, contributing to a higher conversion efficiency for the back contact battery. The application principle of the beneficial effect of the second region having a platform area and part of the second boundary extending above the platform surface included in the platform area can be referred to the application principle of the beneficial effect of the first region having a platform area and part of the first boundary extending above the platform surface included in the platform area, as described above, and will not be repeated here.

[0104] As one possible implementation, where a portion of the first boundary extends above the platform surface included in the platform region, the spacing between the first doped semiconductor layer and the island passivation structure along the thickness direction of the semiconductor substrate is greater than or equal to 1 nm and less than or equal to 500 nm. And / or, where a portion of the second boundary extends above the platform surface included in the platform region, the spacing between the second doped semiconductor layer and the island passivation structure along the thickness direction of the semiconductor substrate is greater than or equal to 1 nm and less than or equal to 500 nm.

[0105] Taking the spacing between the first doped semiconductor layer and the island passivation structure within the aforementioned range as an example, this facilitates effective light transmission between the outer surface of the island passivation structure and the inner surface of the portion of the first doped semiconductor layer extending above the platform surface. This allows these two parts to effectively coordinate in changing the transmission path of the incident light, further improving the absorption ratio of the incident light. Furthermore, all other factors being equal, when the spacing between the first doped semiconductor layer and the island passivation structure increases, the etching amount of the portion of the semiconductor substrate corresponding to the platform region is larger. Therefore, the spacing between the first doped semiconductor layer and the island passivation structure within the aforementioned range also allows the portion of the semiconductor substrate corresponding to the platform region to have a larger absorption depth, improving the utilization rate of light by the semiconductor substrate. The application principle of the beneficial effects of the spacing between the second doped semiconductor layer and the island passivation structure within the aforementioned range can be referred to the application principle of the beneficial effects of the spacing between the first doped semiconductor layer and the island passivation structure within the aforementioned range described above, and will not be repeated here.

[0106] As one possible implementation, if a portion of the first boundary also extends above the platform surface included in the platform region, the extension width of the first boundary relative to the second sidewall is less than or equal to 1 μm along the width direction of the interval region. And / or, if a portion of the second boundary also extends above the platform surface included in the platform region, the extension width of the second boundary relative to the second sidewall is less than or equal to 1 μm along the width direction of the interval region.

[0107] Taking an example where a portion of the first boundary extends above the platform surface included in the platform region, and the extension width is within the aforementioned range, this can prevent the extended portion of the first doped semiconductor layer from having a weak light reflection effect due to an excessively small extension width, thus facilitating a further improvement in the bifaciality of the back contact battery. The application principle of the beneficial effect of a portion of the second boundary extending above the platform surface included in the platform region, and the extension width being within the aforementioned range, can be referenced from the application principle of the beneficial effect of a portion of the first boundary extending above the platform surface included in the platform region, and the extension width being within the aforementioned range, as described above, and will not be repeated here.

[0108] As one possible implementation, at least one island-shaped passivation structure occupies more than 50% of the area within the plateau region. This allows the island-shaped passivation structure to have a larger area within the plateau region, enhancing its ability to adjust the light transmission path, allowing more incident light to be refracted into the battery, increasing the incident light absorption ratio, and further improving the bifaciality of the back-contact battery.

[0109] As one possible implementation, the first boundary has a first alternating concave-convex structure, and the boundaries of at least some of the concave portions in the first alternating concave-convex structure are first sub-boundaries. And / or, the second boundary has a second alternating concave-convex structure, and the boundaries of at least some of the concave portions in the second alternating concave-convex structure are third sub-boundaries.

[0110] Taking the example of a first boundary having a first alternating concave-convex structure, where the boundary of at least some of the recesses in the first alternating concave-convex structure is a first sub-boundary: the first sub-boundary of the first doped semiconductor layer disposed in the first region is opposite to at least some of the recesses in the first alternating concave-convex structure. This is beneficial because it makes the alternating concave-convex structure of the first boundary more compatible with the fluctuation changes of the portion of the first doped semiconductor layer that is recessed into the first region. This reduces the need for increased etching of the semiconductor substrate to achieve the first boundary of the first doped semiconductor layer, which is beneficial for increasing the light absorption area of ​​the semiconductor substrate and improving the conversion efficiency of the back contact cell. The application principle of the beneficial effect of a second boundary having a second alternating concave-convex structure, where the boundary of at least some of the recesses in the second alternating concave-convex structure is a third sub-boundary, can be referred to the application principle of the beneficial effect of a first boundary having a first alternating concave-convex structure, where the boundary of at least some of the recesses in the first alternating concave-convex structure is a first sub-boundary, as described above, and will not be repeated here.

[0111] As one possible implementation, at least a portion of the protrusions in the first and / or second alternating concave-convex structures extend over the groove structure along the width direction of the interval region.

[0112] The first doped semiconductor layer and / or the second doped semiconductor layer are partially suspended above the groove structure corresponding to at least a portion of the protrusion, which is beneficial for reflecting a portion of the light emitted from the first surface of the semiconductor substrate back to the semiconductor substrate and being reused by the semiconductor substrate, thereby improving the light utilization rate of the back contact battery.

[0113] As one possible implementation, at least one convex portion in the first alternating concave-convex structure extends over the groove structure with a width less than or equal to 1 μm relative to the first sidewall. And / or, at least one convex portion in the second alternating concave-convex structure extends over the groove structure with a width less than or equal to 1 μm relative to the third sidewall. The application principle of the beneficial effect in this case can be referenced to the application principle of the beneficial effect described above where a portion of the first boundary also extends above the platform surface included in the platform region, and the width of the first boundary extending over the second sidewall is less than or equal to 1 μm; it will not be repeated here.

[0114] As one possible implementation, along the extension direction of the interval region, the first sidewall has a third alternating concave-convex structure, in which at least some of the protrusions in the third alternating concave-convex structure are staggered with adjacent protrusions in the first alternating concave-convex structure. And / or, along the extension direction of the interval region, the third sidewall has a fourth alternating concave-convex structure, in which at least some of the protrusions in the fourth alternating concave-convex structure are staggered with adjacent protrusions in the second alternating concave-convex structure.

[0115] Taking the example of at least some convex portions in the third alternating concave-convex structure being staggered with adjacent convex portions in the first alternating concave-convex structure, it is advantageous to set island-shaped passivation structures on the portions where the convex or concave portions of the third alternating concave-convex structure intersect with the concave or convex portions of the first alternating concave-convex structure. This increases the bifaciality of the battery while allowing the first doped semiconductor layer to have a larger area ratio in the first region, thereby enhancing the field passivation effect and carrier collection capability of the first doped semiconductor layer. The application principle of the beneficial effect of at least some convex portions in the third alternating concave-convex structure being staggered with adjacent convex portions in the second alternating concave-convex structure can be referred to the application principle of the beneficial effect of at least some convex portions in the third alternating concave-convex structure being staggered with adjacent convex portions in the first alternating concave-convex structure described above, and will not be repeated here.

[0116] Secondly, this application provides a photovoltaic module, including a cell string and an encapsulation layer. The cell string is formed by the electrical connection of multiple back-contact cells as provided in the first aspect and its various implementations; the encapsulation layer covers the surface of the cell string.

[0117] The beneficial effects of the second aspect and its various implementation schemes in this application can be found in the analysis of the beneficial effects of the first aspect and its various implementation schemes, and will not be repeated here. Attached Figure Description

[0118] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of the application and, together with the description, serve to explain the application and do not constitute an undue limitation thereof. In the drawings, unless otherwise stated, the same reference numerals refer to the same parts in all views. In the drawings:

[0119] Figure 1 is a longitudinal cross-sectional view of the first structure of the back contact battery provided in the embodiment of this application;

[0120] Figure 2 is a longitudinal cross-sectional view of a second structure of the back contact battery provided in an embodiment of this application.

[0121] Figure 3 is a partial SEM image of the back contact battery provided in the embodiment of this application at the first boundary of the first doped semiconductor layer near the first region (the direction of the bold arrow in the figure is the extension direction of the spacer region);

[0122] Figure 4 shows (1), (2) and (3) as top view of the back contact battery in a partial spacer area provided in the embodiment of this application (the dashed lines in the figure show the shape of the first sidewall, and the bold arrows in the figure indicate the direction of the extension of the spacer area).

[0123] Figure 5 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0124] Figure 6 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0125] Figure 7 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0126] Figure 8 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0127] Figure 9 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0128] Figure 10 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0129] Figure 11 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0130] Figure 12 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0131] Figure 13 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0132] Figure 14 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application.

[0133] Figure 15 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0134] Figures 16A-16C are top views of a partial structure of a back contact battery including an extension provided in an embodiment of this application; Figure 16D is a SEM image of a partial structure of a back contact battery including an extension provided in an embodiment of this application.

[0135] Figure 17 is a SEM image of a portion of the back contact battery structure provided in an embodiment of this application;

[0136] Figure 18 is a SEM image of a portion of the back contact battery structure provided in an embodiment of this application;

[0137] Figure 19 is a partial SEB diagram of the back contact battery provided in an embodiment of this application;

[0138] Figure 20 is a SEM image of a portion of the back contact battery structure provided in an embodiment of this application;

[0139] Figures 21A and 21B are longitudinal cross-sectional schematic diagrams of a portion of the back contact battery structure including the brim, provided in an embodiment of this application.

[0140] Figure 22 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0141] Figure 23 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0142] Figure 24 is a partial structural diagram of one side of the first surface of the back contact battery provided in the embodiment of this application;

[0143] Figure 25 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0144] Figure 26 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0145] Figure 27 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0146] Figure 28 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0147] Figure 29 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0148] Figure 30 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0149] Figure 31 is a partial structural diagram of one side of the first surface of the back contact battery provided in the embodiment of this application.

[0150] Figure 32 is a schematic diagram of the distribution relationship between the first doped semiconductor layer and the second doped semiconductor layer in the back contact battery provided in the embodiment of this application;

[0151] Figure 33 is a schematic diagram of the distribution relationship between the first doped semiconductor layer and the second doped semiconductor layer in the back contact battery provided in the embodiment of this application;

[0152] Figure 34 is a schematic diagram showing the distribution relationship between the first doped semiconductor layer and the second doped semiconductor layer in the back contact battery provided in the embodiment of this application.

[0153] Figure 35 is a longitudinal cross-sectional schematic diagram of a structure of a back contact battery provided in an embodiment of this application;

[0154] Figure 36 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0155] Figure 37 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0156] Figure 38 is a SEM image of a portion of the first boundary in the back contact battery provided in an embodiment of this application;

[0157] Figure 39 is a second SEM image of a portion of the first boundary in the back contact battery provided in the embodiment of this application;

[0158] Figure 40 is a SEM image of a portion of the second boundary in the back contact battery provided in an embodiment of this application;

[0159] Figure 41 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0160] Figure 42 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0161] Figure 43 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0162] Figure 44 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application.

[0163] Figure 45 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application.

[0164] Figure 46 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application.

[0165] Figure 47 is a longitudinal cross-sectional view of a structure of a back contact battery provided in an embodiment of this application;

[0166] Reference numerals: 11 Semiconductor substrate, 12 First doped semiconductor layer, 13 Second doped semiconductor layer, 14 First region, 15 Second region, 16 Spacer region, 17 Groove structure, 18 First sub-boundary, 19 Second sub-boundary, 20 Recessed boundary, 21 Protruding boundary, 22 First sidewall, 23 Third sidewall, 24 Plateau region, 25 Plateau surface, 26 Second sidewall, 27 Island passivation structure, 28 First Interface passivation layer, 29 is the second interface passivation layer, 30 is the first doped silicon glass layer, 31 is the second doped silicon glass layer, 32 is the surface passivation layer, 33 is the pit, 34 is the ridge, 35 is the butt joint, 36 is the brim, 37 is the exposed part, 38 is the protruding position, 39 is the recessed position, 40 is the extension, 41 is the first boundary, 42 is the second boundary, 43 is the third sub-boundary, 44 is the dotted passivation part, 45 is the strip-shaped doped region, and 46 is the connecting doped region. Detailed Implementation

[0167] The embodiments of this application will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of this application. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0168] The accompanying drawings show various structural schematic diagrams according to embodiments of this application. These drawings are not drawn to scale, and some details have been enlarged and may have been omitted for clarity. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0169] In the context of this application, when a layer / element is referred to as being "on top of" another layer / element, the layer / element can be directly on top of the other layer / element, or there can be an intermediate layer / element between them. Furthermore, if a layer / element is "on top of" another layer / element in one orientation, then when the orientation is reversed, the layer / element can be "below" the other layer / element. To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0170] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise expressly specified. "Several" means one or more, unless otherwise expressly specified.

[0171] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0172] Implementation Plan A

[0173] A solar cell is a device that converts sunlight into electrical energy. Specifically, when a solar cell is in operation, sunlight shines on the semiconductor pn junction, forming new electron-hole pairs. Under the influence of the built-in electric field of the pn junction, photogenerated holes flow to the p-region, and photogenerated electrons flow to the n-region. When the circuit is connected, an electric current is generated. Solar cells where both the positive and negative electrodes are located on the back side of the cell are called back-contact cells. Compared to double-sided contact solar cells, the front side of a back-contact cell has no metal electrodes to block the light, resulting in higher light utilization on the light-facing side. Therefore, back-contact cells have higher short-circuit current and photoelectric conversion efficiency, making them one of the current technological directions for achieving high-efficiency crystalline silicon solar cells.

[0174] Specifically, a back-contact battery typically includes a semiconductor substrate and alternating first-doped and second-doped semiconductor layers disposed on the same surface of the semiconductor substrate. The first and second-doped semiconductor layers have opposite conductivity types to achieve carrier shunting and collection. To reduce the risk of leakage between the first and second-doped semiconductor layers, a groove structure is often provided in the gap between them to ensure that no residue remains in the gap area after the first and second-doped semiconductor layers have been patterned.

[0175] However, in actual manufacturing, due to the presence of the mask structure and the etchant used to etch the groove structure, lateral etching also occurs during the etching of the semiconductor substrate. This results in the ends of the first doped semiconductor layer near the spacer region being suspended above the groove structure. Although this suspended end is beneficial for reflecting some of the light emitted from the first surface back to the semiconductor substrate, because the suspended end is far from the substrate, it cannot directly and effectively collect the photogenerated carriers generated by the substrate. Instead, it acts as a transmission loss, affecting the fill factor. At the same time, the suspended end results in a smaller distance between the first and second doped semiconductor layers, thereby increasing the risk of leakage between the first and second doped semiconductor layers, which have opposite conductivity types.

[0176] To address the aforementioned technical problems, in a first aspect, embodiments of this application provide a back-contact battery. As shown in Figures 1 to 4, the back-contact battery includes: a semiconductor substrate 11, a first doped semiconductor layer 12, and a second doped semiconductor layer 13. The semiconductor substrate 11 includes a first surface and a second surface opposite to each other. The first surface includes alternating first regions 14 and second regions 15, and a spacer region 16 located between the first regions 14 and the second regions 15. Along the direction from the first surface to the second surface, the surface of the spacer region 16 is recessed inward relative to the surface of the first region 14 to form a groove structure 17. The first doped semiconductor layer 12 is at least partially disposed on the first region 14. The second doped semiconductor layer 13 is disposed on the second region 15. The second doped semiconductor layer 13 and the first doped semiconductor layer 12 have opposite conductivity types. Wherein, along the extending direction of the spacer region 16, the first doped semiconductor layer 12 includes a first boundary adjacent to the spacer region 16. Along the width direction of the interval region 16, the first boundary includes a first sub-boundary 18 located within the first region 14, and a second sub-boundary 19 extending from the first region 14 to above the groove structure 17 and located above the groove structure 17.

[0177] When the above technical solution is adopted, the first doped semiconductor layer and the second doped semiconductor layer can effectively shunt and collect carriers when the back contact battery is in operation, which is beneficial for the formation of photocurrent. Secondly, as shown in Figures 1 to 4 and Figure 8, the gap region 16 set between the first region 14 and the second region 15 can separate the first doped semiconductor layer 12 and the second doped semiconductor layer 13, reducing the risk of leakage between them. Furthermore, along the width direction of the gap region 16, the first boundary of the first doped semiconductor layer 12 includes a second sub-boundary 19 extending from the first region 14 to the top of the groove structure 17. At this time, the portion of the first doped semiconductor layer 12 corresponding to the second sub-boundary 19 is suspended above the groove structure 17, which is beneficial for reflecting part of the light emitted from the first surface of the semiconductor substrate 11 back to the semiconductor substrate 11 and being utilized by the semiconductor substrate 11 again, thereby improving the light utilization rate of the back contact battery. Furthermore, the first boundary of the first doped semiconductor layer 12 also includes a first sub-boundary 18 located within the first region 14 and far from the groove structure 17. In this case, the portion of the first doped semiconductor layer 12 corresponding to the first sub-boundary 18 is recessed into the first region 14 relative to the first sidewall 22 of the groove structure 17 (the first sidewall is the sidewall of the groove structure 17 closest to the first region 14; additionally, the groove structure 17 also has a third sidewall 23 close to the second region 15; the boundaries of the first sidewall 22 and / or the third sidewall 23 can be straight, curved, or polygonal, etc., and their specific morphology can be determined according to the actual manufacturing process, without specific limitations here). This increases the distance between the first doped semiconductor layer 12 and the second doped semiconductor layer 13, reducing the leakage risk between them and improving the fill factor of the solar cell. Compared with the prior art where each part of the first boundary is suspended above the groove structure 17, the back contact cell provided in this application embodiment has a lower leakage risk, a lower carrier recombination rate, and a higher fill factor. Compared to the first boundary where each part is recessed into the first region 14, the back contact battery provided in this application embodiment has a higher light utilization rate, which can improve the working performance of the back contact battery.

[0178] In practical applications, this application does not specifically limit the material and conductivity type of the semiconductor substrate. For example, the semiconductor substrate can be a silicon substrate. Alternatively, the semiconductor substrate can be any semiconductor material such as a germanium-silicon substrate, a germanium substrate, or a gallium arsenide substrate. Furthermore, the semiconductor substrate can be an N-type semiconductor substrate, a P-type semiconductor substrate, or an intrinsic semiconductor substrate.

[0179] Secondly, the semiconductor substrate includes a first surface and a second surface opposite to each other. The first surface of the semiconductor substrate corresponds to the back side of the back contact battery, and the second surface of the semiconductor substrate corresponds to the front side of the back contact battery. The distribution of the first region, the second region, and the spacer region on the first surface can be determined based on the distribution of the first doped semiconductor layer and the second doped semiconductor layer formed on the first surface. Specifically, since the first doped semiconductor layer of the back contact battery is at least partially disposed on the first region, the distribution range of the first region on the first surface can be determined based on the distribution requirements of the first doped semiconductor layer in the actual application scenario, as well as the leakage prevention requirements between the first and second doped semiconductor layers. Since the second doped semiconductor layer of the back contact battery is disposed on the second region of the first surface, the distribution range of the second region on the first surface can be determined based on the distribution requirements of the second doped semiconductor layer on the semiconductor substrate in the actual application scenario. As for the spacer region, after the distribution ranges of the first and second regions are determined, the distribution range of the spacer region on the first surface can be determined.

[0180] It is understandable that one of the first and second regions roughly corresponds to the emitter region, and the other roughly corresponds to the back field region. In terms of specific conductivity type, one of the first and second regions roughly corresponds to the P-region, and the other roughly corresponds to the N-region.

[0181] The shapes of the first and second regions can be set according to actual needs, as long as they can be applied to the back contact battery provided in this application embodiment. For example, the first and second regions can be arranged in alternating stripes or in alternating interdigitated shapes.

[0182] In terms of surface morphology, as shown in Figures 1 and 2, the second surface of the semiconductor substrate 11 can be a polished surface. Alternatively, as shown in Figure 5, the second surface of the semiconductor substrate 11 can also be a textured surface to improve the light-trapping effect of the second surface and increase the light utilization rate of the semiconductor substrate 11.

[0183] As for the morphology of the first surface of the semiconductor substrate, the first surface can be a plateau surface, which helps to improve the formation quality of the first doped semiconductor layer and the second doped semiconductor layer on the first surface and improve their field passivation effect.

[0184] Alternatively, as shown in Figure 5, the surface of the spacer region 16 included in the first side can be a textured surface to improve the light trapping effect of the spacer region 16 and increase the bifaciality of the back contact battery.

[0185] In terms of surface height, the surface of the spacer region is recessed into the semiconductor substrate relative to the surface of the first region. The depth of the groove structure within the spacer region can be set according to actual needs and is not specifically limited here.

[0186] As for the surface of the second region, it can be flush with the surface of the first region; or, as shown in FIG6, along the direction from the first surface to the second surface, the surface of the second region 15 can also be recessed into the semiconductor substrate 11 relative to the surface of the first region 14, to prevent residues remaining after the patterned first doped semiconductor layer 12 from remaining on the second region 15, thereby reducing the risk of leakage. In this case, the surface of the second region can be flush with the surface of the spacer region; or, as shown in FIG6, the surface of the second region 15 can also be higher than the bottom surface of the trench of the spacer region 16. As for the depth of the recess of the surface of the second region 15 into the semiconductor substrate 11, it can be set according to actual needs, and is not specifically limited here.

[0187] Regarding the first and second doped semiconductor layers, the embodiments of this application do not specifically limit the conductivity type of the first and second doped semiconductor layers, as long as the conductivity types of the first and second doped semiconductor layers are opposite. Specifically, the conductivity type of the first doped semiconductor layer can be N-type, and the conductivity type of the second doped semiconductor layer can be P-type. Alternatively, the conductivity type of the first doped semiconductor layer can also be P-type, and the conductivity type of the second doped semiconductor layer can be N-type.

[0188] Optionally, the first doped semiconductor layer is a P-type doped semiconductor layer; and / or, the first doped semiconductor layer is an emitter doped layer. In this case, a film layer with strong corrosion resistance, such as a borosilicate glass layer, can be used to protect the first doped semiconductor layer during the patterning process, which helps to ensure that the first boundary of the first doped semiconductor layer simultaneously has the aforementioned first sub-boundary and second sub-boundary, reducing the difficulty of the manufacturing process.

[0189] In terms of materials, the first doped semiconductor layer and / or the second doped semiconductor layer can be made of any semiconductor material such as silicon, germanium-silicon, germanium, or gallium arsenide. In terms of the arrangement of matter, the crystal phase of the first doped semiconductor layer and / or the second doped semiconductor layer can be amorphous, microcrystalline, nanocrystalline, single crystal, or polycrystalline.

[0190] The materials of the first doped semiconductor layer and the second doped semiconductor layer can be the same or different. For example, the materials of the first doped semiconductor layer and the second doped semiconductor layer can both be doped polycrystalline silicon or doped amorphous silicon. Another example is that one of the first doped semiconductor layer and the second doped semiconductor layer is made of doped polycrystalline silicon, and the other is made of doped amorphous silicon.

[0191] In terms of formation location, as shown in Figure 6, at least a portion of the first doped semiconductor layer 12 can be directly disposed on the first region 14. Alternatively, as shown in Figure 7, the back contact cell may further include a first interface passivation layer 28 located between the first doped semiconductor layer 12 and the semiconductor substrate 11. In this case, the passivated contact structure composed of the first interface passivation layer 28 and the first doped semiconductor layer 12 has excellent interface passivation effect and can achieve selective collection of charge carriers, reduce the carrier recombination rate of the first region 14 on the first surface of the semiconductor substrate 11, and further improve the photoelectric conversion efficiency of the back contact cell. The material and thickness of the first interface passivation layer 28 can be set according to the material of the first doped semiconductor layer 12 and actual needs, and are not specifically limited here. For example, when the material of the first doped semiconductor layer is doped polycrystalline silicon, the first interface passivation layer is a tunneling passivation layer. For example, when the material of the first doped semiconductor layer includes at least one of doped amorphous silicon, doped microcrystalline silicon, and doped nanocrystalline silicon, the first interface passivation layer is an intrinsic amorphous silicon layer, an intrinsic microcrystalline silicon layer, an intrinsic nanocrystalline silicon layer, or a mixture of the above three.

[0192] As for the second doped semiconductor layer, it can be directly disposed on the second region. Alternatively, as shown in Figure 7, the back contact cell may further include a second interface passivation layer 29 located between the second doped semiconductor layer 13 and the semiconductor substrate 11. In this case, the passivated contact structure composed of the second interface passivation layer 29 and the second doped semiconductor layer 13 has excellent interface passivation effect and can achieve selective collection of charge carriers, reduce the carrier recombination rate in the second region 15 of the first surface of the semiconductor substrate 11, and further improve the photoelectric conversion efficiency of the back contact cell. The principle for setting the material and thickness of the second interface passivation layer 29 can refer to the principle for setting the material and thickness of the first interface passivation layer 28 described above, and will not be repeated here.

[0193] From the perspective of edge morphology, as shown in Figures 1 to 7, along the width direction of the spacing region 16, the first boundary of the first doped semiconductor layer 12 includes a first sub-boundary 18 located within the first region 14 and far from the groove structure 17, and a second sub-boundary 19 extending from the first region 14 to above the groove structure 17. As mentioned above, the portion of the first doped semiconductor layer 12 corresponding to the first sub-boundary 18 has a relatively large gap with the second doped semiconductor layer 13, which helps to reduce the leakage risk between them. The portion of the first doped semiconductor layer 12 corresponding to the second sub-boundary 19 facilitates the reflection of some light emitted from the first surface of the semiconductor substrate 11 back to the semiconductor substrate 11 and reused by the semiconductor substrate 11, improving the light utilization rate of the back contact battery. Therefore, the length ratio of the first sub-boundary 18 and the second sub-boundary 19 in the first boundary can be determined according to the requirements of leakage risk and light utilization rate of the back contact battery in the actual application scenario; no specific limitation is made here.

[0194] For example, along the extension direction of the spacer region, within a unit length, for example, within a unit length of 1 cm, the total length of the first sub-boundary within the first region can be greater than the total length of the second sub-boundary above the groove structure. The extension direction of the spacer region is perpendicular to the width direction of the spacer region; for example, the extension direction of the spacer region is perpendicular to the direction of the paper in Figures 1 and 2. In this case, it can be understood that the distance between the portion of the first doped semiconductor layer corresponding to the first sub-boundary and the second doped semiconductor layer is larger than the portion of the first doped semiconductor layer corresponding to the second sub-boundary. Based on this, when the total length of the first sub-boundary within the first region is greater than the total length of the second sub-boundary above the groove structure within a unit length, the portion of the first boundary of the first doped semiconductor layer with a larger distance from the second doped semiconductor layer accounts for a higher proportion, which is beneficial for further reducing the leakage risk between the first and second doped semiconductor layers and reducing the carrier recombination rate of the back contact battery.

[0195] Alternatively, along the extension direction of the spacing region, the total length of the first sub-boundary within the first region within a unit length, such as 1 cm, can also be equal to the total length of the second sub-boundary above the groove structure. Or, within at least one 1 cm unit length, the total length of the first sub-boundary within the first region is less than the total length of the second sub-boundary above the groove structure. This reduces the manufacturing difficulty of the back contact battery without requiring the portion of the first doped semiconductor layer corresponding to the second sub-boundary to be smaller, thus reducing the area of ​​the first doped semiconductor layer within the first region. This is beneficial for the first doped semiconductor layer to have a higher field passivation effect and carrier collection capability.

[0196] It should be understood that in this paper, "unit length" refers to a certain length selected along the extension direction of the interval region based on the size of the target to be measured. "Unit length" can also be understood as a measurement unit selected for ease of measurement and comparison. For example, the unit length can be 100μm, 500μm, 1cm, 2cm, etc. To ensure the accuracy of the measurement, the unit length should be selected to ensure that it is more than twice the distance W1 between adjacent concave boundaries or adjacent convex boundaries along the extension direction of the interval region.

[0197] Furthermore, in practical applications, as shown in Figures 3 and 4, the first boundary of the first doped semiconductor layer 12 near the spacer region 16 can have an alternating concave-convex structure, including a concave boundary 20 and a convex boundary 21. It should be understood that the concave boundary 20 and the convex boundary 21 do not completely correspond to the first sub-boundary and the second sub-boundary. In this embodiment, the correspondence between the concave boundary 20 and the convex boundary 21 of the alternating concave-convex structure and the first and second sub-boundaries is not specifically limited. It can be determined based on the positional relationship between the first sidewalls of the groove structure near the first region in the actual application scenario, as well as the leakage risk and light utilization requirements of the back contact battery.

[0198] Optionally, the first sub-boundary includes at least a portion of the concave boundary.

[0199] Optionally, the second sub-boundary includes at least a portion of the convex boundary.

[0200] Optionally, the first sub-boundary includes at least a partially concave boundary and at least a partially convex boundary;

[0201] Optionally, the second sub-boundary may also include at least a partially concave boundary and at least a partially convex boundary.

[0202] Optionally, when the first sub-boundary includes at least a partially concave boundary and the second sub-boundary includes at least a partially convex boundary, the first sub-boundary of the first doped semiconductor layer disposed in the first region is opposite to at least a partially concave boundary in the alternating concave-convex structure, and the second sub-boundary of the first doped semiconductor layer disposed above the groove structure is opposite to at least a partially convex boundary in the alternating concave-convex structure. This is beneficial to make the alternating concave-convex structure presented by the first boundary more matched with the fluctuation changes of the portion of the first doped semiconductor layer that is recessed into the first region and the portion of the first doped semiconductor layer that is suspended and disposed on the groove structure. This can reduce the increase in etching amount of the semiconductor substrate to make the first boundary of the first doped semiconductor layer simultaneously have the first sub-boundary and the second sub-boundary, which is beneficial to increase the light absorption area of ​​the semiconductor substrate and improve the conversion efficiency of the back contact cell.

[0203] For example, along the extension direction of the interval region, the total length of adjacent convex and concave boundaries in the alternating convex-concave structure can be greater than or equal to 0.05 μm and less than or equal to 10 μm. For instance, the total length of adjacent convex and concave boundaries in the alternating convex-concave structure can be 0.05 μm, 0.1 μm, 1 μm, 2 μm, 3 μm, 5 μm, 8 μm, or 10 μm, etc. In this case, the total length of adjacent convex and concave boundaries in the alternating convex-concave structure has a large selectable range, which is beneficial to improving the applicability of the back contact battery provided in this application embodiment under different application scenarios.

[0204] Along the overall extension direction of the first doped semiconductor layer, the distance W1 between adjacent concave boundaries or adjacent convex boundaries can be greater than or equal to 1 μm and less than or equal to 15 μm. It should be understood that the extension direction along the overall extension direction of the first doped semiconductor layer refers to the extension direction along the spacer region, because the alternating concave-convex structure is arranged along the extension direction of the spacer region. The alternation direction of the concave-convex alternating structure (one concave-convex-one-concave-one-convex or one convex-concave-one-concave-one-concave) should be considered as the overall extension direction of the first doped semiconductor layer at its corresponding position. Therefore, the distance W1 between adjacent concave boundaries or adjacent convex boundaries can also be understood as the distance along the extension direction of the spacer region. Furthermore, the distance W1 between adjacent concave boundaries or adjacent convex boundaries can be determined by measuring the distance between the deepest point (valley) of the corresponding concave boundary or the deepest point (peak) of the corresponding convex boundary.

[0205] Optionally, along the width direction of the spacer region, the extension width W2 of the first sub-boundary within the first region is less than or equal to 8 μm. The extension width of the first sub-boundary within the first region can be understood as the maximum horizontal distance between the first sub-boundary and the first sidewall of the groove structure of the spacer region. In this case, the extension width of the first sub-boundary within the first region is within the above-mentioned range, which helps to prevent the area ratio of the first doped semiconductor layer on the first region from being too small due to the extension width W2 of the first sub-boundary within the first region being too large, thereby reducing the effective area of ​​the junction region or field region.

[0206] Optionally, along the width direction of the spacing region, the extension width W3 of the second sub-boundary above the groove structure is less than or equal to 10 μm. The extension width of the second sub-boundary above the groove structure can be understood as the maximum horizontal distance between the second sub-boundary and the first sidewall of the groove structure. Within the above range, it is beneficial to prevent the fill factor from being affected by an excessively large extension width W3 of the second sub-boundary above the groove structure, and to prevent the minimum spacing between the first and second doped semiconductor layers from being too small, thus avoiding a large risk of leakage.

[0207] Optionally, as shown in Figures 3 and 4, the groove structure 17 has a first sidewall 22 near the first region 14 along the width direction of the spacer region 16. The first region 14 may also include a platform region 24 near the first sidewall 22 along the width direction of the spacer region 16. The platform region 24 may include a platform surface 25 substantially perpendicular to the thickness direction of the semiconductor substrate 11. In this case, the platform region 24 includes a platform surface 25 substantially perpendicular to the thickness direction of the semiconductor substrate 11. Optionally, the platform surface 25 of the platform region 24 is relatively flat, for example, it can be a polished surface; the first doped semiconductor layer 12 is at least partially suspended above the platform surface 25. A flat surface helps reduce the number of defects on the platform surface and reduces the carrier recombination rate. Furthermore, the platform surface 25 has high light reflectivity, which helps reduce the probability of light emanating from the platform region 24 within the semiconductor substrate 11, improving the light utilization rate of the back contact cell. It should be noted that if the angle between the platform surface 25 included in the platform region 24 and the thickness direction of the semiconductor substrate 11 is greater than or equal to 85°, it can be considered that the platform surface 25 and the thickness direction of the semiconductor substrate 11 are approximately perpendicular.

[0208] Optionally, the platform surface of the platform region is not perpendicular to the thickness direction of the semiconductor substrate. Optionally, the platform surface can also be an uneven surface with a pyramidal or perforated structure. The morphology of the surface included in the platform region can be set according to actual needs and is not specifically limited here.

[0209] In terms of distribution location, as shown in Figures 9 to 11, at least a portion of the first doped semiconductor layer 12 is suspended above the plateau region 24. Optionally, the first sub-boundary 18 is suspended above the plateau region 24; alternatively, at least a portion of the second sub-boundary extends from above the plateau region 24 to above the groove structure in a suspended manner.

[0210] Optionally, as shown in Figures 9 to 14, the platform region 24 may further include a second sidewall 26 that is away from the first sidewall 22 and continuous with the platform surface 25. The second sidewall 26 is disposed perpendicular to the platform surface 25, or the second sidewall 26 is disposed inclined relative to the platform surface 25. In this case, along the direction from the first surface to the second surface, the platform surface 25 is recessed into the semiconductor substrate 11 relative to the surface of the region in the first region 14 directly covered by the first doped semiconductor layer 12. This can reduce the height variation between the bottom surface of the groove structure 17 and the surface of the region with greater height in the first region 14, which is beneficial to the formation quality and coverage of the surface passivation layer at the junction of the first region 14 and the spacer region 16, reduces the carrier recombination rate at the junction of the first region 14 and the spacer region 16, and at the same time minimizes the transport path of photogenerated carriers on the inclined sidewall, while increasing the lateral transport path that is more conducive to carrier transport.

[0211] For example, the width of the platform area is less than or equal to 10 μm.

[0212] Optionally, the angle between the second sidewall and the platform surface can be greater than or equal to 30° and less than or equal to 150°. For example, the angle between the second sidewall and the platform surface can be 30°, 40°, 50°, 60°, 80°, 100°, 120°, or 150°, etc. In this case, the range of the angle between the second sidewall and the platform surface is relatively large, which can reduce the process difficulty of forming the platform area.

[0213] Regarding the height of the second sidewall, exemplarily, along the thickness direction of the semiconductor substrate, the height of the second sidewall can be greater than or equal to 0.05 μm and less than or equal to 8 μm. For example, the height of the second sidewall can be 0.05 μm, 0.1 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 7 μm, or 8 μm, etc. In this case, the height of the second sidewall is within the above range, which helps to prevent a large height difference between the bottom surface of the groove structure and the surface of the area with a larger height in the first region due to the small height of the second sidewall, and helps to further improve the passivation effect of the surface passivation layer at the junction of the first region and the spacer region. In addition, it can also prevent a large etching amount in the portion of the semiconductor substrate corresponding to the platform region due to the large height of the second sidewall, which helps to make the portion of the semiconductor substrate corresponding to the platform region have a larger light absorption depth, which helps to improve the light utilization rate of the semiconductor substrate and further improve the conversion efficiency of the back contact cell.

[0214] Of course, depending on the size of the back contact battery and the requirements of different practical application scenarios, the height of the second sidewall can be set to any suitable value other than 0.05μm to 8μm; no specific limitation is made here. Furthermore, the height of the second sidewall can be the same or different in different platform regions.

[0215] The size of the plateau region can be determined based on the formation range of the first doped semiconductor layer in the first region, and is not specifically limited here. Specifically, different plateau regions may have the same or different plateau surface areas.

[0216] In addition, in practical applications, besides the surface passivation layer, the platform region of the back contact battery may not have other structures formed. Alternatively, as shown in Figures 3 and 4, the back contact battery may also include an island-shaped passivation structure 27 disposed on the platform region 24. In this case, the island-shaped passivation structure 27 has a passivation function, which can passivate the surface of the region on the semiconductor substrate 11 where the island-shaped passivation structure 27 is formed, reducing the number of defects on the surface of the region and reducing the carrier recombination rate. In addition, the island-shaped passivation structure 27 and the surface of the platform region 24 may have a certain height difference, or the island-shaped passivation structure 27 and the semiconductor substrate 11 may have material differences, so that the side surface and / or top surface of the island-shaped passivation structure 27 can reflect or refract incident light on one side of the first surface of the back contact battery, changing the transmission path of the incident light (such as increasing the reflection path of the incident light), which is beneficial for more incident light to be refracted into the battery, increasing the incident light absorption ratio and improving the bifaciality of the back contact battery. The island passivation structure 27 may be distributed at intervals with the first doped semiconductor layer 12, or at least a portion of the sidewall of the island passivation structure 27 may be adjacent to the first doped semiconductor layer 12.

[0217] From a morphological perspective, at least one island-shaped passivation structure may include multiple non-adjacent, clustered point-like passivation portions. In this case, it is beneficial to increase the specific surface area of ​​a single island-shaped passivation structure, enhance the light-trapping effect of the island-shaped passivation structure, and further improve the incident light absorption ratio and the bifaciality of the back-contact cell. In this case, the number of point-like passivation portions included in a single island-shaped passivation structure, as well as the distribution and morphology of different point-like passivation portions, can be set according to actual needs. The point-like passivation portions can be roughly regular hemispherical, circular / pyramidal, circular / frustum-shaped, circular / prism-shaped, or mountain-like shapes, or they can be irregular shapes with uneven surfaces.

[0218] Alternatively, as shown in Figures 3 and 4, at least one island-shaped passivation structure 27 can also be an integral structure with its different regions continuously distributed. This provides another example of the morphology of the island-shaped passivation structure 27, improving the applicability of the back contact battery provided in this application embodiment in different application scenarios and reducing the manufacturing difficulty of the back contact battery. In this case, the island-shaped passivation structure 27 can have a relatively flat surface (at this time, the morphology of the island-shaped passivation structure 27 can refer to the morphology of the regularly shaped dot-shaped passivation portion described above); or, the surface of the island-shaped passivation structure 27 can also have an undulating morphology. The direction, position, and size of the protrusion or concavity of the undulating morphology can be set according to actual needs and are not specifically limited here. The application principle of the beneficial effects when the different regions of at least one island-shaped passivation structure 27 are continuously distributed and the surface of the island-shaped passivation structure 27 has an undulating morphology can refer to the application principle of the beneficial effects of the island-shaped passivation structure 27 including multiple non-adjacent and clustered dot-shaped passivation portions described above.

[0219] Furthermore, the edge of at least one island-shaped passivation structure can be of a generally regular shape. For example, when the island-shaped passivation structure is hemispherical, its edge is circular. Or, for example, when the island-shaped passivation structure is pyramidal, its edge is polygonal. Alternatively, as shown in Figures 3 and 4, the edge of at least one island-shaped passivation structure 27 can be irregularly shaped. This allows the island-shaped passivation structure 27 to have side surfaces arranged in different directions, thereby reflecting light incident from different directions. This facilitates the refraction of more incident light into the battery, further improving the incident light absorption ratio and the bifaciality of the back-contact battery. In this case, the specific morphology of the irregularly shaped edge of the island-shaped passivation structure 27 can be determined based on the three-dimensional morphology of the island-shaped passivation structure 27 described above, and is not specifically limited here.

[0220] It should be noted that when the island-like passivation structure comprises multiple non-adjacent, clustered passivation portions, the edge of the island-like passivation structure refers to the edge of the area occupied by the collective of these multiple non-adjacent, clustered passivation portions. When different regions of the island-like passivation structure are continuously distributed, the edge of the island-like passivation structure refers to the edge enclosed by the continuously distributed different regions.

[0221] In terms of size, the embodiments of this application do not specifically limit the size of the island passivation structure, but can determine it according to the passivation effect requirements of the island passivation structure and the light trapping requirements of the island passivation structure in the actual application scenario.

[0222] For example, the area occupied by at least one island-shaped passivation structure can be greater than or equal to 1 μm. 2 and less than or equal to 100μm 2For example, the area occupied by at least one island-like passivation structure can be greater than or equal to 1 μm. 2 10μm 2 20μm 2 30μm 2 50μm 2 80μm 2 or 100μm 2 Etc. The area occupied by at least one island-shaped passivation structure is within the aforementioned range. This helps prevent the passivation effect of the island-shaped passivation structure from being too small, and also prevents the light-trapping effect improved by the island-shaped passivation structure itself or by the presence of the island-shaped passivation structure from being too low. This is beneficial for achieving a higher bifaciality of the back-contact battery. Furthermore, it also prevents the area occupied by the island-shaped passivation structure from being too large (the beneficial effects of preventing the area occupied by the island-shaped passivation structure from being too large can be referred to the preceding text, and will not be repeated here).

[0223] For example, the longest side dimension of at least one island-shaped passivation structure can be greater than or equal to 0.5 μm and less than or equal to 9 μm. For instance, the longest side dimension of at least one island-shaped passivation structure can be 0.5 μm, 1 μm, 2 μm, 3 μm, 5 μm, 6 μm, 8 μm, or 9 μm, etc.

[0224] For example, the shortest side dimension of at least one island-shaped passivation structure may be less than or equal to 0.05 μm and less than or equal to 7.5 μm. For instance, the shortest side dimension of at least one island-shaped passivation structure may be 0.05 μm, 0.1 μm, 1 μm, 2 μm, 3 μm, 5 μm, 6 μm, 6.5 μm, 7 μm, or 7.5 μm, etc.

[0225] It should be noted that when the island-like passivation structure comprises multiple non-adjacent, clustered passivation portions, the area occupied by the island-like passivation structure refers to the area occupied by the entire group of non-adjacent, clustered passivation portions. When different regions of the island-like passivation structure are continuously distributed, the area occupied by the island-like passivation structure refers to the area enclosed by the continuously distributed different regions.

[0226] Structurally, the island-shaped passivation structure can be a single-layer structure or a stacked structure composed of different layers. The material used for the island-shaped passivation structure can be any material with passivation properties, as long as it can be applied to the back contact battery provided in the embodiments of this application.

[0227] For example, at least one island-shaped passivation structure may include a doped semiconductor passivation portion; and / or, at least one island-shaped passivation structure may include an interface passivation portion. In this case, the island-shaped passivation structure can be formed by at least two passivation portions that are effective and compatible with battery manufacturing processes: a doped semiconductor passivation portion and an interface passivation portion. This not only provides good passivation effect for the island-shaped passivation structure but also improves the yield of the back contact battery. Furthermore, since the doped semiconductor passivation portion and the interface passivation portion are also materials used to manufacture the back contact battery, the island-shaped passivation structure can be manufactured simultaneously with the corresponding structure in the back contact battery, improving the manufacturing efficiency of the back contact battery and simplifying the manufacturing process.

[0228] It should be noted that the island passivation structure may include only the doped semiconductor passivation portion, or only the interface passivation portion, or it may be an island passivation structure that includes both the interface passivation portion and the doped semiconductor passivation portion (in which case the doped semiconductor passivation portion may be disposed on the side of the interface passivation portion away from the semiconductor substrate).

[0229] The materials and thicknesses of the doped semiconductor passivation portion and the interface passivation portion included in the island passivation structure, as well as the conductivity type of the doped semiconductor passivation portion, can be set according to actual needs and are not specifically limited here.

[0230] For example, the material and conductivity type of the doped semiconductor passivation portion can be the same as those of one of the first doped semiconductor layer and the second doped semiconductor layer. In this case, taking the example where the material and conductivity type of the doped semiconductor passivation portion included in the island passivation structure are the same as those of the second doped semiconductor layer, the island passivation structure can be manufactured simultaneously with the second doped semiconductor layer, improving the manufacturing efficiency of the back contact battery and simplifying the manufacturing process of the back contact battery.

[0231] For example, the thickness of the doped semiconductor passivation portion may be less than or equal to the thickness of one of the first doped semiconductor layer and the second doped semiconductor layer.

[0232] Specifically, the material and conductivity type of the doped semiconductor passivation portion are either the same as those of the first doped semiconductor layer or the second doped semiconductor layer. Secondly, the relationship between the thickness of the doped semiconductor passivation portion and the thicknesses of the first and second doped semiconductor layers can be determined based on the distribution of the island-shaped passivation structure on the plateau region and the relative positional relationship between the island-shaped passivation structure and the first doped semiconductor layer; no specific limitations are made here.

[0233] For example, as shown in Figures 3 and 4, along the width direction of the spacer region 16, if the sidewall of the first doped semiconductor layer and the sidewall of the island passivation structure are adjacent, or if the island passivation structure 27 is located between the first doped semiconductor layer 12 and the spacer region 16, then the material and conductivity type of the doped semiconductor passivation portion can be the same as the material and conductivity type of either the first doped semiconductor layer 12 or the second doped semiconductor layer 13. The thickness of the doped semiconductor passivation portion can be less than or equal to the thickness of the first doped semiconductor layer 12 or the second doped semiconductor layer 13 that has the same conductivity type as the doped semiconductor passivation portion.

[0234] For example, as shown in Figures 9 to 14, if the island-shaped passivation structure (not shown) is at least partially located in the first doped semiconductor layer 12 along the width direction of the spacer region 16, then the material and conductivity type of the doped semiconductor passivation portion included in the island-shaped passivation structure are the same as the material and conductivity type of the second doped semiconductor layer 13. The thickness of the doped semiconductor passivation portion may be less than or equal to the thickness of the second doped semiconductor layer 13.

[0235] Of course, the material of the doped semiconductor passivation portion included in the island passivation structure can also be different from the material of the first doped semiconductor layer and / or the second doped semiconductor layer. In this case, the doped semiconductor passivation portion of the island passivation structure, as well as the first doped semiconductor layer or the second doped semiconductor layer, can be manufactured separately.

[0236] For example, the material of the interface passivation portion is the same as the material of the first interface passivation layer or the second interface passivation layer. The application principle of the beneficial effect in this case can refer to the application principle of the beneficial effect described above, in which the material and conductivity type of the doped semiconductor passivation portion are the same as the material and conductivity type of one of the first doped semiconductor layer and the second doped semiconductor layer, respectively, and will not be repeated here.

[0237] For example, the thickness of the interface passivation portion may be less than or equal to the thickness of the first interface passivation layer or the second interface passivation layer.

[0238] Specifically, the material of the interface passivation portion is either the same as the material of the first interface passivation layer or the same as the material of the second interface passivation layer. Secondly, the relationship between the thickness of the interface passivation portion and the thicknesses of the first and second interface passivation layers can be determined based on the distribution of the island-shaped passivation structures on the plateau region and the relative positional relationship between the island-shaped passivation structures and the first doped semiconductor layer. The principle for determining the correspondence between the material, conductivity type, and thickness of the doped semiconductor passivation portion and the material, conductivity type, and thickness of the first and second doped semiconductor layers, as described above, can be referred to, and will not be repeated here.

[0239] Of course, the material of the interface passivation portion included in the island-shaped passivation structure can also be different from the material of the first interface passivation layer and / or the second interface passivation layer. In this case, the interface passivation portion of the island-shaped passivation structure, as well as the first interface passivation layer or the second interface passivation layer, can be manufactured separately.

[0240] When the back contact battery does not include the first interface passivation layer and / or the second interface passivation layer, the material of the interface passivation portion of the corresponding island passivation structure may include any interface passivation layer material such as silicon oxide, aluminum oxide and intrinsic silicon.

[0241] This embodiment provides an example method for fabricating a back contact battery. The method for fabricating the back contact battery may include the following steps:

[0242] First, a semiconductor substrate 11 is provided; the semiconductor substrate 11 has a back side, on which at least one first region 14 and at least one second region 15 are disposed alternately, and adjacent first regions 14 and second regions 15 are separated by a spacer region 16. The thickness of the semiconductor substrate can be 50 μm-500 μm; the semiconductor substrate 11 can be diamond wire cut and surface chemical polished to make the surface smooth and flat.

[0243] Next, a first doped semiconductor layer 12 is formed on the semiconductor substrate 11 in the first region 14.

[0244] In the actual fabrication process, after providing the semiconductor substrate 11 and before forming the second doped semiconductor layer 13, a first doped semiconductor layer 12 can be formed on the back side of the semiconductor substrate 11, forming a continuous layer. A first mask layer is formed on the portion of the first doped semiconductor layer 12 corresponding to the first region 14. Under the masking effect of the first mask layer, the portions of the first doped semiconductor layer 12 located in the spacer region 16 and the second region 15 are selectively removed, and the thickness of the semiconductor substrate 11 in the first region 14 is greater than the thickness of the semiconductor substrate 11 in the spacer region 16 and the second region 15. The thicknesses of the semiconductor substrates in the first region 14, the second region 15, and the spacer region 16 can be determined according to the actual application scenario and are not specifically limited here. For example, the thicknesses of the semiconductor substrates in the first region 14, the second region 15, and the spacer region 16 are such that the depth of the spacer region 16 relative to the lower of the thicknesses of the semiconductor substrates in the first region 14 and the second region 15 is 1 μm-10 μm.

[0245] The material of the first mask layer can be any material that has a masking function; no specific limitation is made here. The formation process and specific formation procedure of the doped semiconductor layer and the first mask layer can be determined based on the specific materials of the first doped semiconductor layer and the first mask layer.

[0246] For example, when the material of the first doped semiconductor layer includes silicon, forming the first mask layer may include the following steps: forming a monolithically disposed first intrinsic semiconductor layer on the back side of a semiconductor substrate. Next, doping the first intrinsic semiconductor layer to form a first doped semiconductor layer, and forming a monolithically disposed first doped silicon glass layer on the first doped semiconductor layer. Then, using a laser etching process, heat-treating portions of the first doped silicon glass layer corresponding to the spacer region and the second region to form the first mask layer on the untreated portions of the first doped silicon glass layer. Finally, removing the heat-treated portions of the first doped silicon glass layer.

[0247] Specifically, the material of the first doped semiconductor layer, including silicon, can mean that the material of the first doped semiconductor layer includes only silicon; or it can mean that the material of the first doped semiconductor layer includes both silicon and other semiconductor materials such as germanium silicon. Secondly, in the actual fabrication process, a first intrinsic semiconductor layer integrally disposed on one side of the back can be formed using processes such as chemical vapor deposition. Next, the first intrinsic semiconductor layer can be doped using processes such as diffusion. After the above doping treatment, not only the first doped semiconductor layer can be obtained, but also an integrally disposed first doped silicon glass layer can be formed on the first doped semiconductor layer. Then, a portion of the first doped silicon glass layer is heat-treated using a laser etching process. At this time, the density of the laser-treated portion of the first doped silicon glass layer decreases, making it easier to remove. The untreated portions of the first doped silicon glass layer have high density and are not easily removed. Therefore, after heat treatment, different portions of the first doped silicon glass layer have different etching selectivity ratios, resulting in a first mask layer for patterning the first doped semiconductor layer. This eliminates the need for additional mask materials and mask deposition processes, reducing the manufacturing cost of the back contact battery and simplifying the fabrication process. The specific conditions of the laser etching process can be set according to the actual application scenario and are not specifically limited here. The pits in Scheme B below can be formed during the heat treatment of a portion of the first doped silicon glass layer using laser etching.

[0248] Of course, if the material of the first doped semiconductor layer includes silicon, or if the material of the first doped semiconductor layer does not include silicon, chemical vapor deposition and doping processes can be used to form a first doped semiconductor layer that is entirely disposed on one side of the back side. Then, chemical vapor deposition and etching processes can be used to form a first mask layer made of silicon nitride or other materials that have a masking function.

[0249] Furthermore, after forming the first mask layer, wet chemical processes can be used to selectively remove the portion of the first doped semiconductor layer located in the spacer region and the second region under the masking effect of the first mask layer; and to make the thickness of the semiconductor substrate in the first region greater than the thickness of the semiconductor substrate in the spacer region and the second region. By using wet chemical processes to selectively remove the portion of the first doped semiconductor layer located in the spacer region and the second region under the masking effect of the first mask layer, a groove structure recessed into the semiconductor substrate relative to the first region can be formed in the spacer region and the second region, and the end of the first doped semiconductor layer adjacent to the spacer region can be suspended to form the first boundary of the first doped semiconductor layer in this embodiment, the brim in embodiment B, and the island passivation structure in embodiments C and D. The sidewall of the groove structure has a platform surface (such as the platform surface in this embodiment, embodiment B, embodiment C, and embodiment D) arranged horizontally relative to the back of the battery. This platform surface may include pits (such as the pits in embodiment B). As described in embodiment B below, the brim in embodiment B has a certain height relative to the platform surface where the top of the pit is located.

[0250] In the actual fabrication process, wet chemical processes are employed, and under the masking effect of a mask layer, groove structures recessed into the semiconductor substrate relative to the first region are formed in the spacer region and the second region. This prevents damage to the semiconductor substrate from high-temperature lasers and improves the yield of the back contact battery. Furthermore, when forming the groove structure using wet chemical processes, the etching method of the wet chemical solution on the semiconductor substrate is approximately isotropic, which helps to increase the length of the suspended ends in the first doped semiconductor layer, thereby forming the second sub-boundary of the first doped semiconductor layer.

[0251] Specifically, the process conditions for selectively etching the first doped semiconductor layer can be determined based on the etching process used, the material of the first doped semiconductor layer, and the thickness of the semiconductor substrate in the spacer region and the semiconductor substrate in the second region after the operation, etc., without specific limitations here.

[0252] It should be noted that when the prepared back contact battery also includes a first passivation layer located between the first region and the first doped semiconductor layer, after providing the semiconductor substrate and before forming the first doped semiconductor layer on the first region, the preparation method of the back contact battery also includes the following steps: using deposition and etching processes, first forming the first passivation layer on the semiconductor substrate of the first region.

[0253] Alternatively, after providing the semiconductor substrate 11, a first interface passivation layer 28 can be formed entirely on one side of the back surface using processes such as chemical vapor deposition. Then, after forming a first mask layer and selectively etching the first doped semiconductor layer 12 under the masking effect of the first mask layer, the first interface passivation layer 28 is selectively etched. In this case, it is not necessary to form an additional mask layer to form the first interface passivation layer 28, simplifying the fabrication process of the back contact battery.

[0254] Next, after making the thickness of the semiconductor substrate 11 in the first region 14 greater than the thickness of the semiconductor substrate 11 in the spacer region 16 and the second region 15, a second doped semiconductor layer 13 is formed on the second region 15; and the thickness of the semiconductor substrate 11 in the second region 15 is greater than the thickness of the semiconductor substrate 11 in the spacer region 16.

[0255] In the actual fabrication process, after ensuring that the thickness of the semiconductor substrate 11 in the first region 14 is greater than the thickness of the semiconductor substrate 11 in the spacer region 16 and the second region 15, a second doped semiconductor layer 13 is deposited on the first doped semiconductor layer 12, the spacer region 16, and the second region 15; and a second mask layer is formed on the portion of the second doped semiconductor layer 13 corresponding to the second region 15. Next, under the masking effect of the second mask layer, the portions of the second doped semiconductor layer 13 corresponding to the first region 14 and the spacer region 16 are selectively removed; and the thickness of the semiconductor substrate 11 in the second region 15 is greater than the thickness of the semiconductor substrate 11 in the spacer region 16.

[0256] Exemplarily, when the material of the second doped semiconductor layer 13 includes silicon, depositing the second doped semiconductor layer 13 on the first doped semiconductor layer 12, the spacer region 16, and the second region 15; and forming a second mask layer on the portion of the second doped semiconductor layer 13 corresponding to the second region 15 may include the following steps: depositing a second intrinsic semiconductor layer on the first doped semiconductor layer 12, the spacer region 16, and the second region 15. Next, the second intrinsic semiconductor layer is doped to form the second doped semiconductor layer 13, and a second doped silicon glass layer is formed on the second doped semiconductor layer 13. Then, a laser etching process is used to heat-treat the portion of the second doped silicon glass layer corresponding to the first region 14 and the spacer region 16 to form the second mask layer on the portion of the second doped silicon glass layer corresponding to the second region 15. Then, the heat-treated portion of the second doped silicon glass layer is removed.

[0257] Specifically, the material of the second doped semiconductor layer, including silicon, can mean that the material of the second doped semiconductor layer includes only silicon; or it can mean that the material of the second doped semiconductor layer includes both silicon and other semiconductor materials such as germanium silicon. Secondly, in the actual fabrication process, a second intrinsic semiconductor layer can be formed entirely on one side of the back surface using processes such as chemical vapor deposition. Next, the second intrinsic semiconductor layer can be doped using processes such as diffusion. After the above doping treatment, not only is the second doped semiconductor layer obtained, but also a second doped silicon glass layer can be formed entirely on the second doped semiconductor layer. Then, a laser etching process is used to heat-treat the portion of the second doped silicon glass layer corresponding to the first region and the spacer region. At this time, the density of the laser-treated portion of the second doped silicon glass layer decreases, making it easier to remove. The portion of the second doped silicon glass layer corresponding to the second region is not laser-processed. This portion exhibits high density and is difficult to remove. Consequently, after heat treatment, different portions of the second doped silicon glass layer have different etching selectivity ratios, resulting in a second mask layer for patterning the second doped semiconductor layer. This eliminates the need for additional mask materials and mask deposition processes, reducing the fabrication cost of the back contact cell and simplifying the fabrication process. The pits in Embodiment B below can be formed during the heat treatment of a portion of the second doped silicon glass layer using a laser etching process.

[0258] Of course, if the material of the second doped semiconductor layer includes silicon, or if the material of the second doped semiconductor layer does not include silicon, chemical vapor deposition and doping processes can be used to form a second doped semiconductor layer that is entirely disposed on one side of the back surface. Then, chemical vapor deposition and etching processes can be used to form a second mask layer made of silicon nitride or other materials that serve a masking function.

[0259] Furthermore, after forming the second mask layer, wet chemical processes can be used to selectively remove portions of the second doped semiconductor layer located in the spacer region and on the first doped semiconductor layer under the masking effect of the second mask layer; and to make the thickness of the semiconductor substrate in the second region greater than the thickness of the semiconductor substrate in the spacer region. By using wet chemical processes to selectively remove portions of the second doped semiconductor layer located in the spacer region and on the first doped semiconductor layer under the masking effect of the second mask layer, a recessed structure can be formed in the spacer region relative to the first and second regions and into the semiconductor substrate. This also allows for the existence of exposed portions in the second boundary region of embodiment B and the formation of island-like passivation structures in embodiments C and D. These exposed portions are the parts of the second doped semiconductor layer that do not extend to the edge of the semiconductor substrate sidewall or the top edge of the pit, i.e., the portion of the second region near the spacer region where the second boundary of the second doped semiconductor layer is not covered. As described in embodiment B below, the exposed portion not covered by the second doped semiconductor layer between the edge of the top of the pit and the edge of the second doped semiconductor layer creates a certain distance between the edge of the second doped semiconductor layer near the pit and the edge of the top of the pit.

[0260] In the actual fabrication process, wet chemical processes and other techniques are used, and under the masking effect of the mask layer, a groove structure is formed in the spacer area that is recessed into the semiconductor substrate relative to the first and second regions. This can prevent high-temperature laser from damaging the semiconductor substrate and improve the yield of the back contact battery.

[0261] Specifically, the process conditions for selectively etching the second doped semiconductor layer can be determined based on the etching process used, the material of the second doped semiconductor layer, and the thickness of the semiconductor substrate in the spacer region, etc., and are not specifically limited here.

[0262] It should be noted that when the back contact battery is further comprising a second passivation layer located between the second region and the second doped semiconductor layer, after the thickness of the semiconductor substrate 11 of the first region 14 is greater than the thickness of the semiconductor substrate 11 of the spacer region 16 and the second region 15, and before the second doped semiconductor layer 13 is formed on the second region 15, the back contact battery fabrication method further comprises the following steps: using deposition and etching processes to first form the second passivation layer on the second region 15.

[0263] Alternatively, after the thickness of the semiconductor substrate 11 in the first region 14 is greater than the thickness of the semiconductor substrate 11 in the spacer region 16 and the second region 15, and before forming the second doped semiconductor layer 13 on the second region 15, a second interface passivation layer 29 can be deposited on the first doped semiconductor layer 12, the second region 15, and the spacer region 16 using a process such as chemical vapor deposition. Then, after forming the second mask layer and selectively etching the second doped semiconductor layer 13 under the masking effect of the second mask layer, the second interface passivation layer 29 is selectively etched. In this case, it is not necessary to form an additional mask layer to form the second interface passivation layer 29, simplifying the fabrication process of the back contact battery.

[0264] In addition, if the back contact battery also includes a surface passivation layer covering the first doped semiconductor layer 12, the second doped semiconductor layer 13 and the spacer region 16, after making the thickness of the semiconductor substrate 11 of the second region 15 greater than the thickness of the semiconductor substrate 11 of the spacer region 16, a process such as chemical vapor deposition can be used to form the surface passivation layer 32 covering the first doped semiconductor layer 12, the second doped semiconductor layer 13 and the spacer region 16.

[0265] Implementation Plan B

[0266] The edge regions adjacent to the first region and the second region of the interval region are typically flat. While a flat topography is beneficial for passivation, it also results in higher reflectivity of backlight, which is detrimental to backlight absorption.

[0267] To improve back-contact batteries, this application also provides a back-contact battery, as shown in FIG15. One embodiment of the back-contact battery provided by this application includes: a semiconductor substrate 11, a first doped semiconductor layer 12, and a second doped semiconductor layer 13. The semiconductor substrate 11 has a front side and a back side. The back side is provided with at least one alternating first region 14 and at least one second region 15, with adjacent first regions 14 and second regions 15 separated by a spacing region 16. The first doped semiconductor layer 12 and the second doped semiconductor layer 13 have opposite conductivity types. In some embodiments, the first doped semiconductor layer 12 is either an N-type doped semiconductor layer or a P-type doped semiconductor layer; the second doped semiconductor layer 13 is either an N-type doped semiconductor layer or a P-type doped semiconductor layer. The spacing region 16 separates the first doped semiconductor layer 12 and the second doped semiconductor layer 13, which can reduce the carrier recombination rate at the lateral boundary between the first doped semiconductor layer 12 and the second doped semiconductor layer 13, thereby improving the photoelectric conversion efficiency of the back-contact battery. The semiconductor substrate 11 can be a silicon substrate, for example, an N-type silicon substrate or a P-type silicon substrate.

[0268] The surface of the spacer region 16 can be polished or textured. In the case of a polished surface, the surface of the spacer region 16 is relatively flat. Based on this, when the back contact cell also includes a surface passivation layer, compared with a textured surface, the portion of the surface passivation layer formed on the polished surface of the spacer region 16 has a larger thickness. This can improve the passivation effect of the surface passivation layer on the spacer region 16, reduce the carrier recombination rate on the surface of the spacer region 16, and thus improve the photoelectric conversion efficiency of the back contact cell.

[0269] The first doped semiconductor layer 12 is located at least on the semiconductor substrate 11 of the first region 14, and the second doped semiconductor layer 13 is located at least on the semiconductor substrate 11 of the second region 15. As used herein, "at least on" means that the first doped semiconductor layer 12 is located in the first region 14, but may have a brimmed portion extending from the first region 14 to the adjacent spacer region 16, or that the second doped semiconductor layer 13 is located in the second region 15, but may have a brimmed portion extending from the second region 15 to the adjacent spacer region 16, as will be described in detail below.

[0270] The spacer region 16 has a first boundary region adjacent to the first region 14, and a second boundary region adjacent to the second region 15. In some embodiments, the first boundary region may have one or more pits 33. In some embodiments, the second boundary region may have one or more pits 33. In some embodiments, both the first boundary region and the second boundary region have one or more pits 33. As used herein, the "first boundary region" includes the semiconductor substrate at the junction of the spacer region 16 and the first region 14, and the region extending from the edge of the first region 14 away from the spacer region 16 toward the first region 14 at a distance (e.g., 50 μm). This region extending from the edge of the first region 14 away from the spacer region 16 toward the first region 14 can be referred to as the first sub-boundary region. Similarly, the "second boundary region" includes the semiconductor substrate at the junction of the spacer region 16 and the second region 15, and the region extending from the edge of the second region 15 away from the spacer region 16 toward the second region 15 at a distance (e.g., 50 μm). This region extending from the edge of the second region 15 away from the spacer region 16 toward the second region 15 can be referred to as the second sub-boundary region. Figure 15 shows a pit 33 located in the first sub-boundary region, but the location of the pit is not limited to this location. The location of the pit will be described in more detail below with reference to Figures 16A-16D and Figures 17-20. The first boundary region adjacent to the first region and / or the second boundary region adjacent to the second region have one or more pits. The pits exist on the sidewalls of the semiconductor substrate in the corresponding boundary region and the semiconductor substrate in the corresponding sub-boundary region. This can improve the light trapping effect of the back contact cell, enhance the light absorption rate and utilization rate of the back contact cell, and thus improve the photoelectric conversion efficiency.

[0271] As shown in Figures 17 to 20, a recess can include closed recesses and / or non-closed recesses. The sides of a closed recess are surrounded by a semiconductor substrate to form a closed structure (e.g., as shown in Figures 17, 19, and 20), while the sides of a non-closed recess are partially surrounded by a semiconductor substrate to form a non-closed structure (e.g., as shown in Figures 17, 18, and 20). It should be noted that in this document, a "closed recess" has an open top and closed sides and bottom, while a "non-closed recess" has an open top and open sides and bottom; "closed" and "non-closed" are used only to indicate whether the sides and bottom of the recess form a closed structure. The top of the recess refers to the portion further away from the semiconductor substrate in the thickness direction relative to the semiconductor substrate. Furthermore, the sides of a "closed recess" are entirely surrounded by the semiconductor substrate, while the sides of a "non-closed recess" are surrounded by the semiconductor substrate; the remaining portion of a non-closed recess not surrounded by the semiconductor substrate is an open portion. Whether a pit is closed and the direction of its opening both alter the light path, ultimately affecting the light-trapping effect. Combining different types of pits or different opening directions (which can include the direction of the top opening of a closed pit and the opening direction of the side opening of a non-closed pit) can improve the light-trapping effect of the back-contact battery, increase its light absorption and utilization, and thus improve its photoelectric conversion efficiency. The semiconductor substrate surrounding the sides forming the closed and / or non-closed pits has prisms 34 (as shown in Figures 18-20). The presence of the prisms 34 within the pit increases the number of reflections and the absorption rate within the pit, preventing direct reflection of light away from the pit's sides. This improves the light-trapping effect of the back-contact battery, increases its light absorption and utilization, and thus improves its photoelectric conversion efficiency. At least one closed recess has its prisms 34 joined together to form at least one joint 35 (as shown in Figure 19), and / or at least one non-closed recess has its prisms joined together to form at least one joint 35 (as shown in Figures 18 and 20). Since the prisms of the recesses join together to form at least one joint, a larger number of joints indicates a more uneven inner surface of the recess. This increases the number of reflections and absorption rate of light within the recess, preventing direct reflection of light away from the recess's sides. This improves the light-trapping effect of the back-contact battery, enhances its light absorption and utilization rate, and thus improves the photoelectric conversion efficiency.

[0272] As shown in Figures 17, 19, and 20, the top opening of the closed recess has a certain diameter. As the diameter increases, the number of seams formed by the mating of the prisms in the closed recess increases accordingly. For example, in some embodiments, when the arc of the top of the non-closed recess is greater than 120 degrees, the mating of the prisms forms at least one seam; the number of seams formed by the mating of the prisms in the closed recess can be, for example, 1-8 or 1-6. Similar to the closed recess, the diameter of the non-closed recess can be defined relative to the approximate circle corresponding to the arc of the top of the non-closed recess. In one embodiment, when the diameters are equal, the number of seams formed by the mating of the prisms in the closed recess can be greater than the number of seams formed by the mating of the prisms in the non-closed recess. The diameter of the recess can be set according to actual needs and is not specifically limited here. For example, the diameter of the recess can be not less than 2 μm, thereby improving the light trapping effect of the back contact battery, increasing the light absorption rate and utilization rate of the back contact battery, and thus improving the photoelectric conversion efficiency.

[0273] Closed and unclosed recesses can exist in various combinations in the first and second boundary regions. In some embodiments, the first boundary region has only closed recesses. In some embodiments, the first boundary region has both closed and unclosed recesses. In some embodiments, the second boundary region has only unclosed recesses. In some embodiments, the second boundary region has both closed and unclosed recesses. The closed and unclosed recesses in the first and second boundary regions can be used individually or in combination to improve the light trapping effect of the back contact battery in different opening directions of the recesses, thereby improving the light absorption rate and utilization rate of the back contact battery and thus improving the photoelectric conversion efficiency. In some embodiments, the number of closed recesses in the first boundary region is greater than the number of closed recesses in the second boundary region. In some embodiments, the number of unclosed recesses in the second boundary region is greater than the number of unclosed recesses in the first boundary region. By increasing the number of closed pits in the first boundary region to be greater than the number of closed pits in the second boundary region, and / or increasing the number of open pits in the second boundary region to be greater than the number of open pits in the first boundary region, for example, when the first region is a P region and the second region is an N region, the light trapping effect of the back contact battery can be improved, the light absorption rate and utilization rate of the back contact battery can be increased, thereby improving the photoelectric conversion efficiency.

[0274] In the actual fabrication process, the corresponding doped semiconductor layer may have an extended brim 36 (as shown in Figures 21A and 21B). An extended brim 36 may be present above a portion of the pit, which is a portion of the corresponding doped semiconductor layer that extends out and is suspended. In some embodiments, the brim 36 is not adjacent to the surface of the platform where the top of the lower pit is located, and has a certain height relative to the surface of the platform where the top of the lower pit is located (as shown by H in Figure 21A). This height can be set according to actual needs and is not specifically limited here. For example, this height can be 0.2 μm-2 μm. In other embodiments, the brim 36 is adjacent to the surface of the platform where the top of the lower pit is located, as shown in Figure 21B. The brim in Figure 21A is referred to as having a first brim structure, and the brim in Figure 21B is referred to as having a second brim structure. The brim 36 with the first brim structure may exist above part or all of the edge of the top of the pit. The first brim structure and the second brim structure can exist alone or in any combination above part or all of the top edge of a closed or open recess. For example, when the brim 36 with the first brim structure exists above part of the top edge of the recess, the remaining edge of the top of the recess may not have a brim, or the brim 36 with the second brim structure may exist. Alternatively, the brim 36 with the second brim structure may exist above part or all of the top edge of the recess. Furthermore, when the brim 36 with the second brim structure exists above part of the top edge of the recess, the remaining edge of the top of the recess may not have a brim, or the brim 36 with the first brim structure may exist. In addition, during the actual fabrication process, the corresponding doped semiconductor layer may partially cover the semiconductor substrate 11, resulting in an exposed portion 37 on the surface of the semiconductor substrate 11 (as shown in Figures 17-19). Near the top of some pits, there may also be exposed portions 37 not covered by the doped semiconductor layer. These exposed portions are the parts of the semiconductor substrate 11 surface where the doped semiconductor layer does not extend to the edge of the top of the pit. The exposed portions not covered by the doped semiconductor layer between the edge of the top of the pit and the edge of the doped semiconductor layer create a certain distance between the edge of the doped semiconductor layer near the pit and the edge of the top of the pit. This distance can be set according to actual needs and is not specifically limited here. For example, this distance can be 0.2 μm-5 μm. The exposed portions 37 can exist near all edges of the top of the pit, or they can exist only near a portion of the edges of the top of the pit. The brim and the exposed portions can exist in various combinations above and near the top of closed pits and above and near the top of unclosed pits. In some embodiments, a brim is present above a portion of the pits in the first boundary region. In some embodiments, a brim is present above a portion of the pits in the first boundary region, while an exposed portion is present near the top of another portion of the pits.In some embodiments, a portion of the recesses in the second boundary region has an exposed portion near the top. In some embodiments, a portion of the recesses in the second boundary region has an exposed portion near the top, while another portion of the recesses has a brim. For example, in the case where the first region is a P-region and the second region is an N-region, it is more likely that a brim is above the recesses in the first boundary region, while an exposed portion is near the top of the recesses in the second boundary region. The brim can reflect light reaching it to the recesses below, the recesses in the other boundary region, or the semiconductor substrate to increase light absorption and utilization, while the exposed portion can directly increase the light absorption and utilization of the semiconductor substrate. By using different combinations of the brim, exposed portion, and recesses, the light trapping effect of the back contact battery can be improved, the light absorption and utilization of the back contact battery can be increased, thereby improving the photoelectric conversion efficiency.

[0275] In actual fabrication, the thickness of the semiconductor substrate in the first region may be greater than that in the second region. As used herein, the term "thickness" refers to the extent of the semiconductor substrate extending vertically relative to the back side of the back contact cell. In this case, due to the thickness difference between the semiconductor substrates in the first and second regions, light reaching the pits in either the first or second boundary region may be reflected to the pits or semiconductor substrate in the other boundary region, rather than being directly reflected away from the spacer area. This can improve the light trapping effect of the back contact cell, enhance its light absorption and utilization, and thus improve its photoelectric conversion efficiency.

[0276] Furthermore, as shown in Figures 16A and 16B, one of the first doped semiconductor layer 12 or the second doped semiconductor layer 13 may have an extension 40, and can overlap with the other of the first doped semiconductor layer 12 or the second doped semiconductor layer 13 through its extension 40. In Figure 16A, the first doped semiconductor layer 12 has an extension 40, which has the same conductivity type as the first doped semiconductor layer. In Figure 16B, the second doped semiconductor layer 13 has an extension 40, which has the same conductivity type as the second doped semiconductor layer. Additionally, both the first doped semiconductor layer 12 and the second doped semiconductor layer 13 may have extensions 40, and can be connected or overlapped in a spaced region through their respective extensions (as shown in Figure 16C). These extensions can have the same conductivity type as the first doped semiconductor layer 12 and the second doped semiconductor layer 13, respectively, so that the first doped semiconductor layer 12 and the second doped semiconductor layer 13 form a local electrical connection. It should be understood that the "electrical connection" can be a direct connection or a connection through a conductive film layer. The conductive film layer can be any existing film layer, as long as it is conductive, such as a tunneling oxide layer. In this document, although an extension is described as an extension of a specific doped semiconductor layer, the conductivity type of the extension is not necessarily the same as that of the specific doped semiconductor layer. Instead, it can be the same conductivity type as either the first or second doped semiconductor layer, as long as the conductivity type of the extension, combined with the conductivity types of the first and second doped semiconductor layers and possibly another extension, forms a local electrical connection between the first and second doped semiconductor layers 12 and 13. Furthermore, one or more of the different types of extensions shown in Figures 16A-16C can exist, forming several local electrical connections of the same or different types between the first and second doped semiconductor layers 12 and 13. By locally connecting the first and second doped semiconductor layers 12 and 13 with opposite conductivity types through extensions, the risk of hot spots in the back contact battery can be reduced to a certain extent, achieving a hot spot prevention effect and improving the burn-out resistance of the back contact battery, while having a relatively small impact on the operating efficiency of the back contact battery in the forward voltage region.

[0277] In some embodiments, the first boundary region may further include a first location where the spacer region 16 is adjacent to the extension, or the second boundary region may further include a second location where the spacer region 16 is adjacent to the extension. The first location (including, for example, at least one corner) and / or the second location (including, for example, at least one corner) may have one or more pits, as shown in Figures 16A-16C. Furthermore, while the presence of pits is shown in circles at various locations in Figures 16A-16C, this is merely an example, and the location and number of pits may differ from those shown. The circles shown in Figures 16A-16C may represent either closed pits or open pits. For example, more pits, fewer pits, different types of pits, etc., may exist in the first boundary region and the second boundary region (e.g., the sidewall of the semiconductor substrate in the first boundary region, the sidewall of the semiconductor substrate in the second boundary region, various locations of the extension, etc.). In one embodiment, the total number of closed pits at at least one corner of the first or second location is not less than the total number of open pits at that at least one corner. In this case, while achieving the effect of preventing hot spots, by setting an appropriate number of closed or open pits at the first or second position, the light trapping effect of the back contact battery can also be improved, the light absorption rate and utilization rate of the back contact battery can be increased, thereby improving the photoelectric conversion efficiency.

[0278] Figure 16D is an electron microscope image of a partial structure of a back contact battery including an extension according to an embodiment of this application. The scheme shown in Figure 16D is included in the schemes described with reference to Figures 16A-16C. The scheme of Figure 16D can be understood with reference to the description of Figures 16A-16C. It is worth noting that the two sides of the extension 40 shown in Figure 16D may have different pit types, pit numbers, and undulation structures. For example, the left sidewall of the extension 40 shown in Figure 16D may have more pits and a more pronounced degree of undulation than the right sidewall, for example, the degree of indentation and protrusion of the undulation structure is more obvious. The pit types, pit numbers, and undulation structures on both sides of the extension shown in Figure 16D are for illustrative purposes only, and various other situations may exist. For example, in some embodiments, the right sidewall of the extension may have more pits and a more pronounced degree of undulation than the left sidewall, more pits and a similar degree of undulation, approximately the same number of pits and a similar degree of undulation, etc. In this case, while achieving the effect of preventing hot spots, by setting an appropriate number of closed or open recesses on both sides of the extension, the light trapping effect of the back contact cell can also be improved, thereby increasing the light absorption rate and utilization rate of the back contact cell and thus improving the photoelectric conversion efficiency. The undulating structure is described in more detail below with reference to Figure 17.

[0279] In some embodiments, as shown in FIG17, the sidewalls of the semiconductor substrate in the first boundary region and / or the second boundary region may have a wavy, undulating structure in a direction perpendicular to the extending direction of the spacer region 16. Closed recesses may be located at protruding positions 38 of the undulating structure, or non-closed recesses may be located at recessed positions 39 of the undulating structure. As described above, the first region 14 and the second region 15 are alternately distributed, and the extending direction of the spacer region 16 is parallel to the extending directions of the first region 14 and the second region 15 (e.g., the vertical direction parallel to the plane of the paper as shown in FIG17). In contrast, referring to the cross-sectional view of FIG15, the direction perpendicular to the plane of the paper of the spacer region 16 can be considered as the extending direction of the spacer region 16. Furthermore, in Figures 16A-16C, although the top view of the sidewalls of the semiconductor substrate in the first and second boundary regions is shown as straight lines, this is only an example. The sidewalls of the semiconductor substrate in the first and second boundary regions can have a wavy, undulating structure in a direction perpendicular to the extension direction of the spacing region 16. Closed recesses can be located at the protruding position 38 of the undulating structure, or non-closed recesses can be located at the recessed position 39 of the undulating structure, as shown in Figure 17. Different combinations of the undulating structure and recesses of the semiconductor substrate sidewalls can further improve the light-trapping effect of the sidewalls, increase the light absorption rate and utilization rate of the back contact cell, thereby improving the photoelectric conversion efficiency. As for the spacing of the recesses, it can be set according to actual needs and is not specifically limited here. For example, the spacing of the recesses can be 10μm-500μm. In some embodiments, the spacing of the recesses can be changed by adjusting the laser spot.

[0280] In some embodiments, in the first sub-boundary region and / or the second sub-boundary region, the pits closer to the spacer region 16 have a larger diameter than those in the first and second sub-boundary regions farther from the spacer region 16. By giving the pits at different locations different diameters, the adverse effects of the pits on the first or second region can be reduced, while the light trapping effect of the back contact cell can be improved, thereby increasing the light absorption rate and utilization rate of the back contact cell and improving the photoelectric conversion efficiency.

[0281] In practical applications, as shown in Figure 15, the front side of the semiconductor substrate 11 can be a flat surface; or, the front side of the semiconductor substrate can be a textured surface.

[0282] As shown in Figure 15, the first doped semiconductor layer 12 is formed on the first region 14. Therefore, the range of the first region 14 on the back side of the semiconductor substrate 11 can be determined according to the requirements of the formation range of the first doped semiconductor layer 12 in the actual application scenario. Secondly, the second doped semiconductor layer 13 is formed on the second region 15. Therefore, the range of the second region 15 on the back side of the semiconductor substrate 11 can be determined according to the requirements of the formation range of the second doped semiconductor layer 13 in the actual application scenario. As for the spacer region 16, as mentioned above, the spacer region 16 can separate the first doped semiconductor layer 12 and the second doped semiconductor layer 13 with opposite conductivity types, suppressing leakage current. Therefore, the range of the spacer region 16 on the back side can be determined according to the requirements of the leakage prevention spacing between the first doped semiconductor layer 12 and the second doped semiconductor layer 13 in the actual application scenario.

[0283] In terms of conductivity type, the conductivity type of the first or second doped semiconductor layer can be the opposite or the same as that of the semiconductor substrate, as long as the conductivity types of the first and second doped semiconductor layers are opposite. As for the thickness of the first and second doped semiconductor layers, it can be set according to actual needs and is not specifically limited here. For example, the thickness of the first or second doped semiconductor layer can be 100nm-600nm.

[0284] In practical applications, the first doped semiconductor layer can be directly formed on the first region 14 of the semiconductor substrate. Alternatively, as shown in Figure 15, the back contact battery also includes a first interface passivation layer 28 located between the first region 14 of the semiconductor substrate 11 and the first doped semiconductor layer 12. In this case, the first interface passivation layer 28 and the first doped semiconductor layer 12 can form a selective contact structure to achieve chemical passivation of the first region 14 on the back side of the semiconductor substrate 11 and selective collection of carriers of the corresponding conductivity type, thereby reducing the carrier recombination rate on the back side and improving the photoelectric conversion efficiency of the back contact battery.

[0285] The material of the first passivation layer can be determined based on the material of the first doped semiconductor layer and the type of selective contact structure composed of the first passivation layer and the first doped semiconductor layer in the actual application scenario; no specific limitation is made here.

[0286] For example, when the selective contact structure formed by the first passivation layer and the first doped semiconductor layer is a tunneling passivation contact structure, the first doped semiconductor layer is a doped polysilicon layer, and the first passivation layer is a tunneling passivation layer. The material of the tunneling passivation layer may include materials such as silicon oxide, aluminum oxide, or titanium oxide.

[0287] For example, when the selective contact structure formed by the first passivation layer and the first doped semiconductor layer is a heterogeneous contact structure, the first doped semiconductor layer is a doped amorphous silicon layer and / or a doped microcrystalline silicon layer, and the first passivation layer is an intrinsic amorphous silicon layer and / or an intrinsic microcrystalline silicon layer.

[0288] The thickness of the first passivation layer can be set according to actual needs, and no specific limit is made here. For example, the thickness of the first passivation layer can be 0.5nm-10nm.

[0289] The second doped semiconductor layer can be directly formed on the second region of the semiconductor substrate. Alternatively, as shown in FIG15, the back contact cell further includes a second interface passivation layer 29 located between the second region 15 of the semiconductor substrate 11 and the second doped semiconductor layer 13. In this case, the second interface passivation layer 29 and the second doped semiconductor layer 13 can form a selective contact structure to achieve chemical passivation of the second region 15 on the back side of the semiconductor substrate 11 and selective collection of carriers of the corresponding conductivity type, thereby reducing the carrier recombination rate on the back side and improving the photoelectric conversion efficiency of the back contact cell.

[0290] The material and thickness of the second passivation layer can be referenced from the material and thickness of the first passivation layer described above, and will not be repeated here.

[0291] As one possible implementation, as shown in Figure 15, the aforementioned back contact battery may further include a surface passivation layer 32 covering the first doped semiconductor layer 12, the second doped semiconductor layer 13, and the spacer region 16. In this case, the surface passivation layer 32 can passivate the back side of the back contact battery, reducing the carrier recombination rate on the back side.

[0292] Specifically, the material of the aforementioned surface passivation layer can be any insulating material with passivation properties, such as silicon oxide, aluminum oxide, or silicon nitride. The thickness of the surface passivation layer can be determined based on the actual application scenario and is not specifically limited here.

[0293] The method for preparing the back contact battery in this embodiment can refer to embodiment A and any existing method that can be used to prepare a back contact battery, and is not limited here.

[0294] For the fabrication of pits, existing laser etching (laser conditions can refer to the parameters for etching pits on semiconductor materials in existing technologies) or chemical etching (e.g., etching with chemical reagents such as acids and alkalis that can react with semiconductor materials) can be used. The laser intensity, laser spot shape and size, laser treatment time and number of passes are selected based on the desired pit size, depth, and shape; the type and concentration of chemical reagents, treatment time, and treatment range are also selected based on the desired pit size, depth, and shape. Alternatively, the prismatic structure in the pit can be obtained by chemically treating it with alkaline solutions or other chemical reagents after laser etching or chemical etching. It is understandable that, to simplify the fabrication process, existing steps in back-contact battery fabrication methods can be used to fabricate pits. Only specific parameters need to be adjusted according to different pit requirements to obtain the desired structural features and distribution density. For example, laser etching using doped layer patterning can be used to form the pit precursor, and chemical treatment steps can be combined with existing wet etching steps (such as alkaline treatment) to achieve the fabrication of the prismatic structure. Chemical reagents such as alkali solutions can alter the size of prismatic structures, the presence or absence of butt joints, and the number of butt joints.

[0295] Implementation Plan C

[0296] To improve the formation quality and field passivation effect of the doped semiconductor layer on the back side of the battery, existing back-contact batteries have a relatively flat surface on the back side. However, a flat surface has poor light-trapping effect, resulting in low utilization of incident light on the back side of the battery, which is not conducive to improving the bifaciality of the back-contact battery.

[0297] To improve the back-contact battery, this application embodiment also provides a back-contact battery. As shown in Figures 22 to 24, the back-contact battery includes: a semiconductor substrate 11, a first doped semiconductor layer 12, a second doped semiconductor layer 13, and an island passivation structure 27. The semiconductor substrate 11 has a first surface and a second surface opposite to each other. The first surface includes an alternately distributed first region 14 and a second region 15. The first doped semiconductor layer 12 is disposed on the first region 14. The second doped semiconductor layer 13 is disposed on the second region 15. The second doped semiconductor layer 13 and the first doped semiconductor layer 12 have opposite conductivity types. The island passivation structure 27 is disposed on the side of the first doped semiconductor layer 12 and / or the second doped semiconductor layer 13 away from the semiconductor substrate 11, and / or, the island passivation structure 27 is disposed between the first doped semiconductor layer 12 and / or the second doped semiconductor layer 13 and the semiconductor substrate 11.

[0298] When the back contact battery is in operation, the first and second doped semiconductor layers can effectively shunt and collect charge carriers, which is beneficial for the formation of photocurrent. The island-shaped passivation structure 27 provided in the back contact battery has two functions: firstly, it can passivate the surface of the region where the island-shaped passivation structure 27 is formed, reducing the number of defects on the surface of the region and reducing the carrier recombination rate; secondly, it can change the transmission path of incident light (such as increasing the reflection path of incident light), which is beneficial for more incident light to be refracted into the battery, increasing the incident light absorption ratio and improving the bifaciality of the back contact battery. As shown in Figures 22 to 24, taking the island-shaped passivation structure 27 provided on the side of the first doped semiconductor layer 12 away from the semiconductor substrate 11 as an example: the island-shaped passivation structure 27 has a passivation function, which can strengthen the passivation of the surface of the region where the island-shaped passivation structure 27 is formed. Furthermore, the island-shaped passivation structure 27 is not part of the first doped semiconductor layer 12. It is an additional passivation structure with an island shape, disposed on the side of the first doped semiconductor layer 12 away from the semiconductor substrate 11. There may be a certain height difference between the island-shaped passivation structure 27 and the side of the first doped semiconductor layer 12 away from the semiconductor substrate 11, or there may be a difference in material between the island-shaped passivation structure 27 and the first doped semiconductor layer. This allows the side surface of the island-shaped passivation structure 27 to reflect or refract incident light from the first side of the back contact battery, changing the transmission path of the incident light (such as increasing the reflection path of the incident light). This facilitates more incident light being refracted into the battery, increasing the incident light absorption ratio and improving the bifaciality of the back contact battery. It should be noted that the black elliptical outline in Figure 24 is a line drawn to show the approximate location of the island-shaped passivation structure 27 and is not part of the battery structure.

[0299] The beneficial effects of island passivation structures disposed on the side of the second doped semiconductor layer away from the semiconductor substrate, and on the side of the first doped semiconductor layer and / or the second doped semiconductor layer between the semiconductor substrate, are based on the same principle as those of island passivation structures disposed on the side of the first doped semiconductor layer away from the semiconductor substrate, and will not be repeated here. It should be noted that, as shown in Figure 23, when the island passivation structure 27 is disposed on the side of the second doped semiconductor layer 13 away from the semiconductor substrate 11, the island passivation structure 27 is not part of the second doped semiconductor layer 13, but is an additional passivation structure disposed outside the second doped semiconductor layer. As shown in Figure 23, when the island passivation structure 27 is disposed between the first doped semiconductor layer 12 and the semiconductor substrate 11, the island passivation structure 27 is neither part of the first doped semiconductor layer 12 nor the semiconductor substrate 11, but is an additional passivation structure disposed outside the second doped semiconductor layer. As shown in Figures 22 and 23, when the island-shaped passivation structure 27 is disposed between the second doped semiconductor layer 13 and the semiconductor substrate 11, the island-shaped passivation structure 27 belongs neither to the second doped semiconductor layer 13 nor to the semiconductor substrate 11, and is an additional passivation structure disposed outside the second doped semiconductor layer.

[0300] The semiconductor substrate includes a first surface and a second surface opposite to each other. The first surface of the semiconductor substrate corresponds to the back side of the back contact battery, and the second surface of the semiconductor substrate corresponds to the front side of the back contact battery. The distribution of the first region and the second region on the first surface can be determined based on the distribution of the first doped semiconductor layer and the second doped semiconductor layer formed on the first surface. Specifically, since the first doped semiconductor layer of the back contact battery is disposed on the first region, the distribution range of the first region on the first surface can be determined based on the distribution requirements of the first doped semiconductor layer in the actual application scenario. Since the second doped semiconductor layer of the back contact battery is disposed on the second region of the first surface, the distribution range of the second region on the first surface can be determined based on the distribution requirements of the second doped semiconductor layer on the semiconductor substrate in the actual application scenario.

[0301] It is understandable that one of the first and second regions roughly corresponds to the emitter region, and the other roughly corresponds to the back field region. In terms of specific conductivity type, one of the first and second regions roughly corresponds to the P-region, and the other roughly corresponds to the N-region.

[0302] The shapes of the first and second regions can be set according to actual needs, as long as they can be applied to the back contact battery provided in this application embodiment. For example, the first and second regions can be arranged in alternating stripes or in alternating interdigitated shapes.

[0303] In terms of surface morphology, as shown in Figures 22 and 23, the second surface of the semiconductor substrate 11 can be a polished surface. Alternatively, as shown in Figure 25, the second surface of the semiconductor substrate 11 can also be a textured surface to improve the light-trapping effect of the second surface and increase the light utilization rate of the semiconductor substrate 11.

[0304] As for the morphology of the first surface of the semiconductor substrate, as shown in Figure 25, the surfaces of the first region 14 and the second region 15 can be planar to improve the formation quality of the first doped semiconductor layer 12 and the second doped semiconductor layer 13, and improve the field passivation effect of the first doped semiconductor layer 12 and the second doped semiconductor layer 13.

[0305] In terms of distribution, as shown in Figures 22 and 25, the first doped semiconductor layer 12 and the second doped semiconductor layer 13 can be spaced apart along a direction parallel to the first surface. In this case, the first surface of the semiconductor substrate 11 also includes a spacer region 16 located between the first region 14 and the second region 15. The surface of this spacer region 16 can be planar or textured.

[0306] Alternatively, as shown in Figure 26, at least a portion of the first doped semiconductor layer 12 and at least a portion of the second doped semiconductor layer 13 can also be adjacent to each other. In this case, the adjacent portions of the first doped semiconductor layer 12 and the second doped semiconductor layer 13 can form a diode structure with a lower reverse breakdown voltage, thereby reducing the risk of hot spots when the back contact battery is shielded and improving the back contact battery's resistance to burn-out. This application does not specifically limit the range of the adjacent portions of the first doped semiconductor layer 12 and the second doped semiconductor layer 13; it can be determined based on the requirements for hot spot risk and conversion efficiency of the back contact battery in the actual application scenario.

[0307] Alternatively, as shown in Figures 27 and 28, at least a portion of the second doped semiconductor layer 13 is not only disposed on the second region 15 but also extends to cover a portion of the first doped semiconductor layer 12. In this case, within the first region 14, as shown in Figure 27, the second doped semiconductor layer 13 can directly contact the first doped semiconductor layer 12 to form a diode structure with a lower reverse breakdown voltage, reducing the risk of hot spots when the back contact battery is shielded; or, as shown in Figure 28, an insulating layer can also be disposed between the second doped semiconductor layer 13 and the first doped semiconductor layer 12 to electrically isolate the first doped semiconductor layer 12 and the second doped semiconductor layer 13. The material of the insulating layer can include any insulating material such as silicon oxide, silicon nitride, aluminum oxide, or silicon oxynitride, as long as it can be applied to the back contact battery provided in the embodiments of this application. In addition, within the first region 14, the width of the second doped semiconductor layer 13 overlapping the first doped semiconductor layer 12 can be set according to actual needs and is not specifically limited here.

[0308] In terms of formation location, as shown in Figures 25 to 28, the first doped semiconductor layer 12 can be directly disposed on the first region 14. Alternatively, as shown in Figure 29, the back contact cell may further include a first interface passivation layer 28 located between the first doped semiconductor layer 12 and the semiconductor substrate 11. In this case, the passivated contact structure composed of the first interface passivation layer 28 and the first doped semiconductor layer 12 has excellent interface passivation effect and can achieve selective collection of charge carriers, reducing the carrier recombination rate in the first region 14 of the first surface of the semiconductor substrate 11, and further improving the photoelectric conversion efficiency of the back contact cell. The material and thickness of the first interface passivation layer 28 can be set according to the material of the first doped semiconductor layer 12 and actual needs, and are not specifically limited here.

[0309] As for the second doped semiconductor layer, it can be directly disposed on the second region. Alternatively, as shown in Figures 29 and 30, the back contact cell may further include a second interface passivation layer 29 located between the second doped semiconductor layer 13 and the semiconductor substrate 11. (As shown in Figure 30, when at least a portion of the second doped semiconductor layer 13 extends to cover a portion of the first doped semiconductor layer 12, the second interface passivation layer 29 also extends from the second region 15 to the space between the first doped semiconductor layer 12 and the second doped semiconductor layer 13.) In this case, the passivated contact structure composed of the second interface passivation layer 29 and the second doped semiconductor layer 13 has excellent interface passivation effect and can achieve selective collection of charge carriers, reducing the carrier recombination rate in the second region 15 of the first surface of the semiconductor substrate 11, and further improving the photoelectric conversion efficiency of the back contact cell. The principle for setting the material and thickness of the second interface passivation layer 29 can refer to the principle for setting the material and thickness of the first interface passivation layer 28 described above, and will not be repeated here.

[0310] In terms of morphology, as shown in Figure 31, at least one island-shaped passivation structure 27 may include multiple non-adjacent and clustered dot-shaped passivation portions 44. This is beneficial for increasing the specific surface area of ​​a single island-shaped passivation structure 27, increasing the light absorption area of ​​a single island-shaped passivation structure 27, enhancing the light-trapping effect of the island-shaped passivation structure 27, and further improving the incident light absorption ratio and the bifaciality of the back-contact battery. In this case, the number of dot-shaped passivation portions 44 included in a single island-shaped passivation structure 27, as well as the distribution and morphology of different dot-shaped passivation portions 44, can be set according to actual needs. The dot-shaped passivation portions 44 can be roughly regular hemispherical, circular / pyramidal, circular / frustum, circular / prism, or mountain-like shapes, or they can be irregular shapes with uneven surfaces. It should be noted that the black elliptical outline in Figure 31 is a line drawn to show the approximate location of the island-shaped passivation structure 27 and is not part of the battery structure.

[0311] Optionally, as shown in Figure 24, at least one island-shaped passivation structure 27 can also be an integral structure with its different regions continuously distributed. This can provide another example of the morphology of the island-shaped passivation structure 27, improving the applicability of the back contact battery provided in this application embodiment under different application scenarios and reducing the manufacturing difficulty of the back contact battery. In this case, the island-shaped passivation structure 27 can have a relatively flat surface (at this time, the morphology of the island-shaped passivation structure 27 can refer to the morphology of the regularly shaped dot-shaped passivation portion described above); optionally, the surface of the island-shaped passivation structure 27 can also have an undulating morphology, and the direction, position, and size of the protrusion or concavity of the undulating morphology can be set according to actual needs and are not specifically limited here. The application principle of the beneficial effects when the different regions of at least one island-shaped passivation structure 27 are continuously distributed and the surface of the island-shaped passivation structure 27 has an undulating morphology can refer to the application principle of the beneficial effects of the island-shaped passivation structure 27 including multiple non-adjacent and clustered dot-shaped passivation portions described above.

[0312] In terms of distribution, the island-shaped passivation structures included in the back contact battery can be randomly distributed. Optionally, as shown in Figures 24 and 31, at least some of the island-shaped passivation structures 27 can be regularly distributed. In this case, the distribution pattern can be set according to the interaction characteristics between the incident light and the island-shaped passivation structures 27, so that the incident light on the first side of the back contact battery is regularly reflected or refracted. This, combined with the irregular light trapping effect of the island-shaped passivation structures themselves, maximizes the utilization of the incident light and further improves the light trapping effect of the island-shaped passivation structures 27. Alternatively, because the island-shaped passivation structures 27 are provided between the first doped semiconductor layer 12 and / or the second doped semiconductor layer 13 and the semiconductor substrate 11, the side of the first doped semiconductor layer 12 and / or the second doped semiconductor layer 13 facing away from the semiconductor substrate 11 has a high light trapping effect, reducing the light blocking effect and further improving the incident light absorption ratio and the bifaciality of the back contact battery.

[0313] In practical applications, the regular distribution of island passivation structures in a back-contact battery can be determined based on the light-trapping requirements of different areas on the back side of the battery, and is not specifically limited here. As shown in Figures 24 and 31, different island passivation structures 27 disposed on the side of the first doped semiconductor layer 12 and / or the second doped semiconductor layer 13 away from the semiconductor substrate 11 can be regularly distributed; different island passivation structures 27 disposed between the first doped semiconductor layer 12 and / or the second doped semiconductor layer 13 and the semiconductor substrate 11 can also be regularly distributed; or all island passivation structures 27 included in the back-contact battery can be regularly distributed.

[0314] At least some island-like passivation structures exhibit a regular distribution, meaning that the different island-like passivation structures within this portion are distributed in a predictable pattern. For example, different island-like passivation structures may be distributed along a fixed direction (e.g., in a matrix or concentric circles). Another example is that different island-like passivation structures are distributed with approximately the same spacing. Yet another example is that different island-like passivation structures exhibit approximately the same pattern morphology.

[0315] Additionally, it should be noted that, as shown in Figures 32 to 34, both the first doped semiconductor layer 12 and the second doped semiconductor layer 13 may include strip-shaped doped regions 45. Furthermore, the strip-shaped doped regions 45 included in the first doped semiconductor layer 12 and the strip-shaped doped regions 45 included in the second doped semiconductor layer 13 both extend along a first direction and are alternately distributed along a second direction; the first direction is different from the second direction. In the above case, at least a portion of the island-shaped passivation structure 27 included in the back contact battery is distributed between the strip-shaped doped regions 45 and the semiconductor substrate 11, and / or, the island-shaped passivation structure 27 is distributed on the side of the strip-shaped doped regions 45 facing away from the semiconductor substrate 11.

[0316] The specific directions referred to by the first direction and the second direction can be determined based on the morphology of the first doped semiconductor layer and the second doped semiconductor layer, as well as the first region and the second region, and are not specifically limited here.

[0317] For example, as shown in Figure 32, when the first doped semiconductor layer 12 and the second doped semiconductor layer 13 are arranged in alternating stripes, the first direction refers to the length extension direction of the first doped semiconductor layer 12 and the second doped semiconductor layer 13, and the second direction refers to the width direction of the first doped semiconductor layer 12 and the second doped semiconductor layer 13.

[0318] For example, as shown in Figure 34, when the first doped semiconductor layer 12 and the second doped semiconductor layer 13 are alternately distributed in an interdigitated pattern, the first direction refers to the arrangement direction of the first doped semiconductor layer 12 and the second doped semiconductor layer 13, and the second direction refers to the length extension direction of the first doped semiconductor layer 12 and the second doped semiconductor layer 13.

[0319] Optionally, as shown in FIG32, the first doped semiconductor layer 12 and the second doped semiconductor layer 13 may only include strip-shaped doped regions 45. Alternatively, as shown in FIGS. 33 and 34, both the first doped semiconductor layer 12 and the second doped semiconductor layer 13 may include strip-shaped doped regions 45 and connecting doped regions 46. The connecting doped regions 46 included in the first doped semiconductor layer 12 and the second doped semiconductor layer 13 extend along a second direction and are alternately distributed along a first direction. The connecting doped regions 46 included in the first doped semiconductor layer 12 are connected to at least a portion of the strip-shaped doped regions 45 included in the first doped semiconductor layer 12. The connecting doped regions 46 included in the second doped semiconductor layer 13 are connected to at least a portion of the strip-shaped doped regions 45 included in the second doped semiconductor layer 13. The number of strip-shaped doped regions 45 connected to the connecting doped regions 46 included in the first doped semiconductor layer 12 and the second doped semiconductor layer 13 is not specifically limited here according to actual needs. In this case, the island-shaped passivation structure 27 included in the back contact battery can also be disposed between the connection doped region 46 and the semiconductor substrate 11, and / or, the island-shaped passivation structure 27 is distributed on the side of the connection doped region 46 away from the semiconductor substrate 11.

[0320] In different island passivation structures disposed between the same strip-shaped doped region and the semiconductor substrate, or disposed on the side of the same strip-shaped doped region away from the semiconductor substrate, the spacing between two adjacent island passivation structures along the first direction can be equal to the spacing between two adjacent island passivation structures along the second direction. Alternatively, as shown in Figure 24, the spacing between two adjacent island passivation structures 27 along the first direction can also be smaller than the spacing between two adjacent island passivation structures 27 along the second direction. It is understood that the length of the strip-shaped doped region 45 is greater than the width of the strip-shaped doped region 45, and the light-trapping requirement along the length direction (i.e., the first direction) of the strip-shaped doped region 45 is greater than the light-trapping requirement along the width direction (i.e., the second direction). Therefore, the different spacings of the island passivation structures 27 along the first direction and along the second direction can respectively meet the different light-trapping requirements along the first direction and along the second direction, so that the island passivation structures 27 adjacent along the first direction have a higher light-trapping effect, further improving the bifaciality of the back contact cell.

[0321] The distribution of two adjacent island passivation structures in different directions between the same connecting doped region and the semiconductor substrate, or between different island passivation structures on the side of the same connecting doped region away from the semiconductor substrate, can be referred to the distribution of two adjacent island passivation structures in different directions between the same strip doped region and the semiconductor substrate, or between different island passivation structures on the side of the same strip doped region away from the semiconductor substrate, which will not be repeated here.

[0322] As for the specific spacing between two adjacent island passivation structures, it can be determined based on the passivation effect of the island passivation structure and the light trapping requirements of the island passivation structure in the actual application scenario, and no specific limit is made here.

[0323] For example, the spacing between two adjacent island passivation structures can be greater than or equal to 40 μm and less than or equal to 300 μm. For instance, the spacing between two adjacent island passivation structures can be 40 μm, 50 μm, 80 μm, 100 μm, 150 μm, 200 μm, 250 μm, or 300 μm, etc. Setting the spacing between two adjacent island passivation structures within the above range can prevent the distribution density of island passivation structures on the semiconductor substrate from being too large due to a small spacing, thus affecting the formation quality of the first doped semiconductor layer and / or the second doped semiconductor layer on the island passivation structure. Alternatively, when the island passivation structure includes a doped semiconductor passivation portion, and the doped semiconductor passivation portion and its adjacent first or second doped semiconductor layer have opposite conductivity types, it can prevent a high risk of leakage between the island passivation structure and the first or second doped semiconductor layer due to a small spacing between two adjacent island passivation structures. By controlling the spacing between two adjacent island passivation structures, the distribution density of the island passivation structure can be controlled, ensuring that the carrier recombination rate is within a controllable range. Furthermore, it can prevent poor light trapping on the first side of the back contact battery due to a large spacing between two adjacent island passivation structures, thus promoting a higher incident light absorption ratio on the first side and further improving the bifaciality of the back contact battery.

[0324] Optionally, along the first direction, the spacing between two adjacent island passivation structures can be greater than or equal to 40 μm and less than or equal to 200 μm.

[0325] Optionally, along the second direction, the spacing between two adjacent island passivation structures can be greater than or equal to 40 μm and less than or equal to 300 μm.

[0326] When at least one island-shaped passivation structure is disposed between the first doped semiconductor layer and / or the second doped semiconductor layer and the semiconductor substrate, and the surfaces of the first and second regions of the semiconductor substrate also have a tower-like structure recessed along the direction close to the semiconductor substrate; or, when at least one island-shaped passivation structure is disposed on the side of the first doped semiconductor layer and / or the second doped semiconductor layer away from the semiconductor substrate, and the sides of the first and second doped semiconductor layers away from the semiconductor substrate also have a tower-like structure recessed along the direction close to the semiconductor substrate, at least one island-shaped passivation structure can be disposed within the tower-like structure. In this case, the surfaces of the island-shaped passivation structure and the tower-like structure can cooperate to improve the transmission path of incident light, further improving the light utilization rate on the back side of the back contact cell. In this case, the one-dimensional dimension of the tower-like structure can be set according to actual needs and is not specifically limited here. Furthermore, in this case, the area ratio of a single island-shaped passivation structure on the bottom surface of the tower-like structure can be less than or equal to 40%. This allows for better control of the island-like passivation structure's size within a reasonable range, ensuring a certain distance between the sides of the island-like passivation structure and the sides of the tower-like base structure, facilitating the reflection or refraction of incident light. Furthermore, it prevents the island-like passivation structure from occupying too large an area, which could negatively impact the formation quality of the first and / or second doped semiconductor layers formed on it. Alternatively, when the island-like passivation structure includes a doped semiconductor passivation portion, and the doped semiconductor passivation portion has an opposite conductivity type to its adjacent first or second doped semiconductor layer, it can prevent an increase in battery leakage risk due to an excessively large island-like passivation structure, reduce carrier recombination rate, and improve the performance of the back-contact battery.

[0327] For example, at least one island-shaped passivation structure may include a doped semiconductor passivation portion; and / or, at least one island-shaped passivation structure may include an interface passivation portion; and / or, at least one island-shaped passivation structure may include a doped semiconductor passivation portion and a doped silicon glass portion disposed on the side of the doped semiconductor passivation portion facing away from the semiconductor substrate. It is evident that the island-shaped passivation structure can be formed by at least three passivation portions—a doped semiconductor passivation portion, an interface passivation portion, and a doped silicon glass portion—that offer good performance and are compatible with battery manufacturing processes. This not only provides a good passivation effect for the island-shaped passivation structure but also improves the yield of the back contact battery. Different materials have different characteristics in terms of light absorption, light reflection, and light refraction. By combining different materials, the optical path can be altered, improving light utilization. Furthermore, the doped semiconductor passivation portion, the interface passivation portion, and the doped silicon glass portion are also materials used in manufacturing back contact batteries. In this case, the island-shaped passivation structure can be manufactured simultaneously with the corresponding structure in the back contact battery, improving the manufacturing efficiency of the back contact battery and simplifying the manufacturing process.

[0328] It should be noted that the island passivation structure may include only the doped semiconductor passivation portion, or only the interface passivation portion, or only the interface passivation portion and the doped semiconductor passivation portion (in which case the doped semiconductor passivation portion can be disposed on the side of the interface passivation portion away from the semiconductor substrate), or only the doped semiconductor passivation portion and the doped silicon glass portion, or the island passivation structure may simultaneously include the interface passivation portion, the doped semiconductor passivation portion and the doped silicon glass portion (in which case the interface passivation portion, the doped semiconductor passivation portion and the doped silicon glass portion can be stacked sequentially along the direction away from the semiconductor substrate).

[0329] For example, at least one island-shaped passivation structure is disposed on the side of the first doped semiconductor layer away from the semiconductor substrate, or at least one island-shaped passivation structure is disposed between the first doped semiconductor layer and the semiconductor substrate, wherein the material and conductivity type of the doped semiconductor passivation portion may be the same as the material and conductivity type of the second doped semiconductor layer.

[0330] For example, at least one island-shaped passivation structure is disposed on the side of the first doped semiconductor layer away from the semiconductor substrate, or at least one island-shaped passivation structure is disposed between the first doped semiconductor layer and the semiconductor substrate, wherein the thickness of the doped semiconductor passivation portion may be less than or equal to the thickness of the second doped semiconductor layer.

[0331] For example, at least one island-shaped passivation structure is disposed on the side of the second doped semiconductor layer away from the semiconductor substrate, or at least one island-shaped passivation structure is disposed between the second doped semiconductor layer and the semiconductor substrate, wherein the material and conductivity type of the doped semiconductor passivation portion may be the same as those of the first doped semiconductor layer.

[0332] For example, at least one island-shaped passivation structure is disposed on the side of the second doped semiconductor layer away from the semiconductor substrate, or at least one island-shaped passivation structure is disposed between the second doped semiconductor layer and the semiconductor substrate, wherein the thickness of the doped semiconductor passivation portion may be less than or equal to the thickness of the first doped semiconductor layer.

[0333] It is worth noting that, taking the example of the doped semiconductor passivation portion of the island-shaped passivation structure adjacent to the first doped semiconductor layer having the same material and conductivity type as the second doped semiconductor layer, the manufacturing of the doped semiconductor passivation portion of the island-shaped passivation structure adjacent to the first doped semiconductor layer can be achieved simultaneously with the manufacturing of the second doped semiconductor layer, thereby improving the manufacturing efficiency of the back contact battery and simplifying the manufacturing process of the back contact battery.

[0334] Of course, the material and / or conductivity type of the doped semiconductor passivation portion of the island-shaped passivation structure adjacent to the first doped semiconductor layer can also be different from the material and / or conductivity type of the second doped semiconductor layer. In this case, the doped semiconductor passivation portion of the island-shaped passivation structure adjacent to the first doped semiconductor layer and the second doped semiconductor layer can be manufactured separately. The material and / or conductivity type of the doped semiconductor passivation portion of the island-shaped passivation structure adjacent to the second doped semiconductor layer can also be different from the material and / or conductivity type of the first doped semiconductor layer.

[0335] Regarding the interface passivation portion included in at least one island-shaped passivation structure, as described above, when the back contact battery also includes a first interface passivation layer, the material of the interface passivation portion in at least one island-shaped passivation structure disposed on the side of the first doped semiconductor layer away from the semiconductor substrate, or in at least one island-shaped passivation structure disposed between the first doped semiconductor layer and the semiconductor substrate, can be the same as the material of the second interface passivation layer. This is beneficial for improving the manufacturing efficiency of the back contact battery and simplifying the manufacturing process of the back contact battery.

[0336] For example, in at least one island-shaped passivation structure disposed on the side of the first doped semiconductor layer away from the semiconductor substrate, or in at least one island-shaped passivation structure disposed between the first doped semiconductor layer and the semiconductor substrate, the thickness of the interface passivation portion may be less than or equal to the thickness of the second interface passivation layer.

[0337] When the back contact battery also includes a second interface passivation layer, at least one island-shaped passivation structure disposed on the side of the second doped semiconductor layer away from the semiconductor substrate, or at least one island-shaped passivation structure disposed between the second doped semiconductor layer and the semiconductor substrate, wherein the material of the interface passivation portion is the same as the material of the first interface passivation layer. This is beneficial for improving the manufacturing efficiency of the back contact battery and simplifying the manufacturing process of the back contact battery.

[0338] For example, in at least one island-shaped passivation structure disposed on the side of the second doped semiconductor layer away from the semiconductor substrate, or in at least one island-shaped passivation structure disposed between the second doped semiconductor layer and the semiconductor substrate, the thickness of the interface passivation portion is less than or equal to the thickness of the first interface passivation layer.

[0339] Of course, the material of the interface passivation portion of the island-shaped passivation structure adjacent to the first doped semiconductor layer can also be different from the material of the second interface passivation layer. In this case, the interface passivation portion of the island-shaped passivation structure adjacent to the first doped semiconductor layer and the second interface passivation layer can be manufactured separately. The material of the interface passivation portion of the island-shaped passivation structure adjacent to the second doped semiconductor layer can also be different from the material of the first interface passivation layer.

[0340] Regarding the doped silicon glass portion included in at least one island passivation structure, exemplarily, as shown in FIG35, the back contact battery may further include a first doped silicon glass layer 30 disposed on the side of the first doped semiconductor layer 12 facing away from the semiconductor substrate 11, wherein the first doped silicon glass layer 30 has the same conductivity type as the first doped semiconductor layer 12. This passivates the side of the first doped semiconductor layer 12 facing away from the semiconductor substrate 11, and prevents the first doped semiconductor layer 12 from being affected during the fabrication of the second doped semiconductor layer 13, thus improving the first doped semiconductor layer 12's ability to retain, shunt, and collect current. This application embodiment does not specifically limit the doping concentration and thickness of the impurities in the first doped silicon glass layer 30. In this case, in at least one island passivation structure 27 disposed on the side of the second doped semiconductor layer 13 facing away from the semiconductor substrate 11, or in at least one island passivation structure 27 disposed between the second doped semiconductor layer 13 and the semiconductor substrate 11, the material and conductivity type of the doped silicon glass portion are the same as those of the first doped silicon glass layer 30. To improve the manufacturing efficiency of back contact batteries and simplify the manufacturing process of back contact batteries.

[0341] For example, in at least one island-shaped passivation structure disposed on the side of the second doped semiconductor layer away from the semiconductor substrate, or in at least one island-shaped passivation structure disposed between the second doped semiconductor layer and the semiconductor substrate, the thickness of the doped silicon glass portion is less than or equal to the thickness of the first doped silicon glass layer.

[0342] For example, as shown in FIG35, the back contact battery may further include a second doped silicon glass layer 31 disposed on the side of the second doped semiconductor layer 13 facing away from the semiconductor substrate 11. The second doped silicon glass layer 31 has the same conductivity type as the second doped semiconductor layer 13 to passivate the side of the second doped semiconductor layer 13 facing away from the semiconductor substrate 11. This application embodiment does not specifically limit the doping concentration and thickness of the impurities in the second doped silicon glass layer 31. In this case, at least one island-shaped passivation structure 27 disposed on the side of the first doped semiconductor layer 12 facing away from the semiconductor substrate 11, or at least one island-shaped passivation structure 27 disposed between the first doped semiconductor layer 12 and the semiconductor substrate 11, may have the same material and conductivity type for the doped silicon glass portion as for the second doped silicon glass layer 31. This improves the manufacturing efficiency of the back contact battery and simplifies the manufacturing process.

[0343] For example, in at least one island-shaped passivation structure disposed on the side of the first doped semiconductor layer away from the semiconductor substrate, or in at least one island-shaped passivation structure disposed between the first doped semiconductor layer and the semiconductor substrate, the thickness of the doped silicon glass portion may be less than or equal to the thickness of the second doped silicon glass layer.

[0344] Of course, the material and / or conductivity type of the doped silicon glass portion of the island-shaped passivation structure adjacent to the first doped semiconductor layer can also be different from the material and / or conductivity type of the second doped silicon glass layer. In this case, the doped silicon glass portion of the island-shaped passivation structure adjacent to the first doped semiconductor layer and the second doped silicon glass layer can be manufactured separately. The material and / or conductivity type of the doped silicon glass portion of the island-shaped passivation structure adjacent to the second doped semiconductor layer can also be different from the material and / or conductivity type of the first doped silicon glass layer.

[0345] In terms of formation location, the island-shaped passivation structure included in the back contact battery can be disposed only on the side of the first doped semiconductor layer away from the semiconductor substrate, only on the side of the second doped semiconductor layer away from the semiconductor substrate, only between the first doped semiconductor layer and the semiconductor substrate, only between the second doped semiconductor layer and the semiconductor substrate, or a combination of at least two of the above four cases. This application does not specifically limit the formation location of the island-shaped passivation structure; it can be determined according to the actual application scenario and the actual manufacturing process.

[0346] For example, as shown in FIG22, the island passivation structure 27 disposed on the first region 14 may be located on the side of the first doped semiconductor layer 12 away from the semiconductor substrate 11, and the island passivation structure 27 disposed on the second region 15 may be disposed between the second doped semiconductor layer 13 and the semiconductor substrate 11.

[0347] Alternatively, as shown in FIG36, the island passivation structure 27 disposed on the first region 14 is located between the first doped semiconductor layer 12 and the semiconductor substrate 11, and the island passivation structure 27 disposed on the second region 15 is disposed on the side of the second doped semiconductor layer 13 away from the semiconductor substrate 11.

[0348] It is worth noting that the first doped semiconductor layer and the second doped semiconductor layer of the back contact battery are formed on local areas of the first surface in different operation steps. Furthermore, the patterned first and second doped semiconductor layers are obtained by selectively etching the entire layer of doped semiconductor layers during fabrication. Therefore, taking as an example an island-shaped passivation structure located on the side of the first doped semiconductor layer away from the semiconductor substrate in the first region, and an island-shaped passivation structure located between the second doped semiconductor layer and the semiconductor substrate in the second region: In this case, the first doped semiconductor layer can be fabricated first, and the island-shaped passivation structure located between the second doped semiconductor layer and the semiconductor substrate can be fabricated based on the portion of the doped semiconductor material of the first doped semiconductor layer located in the second region. Simultaneously, after forming the first doped semiconductor layer and the island-shaped passivation structure in the second region, the second doped semiconductor layer can be fabricated, and the island-shaped passivation structure located on the side of the first doped semiconductor layer away from the semiconductor substrate can be fabricated based on the portion of the doped semiconductor material of the second doped semiconductor layer located in the first region. This improves the manufacturing efficiency of the back contact battery and simplifies the manufacturing process.

[0349] It should be noted that, taking the example of an island-shaped passivation structure disposed on the side of the first doped semiconductor layer away from the semiconductor substrate in the first region, and an island-shaped passivation structure disposed in the second region between the second doped semiconductor layer and the semiconductor substrate: Structurally, in the island-shaped passivation structure disposed on the side of the first doped semiconductor layer away from the semiconductor substrate, if the back contact cell does not include the second interface passivation layer and the second doped silicon glass layer, then at least one island-shaped passivation structure may only include a doped semiconductor passivation portion, and the material and conductivity type of the doped semiconductor passivation portion may be the same as the material and conductivity type of the second doped semiconductor layer. If the back contact cell includes the second interface passivation layer, then at least one island-shaped passivation structure may only include an interface passivation portion, and the material of the interface passivation portion may be the same as the material of the second interface passivation layer; or, at least one island-shaped passivation structure may include an interface passivation portion and a doped semiconductor passivation portion, the material of the interface passivation portion may be the same as the material of the second interface passivation layer, and the material and conductivity type of the doped semiconductor passivation portion may be the same as the material and conductivity type of the second doped semiconductor layer, respectively. Furthermore, if the back contact cell also includes a second doped silicon glass layer, then at least one island passivation structure may include only an interface passivation portion or only an interface passivation portion and a doped semiconductor passivation portion (when the back contact cell does not include a second interface passivation layer, it only includes a doped semiconductor passivation portion), or at least one island passivation structure may include an interface passivation portion, a doped semiconductor passivation portion, and a doped silicon glass portion (when the back contact cell does not include a second interface passivation layer, it includes a doped semiconductor passivation portion and a doped silicon glass portion), and the material and conductivity type of the doped silicon glass portion may be the same as the material and conductivity type of the second doped silicon glass layer. Additionally, in the island passivation structure disposed between the second doped semiconductor layer and the semiconductor substrate, if the back contact cell does not include a first interface passivation layer and a first doped silicon glass layer, then at least one island passivation structure may include only a doped semiconductor passivation portion, and the material and conductivity type of the doped semiconductor passivation portion may be the same as the material and conductivity type of the first doped semiconductor layer. If the back contact battery includes a first interface passivation layer, then at least one island-shaped passivation structure may consist only of an interface passivation portion, and the material of the interface passivation portion may be the same as the material of the first interface passivation layer; alternatively, at least one island-shaped passivation structure may include an interface passivation portion and a doped semiconductor passivation portion, the material of the interface passivation portion may be the same as the material of the first interface passivation layer, and the material of the doped semiconductor passivation portion may be the same as the material of the first doped semiconductor layer (in this case, the conductivity type of the doped semiconductor passivation portion can be determined based on its own thickness, as well as the material and formation temperature of the second doped semiconductor layer. For example, when the thickness of the doped semiconductor passivation portion is small and the formation temperature of the second doped semiconductor layer is high, due to inward expansion, the conductivity type of the doped semiconductor passivation portion may be opposite to the conductivity type of the first doped semiconductor layer).Furthermore, if the back contact cell also includes a first doped silicon glass layer, then at least one island-shaped passivation structure may include only an interface passivation portion or only an interface passivation portion and a doped semiconductor passivation portion (when the back contact cell does not include the first interface passivation layer, it only includes the doped semiconductor passivation portion), or at least one island-shaped passivation structure may include an interface passivation portion, a doped semiconductor passivation portion, and a doped silicon glass portion (when the back contact cell does not include the first interface passivation layer, it includes the doped semiconductor passivation portion and the doped silicon glass portion), and the material of the doped silicon glass portion may be the same as the material of the first doped silicon glass layer. (In this case, the conductivity type of the doped silicon glass portion can be determined based on its own thickness, as well as the material and formation temperature of the second doped semiconductor layer. For example, when the thickness of the doped silicon glass portion is small and the formation temperature of the second doped semiconductor layer is high, due to the inward expansion, the conductivity type of the doped silicon glass portion may be opposite to the conductivity type of the first doped semiconductor layer.)

[0350] It should be noted that this explanation is based on the simultaneous fabrication of an island-shaped passivation structure located on the side of the first doped semiconductor layer away from the semiconductor substrate and a corresponding structure disposed in the second region, and the simultaneous fabrication of an island-shaped passivation structure disposed between the second doped semiconductor layer and the semiconductor substrate and a corresponding structure disposed in the first region. When the island-shaped passivation structures are fabricated separately, the specific structure and materials of the island-shaped passivation structures can be referred to the previous text, and will not be repeated here.

[0351] For the island passivation structure disposed in the first region between the first doped semiconductor layer and the semiconductor substrate, and the island passivation structure disposed in the second region on the side of the second doped semiconductor layer away from the semiconductor substrate, the specific situation of the island passivation structure can be referred to the analysis above regarding the case where the island passivation structure disposed in the first region is located on the side of the first doped semiconductor layer away from the semiconductor substrate, and the island passivation structure disposed in the second region between the second doped semiconductor layer and the semiconductor substrate, which will not be repeated here.

[0352] In some examples, as shown in Figures 37 to 40, where the first surface also includes a spacer region 16 located between the first region 14 and the second region 15, the surface of the spacer region 16 is recessed into the semiconductor substrate 11 relative to the surface of the first region 14 along the direction from the first surface to the second surface to form a groove structure 17. The groove structure 17 has a first sidewall 22 near the first region 14 and a third sidewall 23 near the second region 15. A first doped semiconductor layer 12 has a first boundary 41 near the spacer region 16. A second doped semiconductor layer 13 has a second boundary 42 near the spacer region 16. At least one island passivation structure 27 is at least partially located between the first boundary 41 and the first sidewall 22; and / or, at least one island passivation structure 27 is at least partially located between the second boundary 42 and the third sidewall 23. Passivation of the surface of the region on the semiconductor substrate 11 where the island passivation structure 27 is formed reduces the number of defects on the surface of the region and reduces the carrier recombination rate. In addition, the island-shaped passivation structure 27 can change the transmission path of incident light (such as increasing the reflection path of incident light), which is beneficial for more incident light to be refracted into the battery, increasing the incident light absorption ratio and improving the bifaciality of the back contact battery. The island-shaped passivation structure 27 is not part of the semiconductor substrate 11; it is an additional passivation structure disposed on the semiconductor substrate 11 and has an island-shaped shape.

[0353] In terms of surface height, the surface of the spacer region is recessed into the semiconductor substrate relative to the surface of the first region. The depth of the groove structure within the spacer region can be set according to actual needs and is not specifically limited here. Furthermore, the first and third sidewalls of the groove structure can be perpendicular to the bottom surface of the groove, or they can be inclined relative to the bottom surface of the groove. The first and third sidewalls can be planar or textured surfaces. When the first and / or third sidewalls are textured surfaces, this embodiment does not specifically limit the type and size of the textured structure provided on the first and / or third sidewalls.

[0354] As for the surface of the second region, it can be flush with the surface of the first region; or, as shown in FIG. 41, along the direction from the first surface to the second surface, the surface of the second region 15 can also be recessed into the semiconductor substrate 11 relative to the surface of the first region 14, in order to reduce the residue remaining on the second region 15 after the patterned first doped semiconductor layer 12, reduce the risk of leakage current, and improve the formation quality of the second doped semiconductor layer 13. In this case, the surface of the second region 15 can be flush with the surface of the spacer region 16; or, as shown in FIG. 41, the surface of the second region 15 can also be higher than the bottom surface of the trench of the spacer region 16. As for the depth of the recess of the surface of the second region 15 into the semiconductor substrate 11, it can be set according to actual needs and is not specifically limited here.

[0355] In terms of boundary morphology, the first sidewall defining the spacing region has a third boundary, and the third sidewall has a fourth boundary. The morphology of the third and fourth boundaries can be determined based on the process method used to form the groove structure in the semiconductor substrate in the actual application scenario, and no specific limitation is made here.

[0356] For example, the third and / or fourth boundaries can be straight lines along the extension direction of the interval region. Alternatively, as shown in Figures 38 and 39, the first sidewall 22 can also have a third alternating concave-convex structure, and / or, as shown in Figure 40, the third sidewall 23 can also have a fourth alternating concave-convex structure; the third and / or fourth alternating concave-convex structures can be serrated, trapezoidal, or wavy, etc. The third and / or fourth alternating concave-convex structures can be periodic structures with a certain regularity, or they can be irregular non-periodic structures with micro-fluctuations and macro-level roughly alternating concave-convex structures. The dimensions and morphologies of the concave and convex portions along the extension direction and width direction of the interval region 16 in the third and / or fourth alternating concave-convex structures can be set according to actual needs, and are not specifically limited here.

[0357] In terms of edge morphology, as shown in Figures 37 to 41, the morphology of the first boundary 41 of the first doped semiconductor layer 12 and / or the second boundary 42 of the second doped semiconductor layer 13 along the width direction of the spacer region 16 can be determined based on the manufacturing process of the first doped semiconductor layer 12 and the second doped semiconductor layer 13, as well as the distribution of the island passivation structure 27 included in the back contact battery on the semiconductor substrate 11, and is not specifically limited here.

[0358] For example, the first boundary and / or the second boundary can be straight. Alternatively, as shown in Figures 38 and 39, the first boundary 41 can also have a first alternating concave-convex structure, and / or, as shown in Figure 40, the second boundary 42 can also have a second alternating concave-convex structure; the first alternating concave-convex structure and / or the second alternating concave-convex structure can be serrated, trapezoidal, or wavy, etc. The first alternating concave-convex structure and / or the second alternating concave-convex structure can be a periodic structure with a certain regularity, or it can be an irregular non-periodic structure with micro-fluctuations and macro-level roughly alternating concave-convex structures. The dimensions and morphologies of the concave and convex portions in the first alternating concave-convex structure and / or the second alternating concave-convex structure along the extension direction and width direction of the interval region 16 can be set according to actual needs, and are not specifically limited here.

[0359] When the first sidewall has a third alternating concave-convex structure along the extension direction of the interval region, the correspondence between the concave and convex parts in the first and third alternating concave-convex structures can be determined according to the size of the island passivation structure and the leakage prevention requirements of the back contact battery in the actual application scenario, and no specific limitation is made here.

[0360] For example, as shown in Figures 38 and 39, at least some of the protrusions in the third alternating concave-convex structure are staggered with the adjacent protrusions in the first alternating concave-convex structure. It is advantageous to provide island-shaped passivation structures 27 on the portions where the protrusions or concave parts of the third alternating concave-convex structure intersect with the concave or convex parts of the first alternating concave-convex structure. This increases the bifaciality of the battery while simultaneously allowing the first doped semiconductor layer 12 to have a larger area ratio in the first region 14, enhancing the field passivation effect and carrier collection capability of the first doped semiconductor layer 12. The number and distribution of protrusions in the third alternating concave-convex structure that are staggered with the adjacent protrusions in the first alternating concave-convex structure can be determined based on the size and distribution of the island-shaped passivation structures 27 located in the first region 14 in the actual application scenario, and are not specifically limited here. Of course, at least some of the protrusions in the third alternating concave-convex structure may also have the same protrusion trend as the adjacent protrusions in the first alternating concave-convex structure.

[0361] For example, as shown in FIG40, when the third sidewall 23 has a fourth alternating concave-convex structure, at least some of the protrusions in the fourth alternating concave-convex structure can be staggered with adjacent protrusions in the second alternating concave-convex structure. The application principle of the beneficial effect in this case can be referred to the previous text, and will not be repeated here. The number and distribution of protrusions in the fourth alternating concave-convex structure that are staggered with adjacent protrusions in the second alternating concave-convex structure can be determined according to the size and distribution of the island-shaped passivation structure 27 located on the second region 15 in the actual application scenario, and are not specifically limited here. Of course, at least some of the protrusions in the fourth alternating concave-convex structure may also have the same protrusion trend as adjacent protrusions in the second alternating concave-convex structure.

[0362] In some cases, as shown in Figures 38 and 39, the first boundary 41 may have a first sub-boundary 18 located within the first region 14 and spaced apart from the first sidewall 22 along the width direction of the spacer region 16, with an island-shaped passivation structure 27 disposed between at least one first sub-boundary 18 and the first sidewall 22. And / or, as shown in Figure 40, the second boundary 42 has a third sub-boundary 43 located within the second region 15 and spaced apart from the third sidewall 23 along the width direction of the spacer region 16, with an island-shaped passivation structure 27 disposed between at least one third sub-boundary 43 and the third sidewall 23.

[0363] As shown in Figures 38 and 39, taking a first sub-boundary 18 located within the first region 14 and spaced apart from the first sidewall 22 of the groove structure 17 along the width direction of the spacing region 16 as an example: When the first boundary 41 also includes the first sub-boundary 18, along the width direction of the spacing region 16, there is not only a spacing region 16 between the portion of the first doped semiconductor layer 12 corresponding to the first sub-boundary 18 and the second doped semiconductor layer 13, but also, because the first sub-boundary 18 is spaced apart from the first sidewall 22 of the groove structure 17, in other words, the portion of the first doped semiconductor layer 12 corresponding to the first sub-boundary 18 is recessed into the first region 14 relative to the first sidewall 22 of the groove structure 17. Therefore, the distance between the first doped semiconductor layer 12 and the second doped semiconductor layer 13 can be increased, further reducing the risk of leakage between them. In addition, the island passivation structure 27 is disposed on the part of the first region 14 that is not directly covered by the first doped semiconductor layer 12. This can reduce the impact of the presence of the island passivation structure 27 on the quality and precision requirements of the conductive electrode formed on the first doped semiconductor layer 12. At the same time, the presence of the island passivation structure 27 can passivate the local surface in the first region 14 of the semiconductor substrate 11 that has a large number of surface defects and a high passivation requirement, which is beneficial to reducing the carrier recombination rate of the local surface and improving the conversion efficiency of the back contact battery.

[0364] The distribution range and location of the first and third sub-boundaries within the first and second boundaries, respectively, can be determined based on the size and distribution of the island-shaped passivation structures located in the first and second regions in the actual application scenario; no specific limitations are made here.

[0365] For example, as shown in Figures 38 and 39, when the first boundary 41 has a first alternating concave-convex structure, the boundary of at least a portion of the concave portion in the first alternating concave-convex structure can be a first sub-boundary 18; and / or, as shown in Figure 40, when the second boundary 42 has a second alternating concave-convex structure, the boundary of at least a portion of the concave portion in the second alternating concave-convex structure can be a third sub-boundary 43.

[0366] Taking the example of a first boundary having a first concave-convex alternating structure, and the boundary of at least a portion of the concave portion in the first concave-convex alternating structure being a first sub-boundary: the first sub-boundary of the first doped semiconductor layer disposed in the first region is opposite to at least a portion of the concave portion in the first concave-convex alternating structure. This is beneficial to make the concave-convex alternating structure of the first boundary more matched with the fluctuation change of the portion of the first doped semiconductor layer that is recessed into the first region. This can reduce the amount of etching required on the semiconductor substrate to make the first boundary of the first doped semiconductor layer have a certain degree of light absorption, which is beneficial to increase the light absorption area of ​​the semiconductor substrate and improve the conversion efficiency of the back contact battery.

[0367] In practical applications, as shown in Figures 38 and 39, only a portion of the concave boundaries in the first alternating concave-convex structure can be the first sub-boundary 18. In this case, some concave boundaries are aligned with the first sidewall 22 of the groove structure 17. Alternatively, some concave boundaries in the first alternating concave-convex structure can extend above the groove structure 17. Of course, all concave boundaries in the first alternating concave-convex structure can also be the first sub-boundary 18.

[0368] As shown in Figures 38, 39, and 8, the convex portion in the first alternating concave-convex structure may be at least partially extended along the width direction of the interval region to the top of the groove structure; or, in the first alternating concave-convex structure, a portion of the convex boundary may be aligned with the first sidewall 22 of the groove structure; or, in the first alternating concave-convex structure, a portion of the convex boundary may be located within the first region (i.e., a portion of the convex boundary may be the first sub-boundary 18); of course, all the convex boundaries in the first alternating concave-convex structure may extend along the width direction of the interval region to the top of the groove structure.

[0369] When the first doped semiconductor layer is partially suspended above the groove structure corresponding to at least a portion of the protrusion, it is beneficial to reflect a portion of the light emitted from the first surface of the semiconductor substrate back to the semiconductor substrate and reuse it, thereby improving the light utilization rate of the back contact cell.

[0370] As for the second concave-convex alternating structure, as shown in Figure 40, only some of the concave boundaries in the second concave-convex alternating structure can be third sub-boundaries 43. In this case, some concave boundaries are aligned with the third sidewall 23 of the groove structure. Alternatively, some concave boundaries in the second concave-convex alternating structure can extend to the top of the groove structure. Of course, all concave boundaries in the second concave-convex alternating structure can be third sub-boundaries 43.

[0371] As shown in Figure 40, the convex parts in the second alternating concave-convex structure may be at least partially extended along the width direction of the interval region to the top of the groove structure; or, in the second alternating concave-convex structure, some convex boundary parts may be aligned with the third sidewall 23 of the groove structure; or, in the second alternating concave-convex structure, some convex boundary parts may be located within the second region (i.e., some convex boundary parts may be the third sub-boundary 43); of course, all convex boundary parts in the second alternating concave-convex structure may extend along the width direction of the interval region to the top of the groove structure.

[0372] The application principle of the beneficial effect when the second doped semiconductor layer is partially suspended above the groove structure corresponding to at least a portion of the protrusion can be referred to the application principle of the beneficial effect when the first doped semiconductor layer is partially suspended above the groove structure, as described above, and will not be repeated here.

[0373] As for the extension width of at least one protrusion in the first alternating concave-convex structure relative to the first sidewall above the groove structure, and / or the extension width of at least one protrusion in the second alternating concave-convex structure relative to the third sidewall above the groove structure, it can be determined according to the requirements of the bifaciality and leakage risk of the back contact battery in the actual application scenario, and no specific limitation is made here.

[0374] For example, the extension width of at least one protrusion in the first alternating concave-convex structure relative to the first sidewall above the groove structure may be less than or equal to 1 μm. For instance, the extension width of at least one protrusion in the first alternating concave-convex structure relative to the first sidewall above the groove structure may be 5 nm, 10 nm, 100 nm, 200 nm, 300 nm, 500 nm, 800 nm, or 1 μm, etc., to further improve the bifaciality of the back contact battery while making the back contact battery have a lower risk of leakage.

[0375] For example, the extension width of at least one protrusion in the second alternating concave-convex structure relative to the third sidewall above the groove structure may be less than or equal to 1 μm. For instance, the extension width of at least one protrusion in the first alternating concave-convex structure relative to the first sidewall above the groove structure may be 5 nm, 10 nm, 100 nm, 200 nm, 300 nm, 500 nm, 800 nm, or 1 μm, etc., to further improve the bifaciality of the back contact battery while ensuring a lower risk of leakage.

[0376] For example, as shown in Figures 38 and 39, the portion of the first region 14 near the first sidewall 22 and not directly covered by the first doped semiconductor layer 12 is a plateau region 24, and / or, as shown in Figure 40, the portion of the second region 15 near the third sidewall 23 and not directly covered by the second doped semiconductor layer 13 is a plateau region 24. It should be noted that the term "plateau region 24" is a broad term, specifically referring to a region, namely, the region of the first region 14 near the first sidewall 22 and not directly covered by the first doped semiconductor layer 12, and / or the region of the second region 15 near the third sidewall 23 and not directly covered by the second doped semiconductor layer 13.

[0377] As shown in Figures 38 to 40, the platform region 24 may include a platform surface 25 that is approximately parallel to the first surface. In this case, the surface of the portion of the first region 14 of the semiconductor substrate 11 that is not directly covered by the first doped semiconductor layer 12 and / or the portion of the second region 15 that is not directly covered by the second doped semiconductor layer 13 (i.e., the platform region 24) is relatively flat. On the one hand, as a transition region between the first region 14 or the second region 15 and the spacer region 16, it can effectively reduce the risk of leakage. Moreover, by setting island-shaped passivation structures 27 in at least a portion of the platform region 24, the surface of the platform region 24 with island-shaped passivation structures 27 can be passivated, reducing the number of defects on the surface of the region and reducing the carrier recombination rate. On the other hand, the platform surface 25 of the platform region 24 increases the light absorption area, promotes the diversification of the light absorption surface morphology, and by setting island-shaped passivation structures 27 in at least a portion of the platform region 24, the island-shaped passivation structures 27 enhance light absorption, thereby comprehensively improving the light utilization rate of the back contact battery. It should be noted that if the angle between the platform surface 25 included in the platform area 24 and the other surfaces of the first surface is less than or equal to 5°, the platform surface 25 can be considered to be approximately parallel to the first surface.

[0378] Alternatively, the platform area includes a platform surface that forms an angle (greater than 5° and less than the inclination angle of the first and / or third sidewalls relative to the bottom of the tank) with respect to the first surface. Furthermore, the surface included in the platform area can be a relatively flat platform surface, or an uneven surface with a pyramidal or perforated structure. The morphology of the surface included in the platform area can be set according to actual needs and is not specifically limited here.

[0379] In terms of distribution location, when the first boundary has a first alternating concave-convex structure and the first region has a platform area, the platform area can be located between at least a portion of the concave portion and the first sidewall in the first alternating concave-convex structure. Alternatively, as shown in Figures 38 and 39, the platform area 24 can be located below at least a portion of the convex portion in the first alternating concave-convex structure. Or, the platform area 24 can also exist between the concave portion and the first sidewall 22 in the first alternating concave-convex structure, and below at least a portion of the convex portion in the first alternating concave-convex structure. The specific distribution of the platform area 24 can be set according to actual needs and is not specifically limited here.

[0380] As for the case where the second boundary has a second alternating concave-convex structure and the second region has a platform area, the distribution of the platform area in the second region can be referred to the distribution of the platform area in the case where the first boundary has a first alternating concave-convex structure and the first region has a platform area, as described above, and will not be repeated here.

[0381] As shown in Figures 38 and 40, at least one island-shaped passivation structure 27 of the back contact battery can be at least partially disposed on the platform surface 25 of the platform region 24. In this case, the size of the platform surface 25 of the platform region 24 will affect the size of the island-shaped passivation structure 27. Therefore, the size and morphology of the platform surface 25 of the platform region 24 can be determined according to the size requirements of the island-shaped passivation structure 27 in the actual application scenario, and no specific limitation is made here.

[0382] For example, along the width direction of the spacer region, the width of the platform surface included in at least one platform region is less than or equal to 1 μm. For example, the width of the platform surface included in at least one platform region can be 10 nm, 50 nm, 100 nm, 300 nm, 500 nm, 800 nm, or 1 μm, etc. In this case, taking the portion of the first region near the first sidewall that is not directly covered by the first doped semiconductor layer as an example, it can be understood that the larger the width of the platform surface included in the platform region, the larger the distance between the portion of the first doped semiconductor layer corresponding to the platform region and the spacer region, and the smaller the area ratio of the first doped semiconductor layer in the first region. Therefore, when the width of the platform surface included in at least one platform region is within the above range, it is beneficial to improve the bifaciality and passivation effect of the back contact cell through the island-like passivation structure, while making the first doped semiconductor layer have a large area ratio in the first region, thereby benefiting the first doped semiconductor layer to have a higher field passivation effect and carrier collection capability, and thus benefiting the back contact cell to have a higher conversion efficiency.

[0383] In terms of surface height, as shown in Figure 42, the platform surface 25 included in the platform area 24 can be flush with the first surface.

[0384] Alternatively, as shown in Figures 9 to 14, when the first region 14 has a platform region 24, at least one platform region 24 further includes a second sidewall 26 that is remote from the first sidewall 22 and continuous with the platform surface 25; and / or, when the second region 15 has a platform region 24, at least one platform region 24 further includes a second sidewall 26 that is remote from the third sidewall 23 and continuous with the platform surface 25. The second sidewall 26 is disposed perpendicular to the platform surface 25, or the second sidewall 26 is disposed obliquely to the platform surface 25.

[0385] Taking a first region having a platform region, and the platform region also including a second sidewall as an example: the platform region also includes a second sidewall that is continuous with the platform surface, indicating that along the direction from the first surface to the second surface, the platform surface is recessed into the semiconductor substrate relative to the surface of the region in the first region that is directly covered by the first doped semiconductor layer. This can reduce the height variation between the bottom surface of the groove structure and the surface of the region with a larger height in the first region, which is beneficial to the formation quality and coverage of the surface passivation layer at the junction of the first region and the spacer region, reduces the carrier recombination rate at the junction of the first region and the spacer region, enhances the diversity of the light absorption surface morphology, and improves the light utilization rate of the back contact cell.

[0386] When the platform region also includes a second sidewall, as shown in Figures 39 and 40, at least one island-shaped passivation structure 27 may be disposed only on the platform surface 25 of the platform region 24. Alternatively, as shown in Figure 38, at least one island-shaped passivation structure 27 may extend from the platform surface 25 to at least a portion of the second sidewall 26. In this case, it is advantageous to increase the passivation contact area of ​​the island-shaped passivation structure 27 on the first side, thereby improving the passivation effect of the island-shaped passivation structure 27. Furthermore, it is also advantageous to increase the surface area of ​​the island-shaped passivation structure 27 on the side facing away from the semiconductor substrate 11, thereby enhancing the light-trapping effect of the first side on which the island-shaped passivation structure 27 is disposed. The extension range of the island-shaped passivation structure 27 on the second sidewall 26 can be set according to actual needs and is not specifically limited here.

[0387] When the platform region also includes a second sidewall, a portion of the sidewalls of the first doped semiconductor layer and / or the second doped semiconductor layer may be aligned with the second sidewall of at least one adjacent platform region. Alternatively, as shown in Figures 40, 9 to 14, a portion of the first boundary 41 and / or the second boundary 42 may extend above the platform surface 25. In this case, when a portion of the sidewalls of the first doped semiconductor layer 12 and / or the second doped semiconductor layer 13 are aligned with the second sidewall 26 of at least one adjacent platform region 24, it is advantageous to increase the relatively large spacing between the first doped semiconductor layer 12 and the second doped semiconductor layer 13, which is beneficial to further reduce the leakage risk between them. When a portion of the first boundary 41 and / or the second boundary 42 can extend above the platform surface 25, taking the first region 14 having a platform region 24 and a portion of the first boundary 41 extending above the platform surface 25 included in the platform region 24 as an example: Although the distance between this portion of the first boundary 41 and the second doped semiconductor layer 13 is relatively small, the portion of the first doped semiconductor layer 12 corresponding to this portion of the first boundary 41 can reflect a portion of the light emitted from the platform surface 25 and / or reflected from the outer surface of the island passivation structure 27, so that a portion of the light can re-enter the semiconductor substrate 11, further improving the light utilization rate of the back contact battery.

[0388] Furthermore, as shown in Figures 39 and 40, the first doped semiconductor layer 12 and the island passivation structure 27 can be spaced apart, which facilitates light transmission between the outer surface of the island passivation structure 27 and the inner surface of the portion of the first doped semiconductor layer 12 extending above the platform surface 25. This alters the transmission path of the incident light, allowing more incident light to refract into the battery, increasing the incident light absorption ratio, and further improving the bifaciality of the back contact battery. Moreover, when the island passivation structure 27 includes a doped semiconductor passivation portion with a conductivity type opposite to that of the first doped semiconductor layer 12, the spaced distribution of the first doped semiconductor layer 12 and the island passivation structure 27 also helps reduce the leakage risk between them, resulting in higher conversion efficiency for the back contact battery. Secondly, when the second boundary 42 extends above the platform surface 25, the second doped semiconductor layer 13 and the island passivation structure 27 can also be spaced apart. The beneficial effects in this case can be found above and will not be repeated here.

[0389] Of course, when an island passivation structure is provided in the first region, the sidewalls of the first doped semiconductor layer and the sidewalls of the island passivation structure can also be adjacent to each other; and / or, when an island passivation structure is provided in the second region, the sidewalls of the second doped semiconductor layer and the sidewalls of the island passivation structure can also be adjacent to each other.

[0390] As for the height of the second sidewall, the spacing between the corresponding doped semiconductor layer and the island passivation structure, and the extension width of the first boundary and / or the second boundary above the platform surface, when part of the first boundary and / or the second boundary extends above the platform surface, can be determined according to the requirements of the bifaciality and leakage risk of the back contact battery in the actual application scenario, and no specific limitation is made here.

[0391] For example, along the thickness direction of the semiconductor substrate, the height of the second sidewall is greater than or equal to 0.05 μm and less than or equal to 8 μm. For instance, the height of the second sidewall can be 0.05 μm, 0.1 μm, 1 μm, 2 μm, 3 μm, 5 μm, 6 μm, 7 μm, or 8 μm, etc. A height within the above range for the second sidewall helps prevent a large height variation between the bottom surface of the groove structure and the surface of the region with greater height in the first region (and / or the second region) due to a small second sidewall height. This further improves the passivation effect of the surface passivation layer at the junction of the first region and the spacer region, and / or at the junction of the second region and the spacer region. Additionally, it prevents a large etching amount in the portion of the semiconductor substrate corresponding to the platform region due to a large third sidewall height, which helps to achieve a larger light absorption depth in the portion of the semiconductor substrate corresponding to the platform region, thereby improving the light utilization rate of the semiconductor substrate and further improving the conversion efficiency of the back contact cell.

[0392] For example, when a portion of the first boundary extends above the platform surface included in the platform region, the spacing between the first doped semiconductor layer and the island passivation structure is greater than or equal to 1 nm and less than or equal to 500 nm along the thickness direction of the semiconductor substrate. And / or, when a portion of the second boundary extends above the platform surface included in the platform region, the spacing between the second doped semiconductor layer and the island passivation structure is greater than or equal to 1 nm and less than or equal to 500 nm along the thickness direction of the semiconductor substrate. Taking the spacing between the first doped semiconductor layer and the island passivation structure within the above range as an example, it facilitates effective light transmission between the outer surface of the island passivation structure and the inner surface of the portion of the first doped semiconductor layer extending above the platform surface, allowing these two portions to effectively cooperate in changing the transmission path of the incident light, further improving the absorption ratio of the incident light. Furthermore, with other factors remaining the same, when the spacing between the first doped semiconductor layer and the island passivation structure increases, the etching amount of the portion of the semiconductor substrate corresponding to the plateau region is larger. Therefore, within the above-mentioned range, the spacing between the first doped semiconductor layer and the island passivation structure can also enable the portion of the semiconductor substrate corresponding to the plateau region to have a larger absorption depth, thereby improving the utilization rate of light by the semiconductor substrate.

[0393] For example, when a portion of the first boundary extends above the platform surface included in the platform region, the extension width of the first boundary relative to the second sidewall is less than or equal to 1 μm along the width direction of the spacing region. And / or, when a portion of the second boundary extends above the platform surface included in the platform region, the extension width of the second boundary relative to the second sidewall is less than or equal to 1 μm along the width direction of the spacing region. Taking the example of a portion of the first boundary extending above the platform surface included in the platform region and the extension width being within the above range: this can prevent the extended portion of the first doped semiconductor layer from having a weak light reflection effect due to an excessively small extension width, which is beneficial for further improving the bifaciality of the back contact battery.

[0394] For example, when a portion of the first boundary extends above the platform surface included in the platform region, the extension width of the first boundary relative to the second sidewall can be greater than or equal to 10 nm along the width direction of the spacing region. And / or, when a portion of the second boundary extends above the platform surface included in the platform region, the extension width of the second boundary relative to the second sidewall can be greater than or equal to 10 nm along the width direction of the spacing region. Taking the example of a portion of the first boundary extending above the platform surface included in the platform region and the extension width being within the above range: this can prevent the manufacturing process of the back contact battery from becoming too difficult due to excessive extension width, and the reduction in leakage risk between the extended portion of the first doped semiconductor layer and the second doped semiconductor layer is small, which is beneficial to further improve the conversion efficiency and yield of the contact battery.

[0395] For example, if a portion of the first boundary extends above the platform surface included in the platform region, the extension width of the first boundary relative to the second sidewall can be 10nm, 20nm, 50nm, 100nm, 200nm, 500nm, 800nm, or 1μm, etc., along the width direction of the interval region.

[0396] For example, if a portion of the second boundary extends above the platform surface included in the platform region, the extension width of the second boundary relative to the second sidewall along the width direction of the interval region can be 10nm, 20nm, 50nm, 100nm, 200nm, 500nm, 800nm, or 1μm, etc.

[0397] Information regarding the morphology, size, area, structure, and materials of the island passivation structures disposed between the first boundary and the first sidewall, and / or between the second boundary and the first sidewall, can be found in the information described above regarding the island passivation structures disposed on the side of the first doped semiconductor layer and / or the second doped semiconductor layer away from the semiconductor substrate, and / or between the first doped semiconductor layer and / or the second doped semiconductor layer and the semiconductor substrate. Further details are omitted here.

[0398] The method for fabricating the back contact battery in this embodiment can refer to Embodiments A and B, as well as any existing method that can be used to fabricate a back contact battery, and is not limited thereto. An island-like passivation structure is formed on the side of the first doped semiconductor layer and / or the second doped semiconductor layer away from the semiconductor substrate, and / or between the first doped semiconductor layer and the semiconductor substrate and / or between the second doped semiconductor layer and the semiconductor substrate. This can be achieved using a patterning step of the doped semiconductor layer. Taking the fabrication of the first doped semiconductor layer followed by the second doped semiconductor layer as an example. If it is necessary to form an island-like passivation structure between the second doped semiconductor layer and the semiconductor substrate, the doping concentration of the first doped semiconductor layer can be increased to make it more difficult to remove, thus forming an island-like passivation structure; the laser conditions used for patterning can also be adjusted, such as the size of the overlapping portion of the laser spot, which corresponds to the formation of an island-like passivation structure; the wet etching used for patterning can also be adjusted by adjusting the concentration of the reaction solution and the reaction time to form an island-like passivation structure; one or more of the above three methods can be used in combination. Similarly, if an island-shaped passivation structure is required on the side of the first doped semiconductor layer away from the semiconductor substrate, the doping concentration of the second doped semiconductor layer can be increased to make it more difficult to remove, thus forming an island-shaped passivation structure. Alternatively, the laser conditions used for patterning can be adjusted, such as the size of the overlapping laser spot, which corresponds to the formation of an island-shaped passivation structure. Wet etching used for patterning can also be adjusted by modifying the reaction solution concentration and reaction time to form an island-shaped passivation structure. One or more of these three methods can be used in combination. When the first doped semiconductor layer is prepared first, followed by the second doped semiconductor layer, if an island-shaped passivation structure is required between the first doped semiconductor layer and the semiconductor substrate, or if an island-shaped passivation structure is required on the side of the second doped semiconductor layer away from the semiconductor substrate, it can be formed through local deposition.

[0399] Taking the fabrication of a second doped semiconductor layer followed by a first doped semiconductor layer as an example. If an island-like passivation structure is required between the first doped semiconductor layer and the semiconductor substrate, the doping concentration of the second doped semiconductor layer can be increased to make it more difficult to remove, thus forming an island-like passivation structure. Alternatively, the laser conditions used for patterning, such as the size of the overlapping laser spot, can be adjusted to form an island-like passivation structure. Another method is to adjust the wet etching process used for patterning by adjusting the concentration of the reaction solution and the reaction time. One or more of these methods can be used in combination. Similarly, if an island-like passivation structure is required on the side of the second doped semiconductor layer away from the semiconductor substrate, the doping concentration of the first doped semiconductor layer can be increased to make it more difficult to remove, thus forming an island-like passivation structure. The laser conditions used for patterning, such as the size of the overlapping laser spot, can also be adjusted to form an island-like passivation structure. The wet etching process used for patterning can also be adjusted by adjusting the concentration of the reaction solution and the reaction time. One or more of these methods can be used in combination. When the second doped semiconductor layer is prepared first and the first doped semiconductor layer is prepared later, if it is necessary to form an island-shaped passivation structure between the second doped semiconductor layer and the semiconductor substrate, or if it is necessary to achieve an island-shaped passivation structure on the side of the first doped semiconductor layer away from the semiconductor substrate, the island-shaped passivation structure can be formed by local deposition.

[0400] Implementation Plan D

[0401] To improve the formation quality and field passivation effect of the doped semiconductor layer on the back side of the battery, existing back-contact batteries have a relatively flat surface on the back side. However, a flat surface has poor light-trapping effect, resulting in low utilization of incident light on the back side of the battery, which is not conducive to improving the bifaciality of the back-contact battery.

[0402] To further improve the back contact battery, this application also provides a back contact battery. It should be noted that, at least in embodiments A and C above, some content related to the back contact battery, particularly the island passivation structure, has been described. In this embodiment D, the same content will not be repeated. Those skilled in the art can refer to the relevant content in at least embodiments A and C to understand this embodiment D. As shown in Figures 43 and 38 to 40, the back contact battery includes: a semiconductor substrate 11, a first doped semiconductor layer 12, a second doped semiconductor layer 13, and an island passivation structure 27. The semiconductor substrate 11 has opposing first and second surfaces. The first surface includes alternately spaced first regions 14 and second regions 15, and a spacing region 16 located between the first regions 14 and the second regions 15. Along the direction from the first surface to the second surface, the surface of the spacing region 16 is recessed into the semiconductor substrate 11 relative to the surface of the first region 14 to form a groove structure 17. The groove structure 17 has a first sidewall 22 near the first region 14 and a third sidewall 23 near the second region 15. A first doped semiconductor layer 12 is disposed on a first region 14, and the first doped semiconductor layer 12 has a first boundary 41 adjacent to the spacer region 16. A second doped semiconductor layer 13 is disposed on a second region 15, and the second doped semiconductor layer 13 has an opposite conductivity type to the first doped semiconductor layer 12, and the second doped semiconductor layer 13 has a second boundary 42 adjacent to the spacer region 16. An island-shaped passivation structure 27 is disposed on the semiconductor substrate 11. At least one island-shaped passivation structure 27 is at least partially located between the first boundary 41 and the first sidewall 22; and / or, at least one island-shaped passivation structure 27 is at least partially located between the second boundary 42 and the third sidewall 23.

[0403] When the back contact cell is in operation, the first and second doped semiconductor layers can effectively shunt and collect carriers, which is beneficial for the formation of photocurrent. As shown in Figures 43 and 38 to 40, the island-shaped passivation structure 27 has a passivation function, which can passivate the surface of the region on the semiconductor substrate 11 where the island-shaped passivation structure 27 is formed, reducing the number of defects on the surface of the region and reducing the carrier recombination rate. In addition, the island-shaped passivation structure 27 can change the transmission path of incident light (such as increasing the reflection path of incident light), which is beneficial for more incident light to be refracted into the cell, increasing the incident light absorption ratio and improving the bifaciality of the back contact cell. The island-shaped passivation structure 27 is not part of the semiconductor substrate 11; it is an additional passivation structure on the semiconductor substrate 11 with an island-shaped shape. Taking at least one island-shaped passivation structure 27 located at least partially between the first boundary 41 and the first sidewall 22 as an example: the island-shaped passivation structure 27 is away from the surface of the semiconductor substrate 11 and has a certain height difference with the local surface of the semiconductor substrate 11 located between the first boundary 41 and the first sidewall 22. Alternatively, the island-shaped passivation structure 27 and the semiconductor substrate 11 have material differences, so that the side surface of the island-shaped passivation structure 27 can reflect or refract incident light on the first side of the back contact battery, change the transmission path of the incident light (such as increasing the reflection path of the incident light), which is beneficial for more incident light to be refracted into the battery, improve the incident light absorption ratio, and improve the bifaciality of the back contact battery.

[0404] Secondly, the semiconductor substrate includes a first surface and a second surface opposite to each other. The first surface of the semiconductor substrate corresponds to the back side of the back contact battery, and the second surface of the semiconductor substrate corresponds to the front side of the back contact battery. The distribution of the first region, the second region, and the spacer region on the first surface can be determined based on the distribution of the first doped semiconductor layer and the second doped semiconductor layer formed on the first surface. Specifically, since the first doped semiconductor layer of the back contact battery is at least partially disposed on the first region, the distribution range of the first region on the first surface can be determined based on the distribution requirements of the first doped semiconductor layer in the actual application scenario, as well as the leakage prevention requirements between the first and second doped semiconductor layers. Since the second doped semiconductor layer of the back contact battery is disposed on the second region of the first surface, the distribution range of the second region on the first surface can be determined based on the distribution requirements of the second doped semiconductor layer on the semiconductor substrate in the actual application scenario. As for the spacer region, after the distribution ranges of the first and second regions are determined, the distribution range of the spacer region on the first surface can be determined.

[0405] It is understandable that one of the first and second regions roughly corresponds to the emitter region, and the other to the back field region. In terms of specific conductivity type, one of the first and second regions roughly corresponds to the P-region, and the other roughly corresponds to the N-region.

[0406] The shapes of the first and second regions can be set according to actual needs, as long as they can be applied to the back contact battery provided in this application embodiment. For example, the first and second regions can be arranged in alternating stripes or in alternating interdigitated shapes.

[0407] The shapes of the first and second regions can be set according to actual needs, as long as they can be applied to the back contact battery provided in this application embodiment. For example, the first and second regions can be arranged in alternating stripes or in alternating interdigitated shapes.

[0408] In terms of surface morphology, as shown in Figure 43, the second surface of the semiconductor s...

Claims

1. A back-contact battery, comprising: A semiconductor substrate, the semiconductor substrate including a first surface and a second surface opposite to each other; the first surface including a first region and a second region that are alternately distributed, and a spacer region located between the first region and the second region; Along the direction from the first surface to the second surface, the surface of the interval region is recessed inward relative to the surface of the first region to form a groove structure; A first doped semiconductor layer is at least partially disposed on the first region; A second doped semiconductor layer is disposed on the second region; the second doped semiconductor layer has an opposite conductivity type to the first doped semiconductor layer. Wherein, along the extending direction of the spacing region, the first doped semiconductor layer includes a first boundary close to the spacing region; along the width direction of the spacing region, the first boundary includes a first sub-boundary located within the first region, and a second sub-boundary extending from the first region to above the groove structure and located above the groove structure.

2. The back contact battery according to claim 1, wherein, Along the extension direction of the interval region, within a unit length, the total length of the first sub-boundary located within the first region is greater than the total length of the second sub-boundary located above the groove structure.

3. The back contact battery according to claim 1, wherein, The first boundary of the first doped semiconductor layer near the spacing region has an alternating concave-convex structure, which includes concave boundaries and convex boundaries.

4. The back contact battery according to claim 3, wherein, The first sub-boundary includes at least a portion of the concave boundary, and the second sub-boundary includes at least a portion of the convex boundary.

5. The back contact battery according to claim 3, wherein, The first sub-boundary includes at least a portion of the concave boundary and at least a portion of the convex boundary; Alternatively, the second sub-boundary may include at least a portion of the concave boundary and at least a portion of the convex boundary.

6. The back contact battery according to claim 3, wherein, Along the extending direction of the interval region, the distance W1 between adjacent recess boundaries or adjacent convex boundaries is greater than or equal to 1 μm and less than or equal to 15 μm. And / or, along the width direction of the interval region, the extension width W2 of the first sub-boundary within the first region is less than or equal to 8 μm; And / or, along the width direction of the interval region, the extension width W3 of the second sub-boundary above the groove structure is less than or equal to 10 μm.

7. The back contact battery according to claim 1, wherein, The first side is the back side, the interval region has a first boundary region adjacent to the first region, the interval region has a second boundary region adjacent to the second region, and the first boundary region and / or the second boundary region has one or more pits.

8. The back contact battery according to claim 7, wherein, The pit includes closed pits and / or non-closed pits, wherein the sides of the closed pits are surrounded by the semiconductor substrate to form a closed structure, and the sides of the non-closed pits are partially surrounded by the semiconductor substrate to form a non-closed structure.

9. The back contact battery according to claim 8, wherein, The semiconductor substrate has prisms surrounding the sides forming the closed recesses and / or the non-closed recesses.

10. The back contact battery according to claim 9, wherein, At least one of the closed recesses' prisms abuts to form at least one abutment seam, and / or at least one of the non-closed recesses' prisms abuts to form at least one abutment seam.

11. The back contact battery according to any one of claims 8-10, wherein, The first boundary region has at least the closed recess; and / or the second boundary region has at least the non-closed recess.

12. The back contact battery according to claim 11, wherein, One or both of the first boundary region and the second boundary region have the closed pit and the non-closed pit.

13. The back contact battery according to any one of claims 8-10, wherein, The number of closed pits in the first boundary region is greater than the number of closed pits in the second boundary region; and / or The number of non-closed pits in the second boundary region is greater than the number of non-closed pits in the first boundary region.

14. The back contact battery according to claim 7, wherein, At least a portion of the recess has an extended brim of a corresponding doped semiconductor layer above it, and / or at least a portion of the recess has an exposed portion near the top that is not covered by the corresponding doped semiconductor layer.

15. The back contact battery according to claim 14, wherein, The first boundary region has at least a portion of the pit above an extended brim of the first doped semiconductor layer, and / or the second boundary region has at least a portion of the pit near the top that is not covered by the second doped semiconductor layer.

16. The back contact battery according to claim 15, wherein, The thickness of the semiconductor substrate in the first region is greater than the thickness of the semiconductor substrate in the second region.

17. The back contact battery according to any one of claims 8-10, wherein, The first doped semiconductor layer has an extension, and / or the second doped semiconductor layer has an extension, at least one of the first doped semiconductor layer and the second doped semiconductor layer overlaps with another doped semiconductor layer of the first doped semiconductor layer and the second doped semiconductor layer through its extension, the first boundary region further includes a first position where the spacing region is adjacent to the extension, or the second boundary region further includes a second position where the spacing region is adjacent to the extension.

18. The back contact battery according to claim 17, wherein, The total number of closed recesses at at least one corner of the first position or the second position is not less than the total number of unclosed recesses at the at least one corner.

19. The back contact battery according to any one of claims 8-10, wherein, The first boundary region includes a first sub-boundary region extending 50 μm from the edge of the first region away from the interval region toward the first region, and the second boundary region includes a second sub-boundary region extending 50 μm from the edge of the second region away from the interval region toward the second region, and the first sub-boundary region and / or the second sub-boundary region have one or more of the pits.

20. The back contact battery according to any one of claims 8-10, wherein, The sidewalls of the semiconductor substrate in the first boundary region and / or the second boundary region have a wavy, undulating structure in a direction perpendicular to the extension direction of the spacing region. The closed recess is located at a protruding position of the undulating structure, or the non-closed recess is located at a recessed position of the undulating structure.

21. The back contact battery according to claim 19, wherein, In the first sub-boundary region and / or the second sub-boundary region, the pits in the first sub-boundary region and the second sub-boundary region that are closer to the interval region have a larger diameter than the pits in the first sub-boundary region and the second sub-boundary region that are farther away from the interval region.

22. The back contact battery according to claim 1, wherein, The groove structure has a first sidewall near the first region and a third sidewall near the second region; The second doped semiconductor layer has a second boundary close to the spacer region; The back contact battery further includes an island-shaped passivation structure disposed on the semiconductor substrate; wherein at least one of the island-shaped passivation structures is at least partially located between the first boundary and the first sidewall; and / or, at least one of the island-shaped passivation structures is at least partially located between the second boundary and the third sidewall.

23. The back contact battery according to claim 22, wherein, At least one of the first sub-boundaries and the first sidewall is provided with the island-shaped passivation structure; And / or, the second boundary has a third sub-boundary located within the second region and spaced apart from the third sidewall along the width direction of the interval region, and at least one of the third sub-boundaries and the third sidewall is provided with the island-shaped passivation structure.

24. The back contact battery according to claim 22, wherein, The portion of the first region that is close to the first sidewall and is not directly covered by the first doped semiconductor layer is a plateau region, and / or the portion of the second region that is close to the third sidewall and is not directly covered by the second doped semiconductor layer is a plateau region; The platform region includes a platform surface that is substantially parallel to the first surface; at least one of the island-shaped passivation structures is disposed on the platform surface included in the platform region.

25. The back contact battery according to claim 24, wherein, Along the width direction of the interval region, at least one of the platform regions includes a platform surface with a width less than or equal to 1 μm.

26. The back contact battery according to claim 24, wherein, In the case where the first region has the platform area, at least one of the platform areas further includes a second sidewall that is remote from the first sidewall and continuous with the platform surface; and / or, in the case where the second region has the platform area, at least one of the platform areas further includes a second sidewall that is remote from the third sidewall and continuous with the platform surface; The second sidewall is either perpendicular to the platform surface or inclined to the platform surface.

27. The back contact battery according to claim 26, wherein, At least one of the island-shaped passivation structures also extends from the platform surface to at least a portion of the second sidewall; And / or, along the thickness direction of the semiconductor substrate, the height of the second sidewall is greater than or equal to 0.05 μm and less than or equal to 8 μm.

28. The back contact battery according to claim 26, wherein, In the case where the first region has the platform region, a portion of the first boundary also extends above the platform surface included in the platform region, and the first doped semiconductor layer and the island passivation structure are distributed at intervals. And / or, in the case where the second region has the platform region, a portion of the second boundary also extends above the platform surface included in the platform region, with the second doped semiconductor layer and the island passivation structure spaced apart.

29. The back contact battery according to claim 28, wherein, Where the first boundary extends above the platform surface included in the platform region, the spacing between the first doped semiconductor layer and the island passivation structure is greater than or equal to 1 nm and less than or equal to 500 nm along the thickness direction of the semiconductor substrate. And / or, where a portion of the second boundary also extends above the platform surface included in the platform region, the spacing between the second doped semiconductor layer and the island passivation structure is greater than or equal to 1 nm and less than or equal to 500 nm along the thickness direction of the semiconductor substrate.

30. The back contact battery according to claim 28, wherein, Where the first boundary extends above the platform surface included in the platform area, the extension width of the first boundary relative to the second sidewall is less than or equal to 1 μm along the width direction of the interval region. And / or, where a portion of the second boundary also extends above the platform surface included in the platform region, the extension width of the second boundary relative to the second sidewall is less than or equal to 1 μm along the width direction of the interval region.

31. The back contact battery according to claim 24, wherein, At least one of the island-shaped passivation structures accounts for more than 50% of the area within the platform region.

32. The back contact battery according to claim 23, wherein, The first boundary has a first concave-convex alternating structure, and the boundary of at least a portion of the concave portion in the first concave-convex alternating structure is the first sub-boundary. And / or, the second boundary has a second concave-convex alternating structure, and the boundary of at least a portion of the concave portion in the second concave-convex alternating structure is the third sub-boundary.

33. The back contact battery according to claim 32, wherein, At least a portion of the protrusions in the first alternating concave-convex structure and / or the second alternating concave-convex structure extend over the groove structure along the width direction of the interval region.

34. The back contact battery according to claim 33, wherein, In the first alternating concave-convex structure, at least one of the protrusions extends over the groove structure with a width of less than or equal to 1 μm relative to the first sidewall; And / or, at least one of the protrusions in the second alternating concave-convex structure extends over the groove structure with a width less than or equal to 1 μm relative to the third sidewall.

35. The back contact battery according to claim 32, wherein, Along the extending direction of the interval region, the first sidewall has a third alternating concave-convex structure, wherein at least some of the protrusions in the third alternating concave-convex structure are staggered with the adjacent protrusions in the first alternating concave-convex structure. And / or, along the extension direction of the interval region, the third sidewall has a fourth alternating concave-convex structure, wherein at least some of the protrusions in the fourth alternating concave-convex structure are staggered with the adjacent protrusions in the second alternating concave-convex structure.

36. The back contact battery according to claim 1, further comprising: An island-shaped passivation structure is disposed on the side of the first doped semiconductor layer and / or the second doped semiconductor layer away from the semiconductor substrate, and / or disposed between the first doped semiconductor layer and / or the second doped semiconductor layer and the semiconductor substrate.

37. The back contact battery according to claim 36, wherein, At least one of the island-shaped passivation structures includes a plurality of non-adjacent, clustered passivation portions; And / or, at least one of the different regions of the island-shaped passivation structure is continuously distributed, and the surface of the island-shaped passivation structure has an undulating morphology.

38. The back contact battery according to claim 36, wherein, The edges of the island-shaped passivation structure are irregular in shape; And / or, at least some of the island-like passivation structures are regularly distributed.

39. The back contact battery according to claim 36, wherein, The spacing between two adjacent island-shaped passivation structures is greater than or equal to 40 μm and less than or equal to 300 μm.

40. The back contact battery according to claim 36, wherein, Both the first doped semiconductor layer and the second doped semiconductor layer include strip-shaped doped regions; the strip-shaped doped regions in the first doped semiconductor layer and the strip-shaped doped regions in the second doped semiconductor layer extend along a first direction and are alternately distributed along a second direction; the first direction is different from the second direction; the distance between two adjacent island-shaped passivation structures along the first direction is smaller than the distance between two adjacent island-shaped passivation structures along the second direction.

41. The back contact battery according to any one of claims 1-40, wherein, The first doped semiconductor layer is a P-type doped semiconductor layer; And / or, the first doped semiconductor layer is an emitter doped layer.

42. A photovoltaic module, comprising: A battery string, wherein the battery string is formed by electrically connecting a plurality of back-contact batteries as described in any one of claims 1-40; as well as An encapsulation layer that covers the surface of the battery string.

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