Solar cell manufacturing methods

Abstract

This invention provides a simplified manufacturing method for solar cells. [Solution] The method includes the steps of: providing a substrate 100 having a first surface 110 and a second surface 120 facing each other; performing a doping treatment on at least the first surface 110 to form a doped layer having a first doping element; performing a first laser treatment on a portion of the doped layer to form an activated portion, making the remaining doped layer a doped portion 121; and using the remaining doped layer as a dead layer, performing a first etching treatment on the first surface 110 to remove the activated portion and form a first textured surface 114.

Description

Technical Field

[0001] The present disclosure relates to the field of photovoltaic power generation, and particularly to solar cells and a method for manufacturing the same.

Background Art

[0002] Currently, as fossil energy is gradually exhausted, solar cells are being increasingly widely used as a new energy alternative. A solar cell is a device that converts solar light energy into electrical energy. By utilizing the principle of photovoltaic effect to generate carriers and then extracting the carriers using electrodes, a solar cell is advantageous for the effective utilization of electrical energy.

[0003] Current solar cells mainly include IBC cells (Interdigitated Back Contact solar cells), TOPCON (Tunnel Oxide Passivated Contact) cells, PERC cells (Passivated emitter and real cell), and heterojunction solar cells, etc.

[0004] However, the photovoltaic conversion efficiency of solar cells formed by different manufacturing methods is different, and there is a need to develop a manufacturing method that is advantageous for improving the photovoltaic conversion efficiency of solar cells or simplifying the manufacturing process.

Summary of the Invention

[0005] Embodiments of the present disclosure provide a solar cell and a method for manufacturing the same, which are advantageous for at least simplifying the manufacturing process of the solar cell and improving the photovoltaic conversion efficiency of the solar cell.

[0006] According to some embodiments of the present disclosure, in one embodiment of the embodiments of the present disclosure, the steps are: to provide a substrate having a first surface and a second surface facing each other; to dope at least the first surface to form a doped layer having a first doped element; to perform a first laser treatment on a portion of the doped layer to form an activated portion, and to make the remaining doped layer a doped portion, and to make the doping concentration of the first doped element in the activated portion lower than the doping concentration of the first doped element in the doped portion; to make the doped portion a dead layer, and to perform a first etching treatment on the first surface to remove the activated portion and form a first textured surface; and at least the A method for manufacturing a solar cell is provided, comprising the steps of sequentially forming a doped polysilicon layer having a second doping element and a silicate glass layer on the side of the substrate away from the doped portion; performing a second laser treatment on at least a portion of the silicate glass layer to form sparse areas; and using the remaining silicate glass layer as a protective layer, performing a second etching treatment on at least the second surface to remove the sparse areas and the doped polysilicon layer facing the sparse areas, thereby forming a second textured surface, wherein the first doping element and the second doping element are of different types, and the first laser treatment and the second laser treatment use different types of lasers.

[0007] In other embodiments, both the first and second surfaces are third texture surfaces, and the step of forming a polished surface is further included after forming the first texture surface and before forming the doped polysilicon layer, and the step of forming the doped polysilicon layer and the silicate glass layer is included in forming the doped polysilicon layer on the polished surface and forming the silicate glass layer on the side of the doped polysilicon layer away from the polished surface.

[0008] In other embodiments, the steps include, after forming the first textured surface and before forming the polished surface, performing an oxidation treatment on at least the first surface to form a first diffusion barrier layer on the doped portion and forming a second diffusion barrier layer on the first textured surface, wherein the steps of forming the doped polysilicon layer and the silicate glass layer further include forming the doped polysilicon layer on both the first diffusion barrier layer and the second diffusion barrier layer, and forming the silicate glass layer on either side of the doped polysilicon layer away from the first diffusion barrier layer and the second diffusion barrier layer.

[0009] In other embodiments, the steps include, after forming the first textured surface and before forming the polished surface, oxidizing at least the first surface to form a first diffusion barrier layer in the doped portion, and forming a second diffusion barrier layer on the first textured surface, wherein the surface composed of both the first and second diffusion barrier layers includes an edge region and a central region surrounded by the edge region, and the steps of forming the doped polysilicon layer and the silicate glass layer further include forming the doped polysilicon layer in the edge region and forming the silicate glass layer on the side of the doped polysilicon layer away from the edge region.

[0010] In other embodiments, the first surface includes first laser regions and first non-laser regions arranged alternately along a first direction, and the second surface includes second laser regions and second non-laser regions arranged alternately along the first direction, wherein the step of performing the first laser treatment on a portion of the doped layer includes performing the first laser treatment on the doped layer located in the first laser region to form the activated portion located in the first laser region, and the step of performing the second laser treatment on at least a portion of the silicate glass layer includes performing the second laser treatment on the silicate glass layer located in the second laser region to form the sparse portion located in the second laser region.

[0011] In other embodiments, the orthographic projection area of ​​the first laser region onto the substrate is different from the orthographic projection area of ​​the second laser region onto the substrate, and / or the orthographic projection of the first laser region onto the substrate at least partially overlaps with or does not overlap with the orthographic projection of the second laser region onto the substrate.

[0012] In other embodiments, the step of performing the second etching treatment on at least the second surface includes the steps of etching the first surface using a second-chain hydrofluoric acid process to remove the silicate glass layer located on the first surface, and etching the first and second surfaces using a second texturing process to remove the doped polysilicon layer, the first diffusion barrier layer and the second diffusion barrier layer located on the first surface, exposing the first textured surface and the doped portion, and removing the sparse portion and the doped polysilicon layer located in the second laser region to form the second textured surface.

[0013] In other embodiments, after performing the second texturing process, the second surface is further cleaned using an acid pickling process to remove the silicate glass layer located in the second non-laser region and expose the doped polysilicon layer located in the second non-laser region.

[0014] In other embodiments, the step of performing the first etching treatment on the first surface includes etching the first surface using a first texturing process to remove the activated portion and form the first textured surface.

[0015] In other embodiments, the first laser processing step further includes forming an oxide layer on the doped layer, and the first etching process on the first surface further includes removing the oxide layer by etching the first surface using a first chain hydrofluoric acid process before etching the first surface using the first texturing process.

[0016] In other embodiments, the first laser treatment uses a red nanosecond laser, a green nanosecond laser, or a violet nanosecond laser, and the second laser treatment uses a violet picosecond laser, a green picosecond laser, a green femtosecond laser, or a violet femtosecond laser.

[0017] According to other embodiments of the present disclosure, in another aspect of the embodiments of the present disclosure, a solar cell is provided which is formed by the manufacturing method described in any one of the above paragraphs.

[0018] The technical means relating to the embodiments of this disclosure have at least the following advantages:

[0019] On the one hand, the first laser treatment activates a portion of the doped layer, reduces the doping concentration of the first doped element in that portion of the doped layer, and improves the regularity of the crystal lattice within that portion of the doped layer, thereby converting that portion of the doped layer into an activated portion and leaving the remaining doped layer as a doped portion. In other words, because the doping concentration of the doped element in the activated portion is lower and the overall regularity of the crystal lattice within the activated portion is higher than that of the doped portion, the doped portion is easier to etch under the same etching conditions. Based on this, when the first etching treatment is subsequently performed on the first surface, the etching rate for the activated portion, where the doping concentration of the first doped element is lower due to the first etching treatment, is much higher than that for the doped portion. As a result, without the need for a separate mask, the doped portion can be treated as a dead layer, the activated portion removed, and the first textured surface can be formed, which is advantageous for simplifying the manufacturing process of solar cells. Furthermore, compared to removing a portion of the doped layer using a laser deposition process to form a selective emitter structure in which the doped layer remains only in a portion of the first surface, the coupled effect of the first laser treatment and the first etching treatment is advantageous in reducing laser damage to the first surface, thereby reducing the surface defect level density of the first surface and improving the photoelectric conversion efficiency of the final solar cell. Moreover, forming a selective emitter structure in which the doped layer, i.e., the doped portion, remains only in a portion of the first surface is advantageous in reducing the contact resistance between the subsequently formed electrodes and the doped portion, and in reducing the probability of carrier recombination in other regions of the first surface.

[0020] On the other hand, the second laser treatment modifies a portion of the silicate glass layer into sparse areas, making the porosity of these sparse areas higher than that of the remaining silicate glass layer. Based on this, when a second etching treatment is subsequently performed on at least the second surface, the etching rate for the sparse areas with higher porosity due to the second etching treatment is much higher than that for the remaining silicate glass layer. As a result, without the need for a separate mask, the remaining silicate glass layer can be used as a protective layer to remove the sparse areas and the doped polysilicon layer facing the sparse areas, thereby forming a second textured surface, which is advantageous for simplifying the manufacturing process of solar cells. Furthermore, removing the doped polysilicon layer facing the sparse areas is advantageous in avoiding parasitic absorption of light by the partially removed doped polysilicon layer. [Brief explanation of the drawing]

[0021] One or more embodiments are illustrated by the corresponding drawings, and these illustrative descriptions are not limiting to the embodiments. Unless otherwise specified, the drawings are not limiting in proportion. To better illustrate the embodiments of the disclosure or the means of the prior art, the following drawings are briefly introduced. Clearly, the drawings in the following description are only some embodiments of the disclosure, and those skilled in the art can obtain other drawings based on these without any creative effort.

[0022] [Figure 1] This is a schematic diagram of a partial cross-sectional structure of a substrate provided in a method for manufacturing a solar cell according to one embodiment of the present disclosure. [Figure 2] This is a schematic diagram of a partial cross-sectional structure formed after doping treatment has been performed on at least the first surface in a method for manufacturing a solar cell according to one embodiment of the present disclosure. [Figure 3] This is a schematic diagram of a partial cross-sectional structure formed after a first laser treatment in a method for manufacturing a solar cell according to one embodiment of the present disclosure. [Figure 4] This is a schematic diagram of a partial cross-sectional structure formed after a first etching process in a method for manufacturing a solar cell according to one embodiment of the present disclosure. [Figure 5] It is a schematic diagram of a partial cross-sectional structure formed after performing an oxidation treatment on at least the first surface in a method for manufacturing a solar cell according to an embodiment of the present disclosure. [Figure 6] It is a schematic diagram of a partial cross-sectional structure formed after performing a polishing treatment on the second surface based on the structure shown in FIG. 5. [Figure 7] It is a schematic diagram of a partial cross-sectional structure in which a doped polysilicon layer and a silicate glass layer are formed based on the structure shown in FIG. 6. [Figure 8] It is a schematic diagram of a partial cross-sectional structure formed after performing a second laser treatment in a method for manufacturing a solar cell according to an embodiment of the present disclosure. [Figure 9] It is a schematic diagram of a partial cross-sectional structure formed after performing etching on the first surface based on the structure shown in FIG. 8. [Figure 10] It is a schematic diagram of a partial cross-sectional structure formed after performing texturing on the first surface and the second surface based on the structure shown in FIG. 9. [Figure 11] It is a schematic diagram of a partial cross-sectional structure formed after performing cleaning on the second surface based on the structure shown in FIG. 10.

Mode for Carrying Out the Invention

[0023] As can be seen from the background art, it is necessary to simplify the manufacturing process of solar cells and improve the photoelectric conversion efficiency of solar cells.

[0024] Embodiments of this disclosure provide a solar cell and a method for manufacturing the same, wherein, on the one hand, the first laser treatment activates a portion of the doped layer and reduces the doping concentration of the first doped element in the portion of the doped layer, thereby improving the regularity of the crystal lattice within the portion of the doped layer. In other words, since the doping concentration of the doped element in the activated portion is lower than that of the doped portion, and the overall regularity of the crystal lattice within the activated portion is higher, the doped portion is more easily etched under the same etching conditions. Based on this, when the first etching treatment is subsequently performed on the first surface, the etching rate for the activated portion, where the doping concentration of the first doped element is lower due to the first etching treatment, is much higher than that for the doped portion. As a result, without providing a separate mask, the doped portion can be treated as a dead layer, the activated portion removed, and the first textured surface can be formed, which is advantageous for simplifying the manufacturing process of the solar cell. Furthermore, compared to removing a portion of the doped layer using a laser deposition process, the combined effect of the first laser treatment and the first etching treatment is advantageous in reducing laser damage to the first surface, thereby reducing the surface defect level density of the first surface and improving the photoelectric conversion efficiency of the final solar cell. Moreover, forming a selective emitter structure in which doped areas remain only in a portion of the first surface is advantageous in reducing the contact resistance between the subsequently formed electrodes and the doped areas, and in reducing the probability of carrier recombination in other areas of the first surface. On the other hand, if the second laser treatment is used to modify a portion of the silicate glass layer to be less porous, and then a second etching treatment is performed on at least the second surface, the etching rate for the less porous areas with higher porosity due to the second etching treatment is much higher than that for the remaining silicate glass layer. As a result, without the need for a separate mask, the remaining silicate glass layer can be used as a protective layer, and the less porous areas and the doped polysilicon layer facing the less porous areas can be removed to form a second textured surface, which is advantageous in simplifying the solar cell manufacturing process. Furthermore, removing the doped polysilicon layer opposite the sparse area is advantageous in avoiding parasitic absorption of light by the partially removed doped polysilicon layer.

[0025] In the description of the embodiments of this disclosure, technical terms such as “first,” “second,” etc., are used solely to distinguish different subjects and should not be understood as indicating or suggesting relative importance, or implicitly indicating the number, specific order, or hierarchical relationship of the technical features shown. In the description of the embodiments of this disclosure, “multiple” means two or more unless explicitly and specifically limited.

[0026] The “Examples” as used herein mean that certain features, structures, or properties described in relation to an Example may be included in at least one Example of this Disclosure. The phrase “Examples” appearing elsewhere in this Specification does not necessarily refer to the same Example, nor are they exclusive, independent, or alternative to other Examples. Those skilled in the art will understand, both explicitly and implicitly, that the Examples described herein can be combined with other Examples.

[0027] In the description of the embodiments of this disclosure, the term "and / or" merely describes the relationship between related objects and indicates that there may be three possible relationships. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In this specification, the letter " / " generally indicates that the preceding and succeeding related objects are in an "or" relationship.

[0028] In the description of the embodiments of this disclosure, the term "multiple" means two or more (including two), similarly, "multiple sets" means two or more sets (including two sets), and "multiple sheets" means two or more sheets (including two).

[0029] In the description of the embodiments of this disclosure, the orientations or positional relationships indicated by technical terms such as "center," "vertical direction," "horizontal direction," "length," "width," "thickness," "top," "bottom," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," "clockwise," "counterclockwise," "axial direction," "radial direction," and "circumferential direction" are based on the orientations or positional relationships shown in the drawings and are merely for the purpose of easily describing and simplifying the embodiments of this disclosure. They do not indicate or suggest that the shown devices or parts have a specific orientation, or that they must be configured and operated in a specific orientation, and should not be understood as limiting the embodiments of this disclosure.

[0030] In the description of the embodiments of this disclosure, unless otherwise explicitly stated and limited, the technical terms “attachment,” “connection,” “connection,” and “fixing” should be understood in a broad sense, and may include, for example, fixed connections, removable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections via an intermediate medium; and internal communication between two parts or interaction relationships between two parts. Those skilled in the art will be able to understand the specific meaning of the above terms in the embodiments of this disclosure depending on the specific circumstances.

[0031] In the drawings corresponding to the embodiments of this disclosure, the thickness and area of ​​layers are shown in magnified form for better understanding and easier explanation. When one component (e.g., a layer, thin film, region, or substrate) is described as being on or on the surface of another component, the component may be located "directly" on the surface of the other component, and a third component may exist between the two components. Conversely, when one component is described as being on the surface of another component, or as being formed or provided on the surface of one component, it indicates that there is no third component between the two components. Also, when one component is described as being "substantially" formed on the surface of another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor on any part of the edge of the entire surface.

[0032] In the descriptions of the embodiments of this disclosure, when one component "includes" another component, unless otherwise specified, this does not exclude other components, and other components may be included. Also, when a component such as a layer, film, region, or plate is described as "being present / located" on another component, that component may be located "directly" on the other component (i.e., located on the surface of the other component with no other components between them), or other components may be present between them. Furthermore, when a component such as a layer, film, region, or plate is "directly located" on another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it indicates that no other components are present between them.

[0033] The terms used in the description of the various embodiments herein are for illustrative purposes only and are not intended to limit the use of any particular embodiment. As used in the description of the various embodiments described and in the appended claims, “the members” is intended to be plural unless the context explicitly indicates otherwise. Members include members such as layers, films, regions, or plates.

[0034] The embodiments of this disclosure will be described in detail below with reference to the drawings. However, as those skilled in the art will understand, the embodiments of this disclosure provide many technical details to help the reader better understand the embodiments of this disclosure. However, these technical details, as well as the various changes and modifications based on the embodiments below, can realize the technical means for which the embodiments of this disclosure seek protection.

[0035] One embodiment of the present disclosure provides a method for manufacturing a solar cell, and the method for manufacturing a solar cell according to one embodiment of the present disclosure will be described in detail below with reference to the drawings. Figures 1 to 11 are schematic diagrams of partial cross-sectional structures corresponding to each step in the method for manufacturing a solar cell according to one embodiment of the present disclosure.

[0036] As shown in Figures 1 to 11, the method for manufacturing a solar cell includes at least the following steps S1 to S7.

[0037] In step S1, Figure 1 is a schematic diagram of a partial cross-sectional structure of a substrate provided in a method for manufacturing a solar cell according to one embodiment of the present disclosure, and as shown in Figure 1, a substrate 100 is provided having a first surface 110 and a second surface 120 facing opposite directions.

[0038] In other embodiments, in step S1, the material of the substrate 100 may be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon or germanium. The elemental semiconductor material may be in a single-crystal state, a polycrystalline state, an amorphous state, or a microcrystalline state (a state having both single-crystal and amorphous states is called a microcrystalline state). For example, silicon may be at least one of single-crystal silicon, polysilicon, amorphous silicon, or microcrystalline silicon. In other embodiments, the material of the substrate 100 may be a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, materials such as silicon germanium, silicon carbide, gallium arsenide, indium galliumide, perovskite, cadmium telluride, and copper indium selenium. Hereinafter, the material of the substrate 100 will be described as silicon as an example.

[0039] In step S2, Figure 2 is a schematic diagram of a partial cross-sectional structure formed after doping treatment is performed on at least the first surface in a method for manufacturing a solar cell according to one embodiment of the present disclosure. As shown in Figure 2, doping treatment is performed on at least the first surface 110 to form a doped layer 101 having a first doping element.

[0040] In step S3, Figure 3 is a schematic diagram of a partial cross-sectional structure formed after the first laser treatment in a method for manufacturing a solar cell according to one embodiment of the present disclosure. As shown in Figures 2 and 3, the first laser treatment is performed on a portion of the doped layer 101 to form an activated portion 111, the remaining doped layer 101 becomes a doped portion 121, and the doping concentration of the first doped element in the activated portion 111 is made lower than the doping concentration of the first doped element in the doped portion 121.

[0041] In step S4, Figure 4 is a schematic diagram of a partial cross-sectional structure formed after the first etching treatment in a method for manufacturing a solar cell according to one embodiment of the present disclosure. As shown in Figures 3 and 4, the doped portion 121 is treated as a dead layer, and the first etching treatment is performed on the first surface 110 to remove the activated portion 111 and form the first textured surface 114.

[0042] In step S5, as shown in Figures 4 to 7, a doped polysilicon layer 102 having a second doping element and a silicate glass layer 103 are sequentially formed on at least the side of the substrate 100 away from the doped portion 121.

[0043] Figure 5 is a schematic diagram of a partial cross-sectional structure formed after oxidation treatment of at least the first surface in a method for manufacturing a solar cell according to one embodiment of the present disclosure; Figure 6 is a schematic diagram of a partial cross-sectional structure formed after polishing treatment of the second surface based on the structure shown in Figure 5; and Figure 7 is a schematic diagram of a partial cross-sectional structure in which a doped polysilicon layer and a silicate glass layer are formed based on the structure shown in Figure 6.

[0044] In step S6, Figure 8 is a schematic diagram of a partial cross-sectional structure formed after the second laser treatment in a method for manufacturing a solar cell according to one embodiment of the present disclosure. As shown in Figure 8, the second laser treatment is performed on at least a portion of the silicate glass layer 103 to form a sparse area 113.

[0045] In step S7, as shown in Figures 8 to 11, the remaining silicate glass layer 103 is used as a protective layer, and a second etching process is performed on at least the second surface 120 to remove the sparse areas 113 and the doped polysilicon layer 102 facing the sparse areas 113, thereby forming the second textured surface 115.

[0046] The first doped element and the second doped element are of different types, and the first laser treatment and the second laser treatment use different types of lasers.

[0047] Figure 9 is a schematic diagram of a partial cross-sectional structure formed after etching the first surface based on the structure shown in Figure 8, Figure 10 is a schematic diagram of a partial cross-sectional structure formed after texturing the first and second surfaces based on the structure shown in Figure 9, and Figure 11 is a schematic diagram of a partial cross-sectional structure formed after cleaning the second surface based on the structure shown in Figure 10.

[0048] Furthermore, the first and second laser treatments differ not only in the type of laser used, but also in the target of the treatment.

[0049] Specifically, in step S3, the first laser treatment processes a portion of the doped layer 101, activating it, reducing the doping concentration of the first doping element in that portion of the doped layer 101, and improving the regularity of the crystal lattice within that portion of the doped layer 101. This converts the portion of the doped layer 101 into an activated portion 111, while the remaining portion of the doped layer 101 that has not undergone the first laser treatment becomes the doped portion 121. In other words, compared to the doped portion 121, the doping concentration of the doping element in the activated portion 111 is lower, and the overall regularity of the crystal lattice within the activated portion 111 is higher. Therefore, under the same etching conditions, the doped portion 121 is more easily etched.

[0050] Based on this, when the first etching treatment is then performed on the first surface 110 in step S4, the etching rate for the activated portion 111, where the doping concentration of the first doped element is lower due to the first etching treatment, is much higher than that for the doped portion 121. As a result, the doped portion 121 can be treated as a dead layer, the activated portion 111 can be removed, and the first textured surface 114 can be formed without providing a separate mask, which is advantageous for simplifying the manufacturing process of solar cells. Furthermore, compared to removing a portion of the doped layer 101 using a laser deposition process to form a selective emitter structure in which the doped layer 101 remains only in a portion of the first surface 110, that is, ablating a portion of the doped layer 101 using a laser directly, the manufacturing method according to one embodiment of the present disclosure is advantageous in reducing damage to the first surface 110 by the laser due to the combined effect of the first laser treatment and the first etching treatment. In other words, the damage to the first surface 110 by the laser used in the first laser treatment is less than that by the laser used in the laser deposition process, thereby reducing the surface defect level density of the first surface 110 and improving the photoelectric conversion efficiency of the final solar cell.

[0051] Furthermore, forming a selective emitter structure in which the doped layer 101, i.e., the doped portion 121, remains only in a portion of the first surface 110 after step S3 is advantageous in reducing the contact resistance between the subsequently formed electrodes and the doped portion 121, as well as reducing the probability of carrier recombination in other regions of the first surface 110, thereby improving the photoelectric conversion efficiency of the final solar cell.

[0052] In step S6, the second laser treatment is performed on at least a portion of the silicate glass layer 103, modifying the portion of the silicate glass layer 103 into a sparse area 113, for example, making the porosity of the sparse area 113 higher than that of the remaining silicate glass layer 103. Based on this, when the second etching treatment is then performed on at least the second surface 120 in step S7, the etching rate on the sparse area 113 with higher porosity due to the second etching treatment is much higher than that on the remaining silicate glass layer 103. As a result, without providing a separate mask, the remaining silicate glass layer 103 can be used as a protective layer, and the sparse area 113 and the doped polysilicon layer 102 facing the sparse area 113 can be removed to form the second textured surface 115, which is advantageous for simplifying the manufacturing process of solar cells.

[0053] Furthermore, removing the doped polysilicon layer 102 facing the sparse area 113 is advantageous in avoiding parasitic absorption of light by the partially removed doped polysilicon layer 102, the exposed second texture surface 115 can improve the utilization rate of light absorption, and is also advantageous in ensuring low contact resistance between the subsequently formed electrode and the remaining doped polysilicon layer 102, thereby improving the photoelectric conversion efficiency of the final solar cell.

[0054] The purpose of the first laser treatment in step S3 is to activate a portion of the doped layer 101 and change the doping concentration of the first doped element in that portion of the doped layer 101 and the regularity of the crystal lattice within that portion of the doped layer 101, thereby making the doped layer 101 with a reduced doping concentration of the first doped element the activated portion 111. In contrast, the purpose of the second laser treatment in step S6 is to modify at least a portion of the silicate glass layer 103 and change the porosity of that portion of the silicate glass layer 103, thereby making the silicate glass layer 103 with increased porosity the sparse portion 113.

[0055] In some cases, a lower doping concentration of the doped elements in the activated portion 111 than that of the doped elements in the doped portion 121 means that, with the surface of the activated portion 111 away from the substrate 100 as the first reference plane and the surface of the doped portion 121 away from the substrate 100 as the second reference plane, the effective doping concentration of the doped elements in the activated portion 111 within a depth of 100 nm from the first reference plane toward the substrate 100 is lower than that of the doped elements in the doped portion 121 within a depth of 100 nm from the second reference plane toward the substrate 100, and that the overall regularity of the crystal lattice within the activated portion 111 is higher.

[0056] In some examples, the doping concentration of the doped element in the activated section 111 is the first doping concentration, and the doping concentration of the doped element in the doped section 121 is the second doping concentration. The ratio of the second doping concentration to the first doping concentration may be 2 to 100, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, or 195.

[0057] In some cases, the effective dope concentration of the activated section 111 and the doped section 121 was measured using the ECV (Electrochemical Capacitance Voltage profiler) method. The results showed that the effective dope concentration of the doped element in the activated section 111 within a depth of 100 nm from the first reference plane toward the substrate 100 was 5 × 10⁻¹⁰. 19 atom / cm 3 The effective doping concentration of the doping element within the doped portion 121, at a depth of 100 nm from the second reference plane toward the substrate 100, is less than 5 × 10⁻¹⁰. 18 atom / cm 3 It is larger than that.

[0058] Furthermore, in the first etching process, treating the doped portion 121 and the activated portion 111 under the same etching conditions means that the doped portion 121 and the activated portion 111 are treated using the same etching solution, and the treatment time for the doped portion 121 and the activated portion 111 is the same.

[0059] In other cases, when the same etching solution is used, the etching depth of the activated portion 111 by the etching solution per unit time is much greater than the etching depth of the doped portion 121. Therefore, the etching rate of the activated portion 111, where the doping concentration of the first doped element is lower due to the first etching treatment, is much higher than that of the doped portion.

[0060] In other examples, when the same etching solution is used, the ratio of the etching depth of the activated portion 111 to the etching depth of the doped portion 121 per unit time is 10 or more. In one example, when etching treatment was performed simultaneously on the activated portion 111 and the doped portion 121 for about 600 s using the same etching solution, the etching depth of the activated portion 111 was about 2 μm, and the etching depth of the doped portion 121 was about 100 nm. In other words, it is considered that the doped portion 121 was hardly etched compared to the activated portion 111, and when the activated portion 111 was completely removed to form the first textured surface in the first etching process, at least the majority of the thickness of the doped portion 121 was not etched.

[0061] In other cases, a higher porosity of the sparse areas 113 compared to the remaining silicate glass layer 103 means that, from a microscopic perspective, ruptured film can be seen within the sparse areas 113, for example, cracks or fragments can be seen within the sparse areas 113, and the maximum size of the fragments does not exceed 100 μm. The porosity of the sparse areas 113 from a microscopic perspective can be determined using a scanning electron microscope (SEM).

[0062] The following describes in detail each step in the method for manufacturing a solar cell according to one embodiment of this disclosure.

[0063] In other embodiments, the substrate 100 may be an N-type semiconductor substrate doped with an N-type doped element, where the first doped element is a P-type doped element and the second doped element is an N-type doped element. In other embodiments, the N-type doped element may be at least one of the Group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As), and the P-type doped element may be doped in the P-type semiconductor substrate, where the P-type doped element may be at least one of the Group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0064] In one example, in step S2, the doping treatment performed on at least the first surface 110 is a boron diffusion treatment, thereby allowing at least a portion of the substrate 100 doped with boron (B) to be considered as a doped layer 101, and the doped layer 101 to be considered as a boron diffusion layer. In step S4, the material of the doped polysilicon layer 102 may be N-type polysilicon, and the material of the silicate glass layer 103 may be phosphate silicate glass.

[0065] In other embodiments, the substrate may be a P-type semiconductor substrate doped with a P-type doped element, where the first doped element in the doped layer is an N-type doped element, and the second doped element in the doped polysilicon layer is a P-type doped element.

[0066] In other embodiments, the solar cell is a single-sided cell, and in step S1, the first surface 110 can be considered as the front of the solar cell, that is, the first surface 110 can function as a light-receiving surface for receiving incident light, and the second surface 120 can function as a backlight surface. In other embodiments, the solar cell is a double-sided cell, and both the first surface 110 and the second surface 120 can function as light-receiving surfaces for receiving incident light. To make it clear, the backlight surface described in one embodiment of this disclosure can also receive incident light, but it is defined as a backlight surface because the degree of light reception for incident light is weaker than the degree of light reception for incident light on the light-receiving surface. Hereinafter, the first surface 110 will be described as a light-receiving surface and the second surface 120 as a backlight surface in an illustrative manner.

[0067] In other embodiments, as shown in Figure 3, a red nanosecond laser, a green nanosecond laser, or a violet nanosecond laser may be used in the first laser treatment in step S3, and as shown in Figure 8, a violet picosecond laser, a green picosecond laser, a green femtosecond laser, or a violet femtosecond laser may be used in the second laser treatment in step S6. In this way, by reducing the doping concentration of the first doped element in a portion of the doped layer 101 with a red nanosecond laser, a green nanosecond laser, or a violet nanosecond laser, the doped layer 101 with reduced doping concentration of the first doped element becomes an activated portion 111, improving the overall regularity of the crystal lattice within the activated portion 111. By changing the porosity of a portion of the silicate glass layer 103 with a violet picosecond laser, a green picosecond laser, a green femtosecond laser, or a violet femtosecond laser, the silicate glass layer 103 with increased porosity becomes a sparse portion 113.

[0068] Furthermore, red nanosecond lasers, green nanosecond lasers, and violet nanosecond lasers all belong to the nanosecond laser category; that is, the laser used for the first laser treatment may be a short-pulse laser; violet picosecond lasers and green picosecond lasers both belong to the picosecond laser category; green femtosecond lasers and violet femtosecond lasers both belong to the femtosecond laser category; and picosecond lasers and femtosecond lasers both belong to the ultrashort-pulse laser category; that is, the laser used for the second laser treatment may be an ultrashort-pulse laser. In other words, the pulse width of the laser used for the first laser treatment is greater than the pulse width of the laser used for the second laser treatment.

[0069] In other examples, the wavelength range of the red nanosecond laser used for the first laser treatment may be 700 nm to 1500 nm, for example, 730 nm, 750 nm, 780 nm, 800 nm, 820 nm, 850 nm, 880 nm, 900 nm, 930 nm, 950 nm, 960 nm, 1000 nm, 1020 nm, 1050 nm, 1060 nm, 1200 nm, 1230 nm, 1250 nm, 1270 nm, 1300 nm, 1320 nm, 1350 nm, 1370 nm, 1420 nm, 1450 nm, or 1480 nm.

[0070] In other examples, the wavelength ranges of the green nanosecond laser used in the first laser processing, and the green picosecond and green femtosecond lasers used in the second laser processing, may all be 492nm to 577nm, for example, 493nm, 495nm, 496nm, 500nm, 502nm, 505nm, 508nm, 510nm, 513nm, 515nm, 516nm, 520nm, 522nm, 525nm, 528nm, 530nm, 532nm, 535nm, 538nm, 540nm, 542nm, 545nm, 548nm, 550nm, 552nm, 555nm, 558nm, 560nm, 562nm, 565nm, 568nm, 570nm, 572nm, 575nm, or 578nm.

[0071] In other examples, the wavelength ranges of the violet nanosecond laser used in the first laser treatment, and the violet picosecond and violet femtosecond lasers used in the second laser treatment, may all be 200nm to 400nm, for example, 205nm, 210nm, 215nm, 220nm, 225nm, 230nm, 235nm, 240nm, 245nm, 250nm, 255nm, 260nm. m, 265nm, 270nm, 275nm, 280nm, 285nm, 290nm, 295nm, 300nm, 305nm, 310nm, 315nm, 320nm, 325nm, 330nm, 335nm, 340nm, 345nm, 350nm, 355nm, 360nm, 365nm, 370nm, 375nm, 380nm, 385nm, 390nm, or 395nm may also be used.

[0072] In other embodiments, as shown in Figures 3 and 4, the step of forming the first textured surface 114 in step S4 may include the step of forming a first groove 104 whose bottom surface is the first textured surface 114.

[0073] Furthermore, the etching rate of the activated portion 111 by the first etching process is much higher than the etching rate of the doped portion 121. Based on this, if the doped portion 121 is treated as a dead layer in step S4, not only can the activated portion 111 be removed, but the first surface 110 exposed after the activated portion 111 has been removed can also be further etched to form the first groove 104. The first groove 104 is further recessed into the substrate 100 relative to the substrate 100 facing the doped portion 121, that is, it is recessed in the direction from the first surface 110 toward the second surface 120. In other words, the first surface 110 includes a first laser region 140 and a first non-laser region 150 arranged alternately along a first direction X, the doped portion 121 not etched by the first etching process is located in the first non-laser region 150, and the first groove 104 is located in the first laser region 140. After step S4, the surface of the substrate 100 located in the first non-laser region 150 is higher than the surface of the substrate 100 located in the first laser region 140, thereby allowing the first groove 104 to be formed in the first laser region 140. Furthermore, by further etching the substrate 100 facing the activated portion 111 based on the first etching process, a first textured surface 114 can be formed at least on the bottom surface of the first groove 104.

[0074] Thus, on the one hand, the first textured surface 114 not only reduces the reflectivity of the bottom surface of the first groove 104 but also forms a light trap, improving the absorption effect of incident light by the first textured surface 114. On the other hand, due to the characteristic that the first groove 104 is recessed into the substrate 100, light incident into the first groove 104 is less likely to be reflected to the outside of the solar cell, further improving the absorption utilization rate of incident light by the first groove 104. Therefore, the cooperation between the first groove 104 and the first textured surface 114 is advantageous in improving the photoelectric conversion efficiency of the solar cell.

[0075] Furthermore, based on the control of the concentration of the etching solution used in the first etching process and / or the processing time of the first etching process, it is possible to control whether the first etching process further etches the first surface 110 that was exposed after the activation portion 111 was removed, that is, whether or not to further form the first groove 104 in the first laser region 140 of the substrate 100, and furthermore, the degree of etching of the substrate 100 facing the activation portion 111 by the first etching process can be controlled, that is, the depth of the formed first groove 104 can be controlled.

[0076] In other examples, the processing time for the first etching process may be 600s to 750s, for example, 610s, 620s, 630s, 640s, 650s, 660s, 670s, 680s, 690s, 700s, 710s, 720s, 730s, or 740s.

[0077] In other examples, the depth of the first groove 104 may be 2.5 μm to 4 μm, for example, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, 3 μm, 3.1 μm, 3.2 μm, 3.3 μm, 3.4 μm, 3.5 μm, 3.6 μm, 3.7 μm, 3.8 μm, or 3.9 μm.

[0078] In Figure 4, a doped area 121 is shown in the first non-laser region 150 of the substrate 100, and a first groove 104 is formed in the first laser region 140 of the substrate 100. However, in actual applications, the surface of the first non-laser region and the surface of the first laser region of the substrate may be kept flat.

[0079] In other embodiments, as shown in Figures 8 to 11, the step of forming the second texture surface 115 in step S7 may include the step of forming a second groove 105 whose bottom surface is the second texture surface 115.

[0080] Furthermore, the etching rate for the sparse areas 113 by the second etching process is much higher than the etching rate for the remaining silicate glass layer 103. Based on this, if the remaining silicate glass layer 103 is used as a protective layer in step S7, not only can the sparse areas 113 be removed, but the second surface 120 exposed after the sparse areas 113 have been removed can also be further etched to form the second groove 105. The second groove 105 is further recessed into the substrate 100 relative to the substrate 100 facing the sparse areas 113, that is, it is recessed in the direction from the second surface 120 toward the first surface 110. In other words, the second surface 120 includes a second laser region 160 and a second non-laser region 170 arranged alternately along the first direction X, the silicate glass layer 103 not etched by the second etching process is located in the second non-laser region 170, and the second groove 105 is located in the second laser region 160. After step S7, the surface of the substrate 100 located in the second non-laser region 170 is higher than the surface of the substrate 100 located in the second laser region 160, thereby allowing the second groove 105 to be formed in the second laser region 160. Furthermore, by further etching the substrate 100 facing the sparse area 113 based on the second etching process, a second textured surface 115 can be formed at least on the bottom surface of the second groove 105.

[0081] Thus, on the one hand, the second texture surface 115 not only reduces the reflectivity of the bottom surface of the second groove 105 but also forms a light trap, improving the absorption effect of incident light by the second texture surface 115. On the other hand, due to the characteristic that the second groove 105 is recessed into the substrate 100, light incident into the second groove 105 is less likely to be reflected to the outside of the solar cell, further improving the absorption utilization rate of incident light by the second groove 105. Therefore, the cooperation between the second groove 105 and the second texture surface 115 is advantageous in improving the photoelectric conversion efficiency of the solar cell.

[0082] Furthermore, based on the control of the concentration of the etching solution used in the second etching process and / or the processing time of the second etching process, it is possible to control whether the second etching process further etches the second surface 120 that is exposed after the removal of the sparse area 113, that is, whether or not to further form the second groove 105 in the second laser region 160 of the substrate 100, and furthermore, the degree of etching of the substrate 100 facing the sparse area 113 by the second etching process can be controlled, that is, the depth of the formed second groove 105 can be controlled.

[0083] In other examples, the processing time for the second etching process may be 600s to 750s, for example, 610s, 620s, 630s, 640s, 650s, 660s, 670s, 680s, 690s, 700s, 710s, 720s, 730s, or 740s.

[0084] In other examples, the depth of the second groove 105 may be 2 μm to 3 μm, for example, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, or 2.9 μm.

[0085] In Figure 10, a silicate glass layer 103 is shown as being left in the second non-laser region 170 of the substrate 100, and a second groove 105 is formed in the second laser region 160 of the substrate 100. However, in actual applications, the surface of the second non-laser region and the surface of the second laser region of the substrate may be kept flat.

[0086] Furthermore, in step S4, a first groove 104 with a first texture surface 114 as its bottom surface can be formed, and then in step S7, a second groove 105 with a second texture surface 115 as its bottom surface can be formed. In other words, it is possible for the first surface 110 to have the first groove 104 and the second surface 120 to have the second groove 105 to occur simultaneously in the final solar cell. This is advantageous in improving both the absorption utilization rate of incident light by the first surface 110 and the absorption utilization rate of incident light by the second surface 120, thereby improving the double-sided ratio of the solar cell.

[0087] In actual applications, when a first groove with a first texture surface as its bottom surface is formed in step S4, a second texture surface that is flush with the surface of the substrate facing the remaining silicate glass layer can be formed in step S7, or when a first texture surface that is flush with the surface of the substrate facing the doped portion is formed in step S4, a second groove with a second texture surface as its bottom surface can be formed in step S7, or when a first texture surface that is flush with the surface of the substrate facing the doped portion is formed in step S4, a second texture surface that is flush with the surface of the substrate facing the remaining silicate glass layer can be formed in step S7. Note that "flush" means that the height difference between the two surfaces is extremely low, or even zero.

[0088] In other embodiments, as shown in Figures 2 and 3, in step S3, an oxide layer (not shown) is formed on the doped layer 101 in the step of performing the first laser treatment, and as shown in Figures 3 and 4, in step S4, the step of performing the first etching treatment on the first surface 110 may include the steps of etching the first surface 110 using a first chain hydrofluoric acid process to remove the oxide layer, and etching the first surface 110 using a first texturing process to remove the activated portion 111 and form a first textured surface 114.

[0089] Furthermore, based on the effect of the laser used in the first laser treatment on the doped layer 101, the surface of the doped layer 101 that is away from the substrate 100 is easily oxidized by heat, thereby forming an oxide layer on the doped layer 101. In other examples, the material of the oxide layer may be silicon dioxide.

[0090] Based on this, the first etching process includes two etching steps, first etching the first surface 110 using a first chain hydrofluoric acid process, and then etching the first surface 110 using a first texturing process, thereby selectively removing the oxide layer and the activated portion 111, respectively, which is advantageous in improving the etching accuracy of the first etching process. In another example, in step S4, it is necessary to ultimately form a first groove 104 whose bottom surface is the first textured surface 114, and designing the first etching process to include two etching steps is advantageous in forming a good stepped shape on the first surface 110, that is, in forming a first groove 104 with a controllable surface shape, for example, in forming a first groove 104 in which the depth of each region is approximately the same.

[0091] In other embodiments, the step of performing a first etching treatment on the first surface includes etching the first surface using a first texturing process to remove the activated portion and form a first textured surface. In other words, the first etching treatment may be a first texturing process, that is, the oxide layer and activated portion are removed and the first textured surface is formed using the first texturing process directly.

[0092] In other embodiments, the first surface 110 includes a first laser region 140 and a first non-laser region 150 arranged alternately along a first direction X, and the second surface 120 includes a second laser region 160 and a second non-laser region 170 arranged alternately along the first direction X. After performing step S4 to form the first textured surface 114, the part of the first surface 110 located in the first non-laser region 150 is still the third textured surface 130 (see Figure 1), the third textured surface 130 has a third pyramidal structure, and the first textured surface 114 has a first pyramidal structure, the size of the third pyramidal structure being larger than the size of the first pyramidal structure.

[0093] In step S1, the entire surface of the first surface 110 of the substrate 100 provided may be the third texture surface 130. After steps S2 to S4 are performed, the etching action on the substrate 100 by the first etching process, that is, further etching of the third texture surface 130 located in the first laser region 140, converts the third texture surface 130 located in the first laser region 140 into the first texture surface 114. Thus, the smaller size of the first pyramidal structure is advantageous in improving the light confinement effect of the first texture surface 114.

[0094] In other embodiments, as shown in Figures 1 and 2, the first surface 110 and the second surface 120 provided in step S1 may both be a third texture surface 130, and as shown in Figures 4 to 6, after forming the first texture surface 114 in step S4 and before forming the doped polysilicon layer 102 in step S5, the manufacturing method may further include a step of polishing the second surface 120 to form a polished surface, and as shown in Figures 6 and 7, the step of forming the doped polysilicon layer 102 and the silicate glass layer 103 includes forming the doped polysilicon layer 102 on the polished surface and forming the silicate glass layer 103 on the side of the doped polysilicon layer 102 away from the polished surface.

[0095] Furthermore, the high flatness of the polished surface and the formation of the doped polysilicon layer 102 on the polished surface are advantageous in terms of improving the uniformity of the doped polysilicon layer 102. In other words, forming a doped polysilicon layer 102 in which the thickness of each region is almost the same is advantageous in improving the passivation effect of the doped polysilicon layer 102 on the surface of the substrate 100, and ultimately improving the photoelectric conversion efficiency of the solar cell formed.

[0096] In other cases, as shown in Figure 2, in step S2, doping is performed on at least the first surface 110, and further doping is performed on the second surface 120 to form a second doping layer 108 having the first doping element on the second surface 120, and the doping layer 101 formed on the first surface 110 can be considered as the first doping layer, and in the step of polishing the second surface 120 as shown in Figures 4 to 6, the second doping layer 108 is removed.

[0097] In other cases, as shown in Figure 5, after forming the first textured surface 114 in step S4 and before forming the polished surface, the manufacturing method may further include the step of performing an oxidation treatment on at least the first surface 110 to form a first diffusion barrier layer 116 on the doped portion 121 and a second diffusion barrier layer 126 on the first textured surface 114.

[0098] The first diffusion barrier layer 116 is formed after a portion of the doped portion 121 has been oxidized. In other examples, the material of the first diffusion barrier layer 116 may be borosilicate glass. The second diffusion barrier layer 126 is formed after a portion of the substrate 100 has been oxidized. In other examples, the material of the second diffusion barrier layer 126 may be silicon dioxide.

[0099] Furthermore, in the step of performing oxidation treatment on at least the first surface 110, further diffusion of the doped elements in the doped portion 121 into the substrate 100 is promoted, which is advantageous in deepening the bonding depth of the doped portion 121 and the bonding depth of the PN junction formed by both the doped portion 121 and the substrate 100. Additionally, the doping concentration of the doped elements in the doped portion 121 is slightly reduced, which reduces the defect level density at the contact site between the electrode and the doped portion 121 formed thereafter, thereby improving the contact performance between the electrode and the doped portion 121. Based on this, as shown in Figure 7, the step of forming the doped polysilicon layer 102 and the silicate glass layer 103 in step S5 may further include the step of forming the doped polysilicon layer 102 on either the first diffusion barrier layer 116 or the second diffusion barrier layer 126, and forming the silicate glass layer 103 on either the side of the doped polysilicon layer 102 away from the first diffusion barrier layer 116 or the second diffusion barrier layer 126. In the step of forming the doped polysilicon layer 102 and the silicate glass layer 103, the second doped element gradually diffuses into the doped polysilicon layer 102 due to the influence of high temperature. Thus, on the one hand, the first diffusion barrier layer 116 located in the doped portion 121 is advantageous in preventing further diffusion of the second doped element into the doped portion 121, avoiding the loss of the second doped element, and preventing the doped portion 121 from being modified by the diffusion of the second doped element, for example, by preventing the doped portion 121 from being converted from P-type to N-type. On the other hand, the second diffusion barrier layer 126 located in the first texture surface 114 is advantageous in preventing further diffusion of the second doped element into the substrate 100, for example, the first laser region 140, and avoiding the loss of the second doped element.

[0100] In other cases, after forming the first textured surface in step S4 and before forming the polished surface, the manufacturing method may further include the step of performing an oxidation treatment on at least the first surface to form a first diffusion barrier layer in the doped area and forming a second diffusion barrier layer on the first textured surface, wherein the surface composed of both the first and second diffusion barrier layers includes an edge region and a central region surrounded by the edge region, and the step of forming the doped polysilicon layer and silicate glass layer may further include the step of forming the doped polysilicon layer in the edge region and forming the silicate glass layer on the side of the doped polysilicon layer away from the edge region. In other words, in the step of forming the doped polysilicon layer and silicate glass layer on the second surface in step S5, the doped polysilicon layer and silicate glass layer are sequentially formed on the edge region of the surface composed of both the first and second diffusion barrier layers by a wrapping-around plating phenomenon. Thus, the first diffusion barrier layer located in the doped area is advantageous in preventing further diffusion of the second doped element into the doped area, and the second diffusion barrier layer located in the first texture surface is also advantageous in preventing further diffusion of the second doped element into the substrate.

[0101] In another example, as shown in Figure 2, in step S2, a second doping layer 108 having a first doping element is further formed on the second surface 120, and based on this, as shown in Figure 5, in the step of performing an oxidation treatment on at least the first surface 110, the second doping layer 108 is further oxidized to form a third diffusion barrier layer 136 on the side of the second doping layer 108 away from the second surface 120. Note that the second diffusion barrier layer 126 and the third diffusion barrier layer 136 may be formed simultaneously by the same oxidation treatment step. In another example, the material of the third diffusion barrier layer 136 and the material of the second diffusion barrier layer 126 may both be silicon oxide. Furthermore, in the step of performing a polishing treatment on the second surface 120, not only the second doping layer 108 but also the third diffusion barrier layer 136 is removed.

[0102] In other cases, during the oxidation treatment step, the temperature is controlled to 1000°C to 1100°C, and may be, for example, 1010°C, 1020°C, 1030°C, 1040°C, 1050°C, 1060°C, 1070°C, 1080°C, or 1090°C.

[0103] In other cases, as shown in Figure 7, the step of forming the doped polysilicon layer 102 and the silicate glass layer 103 may include the steps of forming a semiconductor layer (not shown) on the first surface 110 and the second surface 120 after step S4, forming a doped source layer (not shown) having a second doping element on the side of the semiconductor layer away from the substrate 100, performing a high-temperature treatment on the semiconductor layer and the doped source layer to promote the diffusion of the second doping element into the semiconductor layer, thereby converting the semiconductor layer into a doped polysilicon layer 102 and the doped source layer into a silicate glass layer 103. In other cases, the step of forming the doped polysilicon layer and the silicate glass layer may include the steps of forming a semiconductor layer (not shown) on the second surface 120 after step S4, forming a semiconductor layer in the edge region of the surface composed of both the first diffusion barrier layer and the second diffusion barrier layer by wraparound plating, forming a doped source layer (not shown) having a second doping element on the side of the semiconductor layer away from the substrate, and performing a high-temperature treatment on the semiconductor layer and the doped source layer to promote the diffusion of the second doping element into the semiconductor layer, thereby converting the semiconductor layer into a doped polysilicon layer and the doped source layer into a silicate glass layer.

[0104] In other examples, the semiconductor layer material may be amorphous silicon, and the high-temperature processing step may facilitate the crystallization of amorphous silicon into polysilicon.

[0105] In other embodiments, as shown in Figure 1, the first surface 110 includes a first laser region 140 and a first non-laser region 150 arranged alternately along a first direction X, and the second surface 120 includes a second laser region 160 and a second non-laser region 170 arranged alternately along the first direction X. As shown in Figure 3, the step of performing a first laser treatment on a portion of the doped layer 101 in step S3 may include performing the first laser treatment on the doped layer 101 located in the first laser region 140 to form an activated portion 111 located in the first laser region 140, and as shown in Figure 8, the step of performing a second laser treatment on at least a portion of the silicate glass layer 103 may include performing the second laser treatment on the silicate glass layer 103 located in the second laser region 160 to form a sparse portion 113 located in the second laser region 160.

[0106] Thus, in the final solar cell, the doped portion 121 is located only in the first non-laser region 150, and the doped portion 121 can be considered as a selective emitter located on the first surface 110. This ensures that the subsequent electrodes have good current collection efficiency based on the doped portion 121, and also avoids the first laser region 140 being covered by the doped layer 101, thereby avoiding parasitic absorption of light incident on the first laser region 140 by the doped layer 101, improving the utilization rate of incident light by the first surface 110, and thus improving the photoelectric conversion efficiency of the solar cell.

[0107] In other cases, as shown in Figure 7, in step S5, during the step of forming a doped polysilicon layer 102 having a second doping element, a tunnel layer (not shown) is further formed between the second surface 120 and the doped polysilicon layer 102. In other examples, the material of the tunnel layer is silicon oxide. Based on this, in step S7, the second etching treatment further removes the tunnel layer facing the sparse area 113.

[0108] Thus, in the final solar cell, the tunnel layer and the doped polysilicon layer 102 are located only in the second non-laser region 170, and the tunnel layer and the doped polysilicon layer 102 form a selective passivation contact structure on the second surface 120, ensuring that the tunnel layer and the doped polysilicon layer 102 have a good passivation effect on the second surface 120, while also avoiding the second laser region 160 being covered by the doped polysilicon layer 102, thereby avoiding parasitic absorption of light incident on the second laser region 160 by the doped polysilicon layer 102, improving the utilization rate of incident light by the second surface 120, and thus improving the photoelectric conversion efficiency of the solar cell.

[0109] In other embodiments, as shown in Figure 10 or Figure 11, the first non-laser region 150 and the second non-laser region 170 each include at least the region where the orthographic projection of the electrode (not shown) onto the substrate 100 is located, the region on the first surface 110 other than the first non-laser region 150 is the first laser region 140, and the region on the second surface 120 other than the second non-laser region 170 is the second laser region 160. In order to ensure that the film layer in contact with the electrode has a high doping concentration, or that the regions in contact with the electrode are all high-concentration regions, and to reduce contact resistance, the orthographic projection areas of the first non-laser region 150 and the second non-laser region 170 are generally set to be greater than or equal to the orthographic projection area of ​​the electrode. In other words, the orthographic projection area of ​​the electrode onto the substrate 100 is smaller than the area of ​​the first non-laser region or the second non-laser region, and the orthographic projection position is always within the first non-laser region or the second non-laser region.

[0110] The number of laser regions and non-laser regions may both be multiple, and the laser regions and non-laser regions are arranged alternately along a fixed direction. In other words, the laser regions may be located between adjacent non-laser regions, and the non-laser regions may be located between adjacent laser regions. The laser regions include a first laser region 140 and a second laser region 160, and the non-laser regions include a first non-laser region 150 and a second non-laser region 170.

[0111] In other embodiments, as shown in Figure 10 or Figure 11, the orthographic projection area of ​​the first laser region 140 onto the substrate 100 may differ from the orthographic projection area of ​​the second laser region 160 onto the substrate 100. Furthermore, the orthographic projection area of ​​the first laser region 140 onto the first surface 110 may differ from the orthographic projection area of ​​the second laser region 160 onto the first surface 110 based on differences in the type of solar cell, differences in the light absorption rates of the first surface 110 and the second surface 120, and differences in the design of the doped portion 121 and the doped polysilicon layer 102 formed thereafter. In other embodiments, the size of the first laser region 140 may differ from the size of the second laser region 160. Thus, the manufacturing method according to one embodiment of the present disclosure can be applied to multiple solar cells.

[0112] In one example, the orthographic projection area of ​​the first laser region onto the first surface may be less than or equal to the orthographic projection area of ​​the second laser region onto the first surface, and in another example, the orthographic projection area of ​​the first laser region onto the first surface may be greater than the orthographic projection area of ​​the second laser region onto the first surface. Furthermore, the orthographic projection areas of multiple first laser regions onto the first surface may be the same or different, and can be designed according to actual needs. Similarly, the orthographic projection areas of multiple second laser regions onto the first surface may be the same or different, and can be designed according to actual needs.

[0113] In other embodiments, the orthographic projection of the first laser region onto the first surface does not overlap with the orthographic projection of the second laser region onto the first surface. In other words, the first and second laser regions are avoided facing each other along a second direction, which is the thickness direction of the solar cell. Thus, the laser acting on the first surface by the first laser treatment in step S3 and the laser acting on the second surface by the second laser treatment in step S6 repeatedly treat the same portion of the substrate, thus avoiding damage due to localized repeated overheating of the substrate, and thereby improving the electrical performance of the final solar cell.

[0114] In one example, the first laser region and the second non-laser region may face each other along the second direction, that is, the orthographic projection of the first laser region onto the first surface may overlap with the orthographic projection of the second non-laser region onto the first surface, and the first non-laser region and the second laser region may face each other along the second direction, that is, the orthographic projection of the first non-laser region onto the first surface may overlap with the orthographic projection of the second laser region onto the first surface.

[0115] In other embodiments, the orthographic projection of the first laser region onto the first surface may at least partially overlap with the orthographic projection of the second laser region onto the first surface.

[0116] In actual applications, it is possible that the orthographic projection area of ​​the first laser region onto the first surface may differ from that of the second laser region onto the first surface, and that the orthographic projection of the first laser region onto the first surface may not overlap with that of the second laser region onto the first surface, both occurring simultaneously in the same solar cell. Alternatively, it is possible that the orthographic projection area of ​​the first laser region onto the first surface may differ from that of the second laser region onto the first surface, and that the orthographic projection of the first laser region onto the first surface may at least partially overlap with that of the second laser region onto the first surface, both occurring simultaneously in the same solar cell.

[0117] In other embodiments, as shown in Figures 9 and 10, the step of performing a second etching treatment on at least the second surface 120 includes the steps of etching the first surface 110 using a second-chain hydrofluoric acid process to remove the silicate glass layer 103 located on the first surface 110, and etching the first surface 110 and the second surface 120 using a second texturing process to remove the doped polysilicon layer 102, the first diffusion barrier layer 116, and the second diffusion barrier layer 126 located on the first surface 110, exposing the first textured surface 114 and the doped portion 121, and removing the sparse portion 113 and the doped polysilicon layer 102 located in the second laser region 160 to form the second textured surface 115.

[0118] In step S6, the second laser treatment is performed only on a portion of the silicate glass layer 103 formed on the second surface 120 to form a sparse area 113, while the silicate glass layer 103 formed on the first surface 110 is not treated with laser. That is, the porosity of the remaining silicate glass layer 103 located on the second surface 120 and the porosity of the silicate glass layer 103 located on the first surface 110 are not modified by the second laser treatment, and both are lower than the porosity of the sparse area 113.

[0119] Based on this, the second etching process includes two etching steps, first etching the first surface 110 using a second-chain hydrofluoric acid process to remove the silicate glass layer 103 located on the first surface 110. This is advantageous in avoiding the phenomenon in which the subsequent second texturing process is blocked by the silicate glass layer 103 located on the first surface 110, preventing the removal of the doped polysilicon layer 102 located on the first surface 110. Next, the remaining silicate glass layer 103 located on the second surface 120 is used as a protective layer, and the first surface 110 and the second surface 120 are etched using a second texturing process to remove the doped polysilicon layer 102, the first diffusion barrier layer 116, and the second diffusion barrier layer 126 located on the first surface 110, as well as the sparse area 113 and the doped polysilicon layer 102 located on the second laser region 160. This reduces the number of film layers to be removed from both the first surface 110 and the second surface 120 by the second texturing process to two layers, which is advantageous in improving the etching accuracy of the second etching process. In another example, in step S7, it is necessary to ultimately form a second groove 105 whose bottom surface is the second texture surface 115, and designing the second etching process to include two etching steps, one before and one after, is advantageous in forming a good step shape on the second surface 120, that is, it is advantageous in forming a second groove 105 with a controllable surface shape, for example, in forming a second groove 105 in which the depth of each region is approximately the same.

[0120] In other embodiments, as shown in Figures 10 and 11, after performing the second texturing process, the manufacturing method may further include the step of cleaning the second surface 120 using an acid pickling process to remove the silicate glass layer 103 located in the second non-laser region 170 and expose the doped polysilicon layer 102 located in the second non-laser region 170.

[0121] In summary, the first laser treatment is used to increase the doping concentration of the first doped element in the doped layer 101. Based on this, when the first etching treatment is subsequently performed on the first surface 110, the etching rate for the activated portion 111, where the doping concentration of the first doped element is lower, is much higher than that for the doped portion 121. As a result, the doped portion 121 can be treated as a dead layer, and the activated portion 111 can be removed to form the first textured surface 114 without the need for a separate mask, which is advantageous for simplifying the manufacturing process of solar cells. Furthermore, compared to removing a portion of the doped layer 101 using a laser deposition process, the combined effect of the first laser treatment and the first etching treatment is advantageous in reducing laser damage to the first surface 110. Furthermore, forming a selective emitter structure in which the doped portion 121 remains only in a portion of the first surface 110 is advantageous in reducing the contact resistance between the subsequently formed electrode and the doped portion 121, as well as reducing the probability of carrier recombination in other regions of the first surface 110.

[0122] The second laser treatment is used to modify a portion of the silicate glass layer 103 into a porous area 113. Based on this, if a second etching treatment is subsequently performed on at least the second surface 120, the etching rate on the porous area 113, which has higher porosity due to the second etching treatment, is much higher than that on the remaining silicate glass layer 103. As a result, without providing a separate mask, the remaining silicate glass layer 103 can be used as a protective layer, and the porous area 113 and the doped polysilicon layer 102 facing the porous area 113 can be removed to form a second textured surface 115, which is advantageous for simplifying the manufacturing process of solar cells. Furthermore, removing the doped polysilicon layer 102 facing the porous area 113 is advantageous in avoiding parasitic absorption of light by the partially removed doped polysilicon layer 102. The exposed second textured surface 115 can improve the light absorption utilization rate and is also advantageous in ensuring low contact resistance between the subsequently formed electrodes and the remaining doped polysilicon layer 102.

[0123] Another embodiment of this disclosure provides a solar cell manufactured by the manufacturing method described in the above-described embodiment. A solar cell according to another embodiment of this disclosure will be described in detail below with reference to the drawings. Parts that are the same as or corresponding to the above-described embodiment will not be described here.

[0124] The solar cell includes a solar cell formed by the manufacturing method according to the above-described embodiment.

[0125] The solar cell may also be a battery having a passivation structure, such as a TOPCON battery, a PERC battery, or a heterojunction battery. By forming a solar cell using the manufacturing method described above, and performing two separate laser treatments, a first laser treatment and a second laser treatment of different laser types, a doped portion 121 located only in a portion of the first surface 110 and a doped polysilicon layer 102 located only in a portion of the second surface 120 are formed without the need for a separate mask. This exposes the first textured surface 114 on the first surface 110 and the second textured surface 115 on the second surface 120, thereby improving the utilization rate of incident light by the first surface 110 and the second surface 120, and is advantageous in improving the photoelectric conversion efficiency of the formed solar cell.

[0126] In another embodiment, as shown in Figure 11, the solar cell is a substrate 100 having a first surface 110 and a second surface 120 facing each other, wherein the first surface 110 includes a first laser region 140 and a first non-laser region 150 arranged alternately along a first direction X, and the second surface 120 includes a second laser region 160 and a second non-laser region 170 arranged alternately along the first direction X, a doped portion 121 located in the first non-laser region 150, a doped polysilicon layer 102 located in the second non-laser region 170, a first groove 104 in the first laser region 140 whose bottom surface is a first textured surface 114, and a second groove 105 in the second laser region 160 whose bottom surface is a second textured surface 115.

[0127] Thus, on the one hand, the first texture surface 114 can enhance the absorption effect of incident light, and due to the characteristic that the first groove 104 is recessed into the substrate 100, light incident into the first groove 104 is less likely to be reflected to the outside of the solar cell, further improving the absorption utilization rate of incident light by the first groove 104. Therefore, the cooperation between the first groove 104 and the first texture surface 114 is advantageous in improving the absorption utilization rate of incident light by the first surface 110. On the other hand, the second texture surface 115 can enhance the absorption effect of incident light, and due to the characteristic that the second groove 105 is recessed into the substrate 100, light incident into the second groove 105 is less likely to be reflected to the outside of the solar cell, further improving the absorption utilization rate of incident light by the second groove 105. Therefore, the cooperation between the second groove 105 and the second texture surface 115 is advantageous in improving the absorption utilization rate of incident light by the second surface 120. This multifaceted cooperation is advantageous in improving the photoelectric conversion efficiency of the solar cell.

[0128] In other cases, along the second direction Y, the depth of the first groove 104 is greater than the depth of the second groove 105. In other examples, the depth of the first groove 104 may be 2.5 μm to 4 μm, and the depth of the second groove 105 may be 2 μm to 3 μm.

[0129] In other embodiments, the solar cell may further include a tunnel layer located between the second surface 120 and the doped polysilicon layer 102, which together with the doped polysilicon layer 102 forms a selective passivation contact structure with the second surface 120.

[0130] Those skilled in the art will understand that the above embodiments are specific examples of realizing the present disclosure, and that in actual applications, various modifications can be made in form and detail without departing from the spirit and scope of the embodiments of the present disclosure. Since various modifications and alterations can be made without departing from the spirit and scope of the embodiments of the present disclosure, the scope of protection of the embodiments of the present disclosure should be limited to the scope defined in the claims. [Explanation of symbols]

[0131] 100 circuit boards 110 Page 1 120 Side 2 130 Third Texture Face 140 First Laser Region 150 First Non-Laser Region 160 Second Laser Region 170 Second Non-Laser Region 101 Dope Layer 111 Activation part 121 Dope Section 102 Doped polysilicon layer 103 Silicate glass layer 113 Sparse area 104 First groove 114 First Texture Face 105 Second groove 115 Second Texture Face 116 First Diffusion Barrier Layer 126 Second Diffusion Barrier Layer 136 Third Diffusion Barrier Layer 108 Second Doping Layer

Claims

1. A step of providing a substrate having a first surface and a second surface facing each other, wherein the first surface includes a first region and a second region arranged alternately along a first direction, the second surface includes a third region and a fourth region arranged alternately along the first direction, and the first surface includes a doped layer having a first doped element, The steps include performing a first laser treatment on the doped layer located in the first region, thereby making the doped layer located in the second region a doped portion, The first step is to perform a first etching process on the first surface to remove the doped layer located in the first region that has been first laser-treated, thereby forming a first textured surface. The steps include forming a doped polysilicon layer having a second doping element and a silicate glass layer on the second surface, The steps include performing a second laser treatment on the silicate glass layer located in the third region, The process further includes the step of using the silicate glass layer located in the fourth region as a protective layer, performing a second etching process on at least the second surface to remove the silicate glass layer located in the third region and the doped polysilicon layer located in the third region, which have been second laser-treated, thereby forming a second textured surface. The first doped element and the second doped element are of different types. The first laser treatment makes the doping concentration of the first doped element in the doped layer located in the first region lower than the doping concentration of the first doped element in the doped portion, and makes the etching rate of the doped layer located in the first region higher than that of the doped portion. The second laser treatment modifies the silicate glass layer located in the third region, and by making the porosity of the modified silicate glass layer higher than that of the protective layer, the etching rate of the modified silicate glass layer is made higher than that of the protective layer. A method for manufacturing a solar cell, characterized by the following features.

2. The first laser processing and the second laser processing use different types of lasers. A method for manufacturing a solar cell according to claim 1.

3. After forming the first textured surface and before forming the doped polysilicon layer, The process further includes the step of performing a polishing treatment on the second surface to form a polished surface, The step of forming the doped polysilicon layer and the silicate glass layer is, The steps include forming the doped polysilicon layer on the polished surface and forming the silicate glass layer on the side of the doped polysilicon layer away from the polished surface. A method for manufacturing a solar cell according to claim 1.

4. After forming the first textured surface and before forming the polished surface, The process further includes the steps of performing an oxidation treatment on at least the first surface to form a first diffusion barrier layer on the doped portion, and forming a second diffusion barrier layer on the first textured surface. The step of forming the doped polysilicon layer and the silicate glass layer is, The process further includes the steps of forming the doped polysilicon layer on both the first diffusion barrier layer and the second diffusion barrier layer, and forming the silicate glass layer on either side of the doped polysilicon layer that is away from the first diffusion barrier layer and the second diffusion barrier layer, The method for manufacturing a solar cell according to claim 3.

5. After forming the first textured surface and before forming the polished surface, The process further includes the steps of performing an oxidation treatment on at least the first surface to form a first diffusion barrier layer on the doped portion, and forming a second diffusion barrier layer on the first textured surface. The surface composed of both the first diffusion barrier layer and the second diffusion barrier layer includes an edge region and a central region surrounded by the edge region. The step of forming the doped polysilicon layer and the silicate glass layer is, The further step includes forming the doped polysilicon layer in the edge region and forming the silicate glass layer on the side of the doped polysilicon layer away from the edge region. The method for manufacturing a solar cell according to claim 3.

6. The orthographic projection area of ​​the first region onto the substrate is different from the orthographic projection area of ​​the third region onto the substrate. A method for manufacturing a solar cell according to claim 1.

7. The step of performing the second etching process on at least the second surface is: The steps include etching the first surface using a second-chain hydrofluoric acid process to remove the silicate glass layer located on the first surface, The process includes the steps of etching the first and second surfaces using a second texturing process to remove the doped polysilicon layer, the first diffusion barrier layer, and the second diffusion barrier layer located on the first surface, exposing the first textured surface and the doped portion, and removing the silicate glass layer and the doped polysilicon layer located in the third region, which have been second laser-treated, to form the second textured surface. The method for manufacturing a solar cell according to claim 5, characterized in that it is as described above.

8. After performing the second texturing process, The process further includes cleaning the second surface using an acid pickling process to remove the silicate glass layer located in the fourth region and expose the doped polysilicon layer located in the fourth region. A method for manufacturing a solar cell according to claim 7.

9. The step of performing the first etching process on the first surface is: The process includes the step of etching the first surface using a first texturing process to remove the doped layer located in the first region that has been first laser-treated, thereby forming a first textured surface. A method for manufacturing a solar cell according to claim 1.

10. In the step of performing the first laser processing, an oxide layer is formed on the doped layer, The step of performing the first etching process on the first surface further includes the step of etching the first surface using a first chain hydrofluoric acid process to remove the oxide layer before etching the first surface using the first texturing process, The method for manufacturing a solar cell according to feature 9.

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