Back contact battery, manufacturing method thereof and photovoltaic module

Abstract

The embodiment of the invention relates to the photovoltaic field, and provides a back contact battery and a manufacturing method thereof, and a photovoltaic module, and the manufacturing method comprises the steps: providing a substrate with a first surface and a second surface which are opposite in a first direction, and the second surface is provided with first regions and second regions which are alternately arranged in a second direction; forming a dielectric layer on the second surface; sequentially forming a doping layer and a silica glass layer which are both provided with doping elements on one side, far away from the substrate, of the dielectric layer, wherein the molar percentage content of the doping elements in the silica glass layer is 5%-10%; removing the silica glass layer on the first area or the second area; and performing etching treatment by taking the residual silica glass layer as a mask layer, and removing the doping layer and the dielectric layer which are not covered by the mask layer, thereby at least facilitating the improvement of the manufacturing efficiency of the back contact cell.

Description

Technical Field

[0001] The present application relates to the photovoltaic field, and in particular to a back-contact cell and a manufacturing method thereof, and a photovoltaic module. Background Art

[0002] Solar cells are becoming increasingly popular as a sustainable source of clean energy. A solar cell uses the photovoltaic principle to generate charge carriers, converting sunlight into electricity. Grid lines are typically used in solar cells to extract the charge carriers, allowing for efficient use of the electrical energy. Current mainstream solar cell types include BC cells (back contact cells), TOPCON cells (tunnel oxide passivated contact), PERC cells (passivated emitter and real cell), and heterojunction cells.

[0003] In order to further avoid the grid lines blocking the front of the solar cell, the research on BC cells (Back Contact) has become more and more in-depth. However, the grid lines of different polarities are all located on the back of the solar cell, which requires the repeated use of mask plate technology in the process of preparing BC cells, greatly increasing the process difficulty and production cost, and also reducing the preparation efficiency. Summary of the Invention

[0004] The embodiments of the present application provide a back-contact cell and a manufacturing method thereof, and a photovoltaic module, which are at least beneficial to improving the manufacturing efficiency of the back-contact cell.

[0005] According to some embodiments of the present application, on the one hand, the embodiments of the present application provide a method for manufacturing a back-contact battery, including: providing a substrate, the substrate having a first surface and a second surface opposite to each other along a first direction, the second surface having a first area and a second area alternately arranged along a second direction; forming a dielectric layer on the second surface; forming a stacked doping layer and a silicon glass layer on a side of the dielectric layer away from the substrate, the doping layer and the silicon glass layer both having doping elements, and the molar percentage of the doping elements in the silicon glass layer is 5% to 10%; removing the silicon glass layer located on the first area or the second area; performing etching using the remaining silicon glass layer as a mask layer to remove the doping layer and the dielectric layer not covered by the mask layer.

[0006] In some embodiments, the steps of forming the doping layer and the silicon glass layer include: forming a semiconductor layer on the side of the dielectric layer away from the substrate; performing a doping treatment on the semiconductor layer to convert the semiconductor layer into the doping layer, and forming the silicon glass layer on the side of the doping layer away from the substrate, and controlling the molar percentage of the doping element in the silicon glass layer to be 5%~10%.

[0007] In some embodiments, the dielectric layer includes a first dielectric layer, the semiconductor layer includes a first semiconductor layer, and the doping element includes boron; the doping layer formed after the doping treatment includes a first doping layer, and the silicon glass layer includes a borosilicate glass layer; in the borosilicate glass layer, the molar percentage of boron in silicon oxide is 5%~10%.

[0008] In some embodiments, the step of performing the doping treatment includes: first performing a first expansion treatment, and then performing a first push-knot treatment; the step of performing the first expansion treatment includes: placing the substrate after forming the first semiconductor layer into a reaction chamber, and introducing boron trichloride into the reaction chamber; the step of performing the first push-knot treatment includes: first performing a first aerobic push-knot treatment, and introducing a mixed gas of boron trichloride and oxygen into the reaction chamber; and then performing a first anaerobic push-knot treatment, and introducing boron trichloride into the reaction chamber.

[0009] In some embodiments, the gas flow rate of boron trichloride introduced into the reaction chamber is 50 sccm~200 sccm; and / or the ratio of the treatment time of the first aerobic push-knot treatment to the treatment time of the first anaerobic push-knot treatment is 1:20~1:3.

[0010] In some embodiments, in the step of performing the first aerobic pushing treatment, the ratio of the gas flow rate of oxygen to the gas flow rate of boron trichloride is 2-10.

[0011] In some embodiments, the process temperature used in the first via expansion process is 800° C. to 900° C.; and / or the process temperature used in the first junction pushing process is 900° C. to 1050° C.

[0012] In some embodiments, the dielectric layer includes a second dielectric layer, the semiconductor layer includes a second semiconductor layer, and the doping element includes phosphorus; the doping layer formed after the doping treatment includes a second doping layer, and the silicon glass layer includes a phosphosilicate glass layer; in the phosphosilicate glass layer, the molar percentage content of phosphorus in silicon oxide is 5%~10%.

[0013] In some embodiments, the step of removing the silicon glass layer includes: performing laser processing on the silicon glass layer located on the first region or the second region to form a modified layer; removing the modified layer during the etching step; and performing the etching process using the remaining silicon glass layer as a mask layer during the etching step to remove the doping layer and the dielectric layer covered by the modified layer.

[0014] In some embodiments, the dielectric layer includes a first dielectric layer, the doping element includes boron, the doping layer formed after the doping treatment includes a first doping layer, and the silicon glass layer includes a borosilicate glass layer; the step of performing the laser treatment includes: performing the laser treatment on the borosilicate glass layer located on the second region to convert the borosilicate glass layer located on the second region into a first modified layer; the step of performing the etching treatment includes: removing the first modified layer, and using the remaining borosilicate glass layer located on the first region as a mask layer, removing the first doping layer and the first dielectric layer covered by the first modified layer.

[0015] In some embodiments, the dielectric layer includes a second dielectric layer, the doping element includes phosphorus, the doping layer formed after the doping treatment includes a second doping layer, and the silicon glass layer includes a phosphosilicate glass layer; the step of performing the laser treatment includes: performing the laser treatment on the phosphosilicate glass layer located on the first region to convert the phosphosilicate glass layer located on the first region into a second modified layer; the step of performing the etching treatment includes: removing the second modified layer, and using the remaining phosphosilicate glass layer located on the second region as a mask layer, removing the second doping layer and the second dielectric layer covered by the second modified layer.

[0016] According to some embodiments of the present application, on the other hand, embodiments of the present application further provide a back-contact battery, including a back-contact battery formed by the back-contact battery manufacturing method as described in any one of the above items.

[0017] According to some embodiments of the present application, another aspect of the embodiments of the present application further provides a photovoltaic module, comprising: a cell string, formed by connecting a plurality of back-contact cells formed by the manufacturing method of the back-contact cell described in any of the above items, or formed by connecting a plurality of back-contact cells described in any of the above items; an encapsulation film for covering the surface of the cell string; and a cover plate for covering the surface of the encapsulation film facing away from the cell string.

[0018] The technical solution provided by the embodiments of the present application has at least the following advantages: In the step of forming the silicon glass layer, the molar percentage of the doping element in the silicon glass layer is controlled to be 5% to 10%. On the one hand, this is conducive to making the formed silicon glass layer have a higher density, so as to improve the etching resistance of the silicon glass layer in the subsequent step of using the silicon glass layer as a mask layer, so as to avoid over-etching of the doping layer and the dielectric layer that need to be retained, thereby improving the yield of the back contact cell finally manufactured; on the other hand, controlling the molar percentage of the doping element in the silicon glass layer to be moderate is conducive to increasing the formation rate of the silicon glass layer, thereby improving the manufacturing efficiency of the back contact cell; on the other hand, in the step of patterning the doping layer and the dielectric layer, the silicon glass layer is directly used as the mask layer without the need for an additional mask, which is conducive to simplifying the manufacturing process of the back contact cell, thereby further improving the manufacturing efficiency of the back contact cell. Such multi-faceted cooperation is conducive to improving the yield of the finally manufactured back contact cell while improving the manufacturing efficiency of the back contact cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present application or the technical solutions in the traditional technology, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 A process flow chart corresponding to a method for manufacturing a back-contact battery provided in one embodiment of the present application; Figure 2 A partial cross-sectional schematic diagram of a substrate in a method for manufacturing a back-contact battery provided in one embodiment of the present application; Figure 3 A partial cross-sectional schematic diagram after forming a first dielectric layer in a method for manufacturing a back-contact battery provided in one embodiment of the present application; Figure 4 A schematic partial cross-sectional view after forming a first semiconductor layer in a method for manufacturing a back-contact battery provided in one embodiment of the present application; Figure 5 A schematic partial cross-sectional view of a back-contact cell after doping treatment in a method for manufacturing the back-contact cell provided in one embodiment of the present application; Figure 6 A schematic partial cross-sectional view of a back-contact cell after laser processing in a method for manufacturing a back-contact cell provided in one embodiment of the present application; Figure 7A schematic partial cross-sectional view of a back-contact cell after etching in a method for manufacturing the back-contact cell according to an embodiment of the present application; Figure 8 A partial cross-sectional schematic diagram after forming a second dielectric layer in the manufacturing method of a back-contact battery provided in one embodiment of the present application; Figure 9 A schematic partial cross-sectional view after forming a second semiconductor layer in a method for manufacturing a back-contact battery provided in one embodiment of the present application; Figure 10 Another partial cross-sectional schematic diagram after doping treatment in the manufacturing method of the back contact cell provided in one embodiment of the present application; Figure 11 Another partial cross-sectional schematic diagram of a back-contact cell after laser processing in the method for manufacturing the back-contact cell provided in one embodiment of the present application; Figure 12 Another partial cross-sectional schematic diagram after etching treatment in the manufacturing method of the back contact battery provided in one embodiment of the present application; Figure 13 A partial three-dimensional schematic diagram of a cell string in a photovoltaic module provided in another embodiment of the present application; Figure 14 A partial cross-sectional schematic diagram of a photovoltaic module provided in yet another embodiment of the present application.

[0021] Description of reference numerals: 100. Substrate; 110. First surface; 120. Second surface; 1201. First region; 1202. Second region; 101. Dielectric layer; 111. First dielectric layer; 121. Second dielectric layer; 102. Doped layer; 112. First doped layer; 122. Second doped layer; 103. Silicate glass layer; 113. Borosilicate glass layer; 123. Phosphorus silicate glass layer; 104. Modified layer; 114. First modified layer; 124. Second modified layer; 105. Semiconductor layer; 115. First semiconductor layer; 125. Second semiconductor layer; 40. Back contact battery; 41. Encapsulation film; 42. Cover plate; 43. Conductive tape. DETAILED DESCRIPTION

[0022] As can be seen from the background technology, the manufacturing efficiency of back-contact cells needs to be improved.

[0023] The present invention provides a back-contact cell, a manufacturing method thereof, and a photovoltaic module. In the manufacturing method, in the step of forming a silicon glass layer, the molar percentage of the doping element in the silicon glass layer is controlled to be 5% to 10%. On the one hand, this helps to ensure that the formed silicon glass layer has a higher density, so as to improve the etching resistance of the silicon glass layer in the subsequent step of using the silicon glass layer as a mask layer, thereby preventing the doping layer and the dielectric layer that need to be retained from being over-etched, thereby improving the yield of the final back-contact cell. On the other hand, controlling the molar percentage of the doping element in the silicon glass layer to be moderate helps to increase the formation rate of the silicon glass layer, thereby improving the manufacturing efficiency of the back-contact cell. On the other hand, in the step of patterning the doping layer and the dielectric layer, the silicon glass layer is directly used as the mask layer without the need for an additional mask, which helps to simplify the manufacturing process of the back-contact cell, thereby further improving the manufacturing efficiency of the back-contact cell. Such multi-faceted coordination helps to improve the yield of the final back-contact cell while improving the manufacturing efficiency of the back-contact cell.

[0024] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0025] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0026] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0027] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0028] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0029] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0030] In the accompanying drawings corresponding to the embodiments of this application, the thickness and area of ​​layers are exaggerated for better understanding and ease of description. When a component (such as a layer, film, region, or substrate) is described as being on or on the surface of another component, the component may be "directly" located on the surface of the other component, or a third component may be present between the two components. Conversely, when a component is described as being on the surface of another component, or as being formed or disposed on the surface of one component, it indicates that there is no third component between the two components. Furthermore, when a component is described as being "substantially" formed on another component, this means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0031] In the description of the embodiments of this application, when a component is referred to as "including" another component, unless otherwise specified, this does not exclude other components, and other components may further be included. Furthermore, when a component such as a layer, film, region, or plate is referred to as being "on" another component, it may be "directly on" the other component (i.e., located on the surface of the other component with no other components between them) or another component may be present between them. Furthermore, when a component such as a layer, film, region, or plate is referred to as being "directly on" another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, this means that no other components are located between them.

[0032] The terms used herein in the description of the various embodiments are intended only to describe the specific embodiments and are not intended to be limiting. As used in the description of the various embodiments and the appended claims, "the component" is intended to include the plural form unless the context clearly indicates otherwise. A component includes a layer, film, region, or plate.

[0033] The following will describe the various embodiments of the present application in detail with reference to the accompanying drawings. However, those skilled in the art will appreciate that many technical details are provided in the various embodiments of the present application to help readers better understand the embodiments of the present application. However, even without these technical details and the various variations and modifications based on the following embodiments, the technical solutions claimed in the embodiments of the present application can still be implemented.

[0034] An embodiment of the present application provides a method for manufacturing a back-contact battery. The method for manufacturing a back-contact battery provided by an embodiment of the present application will be described in detail below with reference to the accompanying drawings.

[0035] Combined with reference Figure 1 ,as well as Figures 2 to 12 The manufacturing method of the back contact battery comprises at least the following steps: S1: Reference Figure 2 , Figure 2 A partial cross-sectional schematic diagram of a substrate in a method for manufacturing a back-contact battery provided in an embodiment of the present application is provided, wherein a substrate 100 is provided, wherein the substrate 100 has a first surface 110 and a second surface 120 opposite to each other along a first direction X, and the second surface 120 has first areas 1201 and second areas 1202 alternately arranged along a second direction Y.

[0036] S2: Reference Figure 3 or Figure 7 , a dielectric layer 101 is formed on the second surface 120 .

[0037] S3: Reference Figures 4 and 5 , or refer to Figures 9 and 10 A stacked doping layer 102 and a silicon glass layer 103 are formed on a side of the dielectric layer 101 away from the substrate 100. Both the doping layer 102 and the silicon glass layer 103 contain doping elements, and the molar percentage of the doping elements in the silicon glass layer 103 is 5% to 10%.

[0038] S4: Combined with reference Figure 5 and Figure 7 , or combined with reference Figure 10 and Figure 12 , remove the silicon glass layer 103 located on the first area 1201 or the second area 1202.

[0039] S5: Continue to combine references Figures 5 to 7 , or combined with reference Figures 10 to 12 The remaining silicon glass layer 103 is used as a mask layer for etching to remove the doping layer 102 and the dielectric layer 101 not covered by the mask layer.

[0040] in, Figure 1 A process flow chart corresponding to a method for manufacturing a back-contact battery provided in one embodiment of the present application; Figures 2 to 7 Schematic diagram of partial cross-sections corresponding to each step of the first method for manufacturing a back-contact battery provided in one embodiment of the present application; Figures 8 to 12 This is a partial cross-sectional structural diagram corresponding to each step of the second method for manufacturing a back contact battery provided in an embodiment of the present application. Figures 3 to 12 Provide detailed explanation.

[0041] It is worth noting that by controlling the molar percentage of the doping elements in the formed silicon glass layer 103 to be 5%~10% in step S3, on the one hand, it is beneficial to promote the formed silicon glass layer 103 to have a higher density, so as to improve the etching resistance of the silicon glass layer 103 when the silicon glass layer 103 is used as a mask layer in the subsequent step S5, so as to avoid the doping layer 102 and the dielectric layer 101 that need to be retained from being over-etched, thereby improving the yield of the back contact battery finally manufactured; on the other hand, controlling the molar percentage of the doping elements in the formed silicon glass layer 103 to be moderate is beneficial to improving the formation rate of the silicon glass layer 103 in step S3, thereby improving the manufacturing efficiency of the back contact battery; on the other hand, in the step of patterning the doping layer 102 and the dielectric layer 101 in step S5, the silicon glass layer 103 can be directly used as the mask layer without the need to set up an additional mask, which is beneficial to simplifying the manufacturing process of the back contact battery, that is, reducing the process of preparing additional masks, reducing process time and reducing manufacturing costs, thereby helping to further improve the manufacturing efficiency of the back contact battery. Such multi-faceted coordination is conducive to improving the yield of the final manufactured back contact cell while improving the manufacturing efficiency of the back contact battery.

[0042] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings.

[0043] In some embodiments, the step of removing the silicon glass layer 103 may include: Figure 5 and Figure 6 , or combined with reference Figure 10 and Figure 11 , the silicon glass layer 103 located on the first area 1201 or the second area 1202 is laser processed to form a modified layer 104; Figure 6 and Figure 7 , or combined with reference Figure 11 and Figure 12 , the modified layer 104 is removed in the step of performing an etching process.

[0044] Further, continue to combine reference Figure 6 and Figure 7 , or combined with reference Figure 11 and Figure 12 In the step of etching, the remaining silicon glass layer 103 is also used as a mask layer for etching to remove the doped layer 102 and the dielectric layer 101 covered by the modified layer 104. It is worth noting that the laser-treated portion of the silicon glass layer 103, i.e., the modified layer 104, is modified into a looser structure than the initial portion that has not been laser-treated, and is easier to be removed by subsequent etching. In other words, the modified layer 104 has a looser structure than the silicon glass layer 103 that has not been laser-treated. In this way, not only can the silicon glass layer 103 be used to pattern the doped layer 102 and the dielectric layer 101, but it is also possible to avoid excessive laser power in the step of laser-treating the silicon glass layer 103, thereby avoiding damage to the substrate 100 caused by the laser.

[0045] It should be noted that, based on the different types of doping elements in the silicon glass layer 103 , the laser processing and etching processing performed on the silicon glass layer 103 doped with different types of doping elements will be described in detail later.

[0046] In other embodiments, the step of removing the silicon glass layer may also be: directly removing the silicon glass layer located on the first region or the second region by using a laser.

[0047] In some embodiments, reference Figures 4 and 5 , or refer to Figures 9 and 10 The steps of forming the doping layer 102 and the silicon glass layer 103 may include: referring to Figure 4 or Figure 9 , forming a semiconductor layer 105 on the side of the dielectric layer 101 away from the substrate 100; Figure 4 and Figure 5 , or refer to Figure 9 and Figure 10 , the semiconductor layer 105 is doped to convert the semiconductor layer 105 into a doped layer 102, and a silicon glass layer 103 is formed on the side of the doped layer 102 away from the substrate 100, and the molar percentage content of the doping element in the silicon glass layer 103 is controlled to be 5%~10%.

[0048] It is worth noting that during the steps of preparing the doped layer 102 and the silicon glass layer 103, the doped layer 102 and the silicon glass layer 103 are formed simultaneously. To form the doped layer 102 containing the doping element, the semiconductor layer 105 needs to be doped. During the gradual progress of the doping process, not only does the doping element diffuse into the semiconductor layer 105, converting the semiconductor layer 105 into the doped layer 102, but also, due to an oxidation reaction, the silicon glass layer 103 is ultimately formed on the side of the doped layer 102 away from the substrate 100.

[0049] In some cases, the semiconductor layer 105 may be made of a semiconductor material, and the doping layer 102 may be made of a semiconductor material including a doping element. In one example, the semiconductor layer 105 is made of silicon, the doping layer 102 is made of a silicon material including a doping element, and the silicon glass layer 103 formed by the doping process is made of silicon oxide including a doping element.

[0050] The following describes in detail the method for manufacturing a back contact cell using boron as the doping element as an example.

[0051] In some embodiments, reference Figures 3 and 4 The dielectric layer 101 includes a first dielectric layer 111, the semiconductor layer 105 includes a first semiconductor layer 115, and the doping element includes boron; Figure 4 and Figure 5 , the doped layer 102 formed after the doping treatment includes a first doped layer 112, and the silicon glass layer 103 includes a borosilicate glass layer 113; in the borosilicate glass layer 113, the molar percentage of boron in silicon oxide is 5% to 10%. Based on this, in some cases, removing the silicon glass layer 103 located on the first area 1201 or the second area 1202 in step S4 may include the following steps: Figure 5 and Figure 6 , the borosilicate glass layer 113 located on the second area 1202 is laser treated to convert the borosilicate glass layer 113 located on the second area 1202 into a first modified layer 114; Figure 6 and Figure 7 , the first modified layer 114 is removed in the step of performing an etching process.

[0052] in, Figure 3 A partial cross-sectional schematic diagram after forming a first dielectric layer in a method for manufacturing a back-contact battery provided in one embodiment of the present application; Figure 4 A schematic partial cross-sectional view after forming a first semiconductor layer in a method for manufacturing a back-contact battery provided in one embodiment of the present application; Figure 5 A schematic partial cross-sectional view of a back-contact cell after doping treatment in a method for manufacturing the back-contact cell provided in one embodiment of the present application; Figure 6A schematic partial cross-sectional view of a back-contact cell after laser processing in a method for manufacturing a back-contact cell provided in one embodiment of the present application; Figure 7 This is a schematic partial cross-sectional view of a back-contact cell fabricated in accordance with an embodiment of the present invention after etching. Furthermore, the etching step uses the remaining borosilicate glass layer 113 on the first region 1201 as a mask to remove the first doped layer 112 and the first dielectric layer 111 covered by the first modified layer 114 on the second region 1202.

[0053] It is worth noting that the remaining first doped layer 112 and the first dielectric layer 111 on the first region 1201 together form a first passivation contact structure, providing good interface passivation for the first region 1201. As a result, on the one hand, the first dielectric layer 111 enables selective carrier transport to reduce recombination current; on the other hand, the lateral transport properties of the first doped layer 112 reduce series resistance. These two properties together improve the open-circuit voltage, fill factor, and photoelectric conversion efficiency of the back-contact cell.

[0054] In some cases, the molar percentage of boron in silicon oxide in the borosilicate glass layer 113 can be measured using ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometry). The operating principle of ICP-OES is as follows: boron atoms in a selected sample of the borosilicate glass layer 113 are excited by plasma and quantitatively determined by detecting the intensity of characteristic spectral lines. The testing steps for the selected sample of the borosilicate glass layer 113 are as follows: the selected sample of the borosilicate glass layer 113 is dissolved and diluted to an appropriate concentration; the boron emission spectrum intensity is measured using an ICP-OES instrument; and the molar percentage of boron in the sample is calculated using a standard curve.

[0055] In some cases, reference Figure 3 The first dielectric layer 111 can be formed using an LPCVD (Low Pressure Chemical Vapor Deposition) process. In some examples, the process temperature for forming the first dielectric layer 111 is 500°C to 650°C, for example, 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C, 600°C, 610°C, 620°C, 630°C, or 640°C. It should be noted that this embodiment of the present application does not impose excessive restrictions on the preparation process of the first dielectric layer 111. In actual applications, other processes can also be used to prepare the first dielectric layer.

[0056] In some cases, the first dielectric layer 111 can be considered a tunneling oxide layer. The material of the first dielectric layer 111 includes at least one of silicon oxide, silicon carbide, silicon nitride, and silicon oxynitride. In some examples, the thickness of the first dielectric layer 111 along the first direction X can be 1 nm to 2 nm, for example, 1.1 nm, 1.2 nm, 1.3 nm, 1.4 nm, 1.5 nm, 1.6 nm, 1.7 nm, 1.8 nm, or 1.9 nm.

[0057] In some cases, reference Figure 4 The first semiconductor layer 115 can be formed using an LPCVD process. In some examples, the process temperature for forming the first semiconductor layer 115 is 500° C. to 650° C. It should be noted that this embodiment of the present application does not impose too many restrictions on the preparation process of the first semiconductor layer 115. In actual applications, other processes can also be used to prepare the first semiconductor layer.

[0058] In some cases, the material of the first semiconductor layer 115 can be silicon, and the first semiconductor layer 115 can include at least one of amorphous silicon and polycrystalline silicon. In other words, the morphology of the silicon in the first semiconductor layer 115 varies. In some examples, the thickness of the first semiconductor layer 115 along the first direction X can be 50 nm to 500 nm, for example, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, or 450 nm.

[0059] In some cases, the borosilicate glass layer 113 may have a thickness of 20 nm to 100 nm, for example, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, or 90 nm, along the first direction X. It should be noted that the first direction X is the thickness direction of the substrate 100 .

[0060] In some cases, the molar percentage of boron in silicon oxide in the borosilicate glass layer 113 may be 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9% or 9.5%, etc.

[0061] In some cases, the step of performing the doping treatment includes: first performing a first expansion treatment and then performing a first push-knot treatment; the step of performing the first expansion treatment may include: placing the substrate 100 after forming the first semiconductor layer 115 into a reaction chamber, and introducing boron trichloride into the reaction chamber; the step of performing the first push-knot treatment may include: first performing a first aerobic push-knot treatment, and introducing a mixed gas of boron trichloride and oxygen into the reaction chamber; and then performing a first anaerobic push-knot treatment, and introducing boron trichloride into the reaction chamber.

[0062] It is worth noting that, with the cooperation of the first aerobic push-knot treatment and the first anaerobic push-knot treatment, on the one hand, it is beneficial to control the molar percentage of boron in silicon oxide in the final borosilicate glass layer 113 to be within the range of 5% to 10%, so as to increase the growth rate of the borosilicate glass layer 113 while ensuring the density of the borosilicate glass layer 113; on the other hand, it is beneficial to control the concentration of boron diffused into the first semiconductor layer 115, so as to ensure that the doping concentration of boron in the first doping layer 112 is moderate.

[0063] In some examples, the doping concentration of boron in the first doping layer 112 may be 8×10 18 atom / cm 3 ~8×10 20 atom / cm 3 , for example, it can be 9×10 18 atom / cm 3 , 1×10 19 atom / cm 3 , 3×10 19 atom / cm 3 , 5×10 19 atom / cm 3 , 6×10 19 atom / cm 3 , 8×10 19 atom / cm 3 , 1×10 20 atom / cm 3 , 3×10 20 atom / cm 3 , 5×10 20 atom / cm 3 or 6×10 20 atom / cm 3 wait.

[0064] In some examples, the gas flow rate of boron trichloride introduced into the reaction chamber can be 50 sccm~200 sccm, for example, 60 sccm, 70 sccm, 80 sccm, 90 sccm, 100 sccm, 110 sccm, 120 sccm, 130 sccm, 140 sccm, 150 sccm, 160 sccm, 170 sccm, 180 sccm or 190 sccm, etc.

[0065] It should be noted that, no matter in the step of performing the first expansion treatment or the step of performing the push-in treatment, the gas flow rate of boron trichloride introduced into the reaction chamber can be designed to be within the range of 50 sccm to 200 sccm.

[0066] In some examples, the ratio of the treatment time of the first aerobic pushing treatment to the treatment time of the first anaerobic pushing treatment can be 1:20~1:3, for example, can be 0.1, 0.15, 0.2, 0.25 or 0.3, etc.

[0067] It should be noted that the "anorexia" in the first anaerobic pushing process means that no oxygen is introduced into the reaction chamber during this stage. In practical applications, if required, other gases containing oxygen elements can be introduced into this stage.

[0068] It is worth noting that the molar percentage of boron in silicon oxide in the final borosilicate glass layer 113 is significantly affected by the boron trichloride gas flow rate and the ratio of the treatment time of the first aerobic push-bonding treatment to the treatment time of the first anaerobic push-bonding treatment. Based on this, the boron trichloride gas flow rate is designed to be 50 sccm to 200 sccm, and the ratio of the treatment time of the first aerobic push-bonding treatment to the treatment time of the first anaerobic push-bonding treatment is designed to be 1:20 to 1:3, both of which are conducive to controlling the molar percentage of boron in silicon oxide in the final borosilicate glass layer 113 to be within the range of 5% to 10%.

[0069] In some examples, in the step of performing the first aerobic pushing treatment, the ratio of the oxygen gas flow rate to the boron trichloride gas flow rate can be 2-10, for example, 3, 4, 5, 6, 7, 8 or 9.

[0070] In some examples, the process temperature used in the first expansion treatment is 800°C~900°C, for example, it can be 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C or 890°C.

[0071] In some examples, the pushing temperature used in the first push-bonding process is 900° C. to 1050° C., for example, 910° C., 920° C., 930° C., 940° C., 950° C., 960° C., 970° C., 980° C., 990° C., 1000° C., 1010° C., 1020° C., 1030° C., or 1040° C. It should be noted that the pushing temperature used in both the first aerobic push-bonding process and the first anaerobic push-bonding process can be 900° C. to 1050° C.

[0072] The following describes in detail the method for manufacturing a back contact cell using phosphorus as the doping element as an example.

[0073] In some embodiments, reference Figures 8 and 9 The dielectric layer 101 includes a second dielectric layer 121, the semiconductor layer 105 includes a second semiconductor layer 125, and the doping element includes phosphorus; Figure 9 and Figure 10The doping layer 102 formed after the doping treatment includes a second doping layer 122, and the silicon glass layer 103 includes a phosphosilicate glass layer 123; in the phosphosilicate glass layer 123, the molar percentage content of phosphorus in silicon oxide is 5% to 10%.

[0074] Based on this, in some cases, the removal of the silicon glass layer 103 located on the first area 1201 or the second area 1202 in step S4 may include the following steps: Figure 10 and Figure 11 , laser processing is performed on the phosphosilicate glass layer 123 located on the first region 1201 to convert the phosphosilicate glass layer 123 located on the first region 1201 into a second modified layer 124; Figure 11 and Figure 12 , the second modified layer 124 is removed in the step of performing an etching process.

[0075] in, Figure 8 A partial cross-sectional schematic diagram after forming a second dielectric layer in the manufacturing method of a back-contact battery provided in one embodiment of the present application; Figure 9 A schematic partial cross-sectional view after forming a second semiconductor layer in a method for manufacturing a back-contact battery provided in one embodiment of the present application; Figure 10 Another partial cross-sectional schematic diagram after doping treatment in the manufacturing method of the back contact cell provided in one embodiment of the present application; Figure 11 Another partial cross-sectional schematic diagram of a back-contact cell after laser processing in the method for manufacturing the back-contact cell provided in one embodiment of the present application; Figure 12 Another partial cross-sectional schematic diagram after etching treatment in the manufacturing method of the back contact battery provided in one embodiment of the present application.

[0076] Furthermore, in the etching step, the phosphosilicate glass layer 123 remaining on the second region 1202 is used as a mask layer to remove the second doping layer 122 and the second dielectric layer 121 covered by the second modified layer 124 on the first region 1201. It is worth noting that the second doping layer 122 and the second dielectric layer 121 remaining on the second region 1202 together constitute a second passivation contact structure, providing good interface passivation for the second region 1202. In this way, on the one hand, the second dielectric layer 121 can realize the selective transmission of carriers to reduce the recombination current; on the other hand, the lateral transmission characteristics of the second doping layer 122 reduce the series resistance. The above two characteristics together improve the open circuit voltage, fill factor and photoelectric conversion efficiency of the back contact battery.

[0077] In some cases, the molar percentage of phosphorus in silicon oxide in the phosphosilicate glass layer 123 can also be measured using ICP-OES. The operating principle of ICP-OES is generally as follows: phosphorus atoms in a selected sample of the phosphosilicate glass layer 123 are excited by plasma and quantified by detecting the intensity of characteristic spectral lines. The testing steps for the selected sample of the phosphosilicate glass layer 123 are generally as follows: the selected sample of the phosphosilicate glass layer 123 is dissolved and diluted to an appropriate concentration; the phosphorus emission spectrum intensity is measured using an ICP-OES instrument; and the molar percentage of phosphorus in the sample is calculated using a standard curve.

[0078] It should be noted that the second dielectric layer 121 can also be regarded as a tunneling oxide layer, and the same or corresponding parts of the second dielectric layer 121 and the first dielectric layer 111 are not described again.

[0079] In some cases, the material of the second semiconductor layer 125 may also be silicon, and the second semiconductor layer 125 may include at least one of amorphous silicon and polycrystalline silicon. In other words, the morphology of the silicon in the second semiconductor layer 125 is variable. It should be noted that the same or corresponding parts of the second semiconductor layer 125 and the first semiconductor layer 115 are not further described here.

[0080] In some cases, the thickness of the phosphosilicate glass layer 123 may be 50 nm to 100 nm, for example, 60 nm, 70 nm, 80 nm, or 90 nm, along the first direction X. It should be noted that the first direction X is the thickness direction of the substrate 100 .

[0081] In some cases, the molar percentage of phosphorus in silicon oxide in the phosphosilicate glass layer 123 may be 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9% or 9.5%, etc.

[0082] In some cases, the step of performing the doping treatment includes: first performing a second expansion treatment and then performing a second push-knot treatment; the step of performing the second expansion treatment may include: placing the substrate 100 after forming the second semiconductor layer 125 into a reaction chamber, and introducing nitrogen carrying trichlorophosphate into the reaction chamber; the step of performing the second push-knot treatment may include: first performing a second aerobic push-knot treatment, and introducing a mixed gas of nitrogen carrying trichlorophosphate and oxygen into the reaction chamber; and then performing a second anaerobic push-knot treatment, and introducing nitrogen carrying trichlorophosphate into the reaction chamber.

[0083] It is worth noting that with the cooperation of the second aerobic push-knot treatment and the second anaerobic push-knot treatment, on the one hand, it is beneficial to control the molar percentage content of phosphorus in silicon oxide in the final phosphosilicate glass layer 123 to be within the range of 5% to 10%, so as to increase the growth rate of the phosphosilicate glass layer 123 while ensuring the density of the phosphosilicate glass layer 123; on the other hand, it is beneficial to control the concentration of phosphorus diffused into the second semiconductor layer 125, so as to ensure that the doping concentration of phosphorus in the second doping layer 122 is moderate.

[0084] In some examples, the doping concentration of phosphorus in the second doping layer 122 may be 1×10 19 atom / cm 3 ~1×10 21 atom / cm 3 , for example, it can be 3×10 19 atom / cm 3 , 5×10 19 atom / cm 3 , 6×10 19 atom / cm 3 , 8×10 19 atom / cm 3 , 1×10 20 atom / cm 3 , 3×10 20 atom / cm 3 , 5×10 20 atom / cm 3 , 6×10 20 atom / cm 3 , 8×10 20 atom / cm 3 wait.

[0085] In some examples, the gas flow rate of nitrogen gas carrying phosphorus oxychloride introduced into the reaction chamber can be 800 sccm~2000 sccm, for example, can be 900 sccm, 1000 sccm, 1100 sccm, 1200 sccm, 1300 sccm, 1400 sccm, 1500 sccm, 1600 sccm, 1700 sccm, 1800 sccm or 1900 sccm, etc.

[0086] It should be noted that, no matter in the second expansion step or the push-in step, the gas flow rate of nitrogen gas carrying phosphorus oxychloride introduced into the reaction chamber can be designed to be within the range of 800 sccm to 2000 sccm.

[0087] In some examples, the ratio of the processing time of the second aerobic pushing treatment to the processing time of the second anaerobic pushing treatment is 1:10~1:2, for example, it can be 0.15, 0.2, 0.25, 0.3, 0.35, 0.4 or 0.45, etc.

[0088] It should be noted that the “anaerobic” in the second anaerobic pushing treatment means that no oxygen is introduced into the reaction chamber during this stage, but other gases containing oxygen elements, such as nitrogen carrying phosphorus oxychloride, are introduced.

[0089] It is worth noting that the molar percentage of phosphorus in silicon oxide in the final phosphosilicate glass layer 123 is significantly affected by the flow rate of phosphorus oxychloride and the ratio of the treatment time of the second aerobic push-bonding treatment to the treatment time of the second anaerobic push-bonding treatment. Based on this, the gas flow rate of nitrogen gas carrying phosphorus oxychloride is designed to be 800 sccm to 2000 sccm, and the treatment time of the second aerobic push-bonding treatment is designed to be 1:10 to 1:2. Both are conducive to controlling the molar percentage of phosphorus in silicon oxide in the final phosphosilicate glass layer 123 to be within the range of 5% to 10%.

[0090] In some examples, in the step of performing the second aerobic pushing treatment, the ratio of the gas flow rate of oxygen to the gas flow rate of nitrogen carrying phosphorus oxychloride is 0.5~2, for example, it can be 0.6, 0.7, 0.8, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8 or 1.9, etc.

[0091] In some examples, in the step of performing the second expansion treatment, the process temperature used in the second expansion treatment is 800℃~900℃, for example, it can be 810℃, 820℃, 830℃, 840℃, 850℃, 860℃, 870℃, 880℃ or 890℃, etc.

[0092] In some examples, the second push-bonding process uses a push-bonding temperature of 880° C. to 990° C., for example, 890° C., 900° C., 910° C., 920° C., 930° C., 940° C., 950° C., 960° C., 970° C., or 980° C. It should be noted that the push-bonding temperature used in both the second aerobic push-bonding process and the second anaerobic push-bonding process can be 900° C. to 1050° C.

[0093] In some examples, the step of introducing nitrogen gas carrying phosphorus oxychloride into the reaction chamber may include: providing a thermostatic bath containing liquid phosphorus oxychloride outside the reaction chamber, with a pipeline for gas circulation connecting the thermostatic bath and the reaction chamber; introducing nitrogen gas into the thermostatic bath, and introducing the nitrogen gas carrying phosphorus oxychloride that overflows from the liquid phosphorus oxychloride into the reaction chamber through the pipeline. It is worth noting that phosphorus oxychloride is normally in a liquid state and needs to be processed in liquid form, and the phosphorus oxychloride is provided to the reaction chamber using nitrogen gas.

[0094] In some examples, the temperature of the thermostatic bath may be 20° C. to 25° C., for example, 21° C., 22° C., 23° C., or 24° C.

[0095] In some examples, the proportion of phosphorus oxychloride in the nitrogen carrying phosphorus oxychloride can be 5% to 15%, for example, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13% or 14%.

[0096] It is worth noting that in order to control the proportion of phosphorus oxychloride in the nitrogen gas carrying phosphorus oxychloride, the temperature of the thermostatic bath can be adjusted to know the content of phosphorus oxychloride carried by the nitrogen gas per unit gas flow rate, thereby achieving the molar percentage content of phosphorus in the finally formed phosphosilicate glass layer 123.

[0097] It should be noted that the above-mentioned steps of forming the first doped layer 112 and the first dielectric layer 111 using a borosilicate glass layer 113 having a molar percentage of boron of 5% to 10%, and the above-mentioned steps of forming the second doped layer 122 and the second dielectric layer 121 using a phosphosilicate glass layer 123 having a molar percentage of phosphorus of 5% to 10% can be applied to the same back contact cell manufacturing method, ultimately forming a TBC cell (TOPCon Back Contact, referring to a cross-passivated back contact cell). Moreover, in the back contact cell manufacturing method provided in one embodiment of the present application, there is no restriction on the order of the steps of forming the first doped layer 112 and the first dielectric layer 111 and the steps of forming the second doped layer 122 and the second dielectric layer 121.

[0098] In practical applications, in the manufacturing method of a back-contact battery provided in an embodiment of the present application, on the basis of forming a first doping layer and a first dielectric layer with the help of a borosilicate glass layer with a molar percentage content of 5% to 10% of boron, a second dielectric layer including a material of at least one of amorphous silicon, microcrystalline silicon, and nanocrystalline silicon, and a second doping layer doped with an N-type doping element, such as phosphorus, can be formed on the second region to ultimately form a HTBC battery; or, on the basis of forming a second doping layer and a second dielectric layer with the help of a phosphosilicate glass layer with a molar percentage content of 5% to 10% of phosphorus, a first dielectric layer including a material of at least one of amorphous silicon, microcrystalline silicon, and nanocrystalline silicon, and a first doping layer doped with a P-type doping element, such as boron, can be formed on the first region to ultimately form a HTBC battery.

[0099] Among them, HTBC cells are heterojunction tunnel oxide passivated contact hybrid passivated back contact photovoltaic cells (full name: heterojunction tunnel oxide passivated contact hybrid passivated back contact photovoltaic cells, abbreviated as HTBC).

[0100] In some embodiments, reference Figure 2 The step of providing the substrate 100 includes: providing an initial substrate, and performing alkali polishing on the initial substrate to remove impurities on the surface of the initial substrate, and forming a substrate 100 with a flat surface, which is conducive to the subsequent preparation of the dielectric layer 101 and the doping layer 102.

[0101] In some cases, the reflectivity of the second surface 120 of the alkali-polished substrate 100 is greater than or equal to 40%; the size of the tower base on the second surface 120 can be 10μm~50μm, for example, it can be 15μm, 20μm, 25μm, 30μm, 35μm, 40μm or 45μm, etc.

[0102] In summary, by controlling the molar percentage content of the doping elements in the formed silicon glass layer 103 to be 5%~10% in step S3, on the one hand, it is beneficial to promote the formed silicon glass layer 103 to have higher density, so as to improve the etching resistance of the silicon glass layer 103 when the silicon glass layer 103 is used as the mask layer in the subsequent step S5, so as to avoid the doping layer 102 and the dielectric layer 101 that need to be retained from being over-etched, thereby improving the yield of the back contact battery finally manufactured; on the other hand, controlling the molar percentage content of the doping elements in the formed silicon glass layer 103 to be moderate is beneficial to improving the formation rate of the silicon glass layer 103 in step S3, thereby improving the manufacturing efficiency of the back contact battery; on the other hand, in the step of patterning the doping layer 102 and the dielectric layer 101 in step S5, the silicon glass layer 103 can be directly used as the mask layer without the need to set up an additional mask, which is beneficial to simplifying the manufacturing process of the back contact battery, thereby further improving the manufacturing efficiency of the back contact battery. Such multi-faceted coordination is conducive to improving the yield of the final manufactured back contact cell while improving the manufacturing efficiency of the back contact battery.

[0103] The following is a specific embodiment of a method for manufacturing a back-contact cell provided in one embodiment of the present application, and an expected related comparative example: Example 1 Prepare the back contact cell 1 by the following steps: (1) An N-type single crystal silicon wafer is selected, the resistivity of the N-type single crystal silicon wafer is about 0.5 ohmmm~10 ohmmm, and the thickness of the N-type single crystal silicon wafer in the first direction X is about 130 μm; the N-type single crystal silicon wafer is subjected to alkali polishing treatment, for example, using a trough texturing equipment to perform double-sided polishing on the first surface 110 and the second surface 120 of the substrate 100 to obtain the substrate 100.

[0104] Specifically, the damaged layer on the surface of the N-type single crystal silicon wafer is first removed in a mixed solution including potassium hydroxide and hydrogen peroxide, and then alkaline polishing is performed in a sodium hydroxide solution or a potassium hydroxide solution to form a substrate 100 having a flat tower base morphology on the surface. The size of the tower base is about 15 μm, and the reflectivity of the tower base morphology is about 40%.

[0105] (2) A tunnel oxide layer and an intrinsic amorphous silicon layer are prepared on the second surface 120 using an LPCVD process. The thickness of the tunnel oxide layer is 1.5 nm, and the thickness of the intrinsic amorphous silicon layer is 300 nm. The process temperature used in the LPCVD process is 560°C.

[0106] (3) The intrinsic amorphous silicon layer is subjected to high-temperature boron diffusion using a tubular diffusion device. After the boron diffusion, the intrinsic amorphous silicon layer is transformed into a polycrystalline silicon layer, and the boron doping concentration in the polycrystalline silicon layer is 6×10 19 atom / cm 3to form a doped polysilicon layer; the borosilicate glass layer formed after boron diffusion, i.e., the thickness of BSG, is 60 nm. In BSG, the molar percentage of boron in silicon oxide is controlled at 8%. The deposition temperature of the boron-doped source layer formed during the boron diffusion process is 850°C, the process temperature used in the push-in treatment is 960°C, the flow rate of boron trichloride introduced during the boron diffusion process is 90 sccm, and the ratio of the oxygen gas flow rate to the boron trichloride gas flow rate in the first aerobic push-in treatment is 5.

[0107] (4) Laser processing is performed on the BSG located on one of the first region and the second region to convert the BSG located on one of the first region and the second region into a modified layer.

[0108] (5) performing an etching process using the BSG remaining on the other of the first region and the second region as a mask layer to remove the modified layer, and remove the tunneling oxide layer and the doped polysilicon layer covered by the modified layer.

[0109] (6) Subsequent steps can be performed according to the existing process flow to complete the manufacture of the back contact cell, which will not be described in detail here, so as to finally form the back contact cell 1.

[0110] Comparative Example 1 Prepare back contact cell 2 by the following steps: Steps (1) to (2) are the same as those in Example 1 and will not be repeated here.

[0111] (3) The intrinsic amorphous silicon layer is subjected to high-temperature boron diffusion using a tubular diffusion device. After the boron diffusion, the intrinsic amorphous silicon layer is transformed into a polycrystalline silicon layer, and the boron doping concentration in the polycrystalline silicon layer is 6×10 19 atom / cm 3 .

[0112] (4) Depositing a silicon nitride film on the first region 1201. Specifically, a PECVD process can be used to deposit a silicon nitride film on the first region 1201 as a mask, and the thickness of the silicon nitride film is 60 nm.

[0113] (5) Subsequent steps can be performed according to the existing process flow to complete the manufacture of the back contact cell, which will not be described in detail here, so as to finally form the back contact cell 2.

[0114] Comparative Example 2 The back contact cell 3 was prepared by the following steps: Steps (1) to (2) are the same as those in Example 1 and will not be repeated here.

[0115] (3) The intrinsic amorphous silicon layer is subjected to high-temperature boron diffusion using a tubular diffusion device. After the boron diffusion, the intrinsic amorphous silicon layer is transformed into a polycrystalline silicon layer, and the boron doping concentration in the polycrystalline silicon layer is 3×10 19 atom / cm 3The thickness of the borosilicate glass layer formed after boron diffusion, namely BSG, is 60nm. In BSG, the molar percentage content of boron in silicon oxide is controlled to be less than 5%.

[0116] Steps (4) to (5) are the same as those in Example 1 and will not be repeated here.

[0117] (6) Subsequent steps can be performed according to the existing process flow to complete the manufacture of the back contact cell, which will not be described in detail here, so as to finally form the back contact cell 3.

[0118] Comparative Example 3 The back contact cell was prepared by the following steps: Steps (1) to (2) are the same as those in Example 1 and will not be repeated here.

[0119] (3) The intrinsic amorphous silicon layer is subjected to high-temperature boron diffusion using a tubular diffusion device. After the boron diffusion, the intrinsic amorphous silicon layer is transformed into a polycrystalline silicon layer, and the boron doping concentration in the polycrystalline silicon layer is 8×10 19 atom / cm 3 The thickness of the borosilicate glass layer formed after boron diffusion, namely BSG, is 60nm. In BSG, the molar percentage content of boron in silicon oxide is controlled to be greater than 10%.

[0120] Steps (4) to (5) are the same as those in Example 1 and will not be repeated here.

[0121] (6) The subsequent steps can be completed according to the existing process flow to complete the manufacture of the back contact cell, which will not be described in detail here. It should be noted that because the molar percentage of boron in the BSG in Comparative Example 3 is greater than 10%, it is ultimately impossible to form a finished cell. Therefore, there is no finished cell corresponding to Comparative Example 3 in the subsequent Table 1.

[0122] Table 1 shows the photovoltaic index corresponding to back contact cell 1, back contact cell 2 and back contact cell 3.

[0123] Note: VOC stands for open circuit voltage, Isc stands for short circuit current, FF stands for fill factor, and EFF stands for photoelectric conversion efficiency.

[0124] From the experimental results, the photovoltaic index of the finished battery formed in Example 1 using the BSG formed as a mask in the manufacturing method of the back-contact battery provided in an embodiment of the present application, and the molar percentage content of boron in the BSG is controlled at 8%, namely, the back-contact battery 1, is basically consistent with the photovoltaic index of the finished battery formed in Comparative Example 1 using the silicon nitride film as a mask, namely, the back-contact battery 2. However, in the manufacturing method of the back-contact battery provided in an embodiment of the present application, the BSG formed in the preparation process is used as a mask, which reduces the deposition step of the silicon nitride mask, for example, reducing the process time by about 60 minutes, and at the same time reducing the manufacturing cost. For example, the manufacturing cost of each back-contact battery 1 can be saved by about 1 cent.

[0125] Compared with Example 1, Comparative Example 2 also uses BSG formed during the preparation process as a mask. However, the molar percentage of boron in BSG in Comparative Example 2 is less than 5%, resulting in a lower boron doping concentration in the doped polysilicon layer after boron diffusion. At the same time, due to the lower molar percentage of boron in BSG, the growth rate of BSG is slower, and the process time is 45 minutes longer than that of Example 1. Moreover, compared with the back-contact cell 1 formed in Example 1, the open-circuit voltage, short-circuit current, fill factor, and photoelectric conversion efficiency of the back-contact cell 3 formed in Comparative Example 2 are all reduced. The fill factor of the back-contact cell 3 formed in Comparative Example 2 is significantly reduced, and the photoelectric conversion efficiency is also about 0.17% lower than that of the back-contact cell 1 formed in Example 1.

[0126] Compared with Example 1, Comparative Example 3 also uses BSG formed during the preparation process as a mask, but the molar percentage of boron in BSG in Comparative Example 2 is greater than 10%, resulting in very weak etching resistance of BSG. As a result, in the process of preparing the back-contact battery in Comparative Example 3, BSG as a mask fails to protect the tunneling oxide layer and the doped polysilicon layer under the BSG, and a finished battery cannot be formed.

[0127] Another embodiment of the present application also provides a back-contact battery, formed by the manufacturing method of the back-contact battery provided in the above embodiment. The back-contact battery provided in another embodiment of the present application is described in detail below with reference to the accompanying drawings. It should be noted that parts that are identical or corresponding to the above embodiment are not repeated here.

[0128] The back-contact battery includes a back-contact battery formed by the back-contact battery manufacturing method provided by the aforementioned embodiment.

[0129] Another embodiment of the present application further provides a photovoltaic module for converting received light energy into electrical energy. The photovoltaic module provided in another embodiment of the present application is described in detail below with reference to the accompanying drawings. It should be noted that portions identical or corresponding to the preceding embodiments are not described in detail here.

[0130] Combined with reference Figure 13 and Figure 14 The photovoltaic module includes: a cell string, which is formed by connecting back-contact cells 40 formed by the manufacturing method of back-contact cells provided by multiple aforementioned embodiments, or is formed by connecting back-contact cells 40 provided by multiple aforementioned embodiments; an encapsulation film 41 for covering the surface of the cell string; and a cover plate 42 for covering the surface of the encapsulation film 41 facing away from the cell string.

[0131] in, Figure 13 A partial three-dimensional schematic diagram of a cell string in a photovoltaic module provided in another embodiment of the present application; Figure 14 A partial cross-sectional schematic diagram of a photovoltaic module provided in yet another embodiment of the present application.

[0132] In some embodiments, the back-contact cell 40 is electrically connected in a whole cell or multiple slices to form multiple cell strings, and the multiple cell strings are electrically connected in series and / or parallel. The back-contact cell 40 can be a whole cell or a sliced ​​cell. A sliced ​​cell refers to a cell formed by cutting a complete whole cell.

[0133] In some embodiments, in conjunction with reference Figure 13 and Figure 14 , multiple back contact cells 40 can be electrically connected through conductive tapes 43 . Figure 13 and Figure 14 Only one positional relationship between the back-contact cells 40 is illustrated, i.e., the electrodes of each back-contact cell 40 are arranged on the same side, so that the conductive ribbons 43 connect the same side of two adjacent back-contact cells 40. In other embodiments, the electrodes of two adjacent back-contact cells may be located on different sides, so that the conductive ribbons connect two adjacent back-contact cells on different sides.

[0134] In some embodiments, the encapsulation film 41 includes a first encapsulation layer and a second encapsulation layer, wherein the first encapsulation layer covers one of the front side and the back side of the back-contact cell 40, and the second encapsulation layer covers the other of the front side and the back side of the back-contact cell 40. Specifically, at least one of the first encapsulation layer and the second encapsulation layer can be an organic encapsulation film such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate copolymer (EVA) film, polyethylene octene co-elastomer (POE) film, or polyethylene terephthalate (PET) film. Alternatively, at least one of the first encapsulation layer and the second encapsulation layer can also be an EP film, an EPE film, or a PVP film. EP film refers to a coextruded film composed of stacked EVA film and POE film, EPE film refers to a coextruded film formed by stacking EVA film + POE film + EVA film, and PVP film refers to a coextruded film formed by stacking POE film + EVA film + POE film. Coextruded films can be produced by sequentially extruding one or more raw materials onto another pre-existing film during the film processing process, or by bonding different pre-existing films together.

[0135] In some cases, there is a boundary line between the first encapsulation layer and the second encapsulation layer before lamination. After the lamination process, the photovoltaic module is formed and there is no longer the concept of the first encapsulation layer and the second encapsulation layer, that is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film 41.

[0136] In some embodiments, the cover plate 42 may be a light-transmitting cover plate such as a glass cover plate or a plastic cover plate. Specifically, the surface of the cover plate 42 facing the encapsulation film 41 may have a concave-convex surface or a velvet surface including multiple raised structures, thereby increasing the utilization of incident light. The cover plate 42 includes a first cover plate and a second cover plate. The first cover plate faces the first encapsulation layer, and the second cover plate faces the second encapsulation layer.

[0137] Those skilled in the art will appreciate that the above-described embodiments are specific examples for implementing the present application, and in actual applications, various changes may be made to them in form and detail without departing from the spirit and scope of the embodiments of the present application. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the embodiments of the present application. Therefore, the scope of protection of the embodiments of the present application shall be based on the scope defined in the claims.

Claims

1. A method for manufacturing a back contact battery, characterized in that: include: Providing a substrate, the substrate having a first surface and a second surface opposite to each other along a first direction, the second surface having first areas and second areas alternately arranged along a second direction; forming a dielectric layer on the second surface; A doping layer and a silicon glass layer are stacked on a side of the dielectric layer away from the substrate, wherein both the doping layer and the silicon glass layer contain a doping element, and the molar percentage of the doping element in the silicon glass layer is 5% to 10%; removing the silicon glass layer located on the first region or the second region; The remaining silicon glass layer is used as a mask layer for etching to remove the doping layer and the dielectric layer that are not covered by the mask layer.

2. The method for manufacturing a back contact battery according to claim 1, wherein: The steps of forming the doping layer and the silicon glass layer include: forming a semiconductor layer on a side of the dielectric layer away from the substrate; The semiconductor layer is doped to convert the semiconductor layer into the doped layer, and the silicon glass layer is formed on the side of the doped layer away from the substrate, and the molar percentage of the doping element in the silicon glass layer is controlled to be 5% to 10%.

3. The method for manufacturing a back contact battery according to claim 2, wherein: The dielectric layer includes a first dielectric layer, the semiconductor layer includes a first semiconductor layer, and the doping element includes boron; the doping layer formed after the doping treatment includes a first doping layer, and the silicon glass layer includes a borosilicate glass layer; in the borosilicate glass layer, the molar percentage of boron in silicon oxide is 5%~10%.

4. The method for manufacturing a back contact battery according to claim 3, wherein: The steps of performing the doping treatment include: first performing a first expansion treatment, and then performing a first knot pushing treatment; The step of performing the first expansion treatment includes: placing the substrate after forming the first semiconductor layer into a reaction chamber, and introducing boron trichloride into the reaction chamber; The step of performing the first pushing-bonding treatment includes: first performing a first aerobic pushing-bonding treatment, introducing a mixed gas of boron trichloride and oxygen into the reaction chamber; and then performing a first anaerobic pushing-bonding treatment, introducing boron trichloride into the reaction chamber.

5. The method for manufacturing a back contact battery according to claim 4, wherein: The gas flow rate of boron trichloride introduced into the reaction chamber is 50 sccm~200 sccm; and / or the ratio of the treatment time of the first aerobic pushing treatment to the treatment time of the first anaerobic pushing treatment is 1:20~1:

3.

6. The method for manufacturing a back contact battery according to claim 4 or 5, characterized in that: In the step of performing the first aerobic pushing treatment, the ratio of the gas flow rate of oxygen to the gas flow rate of boron trichloride is 2-10.

7. The method for manufacturing a back contact battery according to claim 4, wherein: The process temperature used in the first expansion treatment is 800° C. to 900° C.; and / or the pushing temperature used in the first pushing treatment is 900° C. to 1050° C.

8. The method for manufacturing a back contact battery according to claim 2, wherein: The dielectric layer includes a second dielectric layer, the semiconductor layer includes a second semiconductor layer, and the doping element includes phosphorus; the doping layer formed after the doping treatment includes a second doping layer, and the silicon glass layer includes a phosphosilicate glass layer; in the phosphosilicate glass layer, the molar percentage content of phosphorus in silicon oxide is 5% to 10%.

9. The method for manufacturing a back contact battery according to claim 1, wherein: The step of removing the silicon glass layer comprises: performing laser processing on the silicon glass layer located on the first area or the second area to form a modified layer; and removing the modified layer during the etching process; In the step of performing the etching process, the etching process is further performed using the remaining silicon glass layer as a mask layer to remove the doping layer and the dielectric layer covered by the modified layer.

10. The method for manufacturing a back contact battery according to claim 9, wherein: The dielectric layer includes a first dielectric layer, the doping element includes boron, the doping layer includes a first doping layer, and the silicon glass layer includes a borosilicate glass layer; The step of performing the laser treatment includes: performing the laser treatment on the borosilicate glass layer located on the second region to convert the borosilicate glass layer located on the second region into a first modified layer; The step of performing the etching treatment includes: removing the first modified layer, and using the borosilicate glass layer remaining on the first region as a mask layer to remove the first doped layer and the first dielectric layer covered by the first modified layer.

11. The method for manufacturing a back contact battery according to claim 9, wherein: The dielectric layer includes a second dielectric layer, the doping element includes phosphorus, the doping layer includes a second doping layer, and the silicon glass layer includes a phosphorus silicon glass layer; The step of performing the laser treatment includes: performing the laser treatment on the phosphosilicate glass layer located on the first region to convert the phosphosilicate glass layer located on the first region into a second modified layer; The step of performing the etching treatment includes: removing the second modified layer, and using the remaining phosphosilicate glass layer on the second region as a mask layer to remove the second doped layer and the second dielectric layer covered by the second modified layer.

12. A back contact battery, characterized in that: A back-contact battery formed by the method for manufacturing a back-contact battery according to any one of claims 1 to 11.

13. A photovoltaic module, characterized in that: include: A battery string formed by connecting a plurality of back-contact batteries formed by the method for manufacturing a back-contact battery according to any one of claims 1 to 11, or by connecting the back-contact batteries according to claim 12; A packaging film, used to cover the surface of the battery string; A cover plate is used to cover the surface of the packaging film facing away from the battery string.

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