Back contact battery and processing method thereof

Abstract

The invention provides a back contact battery and a processing method thereof. The processing method comprises the following steps: after boron diffusion processing and P-type polycrystalline silicon layer deposition are carried out on a first tunneling silicon oxide layer on the back surface of a back contact cell substrate, first laser is applied to a preset N-type region and a mark point position on the back surface of the substrate; after phosphorus diffusion treatment and N-type polycrystalline silicon layer deposition are carried out on a second tunneling silicon oxide layer on the back surface of the substrate, second laser is applied to the mark point positions and a preset P-type region on the back surface of the substrate; performing texturing treatment on the marked point positions treated by the first laser and the second laser so as to process the marked point positions into a textured structure; and after a plurality of film layer structures of the back contact battery are generated on the back surface of the substrate, positioning the mark point positions according to the suede structures so as to carry out silk-screen printing of the back contact battery.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor processing technologies, and particularly to back contact batteries and processing methods thereof. Background Art

[0002] A back contact crystalline silicon solar cell is a silicon solar cell in which both the emitter electrode and the base electrode are designed on the back of the cell. In a back contact crystalline silicon cell, both the P region and the N region are located on the back of the cell. After the electron-hole pairs generated by incident photons are separated, they need to pass through the entire thickness of the silicon substrate before reaching the back surface to be collected by the P region and the N region respectively. Since the emitter and base electrodes of the back contact battery are both designed on the back of the cell wafer and the grid lines of the cell wafer are all placed on the back, there is no grid line occlusion on the front surface. Therefore, the requirement for the alignment printing accuracy of the pattern is relatively high. If the printing accuracy is abnormal, it will cause the P region and the N region to overlap, resulting in leakage. Therefore, it is very important to ensure the high precision of screen printing.

[0003] In the existing manufacturing process of back contact batteries (TOPCon Back Contact, TBC), the method of grasping laser marking (Mark) points is currently used to ensure the screen printing accuracy. The existing laser marking points of back contact batteries are both a circular and a square laser marking point after boron diffusion, and a multi-layer film structure is coated on the laser marking points after boron diffusion. In this process, the process of grasping the laser marking points may affect the printing accuracy, and it is impossible to ensure the sufficient clarity of the marking points during screen printing. Even if the power and number of laser dotting are increased to ensure the clarity of the laser marking points, it will cause greater laser damage to the battery and affect the efficiency of the battery.

[0004] To solve the above problems, the present invention provides a back contact battery and a processing method thereof. By performing texturing treatment on the marked points that have undergone two laser treatments and processing them into a textured surface structure, the positioning accuracy of the marked points in the subsequent screen printing process is improved, thereby avoiding the leakage problem caused by the overlap of the N-type region and the P-type region of the back contact crystalline silicon solar cell, avoiding the laser damage to the back contact crystalline silicon solar cell caused by multiple point markings, and improving the production efficiency of the back contact crystalline silicon solar cell. Summary of the Invention

[0005] The following presents a brief overview of one or more aspects to provide a basic understanding of these aspects. This overview is not an exhaustive survey of all contemplated aspects, and is neither intended to identify key or decisive elements of all aspects nor to attempt to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that follows.

[0006] In order to ensure the screen printing accuracy of the back-contact battery, the present invention provides a back-contact battery and its processing method. By performing texturing treatment on the marked points that have undergone two laser treatments, they are processed into a textured surface structure, improving the positioning accuracy of the marked points in the subsequent screen printing process, thereby avoiding the leakage problem caused by the overlap of the N-type region and the P-type region of the back-contact crystalline silicon solar cell, avoiding laser damage to the back-contact crystalline silicon solar cell caused by multiple point markings, and improving the production efficiency of the back-contact crystalline silicon solar cell.

[0007] Specifically, the processing method of the back-contact battery provided in the first aspect of the present invention includes the following steps: after performing boron diffusion treatment and depositing a P-type polysilicon layer on the back surface of the back-contact battery substrate, applying a first laser to the preset N-type region and marked points on the back surface of the substrate; after performing phosphorus diffusion treatment and depositing an N-type polysilicon layer on the second tunneling oxide layer on the back surface of the substrate, applying a second laser to the marked points and the preset P-type region on the back surface of the substrate; performing texturing treatment on the marked points that have been treated with the first laser and the second laser to process them into a textured surface structure; and after generating multiple film layer structures of the back-contact battery on the back surface of the substrate, positioning the marked points according to the textured surface structure to perform screen printing of the back-contact battery.

[0008] Further, in some embodiments of the present invention, the processing method further includes the following steps: before performing the boron diffusion treatment on the back surface of the substrate, first performing front polishing treatment and first LPCVD treatment on the back surface of the substrate to form the first tunneling oxide layer on the back surface of the substrate; and / or after applying the first laser to the N-type region and the marked points, and before performing phosphorus diffusion treatment on the back surface of the substrate, removing the first by-product on the back surface of the substrate, and / or performing second LPCVD treatment on the back surface of the substrate to form the second tunneling oxide layer on the back surface of the substrate; and / or after applying the second laser to the P-type region and the marked points, and before generating the multiple film layer structures on the back surface of the substrate, removing the second by-product on the back surface of the substrate, and / or performing texturing treatment on the isolation region between the N-type region and the P-type region to process it into a textured surface structure.

[0009] Further, in some embodiments of the present invention, the first laser is selected from a purple laser with a wavelength between 345 nm and 365 nm, or a green laser with a wavelength between 522 nm and 542 nm, and / or the second laser is selected from a purple laser with a wavelength between 345 nm and 365 nm, or a green laser with a wavelength between 522 nm and 542 nm.

[0010] Further, in some embodiments of the present invention, when the first laser is a purple laser, its power ranges from 12W to 22W. When the first laser is a green laser, its power ranges from 21W to 31W. When the second laser is a purple laser, its power ranges from 10W to 20W. When the second laser is a green laser, its power ranges from 29W to 39W.

[0011] Further, in some embodiments of the present invention, the step of applying the first laser to the preset N-type region and the marking points on the back surface of the substrate includes: applying the first laser to a square region of a preset size at the position where the marking points are located. The step of applying the second laser to the marking points and the preset P-type region on the back surface of the substrate includes: applying the second laser to the square region at the position where the marking points are located. The step of texturing the marking points processed by the first laser and the second laser to process them into a textured structure includes: texturing the square region processed by the first laser and the second laser to process it into a textured structure.

[0012] Further, in some embodiments of the present invention, the step of texturing the marking points processed by the first laser and the second laser to process them into a textured structure includes: using a texturing agent on a square region of a preset size at the position where the marking points are located at a process temperature of 65°C to 75°C and maintaining for a preset time to form a light-trapping pyramid structure on the surface of the square region.

[0013] Further, in some embodiments of the present invention, the step of forming multiple film layer structures of the back contact battery on the back surface of the substrate includes: sequentially forming an N-type polysilicon structure, an alumina layer, and a silicon nitride layer on the back surface of the substrate of the back contact battery.

[0014] Further, in some embodiments of the present invention, the step of positioning the marking points according to the textured structure to perform screen printing of the back contact battery includes: positioning the marking points according to the textured structure to perform screen printing of the N-type region electrode, the P-type region electrode, and / or the grid lines of the back contact battery.

[0015] Further, in some embodiments of the present invention, the step of positioning the marking points according to the textured structure to perform screen printing of the back contact battery includes: photographing the back surface of the substrate on which the multiple film layer structures are formed via a screen printing camera to obtain a positioning image of the back surface of the substrate. Analyzing the positioning image to position the marking points according to the position of the textured structure therein. And performing screen printing of the N-type region electrode, the P-type region electrode, and / or the grid lines according to the position of the marking points.

[0016] In addition, a back-contact battery provided according to the second aspect of the present invention includes a substrate, a plurality of film layer structures, and a screen printing structure. Herein, the back surface of the substrate includes an N-type region, a P-type region, and a marking point, wherein the marking point is a suede structure. The plurality of film layer structures are located on the back surface of the substrate. The screen printing structure is located on the back surface of the plurality of film layer structures.

[0017] In addition, a back-contact battery provided according to the third aspect of the present invention is obtained by processing the back-contact battery processing method provided by the first aspect of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] After reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings, the above features and advantages of the present invention can be better understood. In the drawings, the components are not necessarily drawn to scale, and components with similar related characteristics or features may have the same or similar reference numerals.

[0019] Figure 1 A schematic flow chart of the back-contact battery processing method in the present invention is shown.

[0020] Figure 2 A schematic diagram of the marking point after processing the back-contact battery in the present invention is shown.

[0021] Figure 3 A schematic diagram of the marking point during screen printing after processing the back-contact battery in the prior art is shown.

[0022] Figure 4 A schematic diagram of the marking point during screen printing after processing the back-contact battery in the present invention is shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The following specific embodiments illustrate the embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiments, this does not mean that the features of this invention are limited to this embodiment. On the contrary, the purpose of introducing the invention in conjunction with the embodiments is to cover other alternatives or modifications that may be extended based on the claims of the present invention. In order to provide a deep understanding of the present invention, many specific details will be included in the following description. The present invention can also be implemented without using these details. In addition, in order to avoid confusing or obscuring the focus of the present invention, some specific details will be omitted in the description.

[0024] In the description of the present invention, it should be noted that, unless otherwise clearly defined and limited, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] In addition, the "upper", "lower", "left", "right", "top", "bottom", "horizontal", and "vertical" used in the following description should be understood as the orientations shown in this section and the related drawings. This relative term is only for convenience of description and does not represent that the device described needs to be manufactured or operated in a specific orientation, so it should not be construed as a limitation on the present invention.

[0026] It can be understood that although the terms "first", "second", "third", etc. can be used here to describe various components, regions, layers, and / or parts, these components, regions, layers, and / or parts should not be limited by these terms, and these terms are only used to distinguish different components, regions, layers, and / or parts. Therefore, the first component, region, layer, and / or part discussed below can be referred to as the second component, region, layer, and / or part without departing from some embodiments of the present invention.

[0027] As described above, in the prior art, in order to ensure the screen printing accuracy of the back contact battery, the method of grabbing points is currently used to ensure the printing accuracy, and the screen grabs the laser-printed marking points. In the existing back contact battery manufacturing process, the laser marking points are all circular or square laser marking points punched on the surface of the etched borosilicate glass (BSG) after boron diffusion, and multiple film structures are deposited on the laser marking points after boron diffusion. After that, low-pressure chemical vapor deposition (LPCVD) treatment, phosphorus diffusion treatment, laser opening of phosphosilicate glass (PSG), chain removal of phosphosilicate glass (PSG), texturing, and screen printing are carried out. In this process, due to the existence of the multiple film structures on the laser marking points after boron diffusion, it is impossible to ensure that the laser marking points are clear enough during screen printing. Even if the power and number of laser punching are increased to ensure the clarity of the laser marking points, it will cause greater laser damage to the battery, and it is impossible to ensure that the marking points can be completely grabbed by the screen camera.

[0028] In order to overcome the above-mentioned defects of the prior art, the present invention provides a back-contact battery and a processing method thereof. By performing texturing treatment on the marked positions that have undergone two laser treatments and processing them into a textured surface structure, the positioning accuracy of the marked positions in the screen printing process is improved, thereby avoiding the leakage problem caused by the overlap of the N-type region and the P-type region of the back-contact crystalline silicon solar cell, avoiding laser damage to the back-contact crystalline silicon solar cell caused by multiple position markings, and improving the production efficiency of the back-contact crystalline silicon solar cell.

[0029] In some non-limiting embodiments, the above-mentioned back-contact battery provided by the third aspect of the present invention can be obtained by the processing method of the above-mentioned back-contact battery provided by the first aspect of the present invention. Here, the back-contact battery is a crystalline silicon solar cell with a special structure, including a substrate, a plurality of film layer structures, and a screen printing structure. The back surface of the substrate includes an N-type region, a P-type region, and at least one marked position with a textured surface structure. The plurality of film layer structures are also located on the back surface of the substrate and cover the above-mentioned N-type region, P-type region, and at least one marked position with a textured surface structure. The screen printing structure includes, but is not limited to, an N-type region electrode, a P-type region electrode, and / or grid lines, which are arranged on the back surface of the film layer structure through the positioning of the marked positions with a textured surface structure. After processing the marked positions into a textured surface structure, even with the coverage of a plurality of film layer structures, the present invention can still accurately identify the positions of the marked positions through the images captured by the screen printing camera, thereby improving the processing accuracy of the screen printing structure.

[0030] The following will further describe the specific structure and processing flow of the back-contact battery in combination with some embodiments of the processing method of the back-contact battery. Those skilled in the art can understand that the embodiments of the processing method are only some non-limiting implementation manners provided by the present invention, only to clearly show the main concept of the present invention and provide some specific solutions convenient for the public to implement, rather than to limit the processing methods of the various structures in the back-contact battery. Similarly, the various structures in the back-contact battery are also only some non-limiting implementation manners provided by the present invention, and do not limit the implementation objects and sequences of the various steps in the processing method.

[0031] Specifically, please refer to Figure 1 , Figure 1 which shows a schematic flow chart of the processing method of the back-contact battery in the present invention.

[0032] In Figure 1 the embodiment shown, the processing method of the above-mentioned back-contact battery provided by the present invention includes the following steps: Step 1. After performing boron diffusion treatment and depositing a P-type polysilicon layer on the first tunneling oxide layer on the back surface of the back-contact battery substrate, apply a first laser to the preset N-type region and marked positions on the back surface of the substrate; Step 2. After performing phosphorus diffusion treatment on the second tunneling oxide layer on the back of the substrate and depositing the N-type polysilicon layer, apply a second laser to the marked positions and the preset P-type regions on the back of the substrate. Step 3. Perform texturing treatment on the marked positions processed by the first laser and the second laser to process them into a textured structure. Step 4. After generating multiple film layer structures of the back contact battery on the back of the substrate, locate the marked positions according to the textured structure for screen printing of the back contact battery.

[0033] Specifically, in the above Step 1, the purpose of the boron diffusion treatment is mainly to enable the emitter to form a P-N junction with the N-type silicon substrate, thereby effectively shunting carriers. In some embodiments, the deposition of the P-type polysilicon layer can be specifically carried out by Plasma-Enhanced Chemical Vapor Deposition (PECVD) or Low Pressure Chemical Vapor Deposition (LPCVD) to deposit a P-type polysilicon (p-poly) layer on the silicon wafer surface.

[0034] In the above Step 2, the purpose of the phosphorus diffusion treatment is to form a high-low junction with the N-type silicon, thereby enhancing the carrier separation ability. In some embodiments, the deposition of the N-type polysilicon layer can be specifically carried out by Plasma-Enhanced Chemical Vapor Deposition (PECVD) or Low Pressure Chemical Vapor Deposition (LPCVD) to deposit an N-type polysilicon (n-poly) layer on the silicon wafer surface.

[0035] In addition, according to some embodiments of the present invention, before performing the boron diffusion treatment on the back of the substrate, the present invention can first perform a pre-polishing treatment and a first LPCVD treatment on the back of the substrate, thereby forming a first tunneling oxide layer on the back of the substrate. Here, the pre-polishing treatment performed on the back of the substrate can be a mechanical or chemical polishing treatment, and its core purpose is to remove the mechanical damage layer and the oxide layer on the back of the substrate to provide a flat and clean surface for subsequent processes. During the processing of the back contact battery, since the subsequent boron diffusion treatment will generate micro-hole defects (pinholes) on the oxide layer, further causing a p+ / p high-low junction, forming field passivation, and having a higher hole barrier and a smaller tunneling probability compared to the relatively low free electron barrier, the operation of performing the first LPCVD treatment before the boron diffusion treatment and forming a very thin tunneling oxide layer on the silicon surface can effectively improve the tunneling passivation and field passivation levels of the P-type polysilicon layer (p-poly).

[0036] In addition, according to some embodiments of the present invention, after applying the first laser to the N-type region and the marked position, and before performing the phosphorus diffusion treatment on the back surface of the substrate, the present invention can polish and remove the first by-product (e.g., BSG) on the back surface of the substrate. In addition, after applying the first laser to the N-type region and the marked position, and before performing the phosphorus diffusion treatment on the back surface of the substrate, the present invention can also perform a second LPCVD treatment on the back surface of the substrate to form a second tunneling silicon oxide layer on the back surface of the substrate. For the same reason, since the subsequent phosphorus diffusion treatment will cause tiny hole defects (pinholes) on the oxide layer, further causing p+ / p high-low junctions, forming field passivation, and having a higher hole barrier and a smaller tunneling probability compared to the relatively low free electron barrier, the present invention can effectively improve the tunneling passivation and field passivation levels of the N-type polysilicon layer (n-poly) by removing the first by-product on the back surface of the substrate and / or performing a second LPCVD treatment on the back surface of the substrate to form a second tunneling silicon oxide layer on the back surface of the substrate.

[0037] In addition, according to some embodiments of the present invention, after applying the second laser to the P-type region and the marked position, and before generating multiple film layer structures on the back surface of the substrate, the present invention can also chain-remove the second by-product (e.g., PSG) on the back surface of the substrate and / or perform a texturing treatment on the isolation region between the N-type region and the P-type region to process it into a textured surface structure. Here, there are two positions on the back surface of the back contact battery that are textured surface structures, one is the isolation gap, and the other is the marked point position, and the other positions on the back surface of the back contact battery are polished structures.

[0038] In addition, according to some embodiments of the present invention, when the second laser hits the surface of the PSG, the present invention uses a synchronous texturing method to remove the PSG on the front and back surfaces to ensure the formation of a textured surface on the front and the emergence of texture in the isolation gap on the back, thereby ensuring the full absorption of light by the textured surface structure.

[0039] In addition, in some embodiments, the wavelengths and powers of the first laser and the second laser in the above back contact battery processing method can be adjusted according to different processes.

[0040] For example, the first laser can be selected from a purple laser with a wavelength between 345 nm and 365 nm, and its power is between 12 W and 22 W.

[0041] Again, for example, the first laser can be selected from a green laser with a wavelength between 522 nm and 542 nm, and its power is between 21 W and 31 W.

[0042] For example, the second laser can be selected from a purple laser with a wavelength between 345 nm and 365 nm, and its power is between 10 W and 20 W.

[0043] For another example, the second laser can be selected from green lasers with wavelengths between 522 nm and 542 nm, and its power is between 29 W and 39 W.

[0044] In addition, in some embodiments, when applying the first laser to the preset N-type region and the marked points on the back surface of the substrate in the above step 1, the present invention can apply the first laser to a preset-sized square region where the marked points are located.

[0045] Correspondingly, when applying the second laser to the marked points and the preset P-type region on the back surface of the substrate in the above step 2, the present invention can also apply the second laser to the above-mentioned square region where the marked points are located.

[0046] Furthermore, during the process of texturing the marked points treated with the first laser and the second laser in the above step 3, the present invention can texture the square region treated with the first laser and the second laser. Specifically, the present invention can use a texturing agent on the preset-sized square region where the marked points are located after being treated with the first laser and the second laser at a process temperature of 65°C to 75°C and maintain a certain preset time to form a light-trapping pyramid structure, i.e., a textured surface structure, on the surface of the square region. Optionally, use the texturing agent in the laser isolation region and maintain a certain preset time to form a textured isolation region. The textured surface structure formed after the above texturing process can effectively increase the absorption of light. Since the surface of the polished surface on the back of the battery is relatively smooth after being coated with silicon nitride, while the surface of the marked points made into a textured surface structure is rough, when performing screen printing, the gray value of the marked points recognized by the camera will be much lower than the gray values of other positions, so that the marked points can be accurately recognized through the obvious difference in gray values during grasping and recognition, improving the accuracy of screen printing.

[0047] Optionally, the above texturing agent can be KOH with a volume ratio of 2% to 4%, or a texturing additive (ADD) with a volume ratio of 0.5% to 2%. The components of the above texturing additive can be selected as polyethylene glycol, EDTA, and sodium benzoate. The above preset time can be 320 seconds to 520 seconds.

[0048] In addition, in some embodiments, during the process of forming multiple film layer structures of the back contact battery on the back surface of the substrate in the above step 4, the present invention can sequentially form an N-type polysilicon structure, an alumina layer, and a silicon nitride layer on the back surface of the substrate of the back contact battery.

[0049] After that, during the process of positioning the marked points according to the textured surface structure to perform screen printing of the back contact battery in the above step 4, the present invention can position the marked points according to the textured surface structure to perform screen printing of the N-type region electrode, P-type region electrode, and / or grid lines of the back contact battery.

[0050] Specifically, in the present invention, a beam of white light / red light / blue light can be first projected onto the surface of the cell, and then the screen printing camera captures the light reflection formed on the surface of the cell to photograph and generate a positioning image of the back surface of the substrate with multiple film layer structures. After that, the present invention can analyze the positioning image, convert the captured light into gray values, and locate the marked points according to the positions of the matte surface structures therein. Then, based on the positions of the marked points located by the matte surface structures, the present invention can perform screen printing of the back contact cell N-type region electrode, P-type region electrode, and / or grid lines.

[0051] Please further refer to Figures 2 to 4 。 Figure 2 FIG. shows a schematic diagram of the marked points after the processing of the back contact cell in the present invention. Figure 3 FIG. shows a schematic diagram of the marked points during screen printing after the processing of the back contact cell in the prior art. Figure 4 FIG. shows a schematic diagram of the marked points during screen printing after the processing of the back contact cell in the present invention.

[0052] As Figure 2 shown, after adopting the processing method of the back contact cell in the present invention, since the square marked points have a matte surface structure, they have a strong absorption and scattering effect on the received light, so there is an obvious gray level difference between their positioning images and the surrounding positions.

[0053] In addition, as Figure 3 shown, during the screen printing after the processing of the back contact cell in the prior art, due to the unclear marked points, the edges of the marked points are damaged during printing, thus affecting the alignment printing accuracy. On the contrary, as Figure 4 shown, after adopting the processing method of the back contact cell in the present invention, the outlines of each pattern during screen printing are clear, and the printing accuracy is improved.

[0054] In summary, a back contact cell and its processing method provided by the present invention perform texturing treatment on the marked points after two laser treatments, process them into a matte surface structure, improve the positioning accuracy of the marked points in the screen printing process, thereby avoiding the leakage problem caused by the overlap of the N-type region and P-type region of the back contact crystalline silicon solar cell, avoiding the laser damage to the back contact crystalline silicon solar cell caused by multiple point markings, and improving the production efficiency of the back contact crystalline silicon solar cell.

[0055] Although the above methods are illustrated and described as a series of actions for simplicity of explanation, it should be understood and appreciated that these methods are not limited by the order of the actions, because according to one or more embodiments, some actions may occur in a different order and / or occur concurrently with other actions not illustrated and described herein but understood by those skilled in the art.

[0056] The prior description of the present disclosure is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to the present disclosure will be apparent to those skilled in the art, and the general principles defined herein can be applied to other variations without departing from the spirit or scope of the present disclosure. Thus, the present disclosure is not intended to be limited to the examples and designs described herein, but should be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A processing method for a back-contact battery, characterized in that, Including the following steps: After performing boron diffusion treatment on the first tunneling silicon oxide layer on the back surface of the back contact battery substrate and depositing a P-type polysilicon layer, apply a first laser to a preset N-type region and a marked position on the back surface of the substrate; After performing phosphorus diffusion treatment on the second tunneling silicon oxide layer on the back surface of the substrate and depositing an N-type polysilicon layer, apply a second laser to the marked position and a preset P-type region on the back surface of the substrate; Perform texturing treatment on the marked position processed by the first laser and the second laser to process it into a textured structure; And After generating multiple film layer structures of the back contact battery on the back surface of the substrate, position the marked position according to the textured structure to perform screen printing of the back contact battery.

2. The processing method according to claim 1, characterized in that, It further includes the following steps: Before performing the boron diffusion treatment on the back surface of the substrate, first perform front polishing treatment and first LPCVD treatment on the back surface of the substrate to form the first tunneling silicon oxide layer on the back surface of the substrate; And / or After applying the first laser to the N-type region and the marked position, and before performing phosphorus diffusion treatment on the back surface of the substrate, remove the first by-product on the back surface of the substrate, and / or perform second LPCVD treatment on the back surface of the substrate to form the second tunneling silicon oxide layer on the back surface of the substrate; And / or After applying the second laser to the P-type region and the marked position, and before generating the multiple film layer structures on the back surface of the substrate, remove the second by-product on the back surface of the substrate, and / or perform texturing treatment on the isolation region between the N-type region and the P-type region to process it into a textured structure.

3. The processing method according to claim 1, characterized in that, The first laser is selected from a purple laser with a wavelength between 345 nm and 365 nm, or a green laser with a wavelength between 522 nm and 542 nm, and / or The second laser is selected from a purple laser with a wavelength between 345 nm and 365 nm, or a green laser with a wavelength between 522 nm and 542 nm.

4. The processing method according to claim 3, characterized in that, When the first laser is a purple laser, its power is between 12 W and 22 W, When the first laser is a green laser, its power is between 21 W and 31 W, When the second laser is a purple laser, its power is between 10 W and 20 W, When the second laser is a green laser, its power is between 29 W and 39 W.

5. The processing method according to claim 1, characterized in that, The step of applying the first laser to the preset N-type region and the marked position on the back surface of the substrate includes: applying the first laser to a preset square area at the position where the marked position is located, The step of applying the second laser to the marked position and the preset P-type region on the back surface of the substrate includes: applying the second laser to the square area at the position where the marked position is located, The step of performing texturing treatment on the marked position processed by the first laser and the second laser to process it into a textured structure includes: performing the texturing treatment on the square area processed by the first laser and the second laser to process it into a textured structure.

6. The processing method according to claim 1, characterized in that, The step of texturing the marked points processed by the first laser and the second laser to process them into a textured surface structure includes: At a process temperature of 65°C to 75°C, a square area of a preset size at the position of the marked points is treated with a texturing agent and maintained for a preset time to form a light-trapping pyramid structure on the surface of the square area.

7. The processing method according to claim 1, characterized in that, The step of forming multiple film layer structures of the back contact battery on the back surface of the substrate includes: Successively forming an N-type polysilicon structure, an aluminum oxide layer, and a silicon nitride layer on the back surface of the substrate of the back contact battery.

8. The processing method according to claim 1, characterized in that, The step of positioning the marked points according to the textured surface structure to perform screen printing of the back contact battery includes: Positioning the marked points according to the textured surface structure to perform screen printing of the N-type region electrode, P-type region electrode, and / or grid lines of the back contact battery.

9. The processing method according to claim 8, wherein The step of positioning the marked points according to the textured surface structure to perform screen printing of the back contact battery includes: Taking a picture of the back surface of the substrate on which the multiple film layer structures are formed through a screen printing camera to obtain a positioning image of the back surface of the substrate; Analyzing the positioning image to position the marked points according to the position of the textured surface structure therein; and Performing screen printing of the N-type region electrode, the P-type region electrode, and / or the grid lines according to the position of the marked points.

10. A back-contact battery, characterized in that, Comprising: A substrate, the back surface of which includes an N-type region, a P-type region, and marked points, wherein the marked points are textured surface structures; Multiple film layer structures, located on the back surface of the substrate; and A screen printing structure, located on the back surface of the multiple film layer structures.

11. A back-contact battery, characterized in that, The back contact battery is obtained by processing according to the processing method of the back contact battery as described in any one of claims 1 to 9.

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