Method for removing BSG and / or PSG on surface of silicon wafer, crystalline silicon solar cell and photovoltaic system

Abstract

The invention provides a method for removing BSG and / or PSG on the surface of a silicon wafer, a crystalline silicon solar cell and a photovoltaic system, and relates to the technical field of crystalline silicon solar cells. A method for removing BSG and / or PSG on the surface of a silicon wafer comprises the steps that ozone oxidation treatment is conducted on the surface of the silicon wafer, an ozone oxidation layer is formed, and a target silicon wafer is obtained; covering one surface of the target silicon wafer with a layer of water film to form a water film layer; and then carrying out a BSG cleaning process or a PSG cleaning process on the surface, not covered with the water film layer, of the target silicon wafer. According to the method, ozonation treatment is carried out on the silicon wafer needing to remove BSG and / or PSG, the ozonation layer can be formed on the surface of the silicon wafer, then the ozonation layer is covered with the water film, the covering effect of the water film is better, the better water film protection effect can be formed, and therefore the situation that due to the poor water film protection effect, the water film cannot be damaged is effectively relieved. The BSG and / or PSG on the edge or the side surface of the silicon wafer are / is not cleaned, so that the electric leakage proportion of the edge and the side surface of the crystalline silicon solar cell is effectively reduced.

Description

Technical Field

[0001] The present application relates to the technical field of crystalline silicon solar cells, and in particular to a method for removing BSG and / or PSG from the surface of a silicon wafer, a crystalline silicon solar cell and a photovoltaic system. Background Art

[0002] Crystalline silicon solar cells are one of the most common and widely used types of solar cells on the market. Crystalline silicon solar cells have attracted attention due to their high energy conversion efficiency, good stability and long service life. The BSG (boron silicon glass) cleaning process and the PSG (phosphorus silicon glass) cleaning process are both essential processes in the production process of crystalline silicon solar cells, and have a significant impact on the photoelectric conversion efficiency of crystalline silicon solar cells.

[0003] The existing BSG (boron silicate glass) cleaning process and PSG (phosphorus silicate glass) cleaning process may easily lead to incomplete removal of BSG and / or PSG on the edges or sides, thus causing leakage at the edges and / or sides of the crystalline silicon solar cell.

[0004] It should be noted that the above content is not necessarily prior art, nor is it intended to limit the scope of patent protection of this application. Summary of the invention

[0005] In view of the deficiencies in the prior art, the purpose of the present application is to provide a method for removing BSG and / or PSG on the surface of a silicon wafer, a crystalline silicon solar cell and a photovoltaic system. The silicon wafer from which BSG and / or PSG need to be removed is subjected to ozone oxidation treatment. An ozone oxidation layer will be formed on the surface of the silicon wafer, and then a layer of water film will be covered on the ozone oxidation layer. The water film has a better coverage effect and can form a better water film protection effect, thereby effectively alleviating the situation where BSG and / or PSG on the edge or side of the silicon wafer is not cleaned up due to the poor water film protection effect, thereby effectively reducing the proportion of leakage at the edge and side of the crystalline silicon solar cell.

[0006] To achieve the above objectives, this application adopts the following technical solutions: A method for removing BSG and / or PSG from a silicon wafer surface, comprising: Performing ozone oxidation treatment on the surface of the silicon wafer to form an ozone oxidation layer to obtain a target silicon wafer; Covering one surface of the target silicon wafer with a layer of water film to form a water film layer; and then performing a BSG cleaning process or a PSG cleaning process on the surface of the target silicon wafer not covered with the water film layer; Wherein, the water film layer covers the ozone oxidation layer.

[0007] In some embodiments, the thickness of the ozone oxidation layer is 1.8-3.2 mm.

[0008] In some embodiments, the method of performing ozone oxidation treatment on the surface of the silicon wafer includes: placing the silicon wafer in an ozone tank with an ozone concentration of 50-100 ppm for ozone oxidation treatment.

[0009] In some embodiments, the ozone oxidation treatment time is 20 to 30 seconds.

[0010] The present application also provides a method for removing BSG and PSG from the surface of a silicon wafer, comprising: Performing a first ozone oxidation treatment on the surface of the silicon wafer to form a first ozone oxidation layer, thereby obtaining a first target silicon wafer; Covering one surface of the first target silicon wafer with a layer of water film to form a first water film layer; then performing a BSG cleaning process on the surface of the first target silicon wafer not covered with the first water film to obtain a second target silicon wafer; performing a second ozone oxidation treatment on the surface of the second target silicon wafer to form a second ozone oxidation layer, thereby obtaining a third target silicon wafer; Covering one surface of the third target silicon wafer with a layer of water film to form a second water film layer; and then performing a PSG cleaning process on the surface of the third target silicon wafer not covered with the second water film; Wherein, the first water film layer covers the first ozone oxidation layer; and the second water film layer covers the second ozone oxidation layer.

[0011] In some embodiments, before performing a second ozone oxidation treatment on the surface of the second target silicon wafer, the method further includes: performing an annealing treatment on the second target silicon wafer.

[0012] In some embodiments, the annealing treatment is performed at a temperature of 900-950°C.

[0013] In some embodiments, the method satisfies at least one of the following characteristics: (1) The thickness of the first ozone oxidation layer is 1.8-2.2 mm; (2) The thickness of the second ozone oxidation layer is 2.8-3.2 mm; (3) The method of performing a first ozone oxidation treatment on the surface of the silicon wafer comprises: placing the silicon wafer in an ozone tank with an ozone concentration of 50 to 70 ppm for ozone oxidation treatment, and the ozone oxidation treatment time is 20 to 25 seconds; (4) The method of performing a second ozone oxidation treatment on the surface of the second target silicon wafer comprises: placing the second target silicon wafer in an ozone tank with an ozone concentration of 80 to 100 ppm for ozone oxidation treatment, and the ozone oxidation treatment time is 25 to 30 seconds; (5) The conductivity of the first hydrofluoric acid etching solution used in the BSG cleaning process is 350-450 S / m, and the cleaning time is 27-33 s; the temperature T1 of the first hydrofluoric acid etching solution satisfies: 20°C ≤ T1 ≤ 40°C; (6) The conductivity of the second hydrofluoric acid etching solution used in the PSG cleaning process is 160-190 S / m, and the cleaning time is 27-33 s; the temperature T2 of the second hydrofluoric acid etching solution satisfies: 20°C ≤ T2 ≤ 40°C.

[0014] The present application also provides a crystalline silicon solar cell, comprising a silicon wafer, from which BSG and / or PSG are removed by the above method.

[0015] The present application also provides a photovoltaic system, comprising the above-mentioned crystalline silicon solar cell.

[0016] In the technical solution of the present application, the silicon wafer from which BSG and / or PSG need to be removed is subjected to ozone oxidation treatment, and an ozone oxidation layer is formed on the surface of the silicon wafer. Thereafter, a layer of water film is covered on the ozone oxidation layer. The water film has a better coverage effect and can form a better water film protection effect, thereby effectively alleviating the situation in which BSG and / or PSG are not cleaned cleanly on the edge or side of the silicon wafer due to poor water film protection effect, thereby effectively reducing the proportion of leakage at the edge and side of the crystalline silicon solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application. Figure 1 This is a process flow chart of a method for removing BSG and / or PSG from the surface of a silicon wafer according to the present application. DETAILED DESCRIPTION

[0018] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings. In the accompanying drawings, for clarity, the sizes of layers, regions, elements and their relative sizes may be exaggerated. Wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limitations on the present application. It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0019] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there is no intervening element or layer. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present disclosure, the first element, component, region, layer or part discussed below can be represented as the second element, component, region, layer or part. And when the second element, component, region, layer or part is discussed, it does not mean that the present disclosure necessarily has the first element, component, region, layer or part.

[0020] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0021] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0022] In the present application, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to an integer in the numerical interval, it includes the two endpoint integers of the numerical range, and each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical range disclosed in the present application should be understood to include any and all sub-ranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows for broadly including quantitative intervals such as percentage intervals, ratio intervals, and ratio intervals.

[0023] The embodiments of the present application aim to provide a method for removing BSG and / or PSG from the surface of a silicon wafer, a crystalline silicon solar cell, and a photovoltaic system. The silicon wafer from which BSG and / or PSG need to be removed is subjected to ozone oxidation treatment. An ozone oxidation layer is formed on the surface of the silicon wafer, and then a layer of water film is covered on the ozone oxidation layer. The water film has a better coverage effect and can form a better water film protection effect, thereby effectively alleviating the situation in which BSG and / or PSG on the edge or side of the silicon wafer is not cleaned up due to the poor water film protection effect, thereby effectively reducing the proportion of leakage at the edge and side of the crystalline silicon solar cell.

[0024] The present application provides a method for removing BSG and / or PSG from a silicon wafer surface, comprising: Performing ozone oxidation treatment on the surface of the silicon wafer to form an ozone oxidation layer to obtain a target silicon wafer; Covering one surface of the target silicon wafer with a layer of water film to form a water film layer; and then performing a BSG cleaning process or a PSG cleaning process on the surface of the target silicon wafer not covered with the water film layer; Wherein, the water film layer covers the ozone oxidation layer.

[0025] In the embodiment of the present application, the process route for removing only BSG on the surface of the silicon wafer is: ozone oxidation treatment → covering with water film → BSG cleaning process; the process route for removing only PSG on the surface of the silicon wafer is: ozone oxidation treatment → covering with water film → PSG cleaning process; process route one for removing both BSG and PSG on the surface of the silicon wafer is: ozone oxidation treatment → covering with water film → BSG cleaning process + ozone oxidation treatment → covering with water film → PSG cleaning process (that is, process route one is: first remove BSG, then remove PSG); process route two for removing both BSG and PSG on the surface of the silicon wafer is: ozone oxidation treatment → covering with water film → PSG cleaning process + ozone oxidation treatment → covering with water film → BSG cleaning process (that is, process route two is: first remove PSG, then remove BSG).

[0026] In the embodiment of the present application, the surface of the silicon wafer is subjected to ozone oxidation treatment, the purpose of which is to form an ozone oxidation layer, improve the water film coverage effect, and form a better water film protection effect; if the silicon wafer is placed in an ozone tank for oxidation, an ozone oxidation layer will be formed on the surface of the silicon wafer, and only the surface that needs to be protected needs to be covered with a water film. If another ozone oxidation treatment method is selected, ozone oxidation treatment can also be performed only on the surface that needs to be protected, so as to form an ozone oxidation layer on a specific surface.

[0027] In the embodiment of the present application, the silicon wafer can be in the shape of a cuboid, and the surface of the silicon wafer can be recorded as the front side (top side), back side (bottom side), front side, back side, left side, and right side; if the back side of the silicon wafer needs to be protected, it is necessary to perform ozone oxidation treatment on the surface of the silicon wafer (only the back side is also acceptable) to form an ozone oxidation layer, and then cover the back side of the silicon wafer with a layer of water film to form a water film layer, and then perform a BSG cleaning process on the front side, front side, back side, left side, and right side of the silicon wafer. If the front side of the silicon wafer needs to be protected, it is necessary to perform ozone oxidation treatment on the surface of the silicon wafer (only the front side is also acceptable) to form an ozone oxidation layer, and then cover the front side of the silicon wafer with a layer of water film to form a water film layer, and then perform a BSG cleaning process on the back side, front side, back side, left side, and right side of the silicon wafer. The PSG cleaning process is similar to the BSG cleaning process and will not be repeated here.

[0028] In the embodiment of the present application, the thickness of the ozone oxidation layer is: 1~5mm (for example, 1mm, 2mm, 3mm, 4mm, 5mm).

[0029] In an embodiment of the present application, the silicon wafer from which BSG and / or PSG need to be removed is subjected to ozone oxidation treatment, and an ozone oxidation layer is formed on the surface of the silicon wafer. Thereafter, a layer of water film is covered on the ozone oxidation layer. The water film has a better coverage effect and can form a better water film protection effect, thereby effectively alleviating the situation in which BSG and / or PSG are not cleaned cleanly on the edge or side of the silicon wafer due to poor water film protection effect, thereby effectively reducing the proportion of leakage at the edge and side of the crystalline silicon solar cell.

[0030] In an optional embodiment, the thickness of the ozone oxidation layer is 1.8-3.2 mm (for example, 1.8 mm, 2.0 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, 3.0 mm, 3.2 mm). The thickness of the ozone oxidation layer is optimized, and the coverage effect of the water film on the ozone oxidation layer can be further improved to form a better water film protection effect, thereby further alleviating the situation that the BSG and / or PSG on the edge or side of the silicon wafer is not cleaned up due to the poor water film protection effect, and further reducing the proportion of leakage at the edge and side of the crystalline silicon solar cell.

[0031] In an optional embodiment, the method of performing ozone oxidation treatment on the surface of the silicon wafer includes: placing the silicon wafer in an ozone tank with an ozone concentration of 50 to 100 ppm (for example, 50 ppm, 60 ppm, 70 ppm, 80 ppm, 90 ppm, 100 ppm) for ozone oxidation treatment. Optimizing the process parameters of the ozone oxidation treatment can improve the morphology of the ozone oxidation layer, further enhance the coverage of the water film on the ozone oxidation layer, and form a better water film protection effect, thereby further alleviating the situation that the BSG and / or PSG on the edge or side of the silicon wafer is not cleaned up due to the poor water film protection effect, and further reducing the proportion of leakage at the edge and side of the crystalline silicon solar cell.

[0032] In an optional embodiment, the ozone oxidation treatment time is 20 to 30 seconds (for example, 20 seconds, 21 seconds, 22 seconds, 23 seconds, 24 seconds, 25 seconds, 26 seconds, 27 seconds, 28 seconds, 29 seconds, 30 seconds). Optimizing the process parameters of the ozone oxidation treatment can improve the morphology of the ozone oxidation layer, further enhance the coverage of the water film on the ozone oxidation layer, and form a better water film protection effect, thereby further alleviating the situation that the BSG and / or PSG on the edge or side of the silicon wafer is not cleaned up due to the poor water film protection effect, and further reducing the proportion of leakage at the edge and side of the crystalline silicon solar cell.

[0033] The present application also provides a method for removing BSG and PSG from the surface of a silicon wafer, comprising: Performing a first ozone oxidation treatment on the surface of the silicon wafer to form a first ozone oxidation layer, thereby obtaining a first target silicon wafer; Covering one surface of the first target silicon wafer with a layer of water film to form a first water film layer; then performing a BSG cleaning process on the surface of the first target silicon wafer not covered with the first water film to obtain a second target silicon wafer; performing a second ozone oxidation treatment on the surface of the second target silicon wafer to form a second ozone oxidation layer, thereby obtaining a third target silicon wafer; Covering one surface of the third target silicon wafer with a layer of water film to form a second water film layer; and then performing a PSG cleaning process on the surface of the third target silicon wafer not covered with the second water film; Wherein, the first water film layer covers the first ozone oxidation layer; and the second water film layer covers the second ozone oxidation layer.

[0034] When removing BSG and PSG from the silicon wafer surface at the same time, BSG can be removed first and then PSG; or PSG can be removed first and then BSG. In the embodiment of the present application, BSG is removed first and then PSG. This process route has a better effect of removing BSG and PSG, and can effectively reduce the proportion of leakage at the edges and sides of crystalline silicon solar cells.

[0035] In some embodiments, before the second ozone oxidation treatment is performed on the surface of the second target silicon wafer, the method further includes: annealing the second target silicon wafer. The annealing time can be 2-20 minutes. Annealing can effectively improve the crystal defects on the surface of the silicon wafer caused by the BSG cleaning process, and then the second ozone oxidation treatment is performed. The morphology of the second ozone oxidation layer formed is better, which plays a role in improving the morphology of the second ozone oxidation layer, and can further enhance the coverage effect of the water film on the second ozone oxidation layer, forming a better water film protection effect, thereby further alleviating the situation that the BSG and / or PSG on the edge or side of the silicon wafer are not cleaned up due to the poor water film protection effect, thereby further reducing the proportion of leakage at the edge and side of the crystalline silicon solar cell.

[0036] In some embodiments, the temperature of the annealing treatment is 900-950°C (for example, 900°C, 910°C, 920°C, 930°C, 940°C, 950°C). By optimizing the temperature of the annealing treatment, the improvement effect of the crystal defects on the surface of the silicon wafer is better, and then the second ozone oxidation treatment is performed, the morphology of the second ozone oxidation layer is better, which plays a role in improving the morphology of the second ozone oxidation layer, and can further enhance the coverage effect of the water film on the second ozone oxidation layer, forming a better water film protection effect, thereby further alleviating the situation that the BSG and / or PSG on the edge or side of the silicon wafer is not cleaned up due to the poor water film protection effect, and further reducing the proportion of leakage at the edge and side of the crystalline silicon solar cell.

[0037] In some embodiments, the method satisfies at least one of the following characteristics: (1) The thickness of the first ozone oxidation layer is 1.8-2.2 mm; (2) The thickness of the second ozone oxidation layer is 2.8-3.2 mm; (3) The method of performing a first ozone oxidation treatment on the surface of the silicon wafer comprises: placing the silicon wafer in an ozone tank with an ozone concentration of 50 to 70 ppm for ozone oxidation treatment, and the ozone oxidation treatment time is 20 to 25 seconds; (4) The method of performing a second ozone oxidation treatment on the surface of the second target silicon wafer comprises: placing the second target silicon wafer in an ozone tank with an ozone concentration of 80 to 100 ppm for ozone oxidation treatment, and the ozone oxidation treatment time is 25 to 30 seconds; (5) The conductivity of the first hydrofluoric acid etching solution used in the BSG cleaning process is 350-450 S / m, and the cleaning time is 27-33 s; the temperature T1 of the first hydrofluoric acid etching solution satisfies: 20°C ≤ T1 ≤ 40°C; (6) The conductivity of the second hydrofluoric acid etching solution used in the PSG cleaning process is 160-190 S / m, and the cleaning time is 27-33 s; the temperature T2 of the second hydrofluoric acid etching solution satisfies: 20°C ≤ T2 ≤ 40°C.

[0038] In the embodiment of the present application, the thickness of the first ozone oxidation layer and the second ozone oxidation layer are further optimized, which not only ensures the coverage effect of the water film, but also is beneficial to the removal effect of BSG and PSG, thereby further reducing the proportion of leakage at the edges and sides of the crystalline silicon solar cell.

[0039] In the embodiment of the present application, further optimizing the process parameters of the first ozone oxidation treatment and the second ozone oxidation treatment can improve the coverage effect of the water film and form a better water film protection effect, thereby effectively alleviating the situation where the BSG and / or PSG on the edge or side of the silicon wafer are not cleaned cleanly due to the poor water film protection effect, thereby further reducing the proportion of leakage at the edge and side of the crystalline silicon solar cell.

[0040] In the embodiment of the present application, the specific reaction equation of the BSG cleaning process is: SiO2+4HF→SiF4+2H2O, B2O3+6HF→2BF3+3H2O; controlling the conductivity and temperature and other parameters of the hydrofluoric acid etching solution used in the BSG cleaning process and the PSG cleaning process can increase the reaction rate of hydrofluoric acid with the BSG layer and the PSG layer, shorten the reaction time, which is beneficial to the removal effect of BSG and PSG, and at the same time slow down the rate at which hydrofluoric acid erodes the water film protection surface, thereby improving the water film protection effect, and further reducing the proportion of leakage at the edges and sides of the crystalline silicon solar cell.

[0041] The following specific examples further illustrate the present application, but should not be construed as limiting the present application. Without departing from the spirit and substance of the present application, modifications or replacements made to the methods, steps or conditions of the present application are within the scope of the present application.

[0042] Example 1 A method for preparing a TOPCon battery, comprising: (1) Cleaning and texturing: Clean the silicon wafer to remove the damage on the edge after cutting and surface impurities. Texturing treatment forms a surface pyramid structure to obtain a silicon wafer with a velvet surface.

[0043] (2) Boron diffusion: Boron is diffused into the silicon wafer with a velvet surface at a high temperature to form a PN junction, thereby obtaining a boron-diffused silicon wafer.

[0044] (3) Removal of BSG and alkali polishing: 3.1): The boron-diffused silicon wafer is placed in an ozone tank with an ozone concentration of 50 ppm, and the surface of the boron-diffused silicon wafer is subjected to a first ozone oxidation treatment, the ozone oxidation treatment time is 20 seconds, a first ozone oxidation layer is formed, and the thickness of the first ozone oxidation layer is 1.8 mm, so as to obtain a first target silicon wafer; a layer of water film is covered on the front side (top side) of the first target silicon wafer to form a first water film layer; and a BSG cleaning process is performed on the surface of the first target silicon wafer not covered with the first water film, that is, a BSG cleaning process is performed on the back side (bottom side), front side, rear side, left side and right side of the first target silicon wafer to obtain a second target silicon wafer; the conductivity of the first hydrofluoric acid etching solution used in the BSG cleaning process is 350 S / m, and the cleaning time is 27 seconds; the temperature of the first hydrofluoric acid etching solution is 20°C; the HF (hydrofluoric acid) in the first hydrofluoric acid etching solution is prepared by 400L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 250L of pure water.

[0045] 3.2) After removing the BSG, the second target silicon wafer is subjected to an alkali polishing step to obtain an alkali polished silicon wafer.

[0046] (4) Deposition: depositing an ultra-thin oxide layer and a polysilicon layer on the back side of the alkali-polished silicon wafer to obtain a silicon wafer having a polysilicon layer.

[0047] (5) Phosphorus diffusion: forming an N+ layer on the back side of the silicon wafer having the polysilicon layer, performing phosphorus doping, forming a passivation contact structure, and obtaining a passivated silicon wafer.

[0048] (6) Remove PSG and RCA (Radio Corporation of America Clean) cleaning: 6.1): firstly, the passivated silicon wafer is annealed at a temperature of 900° C. for 2 min; then, the passivated silicon wafer is placed in an ozone tank with an ozone concentration of 80 ppm, and the surface of the passivated silicon wafer is subjected to a second ozone oxidation treatment for 25 s to form a second ozone oxidation layer with a thickness of 2.8 mm, thereby obtaining a third target silicon wafer; A layer of water film is covered on the back side (bottom side) of the third target silicon wafer to form a second water film layer; then a PSG cleaning process is performed on the surface of the third target silicon wafer not covered with the second water film to obtain a fourth target silicon wafer; that is, a PSG cleaning process is performed on the front side (top side), front side, rear side, left side and right side of the third target silicon wafer; the conductivity of the second hydrofluoric acid etching solution used in the PSG cleaning process is 160S / m, and the cleaning time is 27s; the temperature of the second hydrofluoric acid etching solution is 20°C; the HF (hydrofluoric acid) in the second hydrofluoric acid etching solution is prepared by 250L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 400L of pure water; 6.2): ​​Perform RCA cleaning on the fourth target silicon wafer to remove surface residues and obtain a cleaned cell.

[0049] (7) Passivation: depositing an aluminum oxide film layer on the front side of the cleaned cell to form a passivation layer, thereby obtaining a passivated cell.

[0050] (8) Front coating: depositing a silicon nitride anti-reflective film on the front side of the passivated cell to obtain a cell with an anti-reflective film.

[0051] (9) Screen printing: Electrodes are made on the cell with the anti-reflection film by screen printing technology, and then sintered at high temperature to prepare a TOPCon cell. TOPCon cells are a type of crystalline silicon solar cells.

[0052] Example 2 A method for preparing a TOPCon battery, comprising: (1) Cleaning and texturing: Clean the silicon wafer to remove the damage on the edge after cutting and surface impurities. Texturing treatment forms a surface pyramid structure to obtain a silicon wafer with a velvet surface.

[0053] (2) Boron diffusion: Boron is diffused into the silicon wafer with a velvet surface at a high temperature to form a PN junction, thereby obtaining a boron-diffused silicon wafer.

[0054] (3) Removal of BSG and alkali polishing: 3.1): The boron-diffused silicon wafer is placed in an ozone tank with an ozone concentration of 70 ppm, and the surface of the boron-diffused silicon wafer is subjected to a first ozone oxidation treatment, the ozone oxidation treatment time is 25 seconds, a first ozone oxidation layer is formed, and the thickness of the first ozone oxidation layer is 2.2 mm, so as to obtain a first target silicon wafer; a layer of water film is covered on the front side (top side) of the first target silicon wafer to form a first water film layer; and then a BSG cleaning process is performed on the surface of the first target silicon wafer not covered with the first water film, that is, a BSG cleaning process is performed on the back side (bottom side), front side, rear side, left side and right side of the first target silicon wafer to obtain a second target silicon wafer; the conductivity of the first hydrofluoric acid etching solution used in the BSG cleaning process is 450 S / m, and the cleaning time is 33 seconds; the temperature of the first hydrofluoric acid etching solution is 40°C; the HF (hydrofluoric acid) in the first hydrofluoric acid etching solution is prepared by 400L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 250L of pure water.

[0055] 3.2) After removing the BSG, the second target silicon wafer is subjected to an alkali polishing step to obtain an alkali polished silicon wafer.

[0056] (4) Deposition: depositing an ultra-thin oxide layer and a polysilicon layer on the back side of the alkali-polished silicon wafer to obtain a silicon wafer having a polysilicon layer.

[0057] (5) Phosphorus diffusion: forming an N+ layer on the back side of the silicon wafer having the polysilicon layer, performing phosphorus doping, forming a passivation contact structure, and obtaining a passivated silicon wafer.

[0058] (6) Remove PSG and RCA (Radio Corporation of America Clean) cleaning: 6.1): firstly, the passivated silicon wafer is annealed at a temperature of 950° C. for 20 min; then, the passivated silicon wafer is placed in an ozone tank with an ozone concentration of 100 ppm, and the surface of the passivated silicon wafer is subjected to a second ozone oxidation treatment for 30 s to form a second ozone oxidation layer with a thickness of 3.2 mm, thereby obtaining a third target silicon wafer; A layer of water film is covered on the back side (bottom side) of the third target silicon wafer to form a second water film layer; then a PSG cleaning process is performed on the surface of the third target silicon wafer not covered with the second water film to obtain a fourth target silicon wafer; that is, a PSG cleaning process is performed on the front side (top side), front side, rear side, left side and right side of the third target silicon wafer; the conductivity of the second hydrofluoric acid etching solution used in the PSG cleaning process is 190S / m, and the cleaning time is 33s; the temperature of the second hydrofluoric acid etching solution is 40°C; the HF (hydrofluoric acid) in the second hydrofluoric acid etching solution is prepared by 250L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 400L of pure water; 6.2): ​​Perform RCA cleaning on the fourth target silicon wafer to remove surface residues and obtain a cleaned cell.

[0059] (7) Passivation: depositing an aluminum oxide film layer on the front side of the cleaned cell to form a passivation layer, thereby obtaining a passivated cell.

[0060] (8) Front coating: depositing a silicon nitride anti-reflective film on the front side of the passivated cell to obtain a cell with an anti-reflective film.

[0061] (9) Screen printing: Electrodes are made on the cell with the anti-reflection film by screen printing technology, and then sintered at high temperature to prepare a TOPCon cell.

[0062] Example 3 The TOPCon battery of Example 3 was prepared by referring to the preparation method of Example 1, except that: Step 3.1) in Example 3 is: placing the boron-diffused silicon wafer into an ozone tank with an ozone concentration of 50 ppm, performing a first ozone oxidation treatment on the surface of the boron-diffused silicon wafer, the ozone oxidation treatment time is 12 seconds, forming a first ozone oxidation layer, the thickness of the first ozone oxidation layer is 1 mm, and obtaining a first target silicon wafer; covering the front (top) surface of the first target silicon wafer with a layer of water film to form a first water film layer; then performing a BSG cleaning process on the surface of the first target silicon wafer not covered with the first water film, that is, performing a BSG cleaning process on the back (bottom), front side, rear side, left side, and right side of the first target silicon wafer, to obtain a second target silicon wafer; the conductivity of the first hydrofluoric acid etching solution used in the BSG cleaning process is 350 S / m, and the cleaning time is 27 seconds; the temperature of the first hydrofluoric acid etching solution is 20° C. HF (hydrofluoric acid) in the first hydrofluoric acid etching solution is prepared by 400 L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 250 L of pure water; Step 6.1) in Example 3 is: firstly, the passivated silicon wafer is subjected to annealing treatment at a temperature of 900°C and a time of 2 minutes; then, the passivated silicon wafer is placed in an ozone tank with an ozone concentration of 80 ppm, and the surface of the passivated silicon wafer is subjected to a second ozone oxidation treatment for 10 seconds to form a second ozone oxidation layer with a thickness of 1 mm, thereby obtaining a third target silicon wafer; a layer of water film is covered on the back (bottom) of the third target silicon wafer to form a second water film layer; then, The surface of the third target silicon wafer not covered by the second water film is subjected to a PSG cleaning process to obtain a fourth target silicon wafer; that is, the front side (top surface), front side surface, rear side surface, left side surface and right side surface of the third target silicon wafer are subjected to a PSG cleaning process; the conductivity of the second hydrofluoric acid etching solution used in the PSG cleaning process is 160S / m, and the cleaning time is 27s; the temperature of the second hydrofluoric acid etching solution is 20°C; the HF (hydrofluoric acid) in the second hydrofluoric acid etching solution is prepared from 250L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 400L of pure water.

[0063] Example 4 The TOPCon battery of Example 4 was prepared according to the preparation method of Example 1, except that: Step 3.1) in Example 4 is: placing the boron-diffused silicon wafer into an ozone tank with an ozone concentration of 50 ppm, performing a first ozone oxidation treatment on the surface of the boron-diffused silicon wafer, the ozone oxidation treatment time is 45 seconds, forming a first ozone oxidation layer, the thickness of the first ozone oxidation layer is 5 mm, and obtaining a first target silicon wafer; covering the front (top) surface of the first target silicon wafer with a layer of water film to form a first water film layer; then performing a BSG cleaning process on the surface of the first target silicon wafer not covered with the first water film, that is, performing a BSG cleaning process on the back (bottom), front side, rear side, left side, and right side of the first target silicon wafer, to obtain a second target silicon wafer; the conductivity of the first hydrofluoric acid etching solution used in the BSG cleaning process is 350 S / m, and the cleaning time is 27 seconds; the temperature of the first hydrofluoric acid etching solution is 20° C. HF (hydrofluoric acid) in the first hydrofluoric acid etching solution is prepared by 400 L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 250 L of pure water; Step 6.1) in Example 4 is: firstly, the passivated silicon wafer is subjected to annealing treatment at a temperature of 900°C and a time of 2 minutes; then, the passivated silicon wafer is placed in an ozone tank with an ozone concentration of 80 ppm, and the surface of the passivated silicon wafer is subjected to a second ozone oxidation treatment for 37 seconds to form a second ozone oxidation layer with a thickness of 5 mm, thereby obtaining a third target silicon wafer; a layer of water film is covered on the back (bottom) of the third target silicon wafer to form a second water film layer; then, The surface of the third target silicon wafer not covered by the second water film is subjected to a PSG cleaning process to obtain a fourth target silicon wafer; that is, the front side (top surface), front side surface, rear side surface, left side surface and right side surface of the third target silicon wafer are subjected to a PSG cleaning process; the conductivity of the second hydrofluoric acid etching solution used in the PSG cleaning process is 160S / m, and the cleaning time is 27s; the temperature of the second hydrofluoric acid etching solution is 20°C; the HF (hydrofluoric acid) in the second hydrofluoric acid etching solution is prepared from 250L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 400L of pure water.

[0064] Example 5 The TOPCon battery of Example 5 was prepared by referring to the preparation method of Example 1, except that: Step 3.1) in Example 5 is: placing the boron-diffused silicon wafer into an ozone tank with an ozone concentration of 20 ppm, performing a first ozone oxidation treatment on the surface of the boron-diffused silicon wafer, the ozone oxidation treatment time is 55 seconds, forming a first ozone oxidation layer, the thickness of the first ozone oxidation layer is 1.8 mm, and obtaining a first target silicon wafer; covering the front side (top side) of the first target silicon wafer with a layer of water film to form a first water film layer; and then performing a first ozone oxidation treatment on the surface of the first target silicon wafer not covered with the first water film. A BSG cleaning process is performed, that is, the back side (bottom), front side, rear side, left side, and right side of the first target silicon wafer are subjected to a BSG cleaning process to obtain a second target silicon wafer; the conductivity of the first hydrofluoric acid etching solution used in the BSG cleaning process is 350S / m, and the cleaning time is 27s; the temperature of the first hydrofluoric acid etching solution is 20°C; the HF (hydrofluoric acid) in the first hydrofluoric acid etching solution is prepared from 400L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 250L of pure water; Step 6.1) in Example 5 is: firstly, the passivated silicon wafer is subjected to annealing treatment at a temperature of 900° C. for 2 min; then, the passivated silicon wafer is placed in an ozone tank with an ozone concentration of 20 ppm, and the surface of the passivated silicon wafer is subjected to a second ozone oxidation treatment for 80 s to form a second ozone oxidation layer with a thickness of 2.8 mm, thereby obtaining a third target silicon wafer; a layer of water film is covered on the back (bottom) of the third target silicon wafer to form a second water film layer; then A PSG cleaning process is performed on the surface of the third target silicon wafer not covered by the second water film to obtain a fourth target silicon wafer; that is, a PSG cleaning process is performed on the front side (top side), front side, rear side, left side and right side of the third target silicon wafer; the conductivity of the second hydrofluoric acid etching solution used in the PSG cleaning process is 160S / m, and the cleaning time is 27s; the temperature of the second hydrofluoric acid etching solution is 20°C; the HF (hydrofluoric acid) in the second hydrofluoric acid etching solution is prepared from 250L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 400L of pure water.

[0065] Example 6 The TOPCon battery of Example 6 was prepared by referring to the preparation method of Example 1, except that: Step 3.1) in Example 6 is: placing the boron-diffused silicon wafer in an ozone tank with an ozone concentration of 200 ppm, performing a first ozone oxidation treatment on the surface of the boron-diffused silicon wafer, the ozone oxidation treatment time is 7 seconds, forming a first ozone oxidation layer, the thickness of the first ozone oxidation layer is 1.8 mm, and obtaining a first target silicon wafer; covering the front side (top side) of the first target silicon wafer with a layer of water film to form a first water film layer; and then performing a first ozone oxidation treatment on the surface of the first target silicon wafer not covered with the first water film. A BSG cleaning process is performed, that is, the back side (bottom), front side, rear side, left side, and right side of the first target silicon wafer are subjected to a BSG cleaning process to obtain a second target silicon wafer; the conductivity of the first hydrofluoric acid etching solution used in the BSG cleaning process is 350S / m, and the cleaning time is 27s; the temperature of the first hydrofluoric acid etching solution is 20°C; the HF (hydrofluoric acid) in the first hydrofluoric acid etching solution is prepared from 400L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 250L of pure water; Step 6.1) in Example 6 is: firstly, the passivated silicon wafer is annealed at a temperature of 900° C. for 2 min; then, the passivated silicon wafer is placed in an ozone tank with an ozone concentration of 200 ppm, and the surface of the passivated silicon wafer is subjected to a second ozone oxidation treatment for 11 s to form a second ozone oxidation layer with a thickness of 2.8 mm, thereby obtaining a third target silicon wafer; a layer of water film is covered on the back (bottom) of the third target silicon wafer to form a second water film layer; then A PSG cleaning process is performed on the surface of the third target silicon wafer not covered by the second water film to obtain a fourth target silicon wafer; that is, a PSG cleaning process is performed on the front side (top side), front side, rear side, left side and right side of the third target silicon wafer; the conductivity of the second hydrofluoric acid etching solution used in the PSG cleaning process is 160S / m, and the cleaning time is 27s; the temperature of the second hydrofluoric acid etching solution is 20°C; the HF (hydrofluoric acid) in the second hydrofluoric acid etching solution is prepared from 250L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 400L of pure water.

[0066] Example 7 The TOPCon battery of Example 7 was prepared by referring to the preparation method of Example 1, except that: Step 6.1) in Example 7 is: firstly, the passivated silicon wafer is subjected to annealing treatment at a temperature of 700° C. for 2 min; then, the passivated silicon wafer is placed in an ozone tank with an ozone concentration of 80 ppm, and the surface of the passivated silicon wafer is subjected to a second ozone oxidation treatment for 25 s to form a second ozone oxidation layer with a thickness of 2.8 mm, thereby obtaining a third target silicon wafer; a layer of water film is covered on the back (bottom) of the third target silicon wafer to form a second water film layer; then A PSG cleaning process is performed on the surface of the third target silicon wafer not covered by the second water film to obtain a fourth target silicon wafer; that is, a PSG cleaning process is performed on the front side (top side), front side, rear side, left side and right side of the third target silicon wafer; the conductivity of the second hydrofluoric acid etching solution used in the PSG cleaning process is 160S / m, and the cleaning time is 27s; the temperature of the second hydrofluoric acid etching solution is 20°C; the HF (hydrofluoric acid) in the second hydrofluoric acid etching solution is prepared from 250L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 400L of pure water.

[0067] Example 8 The TOPCon battery of Example 8 was prepared by referring to the preparation method of Example 1, except that: Step 6.1) in Example 8 is: firstly, the passivated silicon wafer is subjected to annealing treatment at a temperature of 1100° C. for 2 min; then, the passivated silicon wafer is placed in an ozone tank with an ozone concentration of 80 ppm, and the surface of the passivated silicon wafer is subjected to a second ozone oxidation treatment for 25 s to form a second ozone oxidation layer with a thickness of 2.8 mm, thereby obtaining a third target silicon wafer; a layer of water film is covered on the back (bottom) of the third target silicon wafer to form a second water film layer; then A PSG cleaning process is performed on the surface of the third target silicon wafer not covered by the second water film to obtain a fourth target silicon wafer; that is, a PSG cleaning process is performed on the front side (top side), front side, rear side, left side and right side of the third target silicon wafer; the conductivity of the second hydrofluoric acid etching solution used in the PSG cleaning process is 160S / m, and the cleaning time is 27s; the temperature of the second hydrofluoric acid etching solution is 20°C; the HF (hydrofluoric acid) in the second hydrofluoric acid etching solution is prepared from 250L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 400L of pure water.

[0068] Example 9 The TOPCon battery of Example 9 was prepared according to the preparation method of Example 1, except that: Step 6.1) in Example 9 is: placing the passivated silicon wafer in an ozone tank with an ozone concentration of 80 ppm, performing a second ozone oxidation treatment on the surface of the passivated silicon wafer, the ozone oxidation treatment time is 25 seconds, forming a second ozone oxidation layer, the thickness of the second ozone oxidation layer is 2.8 mm, and a third target silicon wafer is obtained; covering the back (bottom) of the third target silicon wafer with a layer of water film to form a second water film layer; and then performing a second water film treatment on the surface of the third target silicon wafer not covered with the second water film. A PSG cleaning process is performed to obtain a fourth target silicon wafer; that is, the PSG cleaning process is performed on the front side (top side), front side, rear side, left side and right side of the third target silicon wafer; the conductivity of the second hydrofluoric acid etching solution used in the PSG cleaning process is 160S / m, and the cleaning time is 27s; the temperature of the second hydrofluoric acid etching solution is 20°C; the HF (hydrofluoric acid) in the second hydrofluoric acid etching solution is prepared from 250L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 400L of pure water.

[0069] Example 10 The TOPCon battery of Example 10 was prepared according to the preparation method of Example 1, except that: Step 6.1) in Example 10 is: firstly, the passivated silicon wafer is subjected to annealing treatment at a temperature of 900° C. for 2 min; then, the passivated silicon wafer is placed in an ozone tank with an ozone concentration of 50 ppm, and the surface of the passivated silicon wafer is subjected to a second ozone oxidation treatment for 20 s to form a second ozone oxidation layer with a thickness of 1.8 mm, thereby obtaining a third target silicon wafer; a layer of water film is covered on the back (bottom) of the third target silicon wafer to form a second water film layer; then A PSG cleaning process is performed on the surface of the third target silicon wafer not covered by the second water film to obtain a fourth target silicon wafer; that is, a PSG cleaning process is performed on the front side (top side), front side, rear side, left side and right side of the third target silicon wafer; the conductivity of the second hydrofluoric acid etching solution used in the PSG cleaning process is 160S / m, and the cleaning time is 27s; the temperature of the second hydrofluoric acid etching solution is 20°C; the HF (hydrofluoric acid) in the second hydrofluoric acid etching solution is prepared from 250L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 400L of pure water.

[0070] Embodiment 11 The TOPCon battery of Example 11 was prepared by referring to the preparation method of Example 1, except that: Step 3.1) in Example 11 is: placing the boron-diffused silicon wafer into an ozone tank with an ozone concentration of 80 ppm, performing a first ozone oxidation treatment on the surface of the boron-diffused silicon wafer, the ozone oxidation treatment time is 25 seconds, forming a first ozone oxidation layer, the thickness of the first ozone oxidation layer is 2.8 mm, and obtaining a first target silicon wafer; covering the front side (top side) of the first target silicon wafer with a layer of water film to form a first water film layer; and then performing a first ozone oxidation treatment on the surface of the first target silicon wafer not covered with the first water film. A BSG cleaning process is performed, that is, the back side (bottom), front side, rear side, left side and right side of the first target silicon wafer are subjected to a BSG cleaning process to obtain a second target silicon wafer; the conductivity of the first hydrofluoric acid etching solution used in the BSG cleaning process is 350S / m, and the cleaning time is 27s; the temperature of the first hydrofluoric acid etching solution is 20°C; the HF (hydrofluoric acid) in the first hydrofluoric acid etching solution is prepared from 400L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 250L of pure water.

[0071] Example 12 The TOPCon battery of Example 12 was prepared by referring to the preparation method of Example 1, except that: Step 3.1) in Example 12 is: placing the boron-diffused silicon wafer into an ozone tank with an ozone concentration of 50 ppm, performing a first ozone oxidation treatment on the surface of the boron-diffused silicon wafer, the ozone oxidation treatment time is 20 seconds, forming a first ozone oxidation layer, the thickness of the first ozone oxidation layer is 1.8 mm, and obtaining a first target silicon wafer; covering the front side (top side) of the first target silicon wafer with a layer of water film to form a first water film layer; and then performing a first ozone oxidation treatment on the surface of the first target silicon wafer not covered with the first water film. A BSG cleaning process is performed, that is, the back side (bottom), front side, rear side, left side, and right side of the first target silicon wafer are subjected to a BSG cleaning process to obtain a second target silicon wafer; the conductivity of the first hydrofluoric acid etching solution used in the BSG cleaning process is 300S / m, and the cleaning time is 27s; the temperature of the first hydrofluoric acid etching solution is 20°C; the HF (hydrofluoric acid) in the first hydrofluoric acid etching solution is prepared from 400L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 250L of pure water; Step 6.1) in Example 12 is: firstly, the passivated silicon wafer is subjected to annealing treatment at a temperature of 900° C. for 2 min; then, the passivated silicon wafer is placed in an ozone tank with an ozone concentration of 80 ppm, and the surface of the passivated silicon wafer is subjected to a second ozone oxidation treatment for 25 s to form a second ozone oxidation layer with a thickness of 2.8 mm, thereby obtaining a third target silicon wafer; a layer of water film is covered on the back (bottom) of the third target silicon wafer to form a second water film layer; then A PSG cleaning process is performed on the surface of the third target silicon wafer not covered by the second water film to obtain a fourth target silicon wafer; that is, the PSG cleaning process is performed on the front side (top side), front side, rear side, left side and right side of the third target silicon wafer; the conductivity of the second hydrofluoric acid etching solution used in the PSG cleaning process is 150S / m, and the cleaning time is 27s; the temperature of the second hydrofluoric acid etching solution is 20°C; the HF (hydrofluoric acid) in the second hydrofluoric acid etching solution is prepared from 250L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 400L of pure water.

[0072] Embodiment 13 The TOPCon battery of Example 13 was prepared by referring to the preparation method of Example 1, except that: Step 3.1) in Example 13 is: placing the boron-diffused silicon wafer into an ozone tank with an ozone concentration of 50 ppm, performing a first ozone oxidation treatment on the surface of the boron-diffused silicon wafer, the ozone oxidation treatment time is 20 seconds, forming a first ozone oxidation layer, the thickness of the first ozone oxidation layer is 1.8 mm, and obtaining a first target silicon wafer; covering the front side (top side) of the first target silicon wafer with a layer of water film to form a first water film layer; and then performing a first ozone oxidation treatment on the surface of the first target silicon wafer not covered with the first water film. A BSG cleaning process is performed, that is, the back side (bottom), front side, rear side, left side, and right side of the first target silicon wafer are subjected to a BSG cleaning process to obtain a second target silicon wafer; the conductivity of the first hydrofluoric acid etching solution used in the BSG cleaning process is 480S / m, and the cleaning time is 27s; the temperature of the first hydrofluoric acid etching solution is 20°C; the HF (hydrofluoric acid) in the first hydrofluoric acid etching solution is prepared from 400L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 250L of pure water; Step 6.1) in Example 13 is: firstly, the passivated silicon wafer is subjected to annealing treatment at a temperature of 900° C. for 2 min; then, the passivated silicon wafer is placed in an ozone tank with an ozone concentration of 80 ppm, and the surface of the passivated silicon wafer is subjected to a second ozone oxidation treatment for 25 s to form a second ozone oxidation layer with a thickness of 2.8 mm, thereby obtaining a third target silicon wafer; a layer of water film is covered on the back (bottom) of the third target silicon wafer to form a second water film layer; then A PSG cleaning process is performed on the surface of the third target silicon wafer not covered by the second water film to obtain a fourth target silicon wafer; that is, the PSG cleaning process is performed on the front side (top side), front side, rear side, left side and right side of the third target silicon wafer; the conductivity of the second hydrofluoric acid etching solution used in the PSG cleaning process is 200S / m, and the cleaning time is 27s; the temperature of the second hydrofluoric acid etching solution is 20°C; HF (hydrofluoric acid) in the second hydrofluoric acid etching solution is prepared from 250L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 400L of pure water.

[0073] Embodiment 14 The TOPCon battery of Example 14 was prepared according to the preparation method of Example 1, except that: Step 3.1) in Example 14 is: covering the front side (top side) of the boron-diffused silicon wafer with a layer of water film to form a first water film layer; then performing a BSG cleaning process on the side of the boron-diffused silicon wafer not covered with the first water film, that is, performing a BSG cleaning process on the back side (bottom side), front side, rear side, left side, and right side of the boron-diffused silicon wafer to obtain a second target silicon wafer; the conductivity of the first hydrofluoric acid etching solution used in the BSG cleaning process is 350S / m, and the cleaning time is 27s; the temperature of the first hydrofluoric acid etching solution is 20°C; the HF (hydrofluoric acid) in the first hydrofluoric acid etching solution is prepared from 400L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 250L of pure water.

[0074] Embodiment 15 The TOPCon battery of Example 15 was prepared according to the preparation method of Example 1, except that: Step 6.1) in Example 15 is: first, the passivated silicon wafer is annealed at a temperature of 900° C. for 2 min; then, a layer of water film is covered on the back (bottom) of the passivated silicon wafer to form a second water film layer; then, the surface of the passivated silicon wafer not covered with the second water film is subjected to a PSG cleaning process to obtain a fourth target silicon wafer; that is, the front (top), front side, rear side, left side, and right side of the passivated silicon wafer are subjected to a PSG cleaning process; the conductivity of the second hydrofluoric acid etching solution used in the PSG cleaning process is 160 S / m, and the cleaning time is 27 s; the temperature of the second hydrofluoric acid etching solution is 20° C.; the HF (hydrofluoric acid) in the second hydrofluoric acid etching solution is prepared from 250 L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 400 L of pure water.

[0075] Example 16 The TOPCon battery of Example 16 was prepared by referring to the preparation method of Example 1, except that: Step 6.1) in Example 16 is: covering the back side (bottom side) of the passivated silicon wafer with a layer of water film to form a second water film layer; then performing a PSG cleaning process on the surface of the passivated silicon wafer not covered with the second water film to obtain a fourth target silicon wafer; that is, performing a PSG cleaning process on the front side (top side), front side, rear side, left side and right side of the passivated silicon wafer; the conductivity of the second hydrofluoric acid etching solution used in the PSG cleaning process is 160S / m, and the cleaning time is 27s; the temperature of the second hydrofluoric acid etching solution is 20°C; the HF (hydrofluoric acid) in the second hydrofluoric acid etching solution is prepared from 250L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 400L of pure water.

[0076] Comparative Example 1 The TOPCon battery of Comparative Example 1 was prepared by referring to the preparation method of Example 1, except that: Step 3.1) in Comparative Example 1 is: a layer of water film is covered on the front side (top side) of the boron-diffused silicon wafer to form a first water film layer; then a BSG cleaning process is performed on the surface of the first target silicon wafer not covered with the first water film, that is, a BSG cleaning process is performed on the back side (bottom side), front side, rear side, left side, and right side of the first target silicon wafer to obtain a second target silicon wafer; the conductivity of the first hydrofluoric acid etching solution used in the BSG cleaning process is 350S / m, and the cleaning time is 27s; the temperature of the first hydrofluoric acid etching solution is 20°C; the HF (hydrofluoric acid) in the first hydrofluoric acid etching solution is prepared by 400L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 250L of pure water; Step 6.1) in Comparative Example 1 is: covering the back side (bottom side) of the passivated silicon wafer with a layer of water film to form a second water film layer; then performing a PSG cleaning process on the surface of the passivated silicon wafer not covered with the second water film to obtain a fourth target silicon wafer; that is, performing a PSG cleaning process on the front side (top side), front side, rear side, left side and right side of the passivated silicon wafer; the conductivity of the second hydrofluoric acid etching solution used in the PSG cleaning process is 160S / m, and the cleaning time is 27s; the temperature of the second hydrofluoric acid etching solution is 20°C; the HF (hydrofluoric acid) in the second hydrofluoric acid etching solution is prepared from 250L of HF (hydrofluoric acid) stock solution with a mass concentration of 49% and 400L of pure water.

[0077] The TOPCon cells prepared in the above examples and comparative examples were subjected to photoelectric tests, and the test results are shown in Table 1 below.

[0078] Table 1 (Using Comparative Example 1 as a reference, the edge / side leakage ratio reduction data of Examples 1-16 are obtained.)

[0079] In Table 1 above, the calculation method of the edge / side leakage ratio reduction (%) is: the edge / side leakage ratio of the battery in Comparative Example 1 is X%, if the edge / side leakage ratio of the battery in Example 1 is Y%, then the edge / side leakage ratio reduction (%) of Example 1 = X%-Y%.

[0080] Referring to the detection data of the above-mentioned embodiments 1-16, it can be known that when the silicon wafer that needs to remove BSG and / or PSG is treated with ozone oxidation, an ozone oxidation layer will be formed on the surface of the silicon wafer, and then a layer of water film will be covered on the ozone oxidation layer. The water film has a better coverage effect and can form a better water film protection effect, thereby effectively alleviating the situation where BSG and / or PSG on the edge or side of the silicon wafer is not cleaned up due to the poor water film protection effect, thereby effectively reducing the proportion of leakage at the edge and side of the crystalline silicon solar cell.

[0081] With reference to the detection data of the above-mentioned Example 1 and Examples 3-4, it can be known that optimizing the thickness of the ozone oxidation layer can further enhance the coverage effect of the water film on the ozone oxidation layer, thereby forming a better water film protection effect, thereby effectively alleviating the situation where the BSG and / or PSG on the edge or side of the silicon wafer are not cleaned cleanly due to the poor water film protection effect, thereby effectively reducing the proportion of leakage at the edge and side of the crystalline silicon solar cell.

[0082] With reference to the detection data of the above-mentioned Example 1 and Examples 5-6, it can be known that optimizing the process parameters of the ozone oxidation treatment can improve the morphology of the ozone oxidation layer, further enhance the coverage effect of the water film on the ozone oxidation layer, and form a better water film protection effect, thereby effectively alleviating the situation in which the BSG and / or PSG on the edge or side of the silicon wafer are not cleaned up due to the poor water film protection effect, thereby effectively reducing the proportion of leakage at the edge and side of the crystalline silicon solar cell.

[0083] With reference to the detection data of the above-mentioned Example 1 and Examples 7-9, it can be known that the annealing treatment can effectively improve the crystal defects on the surface of the silicon wafer caused by the BSG cleaning process. After that, the second ozone oxidation treatment is performed to form a second ozone oxidation layer with better morphology, which plays a role in improving the morphology of the second ozone oxidation layer, and can further enhance the coverage effect of the water film on the second ozone oxidation layer, thereby forming a better water film protection effect, thereby effectively alleviating the situation where the BSG and / or PSG on the edge or side of the silicon wafer are not cleaned up due to the poor water film protection effect, thereby effectively reducing the proportion of leakage at the edge and side of the crystalline silicon solar cell.

[0084] With reference to the detection data of the above-mentioned Example 1, Example 12, and Example 13, it can be known that controlling the parameters such as the conductivity and temperature of the hydrofluoric acid etching solution used in the BSG cleaning process and the PSG cleaning process can increase the reaction rate of hydrofluoric acid with the BSG layer and the PSG layer, shorten the reaction time, and be beneficial to the removal effect of BSG and PSG. At the same time, it slows down the rate at which hydrofluoric acid erodes the water film protection surface, improves the water film protection effect, and further reduces the proportion of leakage at the edges and sides of the crystalline silicon solar cell.

[0085] In summary, the present application performs ozone oxidation treatment on silicon wafers that need to remove BSG and / or PSG. An ozone oxidation layer will be formed on the surface of the silicon wafer, and then a layer of water film will be covered on the ozone oxidation layer. The water film has a better coverage effect and can form a better water film protection effect, thereby effectively alleviating the situation where BSG and / or PSG are not cleaned cleanly on the edge or side of the silicon wafer due to poor water film protection, thereby effectively reducing the proportion of leakage at the edge and side of the crystalline silicon solar cell.

[0086] The present application may provide a crystalline silicon solar cell (not shown), comprising a silicon wafer, from which (surface) BSG and / or PSG are removed by the above-described method.

[0087] The embodiment of the present application can provide a photovoltaic system, including the crystalline silicon solar cell in any of the above embodiments. The advantages of the above-mentioned crystalline silicon solar cell are also possessed by the photovoltaic system, which will not be repeated here. The above-mentioned photovoltaic system has a wide range of applications, not only limited to photovoltaic power stations, such as ground power stations, rooftop power stations and water power stations, but also includes various equipment and devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars and solar buildings. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is to say, the photovoltaic system can be used in all fields where solar energy is required for power generation. Taking the photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple photovoltaic components. For example, multiple photovoltaic components may form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter and is converted into the alternating current required by the mains power grid and then connected to the mains network to realize solar power supply.

[0088] It should be noted that the 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. are only for the convenience of describing 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 present application. The orientation words "inside" and "outside" refer to the inside and outside relative to the outline of each component itself. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Therefore, the exemplary term "above..." can include both "above..." and "below..." orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used here are interpreted accordingly.

[0089] It should also be noted that "one embodiment", "another embodiment", "embodiment", etc. mentioned in this application refer to the specific features, structures or characteristics described in conjunction with the embodiment included in at least one embodiment generally described in this application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Further, when describing a specific feature, structure or characteristic in conjunction with any embodiment, it is claimed that the realization of such feature, structure or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0090] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0091] It should also be noted that the above are only preferred embodiments of the present application, and the patent protection scope of the present application is not limited thereto. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for removing BSG and / or PSG from the surface of a silicon wafer, characterized in that: include: Performing ozone oxidation treatment on the surface of the silicon wafer to form an ozone oxidation layer to obtain a target silicon wafer; Covering one surface of the target silicon wafer with a layer of water film to form a water film layer; and then performing a BSG cleaning process or a PSG cleaning process on the surface of the target silicon wafer not covered with the water film layer; Wherein, the water film layer covers the ozone oxidation layer.

2. The method according to claim 1, characterized in that The thickness of the ozone oxidation layer is 1.8-3.2 mm.

3. The method according to claim 1, characterized in that The method of performing ozone oxidation treatment on the surface of the silicon wafer comprises: placing the silicon wafer in an ozone tank with an ozone concentration of 50-100 ppm for ozone oxidation treatment.

4. The method according to claim 3, characterized in that The ozone oxidation treatment time is 20 to 30 seconds.

5. A method for removing BSG and PSG from the surface of a silicon wafer, characterized in that: include: Performing a first ozone oxidation treatment on the surface of the silicon wafer to form a first ozone oxidation layer, thereby obtaining a first target silicon wafer; Covering one surface of the first target silicon wafer with a layer of water film to form a first water film layer; then performing a BSG cleaning process on the surface of the first target silicon wafer not covered with the first water film to obtain a second target silicon wafer; performing a second ozone oxidation treatment on the surface of the second target silicon wafer to form a second ozone oxidation layer, thereby obtaining a third target silicon wafer; Covering one surface of the third target silicon wafer with a layer of water film to form a second water film layer; and then performing a PSG cleaning process on the surface of the third target silicon wafer not covered with the second water film; Wherein, the first water film layer covers the first ozone oxidation layer; and the second water film layer covers the second ozone oxidation layer.

6. The method according to claim 5, characterized in that Before performing a second ozone oxidation treatment on the surface of the second target silicon wafer, the method further includes: performing an annealing treatment on the second target silicon wafer.

7. The method according to claim 6, characterized in that The temperature of the annealing treatment is 900-950°C.

8. The method according to any one of claims 5 to 7, characterized in that: The method satisfies at least one of the following characteristics: (1) The thickness of the first ozone oxidation layer is 1.8-2.2 mm; (2) The thickness of the second ozone oxidation layer is 2.8-3.2 mm; (3) The method of performing a first ozone oxidation treatment on the surface of the silicon wafer comprises: placing the silicon wafer in an ozone tank with an ozone concentration of 50 to 70 ppm for ozone oxidation treatment, and the ozone oxidation treatment time is 20 to 25 seconds; (4) The method of performing a second ozone oxidation treatment on the surface of the second target silicon wafer comprises: placing the second target silicon wafer in an ozone tank with an ozone concentration of 80 to 100 ppm for ozone oxidation treatment, and the ozone oxidation treatment time is 25 to 30 seconds; (5) The conductivity of the first hydrofluoric acid etching solution used in the BSG cleaning process is 350-450 S / m, and the cleaning time is 27-33 s; the temperature T1 of the first hydrofluoric acid etching solution satisfies: 20°C ≤ T1 ≤ 40°C; (6) The conductivity of the second hydrofluoric acid etching solution used in the PSG cleaning process is 160-190 S / m, and the cleaning time is 27-33 s; the temperature T2 of the second hydrofluoric acid etching solution satisfies: 20°C ≤ T2 ≤ 40°C.

9. A crystalline silicon solar cell, characterized in that: The invention comprises a silicon wafer, wherein BSG and / or PSG are removed from the silicon wafer by the method according to any one of claims 1 to 8.

10. A photovoltaic system, characterized in that: Comprising the crystalline silicon solar cell as claimed in claim 9.

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