Method for processing a semiconductor substrate layer and method for manufacturing a solar cell

Abstract

The present application provides a method for treating a semiconductor substrate layer and a method for manufacturing a solar cell. The method for treating a semiconductor substrate layer includes the steps of providing a single crystal silicon wafer, spraying a diffusion liquid on a surface of the single crystal silicon wafer, and annealing the single crystal silicon wafer, and further includes a step of performing a surface oxidation treatment on the single crystal silicon wafer before spraying the diffusion liquid on the surface of the single crystal silicon wafer, the surface oxidation treatment being used to increase the lyophilicity of the surface of the single crystal silicon wafer with respect to the diffusion liquid and to increase the uniformity of the annealing treatment of the single crystal silicon wafer. The method for treating a semiconductor substrate layer according to the present application can solve the problem of non-uniform spreading of the diffusion liquid, and the characteristics of the semiconductor substrate layer are greatly improved.

Description

Technical Field

[0001] This application claims the priority of a Chinese patent application with an application number of 202210189426.0 and an invention title of "Method for Processing a Semiconductor Substrate Layer and Method for Manufacturing a Solar Cell", which was filed with the China National Intellectual Property Administration on February 28, 2022, and the entire content thereof is incorporated herein by reference.

[0002] This application relates to the field of solar cell manufacturing, and specifically, to a method for processing a semiconductor substrate layer and a method for manufacturing a solar cell.

Background Art

[0003] Solar cells have advantages such as being clean, pollution-free, renewable, and having stable operating performance. Depending on the structure, manufacturing process, and materials used in solar cells, solar cells can be classified into different types, including silicon-based solar cells, multi-element compound thin-film solar cells, polymer multi-layer modified electrode solar cells, organic solar cells, etc. Among them, silicon-based solar cells such as heterojunction solar cells are the most mature. Taking a heterojunction solar cell as an example, a semiconductor layer, a transparent conductive layer, and a metal electrode are fabricated on one or both sides of an N-type substrate to form a cell. Subsequently, a plurality of cells are interconnected and packaged to form a module, and the module generates electricity, and its power is fed back to the power grid through an inverter.

[0004] The N-type substrate is usually a single-crystalline silicon wafer obtained by cutting a single-crystalline silicon rod. In the process of pulling up a single-crystalline silicon rod, due to the very small segregation coefficient of metal impurities, there is a difference in metal content between the front end and the rear end of a single silicon rod. In particular, in the prior art, a method of continuously supplying and pulling up is often used, and a plurality of single-crystalline silicon rods can be continuously pulled up. Within a single batch, the metal impurities in the subsequently pulled-up single-crystalline rod are more than those in the previously pulled-up single-crystalline rod. When manufacturing a solar cell with a single-crystalline silicon wafer, due to the presence of metal impurities, the metal impurities recombine with minority carriers, affecting the photoelectric conversion efficiency, further affecting the conversion efficiency of high-efficiency cells, and leading to a reduction in the service life.

[0005] Gettering is an important method for improving the crystal quality of single-crystal silicon wafers. By gettingtering, the content of metallic impurities in single-crystal silicon wafers can be reduced, leading to greater consistency in the quality of single-crystal silicon wafers, and thereby more concentrated conversion efficiency in high-efficiency batteries. Currently, one of the main methods is phosphate chain spray gettering, in which phosphoric acid is sprayed onto the surface of a single-crystal silicon wafer as a diffusion solution, and after the phosphoric acid is spread naturally, a doping layer is formed by diffusion annealing. In this process, metallic impurities in the single-crystal silicon wafer are deposited into the doping layer, and finally, the doping layer is removed to achieve the objective of impurity removal. However, when a substrate single-crystal silicon wafer is treated with phosphate chain spray gettering, the phosphoric acid often spreads unevenly on the surface of the single-crystal silicon wafer, which may result in unfavorable service life and photoelectric conversion efficiency of the final solar cell. Therefore, a solution is needed to solve the problem of uneven phosphoric acid spread. [Overview of the project] [Problems that the invention aims to solve]

[0006] This application provides a method for processing a semiconductor substrate layer and a method for manufacturing a solar cell, in order to solve the problem of uneven diffusion of the diffusion liquid. [Means for solving the problem]

[0007] The present invention provides a method for processing a semiconductor substrate layer, comprising the steps of: providing a single-crystal silicon wafer; spraying a diffusion solution onto the surface of the single-crystal silicon wafer; and annealing the single-crystal silicon wafer, further comprising the step of performing a surface oxidation treatment on the single-crystal silicon wafer before spraying the diffusion solution onto the surface of the single-crystal silicon wafer, wherein the surface oxidation treatment is used to increase the hydrophilicity of the surface of the single-crystal silicon wafer to the diffusion solution and to improve the uniformity of the annealing treatment of the single-crystal silicon wafer.

[0008] Optionally, the step of performing surface oxidation treatment includes the step of spraying an oxygen-containing gas onto the surface of a single-crystal silicon wafer.

[0009] Selectable options include oxygen-containing gases containing ozone.

[0010] The oxygen-containing gas concentration can be selected from 50 ppm to 300 ppm.

[0011] The selectable injection velocity of the oxygen-containing gas is 0.5 slm to 5 slm.

[0012] The oxygen-containing gas injection time can be selected from 5 to 30 seconds.

[0013] Optionally, during the surface oxidation treatment step, an oxygen-containing gas is sprayed perpendicularly toward the surface of the single-crystal silicon wafer.

[0014] Selectively, the surface oxidation treatment forms an oxide layer on the surface of the single-crystal silicon wafer, and the method for processing the semiconductor substrate layer further includes the following: performing a diffusion annealing treatment on the surface of the single-crystal silicon wafer so that the diffusion ions in the diffusion solution diffuse through the oxide layer to a portion of the thickness of the single-crystal silicon wafer, thereby forming a doping layer covering the oxide layer to a portion of the thickness of the single-crystal silicon wafer, and the diffusion annealing treatment is suitable for moving impurities in the single-crystal silicon wafer to the doping layer.

[0015] Selectively, the diffusion annealing process is chain diffusion annealing.

[0016] Selectively, an oxide layer is formed on the surface of a single-crystal silicon wafer by surface oxidation treatment, with an oxide layer thickness of 0.5 nm to 20 nm.

[0017] Selectively, the material for the single-crystal silicon wafer contains single-crystal silicon, and the material for the oxide layer contains silicon dioxide.

[0018] Optionally, the step of performing diffusion annealing treatment on the surface of the single-crystal silicon wafer includes a heating-up process, a heat-preserving process, and a cooling process that are carried out in sequence. The heat-preserving process is suitable for diffusing the diffusion ions into a part of the thickness of the single-crystal silicon wafer, and the cooling process is suitable for moving the impurities in the single-crystal silicon wafer to the doping layer.

[0019] Optionally, the temperature of the heat-preserving process is 800 °C to 900 °C.

[0020] Optionally, the thickness of the doping layer is 0.15 μm to 0.3 μm.

[0021] Optionally, the diffusion solution contains a phosphoric acid solution.

[0022] Optionally, the concentration of the phosphoric acid solution is 2% by mass to 12% by mass.

[0023] Optionally, before performing surface oxidation treatment on the single-crystal silicon wafer, the step of removing the damaged layer on the surface of the single-crystal silicon wafer, the step of dehydrating the surface of the single-crystal silicon wafer with a hydrophobic solution after removing the damaged layer on the surface of the single-crystal silicon wafer, and the step of drying the single-crystal silicon wafer after the dehydration treatment are further included.

[0024] Optionally, the etching solution used to remove the damaged layer on the surface of the single-crystal silicon wafer is an aqueous NaOH solution, an aqueous KOH solution, or a mixed solution of HF and HNO3.

[0025] Optionally, the hydrophobic solution contains an aqueous HF solution.

[0026] Optionally, the concentration of the aqueous NaOH solution is 2% by mass to 15% by mass.

[0027] Optionally, the concentration of the aqueous KOH solution is 2% by mass to 15% by mass.

[0028] Optionally, the mixed solution of HF and HNO3 is prepared at a volume ratio of 1:3 to 1:9 with HF having a concentration of 45% to 50% by mass and HNO3 having a concentration of 60% to 70% by mass.

[0029] Optionally, after the diffusion annealing treatment, the method further includes a step of removing the oxide layer and, after removing the oxide layer, a step of removing the doping layer.

[0030] Optionally, the etching solution for removing the oxide layer is an HCl aqueous solution, and the concentration of HCl in the HCl aqueous solution is 4% to 5% by mass.

[0031] Optionally, the etching solution used for removing the doping layer is an NaOH aqueous solution or a KOH aqueous solution. Optionally, a mixed solution of HF and HNO3 is used for both removing the oxide layer and removing the doping layer.

[0032] Optionally, the concentration of the NaOH aqueous solution is 2% to 15% by mass. Optionally, the concentration of the KOH aqueous solution is 2% to 15% by mass. Optionally, the mixed solution of HF and HNO3 is prepared at a volume ratio of 1:3 to 1:9 with HF having a concentration of 45% to 50% by mass and HNO3 having a concentration of 60% to 70% by mass.

[0033] Optionally, after removing the doping layer, the method further includes a step of washing the single-crystalline silicon wafer with a neutralization washing solution.

[0034] Optionally, the neutralization washing solution is a mixed solution of HF and HCl.

[0035] The present application further provides a method for manufacturing a solar cell including the method for treating a semiconductor substrate layer according to the present application.

[0036] Selectively, the method for manufacturing the solar cell further includes the steps of: processing the semiconductor substrate layer and then performing a texture treatment on the semiconductor substrate layer; forming a first intrinsic semiconductor layer on one side of the semiconductor substrate layer and a second intrinsic semiconductor layer on the other side of the semiconductor substrate layer after the texture treatment; forming a first doping semiconductor layer on the side of the first intrinsic semiconductor layer opposite to the semiconductor substrate layer and forming a second doping semiconductor layer on the side of the second intrinsic semiconductor layer opposite to the semiconductor substrate layer; forming a first transparent conductive film on the side of the first doping semiconductor layer opposite to the semiconductor substrate layer and forming a second transparent conductive film on the side of the second doping semiconductor layer opposite to the semiconductor substrate layer; forming a first grid electrode on the side of the first transparent conductive film opposite to the semiconductor substrate layer and forming a second grid electrode on the side of the second transparent conductive film opposite to the semiconductor substrate layer. [Effects of the Invention]

[0037] The beneficial effects of this application are as follows:

[0038] In this embodiment, the semiconductor substrate layer processing method involves performing a surface oxidation treatment on the single-crystal silicon wafer before spraying the diffusion solution. This surface oxidation treatment pre-forms an oxide layer on the surface of the single-crystal silicon wafer. Because the oxide layer on the surface of the single-crystal silicon wafer has better hydrophilicity with respect to the diffusion solution, the diffusion solution spreads more effectively when sprayed, and the diffusion speed is increased. As a result, the diffusion solution spreads more uniformly across the surface of the single-crystal silicon wafer. Furthermore, by performing a diffusion annealing treatment on the surface of the single-crystal silicon wafer, the diffusing ions in the diffusion solution diffuse to a portion of the thickness of the single-crystal silicon wafer, forming a doping layer in that portion of the single-crystal silicon wafer. The diffusion annealing treatment is suitable for moving impurities within the single-crystal silicon wafer to the doping layer. Because the diffusion solution spreads more uniformly across the surface of the single-crystal silicon wafer, the distribution of diffusing ions within the doping layer becomes more uniform, the gettering effect of the doping layer becomes more consistent across different regions, and the properties of the semiconductor substrate layer are significantly improved.

[0039] To more clearly describe specific embodiments of the present application or technical solutions in the prior art, the following briefly describes the drawings that are necessary for describing specific embodiments or the prior art. However, the drawings in the following description represent only some embodiments of the present application, and it is clear that those skilled in the art can obtain other drawings based on these without expending any creative effort. [Brief explanation of the drawing]

[0040] [Figure 1] This is a schematic flowchart of the semiconductor substrate layer processing method in one embodiment of the present invention. [Figure 2] This is a detailed schematic flowchart of the semiconductor substrate layer processing method in one embodiment of the present invention. [Figure 3] This is a schematic diagram of the semiconductor substrate layer processing process in one embodiment of the present invention. [Figure 4] This is a schematic diagram of the semiconductor substrate layer processing process in one embodiment of the present invention. [Figure 5] This is a schematic diagram of the semiconductor substrate layer processing process in one embodiment of the present invention. [Figure 6] This is a schematic diagram of the semiconductor substrate layer processing process in one embodiment of the present invention. [Figure 7] This is a schematic diagram of the semiconductor substrate layer processing process in one embodiment of the present invention. [Figure 8]This is a schematic diagram of the semiconductor substrate layer processing process in one embodiment of the present invention. [Figure 9] This is a schematic diagram of the semiconductor substrate layer processing process in one embodiment of the present invention. [Modes for carrying out the invention]

[0041] As described in the background art, after processing a single-crystal silicon wafer substrate using the chain phosphoric acid gettering method, the final photoelectric conversion efficiency and the lifespan of the solar cell may not be ideal. The inventors have investigated and found that the specific reason is that in the chain phosphoric acid gettering process, the phosphoric acid used as a diffusion solution has poor spreading properties and a slow spreading rate. As a result, the phosphoric acid tends to be unevenly distributed on the surface of the single-crystal silicon wafer, and while gettering may be completed locally and corrosion may occur, gettering may not be completed in other areas.

[0042] To solve the problem of the non-uniform spread of the diffusion liquid described above, the present invention provides a method for processing a semiconductor substrate layer, comprising the steps of: providing a single-crystal silicon wafer; spraying a diffusion liquid onto the surface of the single-crystal silicon wafer; and further comprising the step of performing a surface oxidation treatment on the single-crystal silicon wafer before spraying the diffusion liquid onto the surface of the single-crystal silicon wafer, wherein the surface oxidation treatment is used to increase the hydrophilicity of the single-crystal silicon wafer to the diffusion liquid.

[0043] The technical solutions of the present application will be described clearly and completely below with reference to the drawings, but it is clear that the embodiments described are only some, not all, embodiments of the present application. All other embodiments obtained by a person skilled in the art without creative work based on the embodiments of the present application are within the scope of protection of the present application.

[0044] Furthermore, in the description of this application, the directions or positional relationships indicated by terms such as "center," "up," "down," "left," "right," "vertical," "horizontal," "inside," and "outside" are based on the directions or positional relationships shown in the drawings, and are merely for the purpose of facilitating and simplifying the description of this application. They do not indicate or imply that the device or element must necessarily have a specific direction, or be composed of and operate in a specific direction, and therefore should not be understood as limiting this application. In addition, the terms "first," "second," and "third" are used solely for explanatory purposes and should not be understood as indicating or implying relative importance.

[0045] In this description, unless otherwise explicitly stated or limited, the terms “attach,” “connect,” and “connect” should be understood in a broad sense, and may include, for example, a fixed connection, a detachable connection, or an integral connection; a mechanical connection, an electrical connection; a direct connection, an indirect connection via an intermediate medium, or internal communication between two components. The specific meaning of these terms in this specification will be understood by those skilled in the art depending on the context.

[0046] Furthermore, the technical features of each embodiment of the present application described below may be combined with each other, as long as they do not contradict each other.

[0047] Example 1 This embodiment provides a method for processing a semiconductor substrate layer, referring to Figure 1. Step S1 provides a single-crystal silicon wafer, Step S2 involves performing a surface oxidation treatment on a single-crystal silicon wafer, Step S3 involves spraying a diffusion solution onto the surface of a single-crystal silicon wafer, The process includes step S4, which involves performing a diffusion annealing treatment on the surface of a single-crystal silicon wafer.

[0048] In this application, the surface oxidation treatment is used to increase the hydrophilicity of the single-crystal silicon wafer to the diffusion solution. The diffusion solution is used to form a doping layer in the diffusion annealing step and to remove metallic impurities from within the single-crystal silicon wafer.

[0049] In this embodiment, the semiconductor substrate layer processing method involves performing a surface oxidation treatment on the single-crystal silicon wafer before spraying the diffusion solution. The surface oxidation treatment allows for the pre-formation of an oxide layer on the surface of the single-crystal silicon wafer. Because the oxide layer on the surface of the single-crystal silicon wafer has better hydrophilicity with respect to the diffusion solution, the diffusion solution spreads more effectively when sprayed, and the diffusion speed is increased. As a result, the diffusion solution spreads more uniformly on the surface of the single-crystal silicon wafer, improving the uniformity of the annealing treatment of the single-crystal silicon wafer and significantly improving the properties of the semiconductor substrate layer.

[0050] In this embodiment, referring to Figure 2, before performing the surface oxidation treatment on the single-crystal silicon wafer, The process further includes step A1 of removing a damaged layer from the surface of the single-crystal silicon wafer, step A2 of dehydrating the surface of the single-crystal silicon wafer with a hydrophobic solution after removing the damaged layer, and step A3 of drying the single-crystal silicon wafer after the dehydration process.

[0051] In this embodiment, referring to Figure 2, the process further includes step S5 of removing the doping layer after the diffusion annealing treatment.

[0052] The following will provide a detailed explanation with reference to Figures 3 through 9.

[0053] Referring to Figure 3, a single-crystal silicon wafer 100 is provided.

[0054] The material of the single-crystal silicon wafer 100 includes single-crystal silicon. In other embodiments, the material of the single-crystal silicon wafer is another semiconductor material such as germanium or silicon-germanium. The material of the semiconductor substrate layer may also be another semiconductor material.

[0055] In this embodiment, the conductivity type of the single-crystal silicon wafer 100 is N-type, and the conductivity type of the semiconductor substrate layer formed thereafter is also N-type, and the semiconductor substrate layer is used in a solar cell. In other embodiments, the conductivity type of the single-crystal silicon wafer is P-type.

[0056] In this embodiment, the surface of the single-crystal silicon wafer 100 has a damage layer 110. In one specific embodiment, the damage layer 110 is present on both the front and back surfaces of the single-crystal silicon wafer 100. The damage layer 110 is generated during the process of cutting the single-crystal raw material to form the single-crystal silicon wafer 100.

[0057] Referring to Figure 4, the damaged layer 110 (Figure 3) on the surface of the single-crystal silicon wafer 100 is removed.

[0058] In this embodiment, the process for removing the damaged layer 110 includes a wet etching process, and in one specific embodiment, the etching solution used to remove the damaged layer 110 on the surface of the single-crystal silicon wafer 100 is an aqueous NaOH solution, an aqueous KOH solution, or a mixed solution of HF and HNO3. When the etching solution used to remove the damaged layer on the surface of the single-crystal silicon wafer is an aqueous NaOH solution, the concentration of the aqueous NaOH solution is 2% to 15% by mass; when the etching solution used to remove the damaged layer on the surface of the single-crystal silicon wafer is an aqueous KOH solution, the concentration of the aqueous KOH solution is 2% to 15% by mass; and when the etching solution used to remove the damaged layer on the surface of the single-crystal silicon wafer is a mixed solution of HF and HNO3, the mixed solution of HF and HNO3 is prepared by mixing HF with a concentration of 45% to 50% by mass and HNO3 with a concentration of 60% to 70% by mass in a volume ratio of 1:3 to 1:9.

[0059] Referring to Figure 5, after removing the damaged layer 110 from the surface of the single-crystal silicon wafer 100, the surface of the single-crystal silicon wafer is dehydrated with a hydrophobic solution.

[0060] The hydrophobic solution includes an aqueous solution of HF.

[0061] In some other embodiments, if the erosive used to remove the damaged layer 110 is a NaOH solution or a KOH solution, the dehydration process further includes a step of removing the remaining erosive with a neutralizing solution. The neutralizing solution is a mixed solution of HF and HCl.

[0062] Referring to Figure 6, after the dehydration treatment, the single-crystal silicon wafer 100 is dried.

[0063] Referring to Figure 7, a surface oxidation treatment is performed on the single-crystal silicon wafer 100. This surface oxidation treatment forms an oxide layer 120 on the surface of the single-crystal silicon wafer 100. The surface oxidation treatment improves the uniformity of the diffusion liquid that spreads on the surface of the initial semiconductor layer 100 when the diffusion liquid is subsequently sprayed onto the surface of the single-crystal silicon wafer 100.

[0064] In one embodiment, the thickness of the oxide layer 120 is 0.5 nm to 20 nm, and may be, for example, 0.5 nm, 1 nm, or 2 nm.

[0065] Because the oxide layer 120 itself is very thin, it does not affect the diffusion of ions in the diffusion solution through the oxide layer 120 during the subsequent diffusion annealing step.

[0066] When the material of the single-crystal silicon wafer is single-crystal silicon, the material of the oxide layer 120 is silicon dioxide.

[0067] The step of performing surface oxidation treatment includes the step of spraying an oxygen-containing gas onto the surface of the single-crystal silicon wafer 100.

[0068] Specifically, the oxygen-containing gas may be, for example, ozone. Ozone has relatively good oxidizing ability.

[0069] In one embodiment, the concentration of the oxygen-containing gas is 50 ppm to 300 ppm, for example, 50 ppm, 100 ppm, 150 ppm, 200 ppm, 250 ppm, or 300 ppm. If the concentration of the oxygen-containing gas is too low, the oxidation rate will be slow and the process efficiency will decrease, while if the concentration of the oxygen-containing gas is too high, the oxidation rate will be too fast and it will be difficult to control it relatively well during oxidation.

[0070] In one embodiment, the injection rate of the oxygen-containing gas is 0.5 slm to 5 slm (standard liters per minute), for example, 0.5 slm, 1 slm, 2 slm, 4 slm, or 5 slm. If the injection rate of the oxygen-containing gas is too slow, the oxidation rate will be slow and the process efficiency will decrease. If the injection rate of the oxygen-containing gas is too fast, the oxidation rate will be too fast, making it difficult to control the oxidation process relatively well, and furthermore, the utilization of the oxygen-containing gas will be insufficient and wasteful.

[0071] In one embodiment, the injection time of the oxygen-containing gas is 5 to 30 seconds, for example, 5s, 10s, 15s, 20s, 25s, or 30s. If the injection time of the oxygen-containing gas is too short, oxidation will be insufficient, the thickness of the oxide layer 120 will be too thin, the uniformity of the oxide layer 120 will be poor, and the degree of improvement in the uniformity of the diffusion liquid spreading on the surface of the single-crystal silicon wafer will be low. If the injection time of the oxygen-containing gas is too long, the oxide layer 120 will be too thick, which is unfavorable for the diffusion of diffusion ions in the diffusion liquid.

[0072] The oxygen-containing gas is preferably injected in a direction perpendicular to the single-crystal silicon wafer 100.

[0073] In some embodiments, an oxygen-containing gas is injected onto both opposing sides of a single-crystal silicon wafer 100 to form an oxide layer 120 on both opposing sides of the single-crystal silicon wafer 100.

[0074] Referring to Figure 8, a diffusion solution is sprayed onto the surface of a single-crystal silicon wafer 100, and then a diffusion annealing treatment is performed on the surface of the single-crystal silicon wafer 100. The diffusion ions in the diffusion solution diffuse through the oxide layer 120 to a portion of the thickness of the single-crystal silicon wafer 100, forming a doping layer 130 that covers the oxide layer 120 to a portion of the thickness of the single-crystal silicon wafer 100. The diffusion annealing treatment is suitable for moving impurities in the single-crystal silicon wafer 100 to the doping layer 130.

[0075] Because the solid solubility of the doping layer 130 for metal impurities is higher than that of the initial semiconductor layer, the metal impurities gradually move from the portion of the initial semiconductor layer where the doping layer 130 is not formed to the doping layer 130. In this embodiment, after the diffusion annealing treatment, the oxide layer 120 is also doped with diffusion ions, and if the material of the oxide layer 120 is silicon dioxide and the diffusion ions are phosphorus ions, the oxide layer 120 is formed on the oxide layer 120' that has been doped with diffusion ions after the diffusion annealing treatment, and the oxide layer 120' is phosphate glass (PSG).

[0076] In this embodiment, the step of spraying a diffusion solution onto the surface of a single-crystal silicon wafer specifically involves spraying phosphoric acid onto the surface of the initial semiconductor layer and allowing the phosphoric acid to spread naturally across the surface of the initial semiconductor layer. The concentration of the phosphoric acid solution is 2% to 12% by mass.

[0077] In some embodiments, a diffusion solution is sprayed onto opposing sides of a single-crystal silicon wafer 100 to form doping layers 130 on both opposing sides of the single-crystal silicon wafer 100.

[0078] In this embodiment, the diffusion annealing process includes a heating process, a heat retention process, and a cooling process, the heat retention process being suitable for diffusing the diffusion ions to a portion of the thickness of the single-crystal silicon wafer, and the cooling process being suitable for moving impurities within the single-crystal silicon wafer to the doping layer. In this embodiment, the diffusion annealing process is a chain diffusion annealing process performed in a chain diffusion annealing furnace.

[0079] The heating process takes 50 to 100 seconds, for example, 50, 60, 70, 80, 90, and 100 seconds. The heating process raises the temperature from room temperature to 800°C to 900°C, for example, 800°C, 850°C, and 900°C. The temperature is maintained at 800°C to 900°C during the heat retention process. The cooling process takes 50 to 100 seconds, for example, 50, 60, 70, 80, 90, and 100 seconds. The temperature during the cooling process is 300°C to 500°C lower than the temperature during the heat retention process.

[0080] In this embodiment, the material of the initial semiconductor layer 100 is single-crystal silicon, and the doping layer 130 is a silicon layer doped with phosphorus. The thickness of the doping layer 130 is 0.15 μm to 0.3 μm, for example, 0.15 μm, 0.2 μm, 0.25 μm, and 0.3 μm.

[0081] Because the diffusion solution spreads more uniformly across the surface of the single-crystal silicon wafer, the distribution of diffusing ions within the doping layer becomes more uniform, and the gettering effect of the doping layer becomes more consistent across different regions.

[0082] Referring to Figure 9, the oxide layer 120' is removed, and after the oxide layer 120' is removed, the doping layer 130 is removed to form the semiconductor substrate layer 200.

[0083] In this embodiment, the etching solution for removing the oxide layer 120' is an aqueous HCl solution, and the concentration of the aqueous HCl solution is 4% to 5% by mass, for example, 4% or 5%. In this embodiment, the process for removing the doping layer 130 includes a wet etching process. In one specific embodiment, the etching solution used to remove the doping layer 130 is an aqueous NaOH solution or an aqueous KOH solution. When the etching solution used to remove the doping layer 130 is an aqueous NaOH solution, the concentration of the aqueous NaOH solution is 2% to 15% by mass, and when the etching solution used to remove the doping layer 130 is an aqueous KOH solution, the concentration of the aqueous KOH solution is 2% to 15% by mass.

[0084] In other embodiments, a mixed solution of HF and HNO3 is used for both the removal of the oxide layer 120' and the doping layer 130. When the corrosive solution used to remove the oxide layer 120 and the doping layer 130 is a mixed solution of HF and HNO3, the mixed solution of HF and HNO3 is prepared by mixing HF at a concentration of 45% to 50% by mass and HNO3 at a concentration of 60% to 70% by mass in a volume ratio of 1:3 to 1:9.

[0085] Because the gettering effect of the doping layer is more consistent across different regions, the removal of impurities within the semiconductor substrate layer after the doping layer is removed is more effective.

[0086] In some other embodiments, the process further includes the step of cleaning the single-crystal silicon wafer with a neutralizing cleaning solution after removing the doping layer. In these cases, the neutralizing cleaning solution is a mixed solution of HF and HCl.

[0087] Finally, drying is performed to complete the processing of the semiconductor substrate layer 200.

[0088] Using an unoxidized single-crystal silicon wafer as a comparison group, the relative test results of the semiconductor substrate layers obtained by the processing method of this embodiment are as follows (the unoxidized single-crystal silicon wafer is used as the reference value). [Table 1]

[0089] As can be seen, after oxidation treatment, both the average minority carrier lifetime and the minimum minority carrier lifetime of the semiconductor substrate layer are significantly improved, and the maximum minority carrier lifetime and the efficiency of the manufactured batteries are also improved to some extent.

[0090] Example 2 This embodiment provides a method for manufacturing a solar cell, including a method for processing a semiconductor substrate layer according to Example 1.

[0091] In this embodiment, the method for manufacturing a solar cell further includes the steps of: processing the semiconductor substrate layer and then performing a texture treatment on the semiconductor substrate layer; forming a first intrinsic semiconductor layer on one side of the semiconductor substrate layer and forming a second intrinsic semiconductor layer on the other side of the semiconductor substrate layer after the texture treatment; forming a first doping semiconductor layer on the side of the first intrinsic semiconductor layer opposite to the semiconductor substrate layer and forming a second doping semiconductor layer on the side of the second intrinsic semiconductor layer opposite to the semiconductor substrate layer; forming a first transparent conductive film on the side of the first doping semiconductor layer opposite to the semiconductor substrate layer and forming a second transparent conductive film on the side of the second doping semiconductor layer opposite to the semiconductor substrate layer; forming a first grid electrode on the side of the first transparent conductive film opposite to the semiconductor substrate layer and forming a second grid electrode on the side of the second transparent conductive film opposite to the semiconductor substrate layer.

[0092] Because the impurity removal effect of the semiconductor substrate layer is higher, the photoelectric conversion efficiency and service life of the solar cell ultimately formed by the solar cell manufacturing method in this embodiment are higher.

[0093] Clearly, the embodiments described above are merely illustrative examples for clarity and do not limit the embodiments. Those skilled in the art can make various other forms of changes or modifications based on the above description. It is not necessary, nor is it possible, to cover all embodiments here. And any obvious changes or modifications derived in this manner are also within the scope of protection of the present invention. [Explanation of symbols]

[0094] 100 single-crystal silicon wafers 110 damage layer 120 Oxide layer 120' Oxide layer 130 Doping Layer 200 Semiconductor substrate layer

Claims

1. A method for processing a semiconductor substrate layer, comprising the steps of: providing a single-crystal silicon wafer; spraying a diffusion liquid onto the surface of the single-crystal silicon wafer; and annealing the single-crystal silicon wafer, The step of performing a surface oxidation treatment on the single-crystal silicon wafer before spraying a diffusion solution onto the surface of the single-crystal silicon wafer, wherein the diffusion solution comprises a phosphoric acid solution, and the surface oxidation treatment forms an oxide layer on the surface of the single-crystal silicon wafer, and the surface oxidation treatment is used to increase the hydrophilicity of the surface of the single-crystal silicon wafer to the diffusion solution and to improve the uniformity of the annealing treatment of the single-crystal silicon wafer. In the step of performing a diffusion annealing treatment on the surface of the single-crystal silicon wafer, the diffusion ions in the diffusion solution diffuse through the oxide layer to a portion of the thickness of the single-crystal silicon wafer, forming a doping layer that covers the oxide layer to a portion of the thickness of the single-crystal silicon wafer, and the diffusion annealing treatment moves impurities in the single-crystal silicon wafer to the doping layer. A method for processing a semiconductor substrate layer, characterized in that, after the diffusion annealing treatment, the method further comprises the steps of removing the oxide layer and, after removing the oxide layer, removing the doping layer.

2. The step of performing the surface oxidation treatment includes the step of spraying an oxygen-containing gas onto the surface of the single-crystal silicon wafer. The method for processing a semiconductor substrate layer according to claim 1, characterized in that the oxygen-containing gas includes ozone.

3. The concentration of the oxygen-containing gas is 50 ppm to 300 ppm, The injection velocity of the oxygen-containing gas is 0.5 slm to 5 slm. The method for processing a semiconductor substrate layer according to claim 2, characterized in that the injection time of the oxygen-containing gas is 5 seconds to 30 seconds.

4. The method for processing a semiconductor substrate layer according to claim 1, characterized in that the diffusion annealing treatment is a chain diffusion annealing treatment.

5. The thickness of the oxide layer is 0.5 nm to 20 nm. The method for processing a semiconductor substrate layer according to claim 1, characterized in that the material of the single-crystal silicon wafer contains single-crystal silicon, and the material of the oxide layer contains silicon oxide.

6. The method for processing a semiconductor substrate layer according to claim 1, wherein the step of performing a diffusion annealing treatment on the surface of the single crystal silicon wafer includes a heating step, a heat retention step, and a cooling step performed in sequence, wherein the heat retention step diffuses the diffusion ions to a portion of the thickness of the single crystal silicon wafer, and the cooling step moves impurities in the single crystal silicon wafer to the doping layer.

7. The method for processing a semiconductor substrate layer according to claim 6, characterized in that the temperature of the heat retention process is 800°C to 900°C.

8. Before performing surface oxidation treatment on the single-crystal silicon wafer, The steps include removing the damaged layer from the surface of the single-crystal silicon wafer, The steps include removing the damaged layer from the surface of the single-crystal silicon wafer, and then dehydrating the surface of the single-crystal silicon wafer with a hydrophobic solution, The process further includes the step of drying the single-crystal silicon wafer after the dehydration treatment, The etching solution used to remove the damaged layer on the surface of the single-crystal silicon wafer is an aqueous solution of NaOH, an aqueous solution of KOH, or a mixture of HF and HNO ３ A method for processing a semiconductor substrate layer according to any one of claims 1 to 7, characterized in that it is a mixed solution of the following.

9. The method for processing a semiconductor substrate layer according to claim 1, further comprising the step of cleaning the single-crystal silicon wafer with a neutralizing cleaning solution after removing the doping layer.

10. A method for manufacturing a solar cell, characterized by including a method for processing a semiconductor substrate layer according to any one of claims 1 to 5.

11. After processing the semiconductor substrate layer, The steps include: performing a textured process on the semiconductor substrate layer; The steps include: forming a first intrinsic semiconductor layer on one side of the semiconductor substrate layer after the texture processing, and forming a second intrinsic semiconductor layer on the other side of the semiconductor substrate layer; The steps include forming a first doping semiconductor layer on the side of the first intrinsic semiconductor layer opposite to the semiconductor substrate layer, and forming a second doping semiconductor layer on the side of the second intrinsic semiconductor layer opposite to the semiconductor substrate layer, The steps include forming a first transparent conductive film on the side of the first doped semiconductor layer opposite to the semiconductor substrate layer, and forming a second transparent conductive film on the side of the second doped semiconductor layer opposite to the semiconductor substrate layer, The method for manufacturing a solar cell according to claim 10, further comprising the steps of forming a first grid electrode on the side of the first transparent conductive film opposite to the semiconductor substrate layer, and forming a second grid electrode on the side of the second transparent conductive film opposite to the semiconductor substrate layer.

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