A method for reworking single-crystal silicon solar cell with abnormal LPCVD oxidation process
By using sodium hydroxide and HF solution to treat the polycrystalline silicon layer and oxide layer in the rework of single crystal silicon solar cell, the existing rework methods are solved, with complex processes, high costs and large damage, and the effects of simplifying the process, reducing costs and improving efficiency are achieved.
Patent Information
- Application Number
- CN202411942103.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-26
- Publication Date
- 2025-04-04
AI Technical Summary
The existing monocrystalline silicon solar cell reworking methods are complicated and require re-made velvet, which is costly and has great damage to the silicon wafer.
By isolating the monocrystalline silicon solar cell with abnormal LPCVD oxidation process, the polycrystalline silicon layer is treated with sodium hydroxide solution, and then the oxide layer is treated with HF solution to obtain a hydrophobic monocrystalline silicon solar cell, and then returning to the LPCVD oxidation process for processing.
The rework process is simplified, the cost of medicine liquid is reduced, the damage to silicon wafers is reduced, and the product yield and efficiency is improved.
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of solar cell production and processing, and in particular to a method for reworking a single-crystal silicon solar cell sheet with abnormal LPCVD oxidation process. Background Art
[0002] As conventional energy becomes increasingly scarce and environmental issues become increasingly prominent, new energy sources with environmental protection and renewable characteristics are gaining more and more attention from all countries. New energy, also known as unconventional energy, refers to various forms of energy other than traditional energy. Energy sources that are currently being developed or actively studied and are yet to be promoted, such as solar energy, geothermal energy, wind energy, ocean energy, biomass energy, and nuclear fusion energy. Among them, solar energy is increasingly attracting people's attention because of its characteristics of being pollution-free, clean and safe, universal, renewable, and sustainable.
[0003] Solar cells are devices that use the photoelectric effect or photochemical effect to convert light energy into electrical energy. They are also called solar chips or photovoltaic cells. Based on the materials and technologies used, solar cells are mainly divided into two categories: single-crystal silicon solar cells and thin-film solar cells. Currently, single-crystal silicon solar cells have an absolute advantage in all aspects.
[0004] Monocrystalline silicon solar cells are devices that directly convert light energy into electrical energy through the photoelectric effect or photochemical effect. They use the principle of photoelectric conversion to convert solar radiation into electrical energy through semiconductor materials. This photoelectric conversion process is usually called the "photovoltaic effect", so solar cells are also called "photovoltaic cells". Monocrystalline silicon solar cells generally use the TOPCON process, and their main manufacturing process includes: texturing, diffusion, SE, oxidation, etching, LPCVD, phosphorus diffusion, RCA, aluminum oxide, coating, printing and sintering. Among them, the diffusion-made PN junction is the core of crystalline silicon solar cells, and the quality of the PN junction directly determines the conversion efficiency of solar cells. Therefore, the industry is generally seeking a solution to reduce the isolation rate of defective pieces and improve product yield.
[0005] At present, the common single crystal rework scheme popular in the industry is: use a slot machine to feed the reworked wafer from the texturing feeder again through automation; use HF plus HCL to remove organic matter and impurities; use pure water to clean and remove residual chemicals on the surface of the silicon wafer; use soda to remove the mechanical damage layer on the surface of the silicon wafer, and simultaneously remove stubborn appearance defects; use pure water to clean and remove residual chemicals on the surface of the silicon wafer; use alkali plus hydrogen peroxide to remove dirt and fingerprints on the surface of the silicon wafer, and produce a clean micro-surface oxide layer to prepare for texturing; use pure water to clean and remove the residual liquid on the surface of the silicon wafer; re-texture. The appearance of the reworked wafer is significantly different from that of the normal wafer. In addition, due to the different life of the liquid, the concentration of the liquid in the texturing tank of the slot machine will change, causing the corrosion depth and reflectivity of the cleaning and isolation reworked silicon wafer to fluctuate, so it is necessary to adjust the liquid replenishment in real time, that is, each time the reworked silicon wafer is cleaned, it is necessary to change the liquid again, which makes the cost of using the liquid high.
[0006] Therefore, how to provide a reworking method for monocrystalline silicon solar cells with abnormal LPCVD oxidation process, simplify the reworking process, reduce the cost of chemical solutions and reduce the basic damage to silicon wafers is a difficult problem that needs to be solved urgently in this field. Summary of the invention
[0007] In view of this, the present invention provides a reworking method for single crystal silicon solar cell wafers with abnormal LPCVD oxidation process, so as to solve the problems of the existing reworking method, such as complicated process, need for re-texturing, high cost and great damage to silicon wafers.
[0008] In order to achieve the above object, the present invention adopts the following technical solution:
[0009] A method for reworking a monocrystalline silicon solar cell with abnormal LPCVD oxidation process, comprising the following steps:
[0010] 1) isolating a monocrystalline silicon solar cell with abnormal LPCVD oxidation process, treating the polycrystalline silicon layer of the monocrystalline silicon solar cell with abnormal LPCVD oxidation process with a sodium hydroxide solution, and obtaining a monocrystalline silicon solar cell with the polycrystalline silicon layer removed;
[0011] 2) treating the oxide layer of the single crystal silicon solar cell with the polysilicon layer removed by using an HF solution to obtain a hydrophobic single crystal silicon solar cell;
[0012] 3) Return the hydrophobic monocrystalline silicon solar cell to the LPCVD oxidation process and process it according to the conventional production process.
[0013] Preferably, the monocrystalline silicon solar cell with abnormal LPCVD oxidation process is a monocrystalline silicon solar cell with abnormal LPCVD oxidation process machine alarm.
[0014] Preferably, the mass concentration of the sodium hydroxide solution in step 1) is 1-5%, and the temperature of the sodium hydroxide solution treatment is 55-70°C.
[0015] Preferably, the polysilicon layer in step 1) is treated using a tank-type alkaline polishing and cleaning equipment.
[0016] Preferably, the mass concentration of the HF solution in step 2) is 0.1-1%.
[0017] Preferably, the treatment of the oxide layer in step 2) is performed using a tank-type alkaline polishing and cleaning equipment.
[0018] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:
[0019] 1. The present invention uses soda ash as a cleaning agent, and the cleaning stability can be maintained by controlling the soda ash concentration, so that the corrosion depth can be stably controlled during mass production;
[0020] 2. The present invention has a small corrosion depth on the reworked monocrystalline silicon solar cell, so it has a small impact on the rigidity of the monocrystalline silicon solar cell, can reduce the subsequent fragmentation, and reduce the cost of the chemical solution;
[0021] 3. The present invention does not need to prepare liquid separately, and can use the process formula of the production line to remove BSG machine, which can minimize the cost of liquid medicine, and does not need to be re-textured, thus minimizing the loss of production capacity. In the traditional rework machine cleaning, the weight loss of silicon wafer is relatively large, and the texture surface and the structure of the previous process are destroyed, so it is necessary to re-texturize and start the process;
[0022] 4. The rework method of the present invention has little damage to the monocrystalline silicon solar cell and does not affect the yield and efficiency. DETAILED DESCRIPTION
[0023] The present invention provides a method for reworking a monocrystalline silicon solar cell with abnormal LPCVD oxidation process, comprising the following steps:
[0024] 1) isolating a monocrystalline silicon solar cell with abnormal LPCVD oxidation process, treating the polycrystalline silicon layer of the monocrystalline silicon solar cell with abnormal LPCVD oxidation process with a sodium hydroxide solution, and obtaining a monocrystalline silicon solar cell with the polycrystalline silicon layer removed;
[0025] 2) treating the oxide layer of the single crystal silicon solar cell with the polysilicon layer removed by using an HF solution to obtain a hydrophobic single crystal silicon solar cell;
[0026] 3) Return the hydrophobic monocrystalline silicon solar cell to the LPCVD oxidation process and process it according to the conventional production process.
[0027] In the present invention, the monocrystalline silicon solar cell with abnormal LPCVD oxidation process is a monocrystalline silicon solar cell with abnormal LPCVD oxidation process machine alarm.
[0028] In the present invention, the mass concentration of the sodium hydroxide solution in step 1) is 1-5%, specifically 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%; the temperature of the sodium hydroxide solution treatment is 55-70°C, specifically 58°C, 60°C, 62°C, 65°C, 68°C.
[0029] In the present invention, the polysilicon layer in step 1) is treated by a tank-type alkaline polishing and cleaning equipment.
[0030] In the present invention, the mass concentration of the HF solution in step 2) is 0.1-1%, specifically 0.2%, 0.4%, 0.5%, 0.6%, 0.8%.
[0031] In the present invention, the HF solution treatment can neutralize the residues of the previous treatment, remove the oxide layer, form Si-H passivation bonds with the silicon dangling bonds on the surface of the monocrystalline silicon solar cell, and increase the hydrophobicity of the silicon wafer.
[0032] In the present invention, the oxide layer in step 2) is treated by using a tank-type alkaline polishing and cleaning equipment.
[0033] In the present invention, the overall conventional production process of monocrystalline silicon solar cells includes: texturing, diffusion, SE, oxidation, etching, LPCVD oxidation process, phosphorus diffusion, RCA, aluminum oxide, coating, printing and sintering.
[0034] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0035] Example 1
[0036] The defective monocrystalline silicon solar cells after LPCVD are collected, inserted into a flower basket, and processed using the process of this embodiment. The specific process steps are as follows:
[0037] (1) A boat of 2000 pieces of material with abnormal alarm of LPCVD oxidation process machine was taken as the processing object, and the defective reworked single crystal silicon solar cells were immersed in sodium hydroxide solution for cleaning. The mass concentration of sodium hydroxide solution was 5%, and the processing temperature was 60°C. The POLY layer film (polycrystalline silicon layer) on the front and back sides was removed, and then the surface oxide layer was removed using HF solution with a mass concentration of 0.5%. The single crystal silicon solar cells were cleaned and dried, and the drying temperature was controlled at 100°C.
[0038] (2) After the cleaning in step (1) is completed, the surface hydrophobicity of the monocrystalline silicon solar cell is tested, and the test result is normal.
[0039] (3) Returning the monocrystalline silicon solar cell after processing in step (2) to the LPCVD process, and processing it according to the conventional process starting from the LPCVD process.
[0040] The relevant performances of the monocrystalline silicon solar cell treated in this embodiment and the monocrystalline silicon solar cell produced normally (control group) were tested (conversion efficiency-Eta, electromotive force-Uoc, short-circuit current-lsc, fill factor-FF, series resistance-Rs, parallel resistance-Rsh, reverse current-lrev2), and the test results are shown in Table 1.
[0041] Table 1 Test results of related performances of monocrystalline silicon solar cells in Example 1 and the control group
[0042] Eta / % Uoc / V Lsc / A FF / % Rs / Ω Rsh / Ω lrev2 / A Example 1 25.058 0.7115 14.5210 80.07 0.0013 3804 0.1403 Control group 25.079 0.7124 14.5361 80 0.00131 3827 0.123
[0043] The appearance yield of the monocrystalline silicon solar cell obtained in this embodiment is no different from that of the control group (normal cell). In addition, it can be seen from Table 1 that compared with the control group, the efficiency of this embodiment is 0.021% lower, the fragmentation rate is reduced, the need for re-texturing is reduced, the cell circulation time is reduced, the rework process is shortened, and the cost is effectively reduced.
[0044] Example 2
[0045] (1) A boat of 2000 pieces of material with abnormal alarm of LPCVD oxidation process machine was taken as the processing object, and the defective reworked single crystal silicon solar cells were immersed in sodium hydroxide solution for cleaning. The mass concentration of sodium hydroxide solution was 3%, and the processing temperature was 55°C. The POLY layer film (polycrystalline silicon layer) on the front and back sides was removed, and then the surface oxide layer was removed using HF solution with a mass concentration of 0.3%. The single crystal silicon solar cells were cleaned and dried, and the drying temperature was controlled at 100°C.
[0046] (2) After the cleaning in step (1) is completed, the surface hydrophobicity of the monocrystalline silicon solar cell is tested, and the test result is normal.
[0047] (3) Returning the monocrystalline silicon solar cell after processing in step (2) to the LPCVD process, and processing it according to the conventional process starting from the LPCVD process.
[0048] Comparative Example 1
[0049] Collect the defective monocrystalline silicon solar cells after LPCVD of the same batch as Example 2, and according to the rework process of the production line, use a slot machine to feed the reworked pieces again from the texturing feed through automation; 1. Use HF (mass concentration 11%) + HCL (mass concentration 7%) to remove organic matter and impurities; 2. Use pure water to wash and remove residual chemicals on the surface of the monocrystalline silicon solar cells; 3. Use NaOH solution (mass concentration 3%) to remove the surface mechanical damage layer, and simultaneously remove stubborn poor appearance marks; 4. Use pure water to wash and remove residual chemicals on the surface; 5. Use NaOH solution (mass concentration 5%) + hydrogen peroxide (mass concentration 8%) to remove surface dirt and fingerprints, and produce a clean micro-surface oxide layer to prepare for texturing; 6. Use pure water to wash, remove the surface liquid residue, and dry; 7. Process according to conventional processes starting from texturing.
[0050] The relevant performances of the monocrystalline silicon solar cell processed in Example 2 and the monocrystalline silicon solar cell processed in Comparative Example 1 were tested respectively (conversion efficiency-Eta, electromotive force-Uoc, short-circuit current-lsc, fill factor-FF, series resistance-Rs, parallel resistance-Rsh, reverse current-lrev2), and the test results are shown in Table 2.
[0051] Table 2 Test results of related performances of monocrystalline silicon solar cells in Example 2 and Comparative Example 1
[0052] Eta / % Uoc / V Lsc / A FF / % Rs / Ω Rsh / Ω lrev2 / A Example 2 24.945 0.7085 14.5711 79.82 0.00136 3182 0.0831 Comparative Example 1 24.762 0.7077 14.5560 79.29 0.00136 3209 0.0971
[0053] Compared with comparative example 1, the appearance yield of embodiment 2 is increased by 5-10%, the fragmentation rate is reduced by 1-3%, and the circulation rate is increased by 15-20h. It can be seen from Table 2 that the efficiency is increased by 0.183%. The present invention can reduce the fragmentation rate, eliminate the need for re-texturing, reduce the circulation time of the battery cell, shorten the rework process, effectively reduce costs, and improve the rework yield and efficiency.
[0054] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.
[0055] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for reworking a monocrystalline silicon solar cell with abnormal LPCVD oxidation process, characterized in that: The steps include: 1) isolating a monocrystalline silicon solar cell with abnormal LPCVD oxidation process, treating the polycrystalline silicon layer of the monocrystalline silicon solar cell with abnormal LPCVD oxidation process with a sodium hydroxide solution, and obtaining a monocrystalline silicon solar cell with the polycrystalline silicon layer removed; 2) treating the oxide layer of the single crystal silicon solar cell with the polysilicon layer removed by using an HF solution to obtain a hydrophobic single crystal silicon solar cell; 3) Return the hydrophobic monocrystalline silicon solar cell to the LPCVD process and process it according to the conventional production process.
2. A method for reworking a monocrystalline silicon solar cell with abnormal LPCVD oxidation process according to claim 1, characterized in that: The monocrystalline silicon solar cell with abnormal LPCVD oxidation process is a monocrystalline silicon solar cell with abnormal LPCVD oxidation process machine alarm.
3. A method for reworking a single crystal silicon solar cell with abnormal LPCVD oxidation process according to claim 2, characterized in that: The mass concentration of the sodium hydroxide solution in step 1) is 1-5%, and the temperature of the sodium hydroxide solution treatment is 55-70°C.
4. A method for reworking a monocrystalline silicon solar cell with abnormal LPCVD oxidation process according to claim 3, characterized in that: The polysilicon layer in step 1) is treated by a tank-type alkaline polishing and cleaning equipment.
5. A method for reworking a single-crystal silicon solar cell with abnormal LPCVD oxidation process according to any one of claims 1 to 4, characterized in that: The mass concentration of the HF solution in step 2) is 0.1-1%.
6. A method for reworking a single-crystal silicon solar cell with abnormal LPCVD oxidation process according to claim 5, characterized in that: The oxide layer in step 2) is treated by using a tank-type alkaline polishing cleaning equipment.