Monocrystalline silicon cleaning additive as well as preparation method and application thereof

Abstract

The invention relates to a monocrystalline silicon cleaning additive and a preparation method and application thereof, and the monocrystalline silicon cleaning additive comprises the following components by weight: 1-5 parts of an inorganic base; 0.5 to 3 parts of a surfactant; 1-3 parts of a corrosion inhibitor; 1-3 parts of a complexing agent; 2-5 parts of hydrogen peroxide; and 70-90 parts of deionized water. According to the additive disclosed by the invention, the synergistic removal of multiple pollutants such as organic matter degradation, metal ion complexation and particle suspension is realized through a composite formula, the dual purposes of rapid and powerful cleaning of the monocrystalline silicon wafer are achieved, and technical support is provided for cost reduction and efficiency improvement of the photovoltaic industry.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor manufacturing technology, and in particular relates to a single crystal silicon cleaning additive and a preparation method and application thereof. Background Art

[0002] Monocrystalline silicon, the core material of solar cells, has a surface cleanliness that directly impacts the cell's photoelectric conversion efficiency and yield. During the wafer cutting, grinding, and transportation processes, metal ions (such as iron, calcium, and copper), organic matter (such as cutting fluids and adhesives), and particulate contaminants can remain on the surface. If these contaminants are not thoroughly removed, they can lead to uneven texturing, degraded PN junction performance during the diffusion process, and even cause leakage and poor EL performance, ultimately impacting cell efficiency.

[0003] Traditional cleaning processes often rely on rough polishing or multiple cleaning steps using strong chemicals (such as NaOH, H₂O₂, and concentrated sulfuric acid). While strong alkaline cleaning can quickly remove damaged layers, it can easily cause excessive corrosion on the silicon wafer surface, leading to uncontrollable thinning and affecting the uniformity of the subsequent texturing process. If residual alkaline substances are not completely removed, they can also cause uneven doping distribution during the diffusion process, increasing contact resistance. Furthermore, traditional cleaning agents contain harmful components such as phosphorus and chromium, and strong acid and alkaline processes can easily generate harmful gases, posing a threat to operator health and the environment. Some environmentally friendly additives (such as sodium gluconate and EDTA) are used, but their chelating capacity is limited, making them inadequate for wafer sources contaminated by dust, roller fluid contamination, residual chemicals from previous processes (also known as residual chemical solutions), chemical corrosion, and dirt.

[0004] For film sources contaminated by dust, roller fluid, residual chemicals from previous processes, chemical corrosion, and dirt, existing additives are ineffective in cleaning complex contaminants (such as organic-metallic composite contaminants), resulting in "speckled" and "dirty" film residues after cleaning. Therefore, a highly effective cleaning additive is urgently needed. Summary of the Invention

[0005] The technical problem solved by the present invention is: For film sources containing dust-type pollution, roller liquid pollution, residual chemical pollution from the previous process, chemical corrosion, dirt, etc., the existing additives are not effective in cleaning complex pollutants (such as organic-metal composite pollutants), resulting in problems such as "flowery films" and "dirty films" after cleaning.

[0006] In response to the technical challenges of existing technologies, this paper designs a single-crystal silicon cleaning additive, its preparation method, and its application. This composite formula achieves the synergistic removal of multiple pollutants, including organic degradation, metal ion complexation, and particle suspension. This approach aims to achieve the dual goals of rapid and effective cleaning of single-crystal silicon wafers, providing technical support for cost reduction and efficiency improvement in the photovoltaic industry.

[0007] It should be noted that, in the present invention, unless otherwise specified, the specific meaning of "including" in relation to composition limitations and descriptions includes both open-ended "including", "comprising", etc. and similar meanings, as well as closed-ended "consisting of..." etc. and similar meanings.

[0008] In order to solve the above-mentioned technical problems, the present invention adopts the following solutions:

[0009]

The first technical solution

[0010] A single crystal silicon cleaning additive, characterized in that it comprises the following components, calculated in parts by weight: 1-5 parts of inorganic base; 0.5-3 parts of surfactant; 1-3 parts of corrosion inhibitor; 1-3 parts of complexing agent; 2-5 parts hydrogen peroxide; 70-90 parts of deionized water; The surfactant is a polyethylene glycol-based functional copolymer.

[0011] Furthermore, the surfactant is one or more of dihydroxypropylene oxide-ethylene oxide copolyether, polyamide-polyethylene glycol-amino, methoxy polyethylene glycol-glutamic acid, methoxy polyethylene glycol polyaspartic acid, and methoxy polyethylene glycol polylysine.

[0012] Furthermore, the inorganic base is NaOH and / or KOH.

[0013] Furthermore, the corrosion inhibitor is one or more of malic acid, citric acid, tartaric acid, and lactic acid.

[0014] Furthermore, the complexing agent is one or more of methyl p-nitrobenzenesulfonate, sodium m-nitrobenzenesulfonate, sodium p-aminobenzenesulfonate, and sodium p-hydroxybenzenesulfonate.

[0015] In the present invention, in order to further optimize the performance of the single crystal silicon cleaning additive, each component can be optimized, 1-3 parts of inorganic base; 0.5-1.5 parts of surfactant; 1-2 parts of corrosion inhibitor; 1-2 parts of complexing agent; 2.5-3.5 parts of hydrogen peroxide; 80-90 parts of deionized water.

[0016] In the present invention, the surfactant is preferably dihydroxypropylene oxide-ethylene oxide copolyether.

[0017] In the present invention, the corrosion inhibitor is preferably tartaric acid.

[0018] In the present invention, the complexing agent is preferably sodium p-hydroxybenzenesulfonate.

[0019] In the present invention, the single crystal silicon cleaning additive does not contain low-boiling point components, and the low-boiling point components refer to components with a boiling point 60° C.-68° C. lower than the cleaning temperature.

[0020] In the present invention, a polyethylene glycol-based functionalized copolymer is used as a surfactant. The specific functional groups or segments on or connected to the PEG segment can reduce the surface tension of water. Among them, dihydroxypropylene oxide-ethylene oxide copolyether is a preferred surfactant. Its molecular chain contains both propylene oxide (PPO) segments and ethylene oxide (PEO) segments. The unique segment structure enables it to form an effective interface between water and oil stains, reduce the surface tension of water, and thus help the cleaning agent better penetrate into the surface of pollutants such as oil stains and suspended particles to achieve a cleaning effect.

[0021] The present invention also uses hydroxycarboxylic acid compounds as corrosion inhibitors, whose multiple carboxyl and hydroxyl groups in the molecule give them unique functionality. The sulfonic acid groups in the complexing agent reduce the surface tension of the solution and enhance its penetration into microcracks on the metal surface. After adsorption on the silicon wafer surface, the sulfonic acid groups complement the corrosion inhibitor, synergistically enhancing the wettability of the solution. Combined with a surfactant, the three form a synergistic mechanism, significantly improving cleaning performance.

[0022] In the present invention, the complexing agent in the cleaning additive has a unique function:

[0023] First, its molecular structure has one end that is hydrophilic and the other end that is lipophilic. This property enables it to effectively reduce the surface tension of the cleaning agent and combine with metal ions such as calcium and magnesium remaining on the surface of the silicon wafer to form precipitates, thereby softening the water quality and preventing these metal ions from reacting with other components in the cleaning agent, affecting the decontamination and cleaning effects.

[0024] Secondly, it can form complexes with metal ions and some organic pollutants remaining on the surface of the silicon wafer, making the metal ions more stable in the cleaning agent and easier to be cleaned and removed.

[0025] At the same time, under hydrogen peroxide and alkaline conditions, organic matter can be oxidized and decomposed into harmless carbon dioxide and water, thereby improving the efficiency of organic matter degradation; while the surfactant reduces the surface tension of the solution, it enables the cleaning agent to fully contact and wet all parts of the silicon wafer surface, and can also form an oxide film on the surface of the single crystal silicon wafer, effectively preventing the re-adsorption of metal ions, impurity particles, and organic pollutants.

[0026]

Second technical solution

[0027] A method for preparing the above-mentioned single crystal silicon cleaning additive comprises the following steps:

[0028] Weigh appropriate amounts of inorganic base, surfactant, complexing agent, corrosion inhibitor and hydrogen peroxide and add them to deionized water. Stir thoroughly at 20-25°C for 2-3 hours until all components are evenly mixed to obtain the single crystal silicon cleaning additive.

[0029]

The third technical solution

[0030] A cleaning agent comprises the above-mentioned single crystal silicon cleaning additive, inorganic alkali, hydrogen peroxide and deionized water.

[0031] Furthermore, the mass ratio of the cleaning agent in the pre-cleaning process before texturing and in the alkaline cleaning process after texturing is different;

[0032] In the pre-cleaning process before texturing, the mass ratio of the single crystal silicon cleaning additive, inorganic alkali, hydrogen peroxide and deionized water is 0.5-0.6:0.1-0.3:1-2:100;

[0033] In the alkaline cleaning process after texturing, the mass ratio of the single crystal silicon cleaning additive, inorganic alkali, hydrogen peroxide and deionized water is 0.5-0.6:0.3-0.5:1-2:100.

[0034] In the cleaning agent of the present invention, the inorganic base is NaOH and / or KOH.

[0035] In the pre-cleaning process before texturing, the mass ratio of the single crystal silicon cleaning additive, inorganic alkali, hydrogen peroxide and deionized water is preferably 0.5:0.1:1.5:100.

[0036] In the alkaline cleaning process after texturing, the mass ratio of the single crystal silicon cleaning additive, inorganic alkali, hydrogen peroxide and deionized water is preferably 0.6:0.3:1.5:100.

[0037]

The fourth technical solution

[0038] A method for preparing the above-mentioned cleaning agent comprises the following steps:

[0039] The single crystal silicon cleaning additive, inorganic alkali and hydrogen peroxide are weighed, added into deionized water respectively, and stirred for 1-2 minutes until the mixture is uniform, thereby obtaining the cleaning agent.

[0040] When the cleaning agent is added to the pre-cleaning process before texturing, the mixing temperature is 60-62°C;

[0041] When the cleaning agent is added to the alkaline cleaning process after texturing, the mixing temperature is 65-68°C.

[0042]

Fifth technical solution

[0043] A method for using the above-mentioned cleaning agent comprises the following steps:

[0044] Pre-cleaning before texturing: Heat the above cleaning agent to 60-62°C, take out the single crystal silicon wafer and put it into the above cleaning agent for pre-cleaning. The pre-cleaning time is 240-260 seconds. Take out the single crystal silicon wafer and rinse the front and back of the silicon wafer with deionized water for 20-25 seconds each.

[0045] Texturing: Texturing the pre-cleaned silicon wafer. After texturing, remove the silicon wafer and rinse the front and back sides of the wafer with deionized water for 20-25 seconds each.

[0046] Alkali cleaning after texturing: Heat the above cleaning agent to 65-68°C, take the texturing silicon wafer rinsed with deionized water and put it into the above cleaning agent for alkaline cleaning. The alkaline cleaning time is 120-150s. Take out the silicon wafer and rinse the front and back sides of the silicon wafer with deionized water and anhydrous ethanol respectively for 20-25s each, and dry the silicon wafer surface under N2 protection conditions.

[0047] In the pre-cleaning process before texturing of the present invention, the cleaning temperature may be preferably 60° C., the pre-cleaning time may be preferably 240 s, and the single crystal original silicon wafer is taken out and the front and back sides of the silicon wafer are rinsed with deionized water for 25 s each.

[0048] In the alkaline cleaning process after texturing of the present invention, the cleaning temperature can be preferably 68°C, and the alkaline cleaning time can be preferably 120-135 seconds, more preferably 120 seconds. The silicon wafer is removed and rinsed with deionized water and anhydrous ethanol for 25 seconds on both sides. The N2 drying time is 200-300 seconds, preferably 240-270 seconds, more preferably 240 seconds.

[0049] The present invention improves the cleaning effect through the combined effect of pre-cleaning and alkaline cleaning before and after texturing:

[0050] Pre-cleaning before texturing removes all kinds of impurities on the surface of the wafer, improves the cleanliness of the silicon wafer surface and improves the texturing effect;

[0051] Alkaline washing after texturing removes the chemicals from the previous process remaining on the surface of the silicon wafer during the texturing process, neutralizes the residual alkali solution, cleans the silicon wafer, and prepares for the next process.

[0052] The use of monocrystalline silicon cleaning additives in the pre-cleaning and alkaline cleaning processes ensures the cleanliness of the silicon wafer surface and good texturing effect, effectively improves the yield rate of the cell, and provides a strong guarantee for the production of high-quality solar cells.

[0053]

Sixth Technical Solution

[0054] A use of the above-mentioned single crystal silicon cleaning additive in cleaning single crystal silicon wafers.

[0055] Furthermore, a single crystal silicon cleaning additive is used in the pre- and post-cleaning of single crystal silicon solar cell sheets during the texturing process, alkali polishing process and RCA de-wrapping process.

[0056] The present invention provides a single crystal silicon cleaning additive and its preparation method and application, which have the following beneficial effects:

[0057] 1. This invention uses a polyethylene glycol-based functionalized copolymer as a surfactant. Its unique segment structure enables it to form an effective interface between water and oil, reducing the surface tension of water, thereby helping the cleaning agent to better penetrate the surface of pollutants such as oil and suspended particles to achieve a cleaning effect.

[0058] 2. The molecular structure of the complexing agent in the single crystal silicon cleaning additive of the present invention is hydrophilic at one end and lipophilic at the other end. This property enables it to effectively reduce the surface tension of the cleaning agent and combine with metal ions such as calcium and magnesium remaining on the surface of the silicon wafer to form a precipitate, thereby softening the water quality and preventing these metal ions from reacting with other components in the cleaning agent and affecting the decontamination and cleaning effects.

[0059] 3. The complexing agent in the single crystal silicon cleaning additive of the present invention can form complexes with metal ions and some organic pollutants remaining on the surface of the silicon wafer, making the metal ions more stable in the cleaning agent and easier to clean and remove. At the same time, hydrogen peroxide, under alkaline conditions, oxidizes and decomposes organic matter into harmless carbon dioxide and water, thereby improving the efficiency of organic matter degradation. The surfactant reduces the surface tension of the solution while allowing the cleaning agent to fully contact and wet all parts of the silicon wafer surface. It can also form an oxide film on the surface of the single crystal silicon wafer, effectively preventing the re-adsorption of metal ions, impurity particles, and organic pollutants.

[0060] 4. The cleaning agent containing the monocrystalline silicon cleaning additive of the present invention can effectively remove organic pollutants on the surface of monocrystalline silicon wafers and chemical residues caused by other processes, ensuring the cleanliness of the silicon wafers and providing a high-quality foundation for subsequent solar cell manufacturing processes.

[0061] 5. This invention enhances cleaning effectiveness through the combined effects of pre-cleaning before the process and alkaline cleaning after the process: Pre-cleaning before texturing removes various surface impurities from the wafer, improving the cleanliness of the silicon wafer surface and the texturing effect; alkaline cleaning after texturing removes residual chemical solution on the silicon wafer surface during the texturing process, neutralizes the residual alkaline solution, and cleans the silicon wafer in preparation for the next process. The use of monocrystalline silicon cleaning additives in both the pre-cleaning and alkaline cleaning processes ensures excellent silicon wafer surface cleanliness and texturing results, effectively improving the cell yield and providing a strong guarantee for the production of high-quality solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1: This is a photo of a silicon wafer after the texturing process was performed using Example 1 and alkaline cleaning treatment;

[0063] Figure 2 : This is a photo of the silicon wafer after the texturing silicon wafer was alkaline cleaned using Comparative Example 1. DETAILED DESCRIPTION

[0064] The present invention will be further described below with reference to specific embodiments and accompanying drawings:

[0065] In the present invention, Examples 1-8 and Comparative Examples 1-5 disclose a variety of single crystal silicon cleaning additives, the components and mass ratios of which are shown in Table 1 and Table 2.

[0066] The preparation method of the single crystal silicon cleaning additive is as follows:

[0067] Weigh appropriate amounts of inorganic base, surfactant, complexing agent, corrosion inhibitor and hydrogen peroxide and add them to deionized water. Stir them thoroughly for 3 hours at room temperature of 25°C until all components are evenly mixed to obtain the desired single crystal silicon cleaning additive.

[0068] Table 1 Example 1-Example 8 Example Inorganic base mass parts Surfactant mass parts Complexing agent mass parts Corrosion inhibitor mass parts Hydrogen peroxide mass parts Deionized water mass parts 1 2 parts NaOH 1 part of dihydroxypropylene oxide-ethylene oxide copolyether 1.5 parts of sodium p-hydroxybenzenesulfonate 1 part tartaric acid 3 servings 90 servings 2 1 part NaOH 0.5 parts of dihydroxypropylene oxide-ethylene oxide copolyether 1 part sodium p-hydroxybenzenesulfonate 1 part tartaric acid 2.5 servings 70 servings 3 2 parts NaOH 3 parts of polyamide polyethylene glycol amino 1.5 parts of sodium p-hydroxybenzenesulfonate 1 part tartaric acid 3 servings 90 servings 4 2 parts KOH 1 part of dihydroxypropylene oxide-ethylene oxide copolyether 3 parts of methyl p-nitrobenzenesulfonate 1 part tartaric acid 5 servings 90 servings 5 3 parts NaOH 1 part of dihydroxypropylene oxide-ethylene oxide copolyether 1.5 parts of sodium p-hydroxybenzenesulfonate 1 part malic acid 3 servings 90 servings 6 1.5 parts of NaOH 1.5 parts of methoxy polyethylene glycol polyglutamic acid 2 parts of sodium p-aminobenzenesulfonate 1.5 parts of lactic acid 3.5 servings 80 servings 7 2 parts NaOH 1 part methoxy polyethylene glycol polyaspartic acid 1 part sodium m-nitrobenzenesulfonate 2 parts tartaric acid 2 servings 90 servings 8 5 parts of NaOH 1 part methoxy polyethylene glycol polylysine 1.5 parts of methyl p-nitrobenzenesulfonate 3 parts citric acid 3 servings 90 servings

[0069] Table 2 Comparative Examples 1-5 Comparative Example Inorganic base mass parts Surfactant mass parts Complexing agent mass parts Corrosion inhibitor mass parts Hydrogen peroxide mass parts Deionized water mass parts 1 2 parts NaOH - 1.5 parts of sodium p-hydroxybenzenesulfonate 1 part tartaric acid 3 servings 90 servings 2 2 parts NaOH 1 part of dihydroxypropylene oxide-ethylene oxide copolyether - 1 part tartaric acid 3 servings 90 servings 3 2 parts NaOH 1 part of dihydroxypropylene oxide-ethylene oxide copolyether 1.5 parts of sodium p-hydroxybenzenesulfonate - 3 servings 90 servings 4 2 parts NaOH 1 part polyethylene glycol-polyglutamic acid copolymer 1.5 parts of sodium p-hydroxybenzenesulfonate 1 part tartaric acid 3 servings 90 servings 5 2 parts NaOH 1 part of dihydroxypropylene oxide-ethylene oxide copolyether 1.5 parts sodium p-hydroxybenzoate 1 part tartaric acid 3 servings 90 servings

[0070] The preparation method of the cleaning agent in the pre-cleaning process before texturing of the present invention is as follows:

[0071] The single crystal silicon cleaning additive, inorganic base, hydrogen peroxide and deionized water prepared above are weighed according to a mass ratio of 0.5:0.1:1.5:100 respectively, and the cleaning additive, inorganic base and hydrogen peroxide are added to deionized water at 60°C and stirred for 2 minutes until uniformly mixed, thereby preparing a single crystal silicon pre-cleaning agent before texturing.

[0072] The preparation method of the cleaning agent in the alkaline cleaning process after texturing of the present invention is as follows:

[0073] The above-prepared single crystal silicon cleaning additive, inorganic base, hydrogen peroxide and deionized water are weighed respectively at a mass ratio of 0.6:0.3:1.5:100, and the cleaning additive, inorganic base and hydrogen peroxide are added to 68°C deionized water and stirred for 2 minutes until uniformly mixed, thereby preparing a single crystal silicon post-texturing alkaline cleaning agent.

[0074] About how to use the cleaning agent:

[0075] Pre-cleaning process before texturing: Place the single crystal silicon wafer in the pre-cleaning agent before texturing for pre-cleaning treatment at a temperature of 60°C for 240 seconds. After the pre-cleaning is completed, take out the single crystal silicon wafer and rinse the front and back sides of the wafer with deionized water for 25 seconds each.

[0076] Texturing: Place the pre-cleaned silicon wafer into the texturing tank for texturing reaction. After texturing is completed, take out the silicon wafer and rinse the front and back sides of the silicon wafer with deionized water for 25 seconds each.

[0077] Alkaline cleaning process after texturing: Then take the texturing silicon wafer rinsed with deionized water and put it into the single crystal silicon texturing alkaline cleaning agent for alkaline cleaning treatment. The alkaline cleaning temperature is 68°C and the alkaline cleaning time is 120s. After the alkaline cleaning is completed, take out the silicon wafer and rinse the front and back of the silicon wafer with deionized water and anhydrous ethanol respectively for 25s each, and dry it under N2 protection for 240s.

[0078] About performance testing and description:

[0079] 500 single crystal silicon wafers were placed in a pre-texturing pre-cleaning agent for pre-cleaning treatment, with a pre-cleaning temperature of 60°C and a pre-cleaning time of 240s. After the pre-cleaning, the front and back sides of the silicon wafers were rinsed with deionized water for 25s each, and then the silicon wafers were transferred to a texturing tank for texturing reaction. After the texturing was completed, the front and back sides of the silicon wafers were rinsed again with deionized water for 25s each, and then the texturized silicon wafers were transferred to a single crystal silicon post-texturing alkaline cleaning agent for alkaline cleaning treatment, with an alkaline cleaning temperature of 68°C and an alkaline cleaning time of 120s. After the alkaline cleaning was completed, the silicon wafers were rinsed with deionized water and anhydrous ethanol for 25s each on both sides, and dried under N2 protection conditions for 240s.

[0080] After cleaning, the silicon wafers are prepared into solar cells and then subjected to performance and yield testing. Types of solar cell EL defects reported in the test data primarily include dust contamination, roller contamination, residual chemical solution, chemical corrosion, and contamination. FF stands for Fill Factor, which is the ratio of maximum output power to the product of open-circuit voltage and short-circuit current. A higher FF value indicates a higher module efficiency.

[0081] The performance test and yield test results of the battery cells obtained in Examples 1 to 8 and Comparative Examples 1 to 5 are shown in Table 3.

[0082] Table 3 Test data Example / Comparative Example Filling factor FF (%) EL defect ratio (%) Example 1 84.94 2.6 Example 2 84.90 3.1 Example 3 84.86 3.5 Example 4 84.89 3.2 Example 5 84.92 2.8 Example 6 84.85 3.6 Example 7 84.83 3.8 Example 8 84.80 4.5 Comparative Example 1 84.53 9.2 Comparative Example 2 84.68 6.1 Comparative Example 3 84.70 5.6 Comparative Example 4 84.62 8.1 Comparative Example 5 84.75 5.2

[0083] Analysis of the test results: It can be seen from the test data in Table 3 that after using the cleaning agent and cleaning process prepared by the single crystal silicon cleaning additives of Examples 1-8, the fill factor FF value is significantly improved, indicating that the performance of the battery cell is significantly improved, the EL defect is significantly reduced, and the proportion is significantly reduced, indicating that the embodiment can effectively improve the cleaning ability before and after texturing and improve the cleaning effect compared with the comparative example.

[0084] Comparative Example 1 lacks dihydroxypropylene oxide-ethylene oxide copolyether, resulting in increased EL and poor cleaning effect;

[0085] Comparative Example 2 lacks sodium p-hydroxybenzenesulfonate, resulting in increased EL and poor cleaning effect;

[0086] Comparative Example 3 lacks tartaric acid, resulting in increased EL and poor cleaning effect;

[0087] Comparative Example 4 uses polyethylene glycol-polyglutamic acid copolymer as a surfactant, which results in an increase in EL and poor cleaning effect;

[0088] Comparative Example 5 uses sodium p-hydroxybenzoate as a complexing agent, which results in an increase in EL and a poor cleaning effect.

[0089] Further comparison is made through the accompanying drawings in the specification:

[0090] Figure 1 This is a picture of the appearance of the silicon wafer surface after the texturing silicon wafer is alkaline cleaned using Example 1; Figure 2 This is a picture of the appearance of the silicon wafer surface after the texturing silicon wafer was alkaline cleaned using Comparative Example 1.

[0091] from Figure 1 It can be seen that when the cleaning agent prepared with the cleaning additive of Example 1 is used to clean silicon wafers with poor wafer quality, the black spots and dirty areas on the silicon wafers after texturing are significantly reduced, and no other abnormalities are observed.

[0092] contrast Figure 2 The cleaning agent prepared with the cleaning additive of Comparative Example 1 was used to clean silicon wafers with poor wafer sources. After texturing, the blackened and dirty areas of the silicon wafers were obvious, and problems such as fingerprints, flower basket prints and card point prints were highlighted after texturing.

[0093] In summary, compared with Comparative Example 1, Example 1 has a better cleaning effect, reduces the residual metal ions on the surface of the silicon wafer, and can further improve the photoelectric conversion efficiency of the solar cell.

[0094] The present invention has been described above by way of example in conjunction with the embodiments and accompanying drawings. It is obvious that the implementation of the present invention is not limited to the above-mentioned methods. As long as various improvements are made using the method concepts and technical solutions of the present invention, or the concepts and technical solutions of the present invention are directly applied to other occasions without improvement, they are all within the scope of protection of the present invention.

Claims

1. A single crystal silicon cleaning additive, characterized in that: Calculated by weight, it includes the following components: 1-5 parts of inorganic base; 0.5-3 parts of surfactant; 1-3 parts of corrosion inhibitor; 1-3 parts of complexing agent; 2-5 parts hydrogen peroxide; 70-90 parts of deionized water; The surfactant is a polyethylene glycol-based functional copolymer.

2. The single crystal silicon cleaning additive according to claim 1, characterized in that: The surfactant is one or more of dihydroxypropylene oxide-ethylene oxide copolyether, polyamide-polyethylene glycol-amino, methoxy polyethylene glycol-glutamic acid, methoxy polyethylene glycol polyaspartic acid, and methoxy polyethylene glycol polylysine.

3. The single crystal silicon cleaning additive according to claim 1, wherein: The corrosion inhibitor is one or more of malic acid, citric acid, tartaric acid and lactic acid.

4. The single crystal silicon cleaning additive according to claim 1, wherein: The complexing agent is one or more of methyl p-nitrobenzenesulfonate, sodium m-nitrobenzenesulfonate, sodium p-aminobenzenesulfonate, and sodium p-hydroxybenzenesulfonate.

5. A method for preparing the single crystal silicon cleaning additive according to any one of claims 1 to 4, characterized in that The following steps are involved: Weigh corresponding amounts of inorganic base, surfactant, complexing agent, corrosion inhibitor and hydrogen peroxide and add them into deionized water. Stir thoroughly for 2-3 hours at 20-25°C until all components are evenly mixed to obtain the single crystal silicon cleaning additive.

6. A cleaning agent, characterized in that: The cleaning agent comprises the single crystal silicon cleaning additive according to any one of claims 1 to 4 or the single crystal silicon cleaning additive prepared by the method according to claim 5, an inorganic base, hydrogen peroxide and deionized water.

7. The cleaning agent according to claim 6, characterized in that: The cleaning agent is used in the pre-cleaning process before texturing, and the mass ratio of the single crystal silicon cleaning additive, inorganic alkali, hydrogen peroxide and deionized water is 0.5-0.6:0.1-0.3:1-2:100; And / or, the cleaning agent is used in the alkaline cleaning process after texturing, and the mass ratio of the single crystal silicon cleaning additive, inorganic alkali, hydrogen peroxide and deionized water is 0.5-0.6:0.3-0.5:1-2:

100.

8. A method for preparing the cleaning agent according to claim 6 or 7, characterized in that The following steps are involved: The single crystal silicon cleaning additive, inorganic alkali and hydrogen peroxide are weighed, added into deionized water, and stirred for 1-2 minutes until the mixture is uniform, thereby obtaining the cleaning agent.

9. A method for using the cleaning agent according to claim 6 or 7, characterized in that: The following steps are involved: Pre-cleaning before texturing: Heat the above cleaning agent to 60-62°C, take out the single crystal silicon wafer and put it into the above cleaning agent for pre-cleaning. The pre-cleaning time is 240-260 seconds. Take out the single crystal silicon wafer and rinse the front and back of the silicon wafer with deionized water for 20-25 seconds each. Texturing: Texturing is performed on the pre-cleaned silicon wafer. After texturing, the silicon wafer is taken out and rinsed with deionized water on both sides for 20-25 seconds each. Alkali cleaning after texturing: Heat the above cleaning agent to 65-68°C, take the texturing silicon wafer rinsed with deionized water and put it into the above cleaning agent for alkaline cleaning. The alkaline cleaning time is 120-150s. Take out the silicon wafer and rinse the front and back sides of the silicon wafer with deionized water and anhydrous ethanol respectively for 20-25s each, and dry the silicon wafer surface under N2 protection conditions.

10. Use of the single crystal silicon cleaning additive according to any one of claims 1 to 4 in cleaning single crystal silicon solar cells.

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