Inverted pyramid acidic texturing liquid for monocrystalline silicon

Abstract

The invention provides an inverted pyramid acidic texturing liquid for monocrystalline silicon, which belongs to the technical field of monocrystalline silicon texturing, optimizes the raw material ratio on the basis of the prior art, does not contain metal ions, and avoids the problem that metal particle residues of metal etching monocrystalline silicon are difficult to remove, and a surfactant can change interfacial tension, so that the texturing effect is improved. The corrosion inhibitor promotes the dispersion degree of hydrogen gas generated by etching on the surface of monocrystalline silicon, enables bubbles to be timely separated from the surface of silicon, increases texturing points on the surface of monocrystalline silicon, facilitates removal of an oxide layer or pollutants on the surface of a silicon wafer, can slow down the corrosion rate of texturing liquid, can protect the surface of the silicon wafer from oxidative damage to a certain extent, and improves the texturing quality of the silicon wafer. The etching is controlled by controlling the raw material ratio of the texturing liquid so as to improve the uniformity and flatness of the pyramid textured surface, the large-area inverted pyramid textured surface structure can be prepared on the surface of the monocrystalline silicon, the method can be compatible with existing texturing process groove type equipment, the operation is simple, and the production cost is relatively low.

Description

Technical Field

[0001] The invention belongs to the technical field of single crystal silicon texturing, and in particular relates to an acidic texturing liquid for single crystal silicon inverted pyramid. Background Art

[0002] The inverted pyramid structure has become a research hotspot for the surface preparation structure of high-efficiency batteries due to its excellent anti-reflection performance, low specific surface area, and easy passivation. The first to apply the inverted pyramid structure to solar cells and improve battery performance was the Martin Green research team at the University of New South Wales. The p-PERC / n-PERT battery structure based on the inverted pyramid structure they developed has set a world record for the efficiency of silicon-based solar cells, with a battery efficiency of up to 25%. At that time, the inverted pyramid structure on the surface of the silicon wafer was realized using mask plus photolithography technology, which was not only complex in process but also costly and was not suitable for large-scale production of solar cells. In addition, wet chemical etching can also prepare inverted pyramid structures. Wet chemical etching often uses precious metal ions such as silver and copper as catalysts to assist in etching single crystal silicon to form an inverted pyramid structure. This method has the problem of residual nano-metal particles, which greatly affects the subsequent process and the final battery efficiency. In addition, the use of precious metal ions will lead to excessively high texturing costs and cannot be applied on a large scale.

[0003] In summary, the existing methods for preparing inverted pyramid velvet structures have a series of problems such as high preparation cost and residual precious metals, which makes it difficult to apply them on a large scale. Therefore, the development of non-metallic inverted pyramid velvet technology has innovative significance for the current monocrystalline silicon velvet process and is of great significance for further improving the efficiency of monocrystalline silicon cells. Summary of the invention

[0004] The purpose of the present invention is to provide an acidic texturing solution for inverted pyramid of single crystal silicon, which is used to solve the technical problems in the prior art of high cost of texturing with precious metal catalysts and difficulty in removing metal particle residues.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The invention discloses an acid texturing solution for inverted pyramid of single crystal silicon, which is prepared by mixing an acid etching solution and a texturing additive in a mass ratio of 100:0.01-1.

[0007] The acidic texturing solution for the inverted pyramid of single crystal silicon does not contain metal ions.

[0008] The texturing additive comprises the following components in percentage by mass: 1% to 60% of a cationic surfactant, 0.2% to 40% of a nonionic surfactant, 0.5% to 10% of an organic acid, 0.1% to 5% of an alcohol, 0.1% to 5% of a corrosion inhibitor, and the remainder being deionized water.

[0009] Preferably, the cationic surfactant is one or more combinations of polyquaternary ammonium salt type, pyridine ring type, morpholine ring type, piperazine ring type, and fatty amine salt type.

[0010] Preferably, the nonionic surfactant is one or more combinations of polyoxyethylene ether, polyvinyl alcohol, ethanolamine, alkyl glycoside, polyvinyl pyrrolidone, xanthan gum, and gum arabic.

[0011] Preferably, the organic acid is one or more combinations of isovaleric acid, propionic acid, lactic acid, succinic acid and citric acid.

[0012] Preferably, the alcohol is one or more combinations of ethylene glycol, inositol, cyclohexanol and cyclopentanol.

[0013] Preferably, the corrosion inhibitor is one or more combinations of lauryl dimethylamine oxide, sulfurous acid, ammonium pyrosulfite, methylphenyl silicone oil and dimethyl silicone oil.

[0014] Preferably, the acidic etching solution comprises hydrofluoric acid and an oxidant, and the mass ratio of the acidic etching solution to the texturing additive is 100:0.01-10.

[0015] Preferably, the concentration of the hydrofluoric acid is 35 wt % to 50 wt %, and preferably the concentration is 48 wt % of hydrofluoric acid.

[0016] Preferably, the oxidant is one or more combinations of hydrogen peroxide, concentrated sulfuric acid and nitric acid.

[0017] The present invention also provides a method for preparing an acidic texturing solution for inverted pyramids of single crystal silicon, comprising the following steps:

[0018] S1. preparing a texturing additive: adding a cationic surfactant, a nonionic surfactant, an organic acid, an alcohol and a corrosion inhibitor into the remaining deionized water according to the mass percentage, and stirring to obtain a texturing additive;

[0019] S2. preparing an acidic etching solution: uniformly mixing hydrofluoric acid and an oxidant to prepare an acidic etching solution;

[0020] S3. Prepare an inverted pyramid acidic texturing solution: evenly mix the acidic etching solution and the texturing additive to obtain an inverted pyramid acidic texturing solution for single crystal silicon.

[0021] The present invention also provides an application of an acidic texturing liquid for monocrystalline silicon inverted pyramid in the preparation of an inverted pyramid texture structure, characterized in that the preparation method of the inverted pyramid texture structure comprises the following steps:

[0022] S11, adding the cleaned single crystal silicon wafer into the single crystal silicon inverted pyramid acidic texturing liquid, the texturing temperature is 5-50°C, and the time is controlled at 300-1800s;

[0023] S12. After etching, wash with deionized water and dry with nitrogen to obtain a single crystal silicon wafer with an inverted pyramid velvet surface.

[0024] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0025] 1. The present invention provides an acidic texturing liquid for inverted pyramid texturing of single crystal silicon. The raw material ratio is optimized on the basis of the existing technology, and it does not contain metal ions, thus avoiding the problem that the metal particle residues of single crystal silicon etched by metal are difficult to remove. The etching can be controlled by controlling the raw material ratio of the texturing liquid to improve the uniformity and flatness of the pyramid texture surface. A large-area inverted pyramid texture surface structure can be prepared on the surface of single crystal silicon, and it is compatible with the existing texturing process trough equipment, and the operation is simple and the production cost is low.

[0026] 2. The surfactants added in the present invention include cationic surfactants and non-ionic surfactants that do not contain metal ions. These two types of surfactants have excellent stability in acidic solutions and will not be doped with metal ions. When used in acidic texturing solutions, they can change the interfacial tension of the solution, promote the dispersion of hydrogen gas generated by etching on the surface of single crystal silicon, and enable bubbles to detach from the silicon surface in time, thereby increasing the number of texturing points on the surface of single crystal silicon and improving the uniformity and coverage of preparing large-area inverted pyramid texturing surfaces.

[0027] 3. The organic acid added in the present invention can adjust the acidity and etching rate of the texturing solution and shorten the texturing time. Alcohols contain rich hydroxyl groups and carbon ring structures and have strong adsorption capacity on the surface of single crystal silicon. The combination with organic acids can promote the production of continuous, uniform and dense texturing points.

[0028] 4. The corrosion inhibitor added in the present invention can neutralize part of the oxidant or dilute the oxidant concentration by changing the consistency of the texturing solution to slow down the corrosion rate of the texturing solution, and helps to remove the oxide layer or pollutants on the surface of the silicon wafer, and can protect the surface of the silicon wafer from oxidation damage to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the appearance of the inverted pyramid velvet surface of Example 2 of the present invention.

[0030] Figure 2 This is a SEM top view of the inverted pyramid of Example 2 of the present invention.

[0031] Figure 3 This is an oblique SEM view of the inverted pyramid of Example 2 of the present invention.

[0032] Figure 4 This is a SEM side view of the inverted pyramid of Example 2 of the present invention. DETAILED DESCRIPTION

[0033] 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 the embodiments. 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.

[0034] Example 1: This example discloses an acidic texturing solution for inverted pyramids of single-crystal silicon, comprising an acidic etching solution and a texturing additive.

[0035] The acidic etching solution was prepared from the following ingredients: 8 kg of 48 wt % hydrofluoric acid and 2 kg of 30 wt % hydrogen peroxide.

[0036] The texturing additive is prepared from the following ingredients: 5 g of a cationic surfactant, 10 g of a nonionic surfactant, 0.5 g of an organic acid, 0.2 g of an alcohol, 0.2 g of a corrosion inhibitor and 89.1 g of deionized water.

[0037] The cationic surfactant is composed of a mixture of 3g of polyquaternium-7 and 2g of coconut fatty acid diethylamide, the nonionic surfactant is composed of a mixture of 3g of dodecyl polyoxyethylene ether, 4g of polyvinyl pyrrolidone and 3g of xanthan gum, the organic acid is citric acid, the alcohol is ethylene glycol, and the corrosion inhibitor is lauryl dimethyl amine oxide.

[0038] This embodiment also discloses a method for preparing an acidic texturing solution for inverted pyramids of single crystal silicon, comprising the following steps:

[0039] S1. Prepare a texturing additive: add 5 g of a cationic surfactant, 10 g of a nonionic surfactant, 0.5 g of an organic acid, 0.2 g of an alcohol and 0.3 g of a corrosion inhibitor to 89.1 g of deionized water, and stir to prepare 100 g of a texturing additive;

[0040] S2, preparing an acidic etching solution: 8 kg of 48 wt% hydrofluoric acid and 2 kg of 30 wt% hydrogen peroxide are uniformly mixed to prepare an acidic etching solution;

[0041] S3. Prepare an inverted pyramid acidic texturing solution: evenly mix 10 kg of acidic etching solution and 100 g of texturing additive to prepare an inverted pyramid acidic texturing solution for single crystal silicon.

[0042] This embodiment also provides a method for making an inverted pyramid pile surface, comprising the following steps:

[0043] S11, adding the cleaned single crystal silicon wafer into the single crystal silicon inverted pyramid acidic texturing liquid, the texturing temperature is 30°C, and the time is controlled at 900s;

[0044] S12. After etching, wash with deionized water and dry with nitrogen to obtain a single crystal silicon wafer with an inverted pyramid velvet surface.

[0045] Example 2: This example discloses an acidic texturing solution for inverted pyramids of single-crystal silicon, comprising an acidic etching solution and a texturing additive.

[0046] The acidic etching solution was prepared from the following ingredients: 8 kg of 48 wt % hydrofluoric acid and 2 kg of 30 wt % hydrogen peroxide.

[0047] The texturing additive is prepared from the following ingredients: 15 g of a cationic surfactant, 2 g of a nonionic surfactant, 0.5 g of an organic acid, 0.3 g of an alcohol, 0.2 g of a corrosion inhibitor and 82 g of deionized water.

[0048] The cationic surfactant is polyquaternium-51, the nonionic surfactant is a mixture of 1g polyvinyl pyrrolidone and 1g gum arabic, the organic acid is isovaleric acid, the alcohol is cyclohexanol, and the corrosion inhibitor is ammonium pyrosulfite.

[0049] This embodiment also discloses a method for preparing an acidic texturing solution for inverted pyramids of single crystal silicon, comprising the following steps:

[0050] S1. Prepare a texturing additive: add 15 g of a cationic surfactant, 2 g of a nonionic surfactant, 0.5 g of an organic acid, 0.3 g of an alcohol and 0.2 g of a corrosion inhibitor to 82 g of deionized water, and stir to prepare 100 g of a texturing additive;

[0051] S2. Prepare an acidic etching solution: evenly mix 15 kg of 48 wt% hydrofluoric acid and 5 kg of 30 wt% hydrogen peroxide to prepare an acidic etching solution;

[0052] S3. Prepare an inverted pyramid acidic texturing solution: evenly mix 20 kg of acidic etching solution and 100 g of texturing additive to prepare an inverted pyramid acidic texturing solution for single crystal silicon.

[0053] This embodiment also provides a method for making an inverted pyramid pile surface, comprising the following steps:

[0054] S11, adding the cleaned single crystal silicon wafer into the single crystal silicon inverted pyramid acidic texturing liquid, the texturing temperature is 40°C, and the time is controlled at 1200s;

[0055] S12. After etching, wash with deionized water and dry with nitrogen to obtain a single crystal silicon wafer with an inverted pyramid velvet surface.

[0056] Example 3: This example discloses an acidic texturing solution for inverted pyramids of single-crystal silicon, comprising an acidic etching solution and a texturing additive.

[0057] The acidic etching solution was prepared from the following ingredients: 29 kg of 48 wt % hydrofluoric acid and 1 kg of 98 wt % sulfuric acid.

[0058] The texturing additive is prepared from the following ingredients: 30 g of a cationic surfactant, 5 g of a nonionic surfactant, 1 g of an organic acid, 0.1 g of an alcohol, 0.4 g of a corrosion inhibitor and 63.5 g of deionized water.

[0059] The cationic surfactant is a mixture of 20g N-dodecylmorpholine and 10g methanedisulfonic acid dipyridinium salt, the nonionic surfactant is dodecylbenzenesulfonyltriethanolamine, the organic acid is propionic acid, the alcohol is a mixture of 0.05g inositol and 0.05g cyclohexanol, and the corrosion inhibitor is a mixture of 0.2g sulfite and 0.2g dimethyl silicone oil.

[0060] This embodiment also discloses a method for preparing an acidic texturing solution for inverted pyramids of single crystal silicon, comprising the following steps:

[0061] S1. Prepare a texturing additive: add 30 g of a cationic surfactant, 5 g of a nonionic surfactant, 1 g of an organic acid, 0.1 g of an alcohol and 0.4 g of a corrosion inhibitor to 63.5 g of deionized water, and stir to prepare 100 g of a texturing additive;

[0062] S2. Prepare an acidic etching solution: evenly mix 29 kg of 48 wt % hydrofluoric acid and 1 kg of 98 wt % sulfuric acid to prepare an acidic etching solution;

[0063] S3. Prepare an inverted pyramid acidic texturing liquid: evenly mix 10 kg of acidic etching liquid and 100 g of texturing additive to prepare an inverted pyramid acidic texturing liquid for single crystal silicon.

[0064] This embodiment also provides a method for making an inverted pyramid pile surface, comprising the following steps:

[0065] S11, adding the cleaned single crystal silicon wafer into the single crystal silicon inverted pyramid acidic texturing liquid, the texturing temperature is 10°C, and the time is controlled at 600s;

[0066] S12. After etching, wash with deionized water and dry with nitrogen to obtain a single crystal silicon wafer with an inverted pyramid velvet surface.

[0067] Example 4: This example discloses an acidic texturing solution for inverted pyramids of single-crystal silicon, comprising an acidic etching solution and a texturing additive.

[0068] The acidic etching solution was prepared from the following ingredients: 9.5 kg of 48 wt % hydrofluoric acid and 0.5 kg of 68 wt % nitric acid.

[0069] The texturing additive is prepared from the following ingredients: 6.5 g of a cationic surfactant, 1.2 g of a nonionic surfactant, 0.8 g of an organic acid, 0.2 g of an alcohol, 0.3 g of a corrosion inhibitor and 91 g of deionized water.

[0070] The cationic surfactant is a mixture of 3g of methylsulfonylpiperazine, 0.5g of dodecylamine hydrochloride and 2g of tetramethylammonium sulfate, the nonionic surfactant is a mixture of 0.2g of pentadecyl D-glucoside, 0.5g of polyvinylpyrrolidone and 0.5g of xanthan gum, the organic acid is citric acid, the alcohol is cyclopentanol, and the corrosion inhibitor is methylphenyl silicone oil.

[0071] This embodiment also discloses a method for preparing an acidic texturing solution for inverted pyramids of single crystal silicon, comprising the following steps:

[0072] S1. Prepare a texturing additive: add 6.5 g of a cationic surfactant, 1.2 g of a nonionic surfactant, 0.8 g of an organic acid, 0.2 g of an alcohol and 0.3 g of a corrosion inhibitor to 65 g of deionized water, and stir to prepare 100 g of a texturing additive;

[0073] S2, preparing an acidic etching solution: 9.5 kg of 48 wt % hydrofluoric acid and 0.5 kg of 68 wt % nitric acid are uniformly mixed to prepare 10 kg of an acidic etching solution;

[0074] S3. Prepare an inverted pyramid acidic texturing liquid: evenly mix 10 kg of acidic etching liquid and 100 g of texturing additive to prepare an inverted pyramid acidic texturing liquid for single crystal silicon.

[0075] This embodiment also provides a method for making an inverted pyramid pile surface, comprising the following steps:

[0076] S11, adding the cleaned single crystal silicon wafer into the single crystal silicon inverted pyramid acidic texturing liquid, the texturing temperature is 50°C, and the time is controlled at 1800s;

[0077] S12. After etching, wash with deionized water and dry with nitrogen to obtain a single crystal silicon wafer with an inverted pyramid velvet surface.

[0078] Example 5: This example discloses an acidic texturing solution for inverted pyramids of single-crystal silicon, comprising an acidic etching solution and a texturing additive.

[0079] The acidic etching solution was prepared from the following ingredients: 15 kg of 49 wt % hydrofluoric acid and 5 kg of 68 wt % nitric acid.

[0080] The texturing additive is prepared from the following ingredients: 20 g of a cationic surfactant, 10 g of a nonionic surfactant, 8 g of an organic acid, 1 g of an alcohol, 1 g of a corrosion inhibitor and 60 g of deionized water.

[0081] The cationic surfactant is a mixture of 10g of polyquaternium-7 and 10g of polyquaternium-51, the nonionic surfactant is a mixture of 2g of pentadecyl D-glucoside and 8g of nonadecyl D-glucoside, the organic acid is citric acid, the alcohol is ethylene glycol, and the corrosion inhibitor is a mixture of 0.5g of methylphenyl silicone oil and 0.5g of dimethyl silicone oil.

[0082] This embodiment also discloses a method for preparing an acidic texturing solution for inverted pyramids of single crystal silicon, comprising the following steps:

[0083] S1. Prepare a texturing additive: add 20g of a cationic surfactant, 10g of a nonionic surfactant, 8g of an organic acid, 1g of an alcohol and 1g of a corrosion inhibitor to 60g of deionized water, and stir to prepare 100g of a texturing additive;

[0084] S2, preparing an acidic etching solution: 15 kg of 49 wt % hydrofluoric acid and 5 kg of 68 wt % nitric acid are uniformly mixed to prepare 10 kg of an acidic etching solution;

[0085] S3. Prepare an inverted pyramid acidic texturing solution: evenly mix 20 kg of acidic etching solution and 100 g of texturing additive to prepare an inverted pyramid acidic texturing solution for single crystal silicon.

[0086] This embodiment also provides a method for making an inverted pyramid pile surface, comprising the following steps:

[0087] S11, adding the cleaned single crystal silicon wafer into the single crystal silicon inverted pyramid acidic texturing liquid, the texturing temperature is 30°C, and the time is controlled at 900s;

[0088] S12. After etching, wash with deionized water and dry with nitrogen to obtain a single crystal silicon wafer with an inverted pyramid velvet surface.

[0089] Example 6: This example discloses an acidic texturing solution for inverted pyramids of single-crystal silicon, comprising an acidic etching solution and a texturing additive.

[0090] The acidic etching solution was prepared from the following ingredients: 8 kg of 40 wt % hydrofluoric acid and 2 kg of 98 wt % sulfuric acid.

[0091] The texturing additive is prepared from the following ingredients: 20 g of a cationic surfactant, 5 g of a nonionic surfactant, 5 g of an organic acid, 3 g of an alcohol, 2 g of a corrosion inhibitor and 65 g of deionized water.

[0092] The cationic surfactant is dodecylamine hydrochloride, the nonionic surfactant is a mixture of 10g polyvinyl alcohol 2699 and 10g polyvinyl alcohol 2488, the organic acid is a mixture of 3g citric acid and 2g lactic acid, the alcohol is a mixture of 1g cyclopentanol and 2g cyclohexanol, and the corrosion inhibitor is a mixture of 1g sulfite and 1g ammonium pyrosulfite.

[0093] This embodiment also discloses a method for preparing an acidic texturing solution for inverted pyramids of single crystal silicon, comprising the following steps:

[0094] S1. Prepare a texturing additive: add 20 g of a cationic surfactant, 5 g of a nonionic surfactant, 5 g of an organic acid, 3 g of an alcohol and 2 g of a corrosion inhibitor to 65 g of deionized water, and stir to prepare 100 g of a texturing additive;

[0095] S2, preparing an acidic etching solution: 8 kg of 40 wt% hydrofluoric acid and 2 kg of 98 wt% sulfuric acid are uniformly mixed to prepare 10 kg of an acidic etching solution;

[0096] S3. Prepare an inverted pyramid acidic texturing solution: evenly mix 10 kg of acidic etching solution and 100 g of texturing additive to prepare an inverted pyramid acidic texturing solution for single crystal silicon.

[0097] This embodiment also provides a method for making an inverted pyramid pile surface, comprising the following steps:

[0098] S11, adding the cleaned single crystal silicon wafer into the single crystal silicon inverted pyramid acidic texturing liquid, the texturing temperature is 40°C, and the time is controlled at 1000s;

[0099] S12. After etching, wash with deionized water and dry with nitrogen to obtain a single crystal silicon wafer with an inverted pyramid velvet surface.

[0100] Example 7: This example discloses an acidic texturing solution for inverted pyramids of single-crystal silicon, comprising an acidic etching solution and a texturing additive.

[0101] The acidic etching solution was prepared from the following ingredients: 9.5 kg of 35 wt % hydrofluoric acid and 0.5 kg of 30 wt % hydrogen peroxide.

[0102] The texturing additive is prepared from the following ingredients: 10 g of a cationic surfactant, 5 g of a nonionic surfactant, 2 g of an organic acid, 2 g of an alcohol, 1 g of a corrosion inhibitor and 80 g of deionized water.

[0103] The cationic surfactant is a mixture of 3g N-dodecyldodecane-1-amine hydrochloride, 3g dodecylamine hydrochloride and 4g tetramethylammonium sulfate, the nonionic surfactant is a mixture of 2.5g xanthan gum and 2.5g gum arabic, the organic acid is a mixture of 1g citric acid and 1g propionic acid, the alcohol is a mixture of 1g ethylene glycol and 1g inositol, and the corrosion inhibitor is a mixture of 0.5g lauryl dimethylamine oxide and 0.5g ammonium pyrosulfite.

[0104] This embodiment also discloses a method for preparing an acidic texturing solution for inverted pyramids of single crystal silicon, comprising the following steps:

[0105] S1. Prepare a texturing additive: add 10g of a cationic surfactant, 5g of a nonionic surfactant, 2g of an organic acid, 2g of an alcohol and 1g of a corrosion inhibitor deionized water into 80g of deionized water, and stir to prepare 100g of a texturing additive;

[0106] S2, preparing an acidic etching solution: 9.5 kg of 35 wt% hydrofluoric acid and 0.5 kg of 30 wt% hydrogen peroxide are uniformly mixed to prepare 10 kg of an acidic etching solution;

[0107] S3. Prepare an inverted pyramid acidic texturing liquid: evenly mix 10 kg of acidic etching liquid and 100 g of texturing additive to prepare an inverted pyramid acidic texturing liquid for single crystal silicon.

[0108] This embodiment also provides a method for making an inverted pyramid pile surface, comprising the following steps:

[0109] S11, adding the cleaned single crystal silicon wafer into the single crystal silicon inverted pyramid acidic texturing liquid, the texturing temperature is 30°C, and the time is controlled at 800s;

[0110] S12. After etching, wash with deionized water and dry with nitrogen to obtain a single crystal silicon wafer with an inverted pyramid velvet surface.

[0111] Example 8: This example discloses an acidic texturing solution for inverted pyramids of single-crystal silicon, comprising an acidic etching solution and a texturing additive.

[0112] The acidic etching solution was prepared from the following ingredients: 9.5 kg of 48 wt % hydrofluoric acid and 0.5 kg of 68 wt % nitric acid.

[0113] The texturing additive is prepared from the following ingredients: 5 g of a cationic surfactant, 10 g of a nonionic surfactant, 0.5 g of an organic acid, 0.2 g of an alcohol, 0.2 g of a corrosion inhibitor and 89.1 g of deionized water.

[0114] The cationic surfactant is a mixture of 3g N-dodecylmorpholine, 0.5g methanedisulfonic acid dipyridinium salt and 1g methylsulfonylpiperazine, the nonionic surfactant is a mixture of 0.2g pentadecyl D-glucoside, 0.5g polyvinylpyrrolidone and 0.5g xanthan gum, the organic acid is a mixture of 0.25g succinic acid and 0.25g isovaleric acid, the alcohol is a mixture of 0.1g cyclohexanol and 0.1g cyclopentanol, and the corrosion inhibitor is a mixture of 0.1g sulfite and 0.1g methylphenyl silicone oil.

[0115] This embodiment also discloses a method for preparing an acidic texturing solution for inverted pyramids of single crystal silicon, comprising the following steps:

[0116] S1. Prepare a texturing additive: add 5 g of a cationic surfactant, 10 g of a nonionic surfactant, 0.5 g of an organic acid, 0.2 g of an alcohol and 0.2 g of a corrosion inhibitor to 89.1 g of deionized water, and stir to prepare 100 g of a texturing additive;

[0117] S2, preparing an acidic etching solution: 9.5 kg of 48 wt % hydrofluoric acid and 0.5 kg of 68 wt % nitric acid are uniformly mixed to prepare 10 kg of an acidic etching solution;

[0118] S3. Prepare an inverted pyramid acidic texturing solution: evenly mix 10 kg of acidic etching solution and 100 g of texturing additive to prepare an inverted pyramid acidic texturing solution for single crystal silicon.

[0119] This embodiment also provides a method for making an inverted pyramid pile surface, comprising the following steps:

[0120] S11, adding the cleaned single crystal silicon wafer into the single crystal silicon inverted pyramid acidic texturing liquid, the texturing temperature is 50°C, and the time is controlled at 1800s;

[0121] S12. After etching, wash with deionized water and dry with nitrogen to obtain a single crystal silicon wafer with an inverted pyramid velvet surface.

[0122] Example 9: This example discloses an acidic texturing solution for inverted pyramids of single-crystal silicon, comprising an acidic etching solution and a texturing additive.

[0123] The acidic etching solution was prepared from the following ingredients: 9.5 kg of 48 wt % hydrofluoric acid and 0.5 kg of 98 wt % sulfuric acid.

[0124] The texturing additive is prepared from the following ingredients: 30 g of a cationic surfactant, 5 g of a nonionic surfactant, 1 g of an organic acid, 0.1 g of an alcohol, 0.4 g of a corrosion inhibitor and 63.5 g of deionized water.

[0125] The cationic surfactant is a mixture of 3g of methylsulfonylpiperazine, 1g of methylsulfonylpiperazine and 1g of tetramethylammonium sulfate, the nonionic surfactant is a mixture of 0.2g of pentadecyl D-glucoside, 0.5g of polyvinylpyrrolidone and 0.5g of xanthan gum, the organic acid is citric acid, the alcohol is cyclopentanol, and the corrosion inhibitor is methylphenyl silicone oil.

[0126] This embodiment also discloses a method for preparing an acidic texturing solution for inverted pyramids of single crystal silicon, comprising the following steps:

[0127] S1. Prepare a texturing additive: add 30 g of a cationic surfactant, 5 g of a nonionic surfactant, 1 g of an organic acid, 0.1 g of an alcohol and 0.4 g of a corrosion inhibitor 63.5 g into deionized water, and stir to prepare 100 g of a texturing additive;

[0128] S2, preparing an acidic etching solution: 9.5 kg of 48 wt % hydrofluoric acid and 0.5 kg of 98 wt % sulfuric acid are uniformly mixed to prepare 10 kg of an acidic etching solution;

[0129] S3. Prepare an inverted pyramid acidic texturing solution: evenly mix 10 kg of acidic etching solution and 100 g of texturing additive to prepare an inverted pyramid acidic texturing solution for single crystal silicon.

[0130] This embodiment also provides a method for making an inverted pyramid pile surface, comprising the following steps:

[0131] S11, adding the cleaned single crystal silicon wafer into the single crystal silicon inverted pyramid acidic texturing liquid, the texturing temperature is 10°C, and the time is controlled at 400s;

[0132] S12. After etching, wash with deionized water and dry with nitrogen to obtain a single crystal silicon wafer with an inverted pyramid velvet surface.

[0133] Example 10: This example discloses an acidic texturing solution for inverted pyramids of single crystal silicon, comprising an acidic etching solution and a texturing additive.

[0134] The acidic etching solution was prepared from the following ingredients: 9 kg of 48 wt % hydrofluoric acid and 1 kg of 30 wt % hydrogen peroxide.

[0135] The texturing additive is prepared from the following ingredients: 30 g of a cationic surfactant, 5 g of a nonionic surfactant, 1 g of an organic acid, 0.1 g of an alcohol, 0.4 g of a corrosion inhibitor and 63.5 g of deionized water.

[0136] The cationic surfactant is polyquaternium-51, the nonionic surfactant is polyvinyl pyrrolidone, the organic acid is citric acid, the alcohol is cyclopentanol, and the corrosion inhibitor is lauryl dimethyl amine oxide.

[0137] This embodiment also discloses a method for preparing an acidic texturing solution for inverted pyramids of single crystal silicon, comprising the following steps:

[0138] S1. Prepare a texturing additive: add 30 g of a cationic surfactant, 5 g of a nonionic surfactant, 1 g of an organic acid, 0.1 g of an alcohol and 0.4 g of a corrosion inhibitor 63.5 g into deionized water, and stir to prepare 100 g of a texturing additive;

[0139] S2. Prepare an acidic etching solution: evenly mix 9 kg of 48 wt% hydrofluoric acid and 1 kg of 30 wt% hydrogen peroxide to prepare 10 kg of acidic etching solution;

[0140] S3. Prepare an inverted pyramid acidic texturing solution: evenly mix 10 kg of acidic etching solution and 100 g of texturing additive to prepare an inverted pyramid acidic texturing solution for single crystal silicon.

[0141] This embodiment also provides a method for making an inverted pyramid pile surface, comprising the following steps:

[0142] S11, adding the cleaned single crystal silicon wafer into the single crystal silicon inverted pyramid acidic texturing liquid, the texturing temperature is 20°C, and the time is controlled at 600s;

[0143] S12. After etching, wash with deionized water and dry with nitrogen to obtain a single crystal silicon wafer with an inverted pyramid velvet surface.

[0144] Comparative Example 1: The difference between this comparative example and Example 2 is that the acidic etching solution composition is changed to 8 kg of 60 wt % hydrofluoric acid and 2 kg of 10 wt % hydrogen peroxide.

[0145] Comparative Example 2: The difference between this comparative example and Example 2 is that no organic acid is added to the texturing additive component and the alcohol is replaced by ethanol.

[0146] Comparative Example 3: This comparative example differs from Example 2 in that no cationic surfactant is added.

[0147] Comparative Example 4: This comparative example differs from Example 2 in that no nonionic surfactant is added.

[0148] Comparative Example 5: This comparative example differs from Example 2 in that no corrosion inhibitor is added.

[0149] Performance test characterization

[0150] 1. Single crystal silicon micro texture characterization test

[0151] The texture structure of inverted pyramid textured single crystal silicon was observed using a TM 3000 scanning electron microscope. Figures 2 to 4This is the SEM image of the silicon wafer obtained in Example 2.

[0152] 2. Single crystal silicon suede reflectivity test

[0153] The reflectivity of the inverted pyramid velvet surfaces obtained in each embodiment and comparative example was tested using a Carry 100 self-visible spectrophotometer. The test results are shown in Table 1:

[0154] Serial number Reflectivity / % Example 1 6.2％ Example 2 5.5％ Example 3 5.3％ Example 4 5.0％ Example 5 6.5％ Example 6 3.7％ Example 7 4.6％ Example 8 5.5％ Example 9 3.5％ Example 10 5.8％ Comparative Example 1 11.6％ Comparative Example 2 8.0％ Comparative Example 3 9.3％ Comparative Example 4 7.7％ Comparative Example 5 7.4％

[0155] Depend on Figures 1 to 4 It can be seen that the size of the inverted pyramid of the present invention is between 1 and 3 um, and the inverted pyramid velvet surface has good uniformity and coverage. From the data in Table 1, it can be seen that the inverted pyramid velvet surface prepared by the present invention is uniform, and the reflectivity is between 3.5 and 6.5%, indicating that the acidic velvet liquid for monocrystalline silicon inverted pyramid prepared by the present invention greatly improves the reflectivity of the inverted pyramid velvet surface.

[0156] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

[0157] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. An acidic texturing solution for inverted pyramid of single crystal silicon, characterized in that: It is made by mixing acidic etching solution and texturing additive in a mass ratio of 100:0.01-1; The acidic texturing solution for inverted pyramids of single crystal silicon does not contain metal ions; The texturing additive comprises the following components in percentage by mass: 1% to 60% of a cationic surfactant, 0.2% to 40% of a nonionic surfactant, 0.5% to 10% of an organic acid, 0.1% to 5% of an alcohol, 0.1% to 5% of a corrosion inhibitor, and the remainder being deionized water.

2. The acidic texturing solution for inverted pyramid of single crystal silicon according to claim 1, characterized in that: The cationic surfactant is one or more combinations of polyquaternary ammonium salt type, pyridine ring type, morpholine ring type, piperazine ring type and fatty amine salt type.

3. The acidic texturing solution for inverted pyramid of single crystal silicon according to claim 1, characterized in that: The nonionic surfactant is one or more combinations of polyoxyethylene ether, polyvinyl alcohol, ethanolamine, alkyl glycoside, polyvinyl pyrrolidone, xanthan gum and gum arabic.

4. The acidic texturing solution for inverted pyramid of single crystal silicon according to claim 1, characterized in that: The organic acid is one or more combinations of isovaleric acid, propionic acid, lactic acid, succinic acid and citric acid; the alcohol is one or more combinations of ethylene glycol, inositol, cyclohexanol and cyclopentanol.

5. The acidic texturing solution for inverted pyramid of single crystal silicon according to claim 1, characterized in that: The corrosion inhibitor is one or more combinations of lauryl dimethylamine oxide, sulfurous acid, ammonium pyrosulfite, methylphenyl silicone oil and dimethyl silicone oil.

6. The acidic texturing solution for inverted pyramid of single crystal silicon according to claim 1, characterized in that: The acidic etching solution comprises hydrofluoric acid and an oxidant, the mass ratio of hydrofluoric acid to the oxidant is 1:0.01-1; the concentration of the hydrofluoric acid is 35wt%-50wt%; the oxidant is one or more combinations of hydrogen peroxide, concentrated sulfuric acid and nitric acid.

7. A method for preparing an acidic texturing solution for inverted pyramids of single crystal silicon, characterized in that: The steps include: S1. preparing a texturing additive: adding a cationic surfactant, a nonionic surfactant, an organic acid, an alcohol and a corrosion inhibitor into the remaining deionized water according to the mass percentage, and stirring to obtain a texturing additive; S2. preparing an acidic etching solution: uniformly mixing hydrofluoric acid and an oxidant to prepare an acidic etching solution; S3. Prepare an inverted pyramid acidic texturing solution: evenly mix the acidic etching solution and the texturing additive to obtain an inverted pyramid acidic texturing solution for single crystal silicon.

8. An application of an acidic texturing liquid for inverted pyramid of single crystal silicon in the preparation of an inverted pyramid texture structure, characterized in that: The preparation method of the inverted pyramid velvet structure comprises the following steps: S11, adding the cleaned single crystal silicon wafer into the single crystal silicon inverted pyramid acidic texturing liquid, the texturing temperature is 5-50°C, and the time is controlled at 300-1800s; S12. After etching, wash with deionized water and blow dry with nitrogen to obtain a single crystal silicon wafer with an inverted pyramid velvet surface.

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