Silicon wafer cleaning solution as well as preparation method and application thereof

Abstract

The invention provides a silicon wafer cleaning solution. The silicon wafer cleaning solution comprises the following components in percentage by mass: 2-8% of potassium hydroxide, 5-15% of a chelating agent, 1-5% of an ether stabilizer, 5-10% of a surfactant and the balance of water, the surface active agent comprises a corrosion inhibition type surface active agent and a cleaning type surface active agent, and the mass ratio of the cleaning type surface active agent to the corrosion inhibition type surface active agent is (0.2-3): 1, preferably (1-2): 1. Through cooperation of the cleaning type surfactant and the corrosion inhibition type surfactant, the cleaning liquid can play a corrosion inhibition effect and can effectively remove metal ions and oil stains on the surface of a silicon wafer, the surface of the cleaned silicon wafer is free of particle residues and pits, and the cleaning liquid still has an excellent cleaning effect after being placed for a long time.

Description

Technical Field

[0001] This invention relates to the field of cleaning solutions, specifically to a silicon wafer cleaning solution, its preparation method, and its application. Background Technology

[0002] Integrated circuits are one of the main high-tech drivers of socio-economic and information technology development. Single-crystal silicon wafers, as the fundamental material in integrated circuit manufacturing, are the core and foundation of the semiconductor industry, and their surface quality directly affects the overall performance of integrated circuits. After undergoing various processing techniques such as slicing, grinding, and polishing, single-crystal silicon wafers introduce numerous scratches and impurities onto their surface. Therefore, the cleaning process after ultra-precision silicon wafer processing is a crucial step in integrated circuit manufacturing, and the cleaning effect directly determines the performance of the entire integrated circuit. Cleaning single-crystal silicon wafers must not only remove various impurities adhering to their surface but also effectively remove surface oil stains, which is of great significance for effectively improving the performance of single-crystal silicon components.

[0003] Patent CN202211640108.8 discloses a silicon wafer cleaning solution composed of potassium hydroxide, a complexing agent, tetramethylammonium hydroxide, and hydrogen peroxide. However, it cannot effectively clean oil stains on the silicon wafer surface, and the additives are harmful to the environment and unstable. Patent CN202311790146.6 discloses an environmentally friendly silicon wafer cleaning solution that can effectively remove impurities from the silicon wafer surface without polluting the environment. However, it has poor ability to remove oil stains from the silicon wafer surface, and the amount of cleaning solution used during cleaning is large, resulting in poor economic efficiency. Patent CN202011047317.2 discloses a silicon wafer cleaning solution additive, a silicon wafer cleaning solution, and its application. It uses glycerol and other surfactants, polyquaternium salts and other stabilizers, and polyethyleneimine and serine as metal chelating agents. It can effectively remove metal ions from the silicon wafer surface, but the amount of cleaning solution used during cleaning is large, resulting in poor economic efficiency. Patent CN202010783255.5 discloses a silicon wafer cleaning solution for power semiconductor devices, which uses C12 fatty alcohol polyoxyethylene ether and alkyl diphenyl ether disulfonate as compounding agents, and adds sodium alkylbenzene sulfonate, sodium hydroxide and deionized water to prepare the silicon wafer cleaning solution. However, the solution has poor stability. Therefore, it is very important to develop a silicon wafer cleaning solution that is cost-effective, stable and has good cleaning effect. Summary of the Invention

[0004] To address the above problems, the present invention provides a silicon wafer cleaning solution, wherein the components and mass percentages of the cleaning solution are as follows: 2-8% potassium hydroxide, 5-15% chelating agent, 1-5% ether stabilizer, 5-10% surfactant and the balance water.

[0005] Furthermore, the surfactant includes a corrosion-inhibiting surfactant and a cleaning surfactant, wherein the mass ratio of the cleaning surfactant to the corrosion-inhibiting surfactant is (0.2-3):1, preferably (1-2.5):1.

[0006] Furthermore, the corrosion-inhibiting surfactant is stable under strong alkaline conditions and comprises one or more of the following: tridecyl polyoxyethylene ether phosphate, polyoxyethylene nonylphenol phosphate, isooctanol polyoxyethylene ether monophosphate, isodecyl alcohol polyether phosphate, amino-dodecyl polyethylene glycol-carboxylic acid, or C8 fatty alcohol ethylene ether phosphate monoester.

[0007] Furthermore, the cleaning surfactant comprises one or more of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, sodium α-alkenyl sulfonate, isotridecyl alcohol polyoxyethylene ether, cocamidopropyl betaine, or sodium fatty acid methyl ester sulfonate.

[0008] Furthermore, the fatty alcohol polyoxyethylene ether comprises at least one of AEO-3, AEO-5, or AEO-9; Furthermore, the alkylphenol polyoxyethylene ether comprises at least one of OP-7 or OP-10; Furthermore, the sodium fatty acid methyl ester sulfonate comprises at least one of C14 sodium fatty acid methyl ester sulfonate, C16 sodium fatty acid methyl ester sulfonate, or C18 sodium fatty acid methyl ester sulfonate.

[0009] Furthermore, the chelating agent comprises one or more of the following: sodium gluconate, EDTA-2Na, EDTA-4Na, diethylenetriaminepentamethylphosphonic acid, trisodium citrate, hydroxyethylidene diphosphonic acid, 2-pyridinecarboxylic acid, aminotrimethylenephosphonic acid, nitrotriacetic acid, ethylenediaminetetramethylenephosphonic acid, sodium tripolyphosphate, sodium hexametaphosphate, diethylenetriaminepentaacetic acid, or citric acid.

[0010] Furthermore, the ether stabilizer comprises one or more of diethylene glycol butyl ether, ethylene glycol phenyl ether, dipropylene glycol butyl ether, propylene glycol butyl ether, dipropylene glycol ethyl ether, ethylene glycol ethyl ether, and propylene glycol ethyl ether.

[0011] Furthermore, the potassium hydroxide has a mass percentage of 4-6%, and the total content of other metal ions besides potassium ions is <5 ppm.

[0012] The present invention also provides a method for preparing a silicon wafer cleaning solution, wherein potassium hydroxide, a chelating agent, an ether stabilizer and a surfactant are added to water under stirring conditions, and the mixture is stirred for 0.5-2 hours after the addition is completed to obtain the silicon wafer cleaning solution.

[0013] The present invention also provides a method for using silicon wafer cleaning solution, wherein the silicon wafer cleaning solution is diluted with deionized water at a mass ratio of 1:20-1:40, heated to 70°C, and the silicon wafer is placed in the cleaning solution for ultrasonic cleaning for 5-10 minutes.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The silicon wafer cleaning solution provided by this invention does not contain hydrogen peroxide, but instead contains surfactants that remain active in a strongly alkaline environment. Through the synergistic effect of corrosion inhibitors and cleaning surfactants, it can both inhibit corrosion and effectively remove metal ions and oil stains from the silicon wafer surface. The cleaned silicon wafer surface is free of particle residue and dents, and it still has excellent cleaning effect after long-term storage. The silicon wafer cleaning solution of this invention can be diluted before use, and still has good cleaning effect after dilution, without damaging the silicon wafer surface, thus having high economic benefits. Attached Figure Description

[0015] Figure 1 Example 1 Comparison of silicon wafer before and after cleaning: (a) Microscopic surface image of silicon wafer before cleaning, (b) Microscopic surface image of silicon wafer after cleaning, (c) SEM simulation image of silicon wafer after cleaning.

[0016] Figure 2 Comparative Example 2: Comparison of silicon wafers before and after cleaning: (a) Microscopic surface image of silicon wafers before cleaning, (b) Microscopic surface image of silicon wafers after cleaning, (c) SEM simulation image of silicon wafers after cleaning.

[0017] Figure 3 Comparative Example 3: Comparison of silicon wafers before and after cleaning: (a) Microscopic surface image of silicon wafers before cleaning, (b) Microscopic surface image of silicon wafers after cleaning, (c) SEM simulation image of silicon wafers after cleaning. Detailed Implementation

[0018] The present invention will be further described below through embodiments and comparative examples. The embodiments described in the present invention are preferred embodiments. For those skilled in the art, corresponding adjustments and improvements can be made without departing from the technical principles of the present invention, and these adjustments and improvements should also be considered within the scope of protection of the present invention.

[0019] The composition and weight content of the silicon wafer cleaning solution in the examples and comparative examples are shown in Table 1. The balance is water, and the sum of the mass percentages of each component is 100%.

[0020] Preparation of silicon wafer cleaning solution: According to the proportions in Table 1, potassium hydroxide, chelating agent, ether stabilizer, and surfactant are added to deionized water in sequence under high-speed stirring. After the addition is complete, stir for another 1 hour to obtain the silicon wafer cleaning solution.

[0021] Silicon wafer cleaning: Dilute the silicon wafer cleaning solution obtained in the above steps with deionized water at a mass ratio of 1:20, heat it to 70°C in an ultrasonic cleaner, and then immerse the silicon wafer in the cleaning solution for 5 minutes. The contact angle α0 between the cleaned silicon wafer and water is shown in Table 1.

[0022] The silicon wafer cleaning solution was left to stand for one month before being used to clean the silicon wafers again. The contact angle α1 between the cleaned silicon wafers and water is shown in Table 1.

[0023] Table 1. Formulations and contact angles between silicon wafers and water after cleaning in the examples and comparative examples.

[0024] As shown in the figure, after cleaning the silicon wafer with the cleaning solution of Example 1, the surface of the silicon wafer is clean and basically without damage or corrosion. Figure 2 The surface after cleaning with Comparative Example 2 shows that the silicon wafer surface has many pits. Figure 3 The surface after cleaning with Comparative Example 3 shows that there are still many residues on the silicon wafer surface, indicating that it was not completely cleaned.

[0025] As can be seen from the attached figures and the data in Table 1, the cleaning solution provided by the present invention, by compounding corrosion-inhibiting surfactants and cleaning surfactants in a certain proportion, can significantly improve the cleaning effect in an alkaline cleaning solution system without hydrogen peroxide. The silicon wafer surface is free of oil stains and particle residues, and the cleaning solution with the two surfactants added can still maintain excellent cleaning effect after being left for a month and then used again.

Claims

1. A silicon wafer cleaning solution, characterized in that: The cleaning solution comprises the following components and mass percentages: 2-8% potassium hydroxide, 5-15% chelating agent, 1-5% ether stabilizer, 5-10% surfactant, and the balance being water.

2. The silicon wafer cleaning solution according to claim 1, characterized in that, The surfactants include corrosion inhibitors and cleaning agents, and the mass ratio of the cleaning agent to the corrosion inhibitor is (0.2-3):1, preferably (1-2.5):

1.

3. The silicon wafer cleaning solution according to claim 2, characterized in that, The corrosion-inhibiting surfactant described herein is stable under strong alkaline conditions and comprises one or more of the following: tridecyl polyoxyethylene ether phosphate, polyoxyethylene nonylphenol phosphate, isooctanol polyoxyethylene ether monophosphate, isodecyl alcohol polyether phosphate, amino-dodecyl polyethylene glycol-carboxylic acid, or C8 fatty alcohol ethylene ether phosphate monoester.

4. The silicon wafer cleaning solution according to claim 2, characterized in that, The cleaning surfactant comprises one or more of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, sodium α-alkenyl sulfonate, isotridecyl alcohol polyoxyethylene ether, cocamidopropyl betaine, or sodium fatty acid methyl ester sulfonate.

5. The silicon wafer cleaning solution according to claim 4, characterized in that, The fatty alcohol polyoxyethylene ether contains at least one of AEO-3, AEO-5, or AEO-9; The alkylphenol polyoxyethylene ether comprises at least one of OP-7 or OP-10; The sodium fatty acid methyl ester sulfonate comprises at least one of C14 sodium fatty acid methyl ester sulfonate, C16 sodium fatty acid methyl ester sulfonate, or C18 sodium fatty acid methyl ester sulfonate.

6. The silicon wafer cleaning solution according to claim 1, characterized in that, The chelating agent comprises one or more of the following: sodium gluconate, EDTA-2Na, EDTA-4Na, diethylenetriaminepentamethylphosphonic acid, trisodium citrate, hydroxyethylidene diphosphonic acid, 2-pyridinecarboxylic acid, aminotrimethylenephosphonic acid, nitrotriacetic acid, ethylenediaminetetramethylenephosphonic acid, sodium tripolyphosphate, sodium hexametaphosphate, diethylenetriaminepentaacetic acid, or citric acid.

7. The silicon wafer cleaning solution according to claim 1, characterized in that, The ether stabilizers include one or more of diethylene glycol butyl ether, ethylene glycol phenyl ether, dipropylene glycol butyl ether, propylene glycol butyl ether, dipropylene glycol ethyl ether, ethylene glycol ethyl ether, and propylene glycol ethyl ether.

8. The silicon wafer cleaning solution according to claim 1, characterized in that, The potassium hydroxide is 4-6% by mass, and the total content of metal ions other than potassium ions is <5ppm.

9. The method for preparing the silicon wafer cleaning solution according to any one of claims 1-8, characterized in that, Potassium hydroxide, chelating agent, ether stabilizer and surfactant are added to water under stirring. After the addition is complete, the mixture is stirred for 0.5-2 hours to obtain silicon wafer cleaning solution.

10. The application of the silicon wafer cleaning solution according to any one of claims 1-8, characterized in that, Dilute the silicon wafer cleaning solution with deionized water at a mass ratio of 1:20-1:40, heat to 70℃, and then immerse the silicon wafer in the cleaning solution for ultrasonic cleaning for 5-10 minutes.

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