A cleaning agent for silicon carbide substrate and a cleaning process for silicon carbide substrate

Abstract

This invention provides a cleaning agent and a cleaning process for silicon carbide substrates, comprising the following components by mass fraction: sulfuric acid: 0.1wt%–50wt%, hydrogen peroxide: 5wt%–50wt%, metal ion chelating agent: 0.1wt%–10wt%, cationic surfactant: 0.1wt%–10wt%, nonionic surfactant: 0.1wt%–10wt%, defoamer: 0.02wt%–6wt%, dispersant: 0.1wt%–5wt%, with the balance being water. The cleaning agent of this invention can effectively solve the problem of surface contamination residue on silicon carbide substrates after alumina polishing, effectively cleaning polishing fluid, metal ions, inorganic particles, and other contaminants remaining on the surface of the silicon carbide substrate, and effectively improving the apparent cleanliness of the silicon carbide substrate after CMP.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductors, and in particular relates to a cleaning agent for a silicon carbide substrate and a cleaning process for the silicon carbide substrate. Background Art

[0002] During the production of silicon carbide substrates, polishing liquid, metal ions, and other pollutants such as air particles will be present on the surface of the substrate after polishing. These pollutants exist in the form of physical adsorption and chemical adsorption. Physical adsorption is mainly the intermolecular force, electrostatic attraction, and capillary force formed between the molecules on the surface of the silicon carbide substrate and the stain particles. Chemical adsorption is mainly the chemical bonding between the substrate surface and the stain. This bonding force is mostly covalent bonding, that is, new substances are generated on the solid surface. Compared with the intermolecular force, the chemical bond force is greater, and long-term placement may cause the stains on the surface of the silicon carbide substrate to be transformed from physical adsorption to chemical adsorption. The stains left in this way are also more difficult to clean. Therefore, the silicon carbide substrate needs to be cleaned promptly and effectively after the processing is completed to avoid increasing the time and cost of the cleaning process. Summary of the invention

[0003] The purpose of the present invention is to provide a cleaning agent for silicon carbide substrates and a cleaning process for silicon carbide substrates. The cleaning agent in the present invention can more effectively solve the problem of residual dirt such as polishing liquid, metal ions, inorganic particles, etc. on the surface of silicon carbide substrates after CMP, thereby improving the cleaning quality of silicon carbide substrates.

[0004] The present invention provides a cleaning agent for a silicon carbide substrate, comprising the following components in mass fractions:

[0005] Sulfuric acid: 0.1wt%-50wt%, hydrogen peroxide: 5wt%-50wt%, metal ion chelating agent: 0.1wt%-10wt%, cationic surfactant: 0.1wt%-10wt%, nonionic surfactant: 0.1wt%-10wt%, defoaming agent: 0.02wt%-6wt%, dispersant: 0.1wt%-5wt%.

[0006] Preferably, the mass fraction of the sulfuric acid is 20wt% to 50wt%.

[0007] Preferably, the mass fraction of the hydrogen peroxide is 10wt% to 50wt%.

[0008] 4. The cleaning agent for silicon carbide substrate according to claim 1, characterized in that the metal ion chelating agent comprises one or more of sodium gluconate, sodium citrate, polymethacrylic acid and polymaleic acid;

[0009] The mass fraction of the metal ion chelating agent is 1 wt% to 4 wt%.

[0010] Preferably, the cationic surfactant comprises hexadecyltrimethylammonium bromide and / or dodecyltrimethylammonium bromide;

[0011] The mass fraction of the cationic surfactant is 3wt% to 8wt%.

[0012] Preferably, the nonionic surfactant comprises alkylphenol polyoxyethylene ether and / or polyoxyethylene fatty alcohol ether;

[0013] The mass fraction of the nonionic surfactant is 3wt% to 8wt%.

[0014] Preferably, the defoaming agent comprises GP type glycerol polyether and polydimethylsiloxane; the mass ratio of the GP type glycerol polyether to polydimethylsiloxane is 1:(0.005-0.04);

[0015] The mass fraction of the defoaming agent is 0.1wt% to 5wt%.

[0016] The present invention provides a cleaning process for a silicon carbide substrate, comprising the following steps:

[0017] A) placing the silicon carbide substrate in a cleaning tank filled with a cleaning solution and performing ultrasonic cleaning; the cleaning solution is a mixture of the cleaning agent for the silicon carbide substrate in claim 1 and water in a mass ratio of 1: (5-15);

[0018] B) placing the silicon carbide substrate cleaned in step A) in a water tank for heated ultrasonic cleaning;

[0019] C) Repeat steps A) and B) 1 to 2 times

[0020] D) placing the silicon carbide substrate cleaned in step C) in a water tank and performing ultrasonic cleaning at room temperature;

[0021] E) Drying the cleaned silicon carbide substrate in step D) to obtain a cleaned silicon carbide substrate.

[0022] Preferably, the temperature of ultrasonic cleaning in step A) is 40-80° C. and the time of ultrasonic cleaning is 10-15 min.

[0023] Preferably, the temperature of the heated ultrasonic cleaning in step B) is 50-60° C.; and the time of the heated ultrasonic cleaning is 5-15 min.

[0024] The present invention provides a cleaning agent for silicon carbide substrates, comprising the following components by mass fraction: sulfuric acid: 0.1wt% to 50wt%, hydrogen peroxide: 5wt% to 50wt%, metal ion chelating agent: 0.1wt% to 10wt%, cationic surfactant: 0.1wt% to 10wt%, nonionic surfactant: 0.1wt% to 10wt%, defoaming agent: 0.02wt% to 6wt%, dispersant: 0.1wt% to 5wt%, and the balance is water. The cleaning agent of the present invention can effectively solve the problem of residual stains on the surface of the silicon carbide substrate after aluminum oxide polishing, can effectively clean the polishing liquid, metal ions, inorganic particles and other dirt remaining on the surface of the silicon carbide substrate, and can effectively improve the apparent cleanliness of the silicon carbide substrate after CMP. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0026] Figure 1 The overall surface residue of the silicon carbide substrate after cleaning in Comparative Example 1 of the present invention;

[0027] Figure 2 This is an enlarged view of a portion of the surface residue of the silicon carbide substrate after cleaning in Comparative Example 1 of the present invention;

[0028] Figure 3 This is an enlarged view of another part of the surface residue of the silicon carbide substrate after cleaning in Comparative Example 1 of the present invention;

[0029] Figure 4 This is a particle test diagram of the cleaned silicon carbide substrate in Example 3 of the present invention. DETAILED DESCRIPTION

[0030] The present invention provides a cleaning agent for a silicon carbide substrate, comprising the following components in mass fractions:

[0031] Sulfuric acid: 0.1wt%-50wt%, hydrogen peroxide: 5wt%-50wt%, metal ion chelating agent: 0.1wt%-10wt%, cationic surfactant: 0.1wt%-10wt%, nonionic surfactant: 0.1wt%-10wt%, defoaming agent: 0.02wt%-6wt%, dispersant: 0.1wt%-5wt%, and the balance is water.

[0032] In the present invention, the sulfuric acid can directly react with the alumina particles to elute the alumina solid abrasive attached to the surface of the substrate, and react with the organic matter attached to the surface of the substrate at the same time; the mass fraction of the sulfuric acid is preferably 0.1wt% to 50wt%, more preferably 20wt% to 50wt%, such as 0.1wt%, 1wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 34wt%, 40wt%, 45wt%, 50wt%, preferably a range value with any of the above values ​​as the upper or lower limit.

[0033] In the present invention, the hydrogen peroxide can react with potassium permanganate attached to the surface of the substrate, and promote sulfuric acid to elute impurities attached to the surface of the substrate; the mass fraction of the hydrogen peroxide is preferably 5wt% to 50wt%, more preferably 10wt% to 50wt%, such as 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, preferably a range value with any of the above values ​​as the upper or lower limit.

[0034] In the present invention, the metal ion chelating agent can be 3+ , Fe 3+ , Fe 2+ , Cu 2+ , Ga 2+ The metal ions can be chelated, and it can also act as a dispersant to prevent the solution from flocculating, which is beneficial for the solution to be circulated and filtered in the equipment; the metal ion chelating agent includes one or more of sodium gluconate, sodium citrate, polymethacrylic acid and polymaleic acid; the mass fraction of the metal ion chelating agent is preferably 0.1wt% to 10wt%, more preferably 3wt% to 10wt%, such as 0.1wt%, 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, preferably with any of the above values ​​as the upper or lower limit of the range value.

[0035] In the present invention, the cationic surfactant preferably includes hexadecyltrimethylammonium bromide and / or dodecyltrimethylammonium bromide; the mass fraction of the cationic surfactant is preferably 0.1wt% to 10wt%, more preferably 3wt% to 8wt%, such as 0.1wt%, 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, preferably a range value with any of the above values ​​as the upper or lower limit.

[0036] In the present invention, the nonionic surfactant preferably includes alkylphenol polyoxyethylene ether and / or polyoxyethylene fatty alcohol ether; the mass fraction of the nonionic surfactant is preferably 0.1wt% to 10wt%, more preferably 3wt% to 8wt%, such as 0.1wt%, 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, preferably a range value with any of the above values ​​as the upper or lower limit.

[0037] In the present invention, the cationic surfactant and the nonionic surfactant have excellent activity against strong acid, and are soluble in water, promoting the dissolution or shedding of insoluble substances on the surface of the substrate, so that dirt is transferred from the surface of the substrate to the solution, and then filtered or completely dissolved into the solution during the circulation process. Cationic surfactants are combined with nonionic surfactants to better play the emulsification, wetting, penetration and dispersion effects, allowing sulfuric acid and hydrogen peroxide to react more fully with the stains attached to the surface of the substrate. In a microscopic environment, the reaction of sulfuric acid with aluminum oxide particles and the reaction of hydrogen peroxide with potassium permanganate are carried out from the "surface" to the "inside". The two surfactants can promote the reaction rate of the reaction. The emulsification and dispersion effects can accelerate the "peeling" of the reaction products from the surface of the substrate under the action of ultrasound, so that the location where the reaction occurs becomes clean.

[0038] In the present invention, the defoamer preferably includes GP-type glycerol polyether and polydimethylsiloxane. The defoamer GP-type glycerol polyether can avoid excessive foam generation under the condition of high surfactant concentration, which causes the foam to overflow the cleaning equipment or fill the circulation system of the equipment, causing the equipment to fail to work normally. However, under the condition of high surfactant concentration, the process of GP-type glycerol polyether producing defoaming effect is slow and cannot effectively remove foam. In the present invention, GP-type glycerol polyether and polydimethylsiloxane are used together. Polydimethylsiloxane is insoluble in aqueous solution as a silicone oil defoamer, but can promote GP-type glycerol polyether to quickly produce defoaming effect and play a defoaming role. In the present invention, the mass ratio of the GP-type glycerol polyether to the polydimethylsiloxane is preferably 1:(0.005-0.04), more preferably 1:(0.01-0.035), such as 1:0.005, 1:0.01, 1:0.015, 1:0.02, 1:0.025, 1:0.03, 1:0.035, 1:0.04, preferably a range value with any of the above values ​​as the upper or lower limit. The mass fraction of the defoaming agent is preferably 0.02wt% to 6wt%, more preferably 0.05wt% to 5wt%, such as 0.02wt%, 0.05wt%, 0.1wt%, 0.5wt%, 1wt%, 1.1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.1wt%, 3.5wt%, 4wt%, 4.1wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, preferably a range value with any of the above values ​​as the upper or lower limit.

[0039] In the present invention, the dispersant is preferably a polycarboxylic acid dispersant, more preferably one or more of polyaspartic acid, polyepoxysuccinic acid, polyacrylic acid and polymaleic acid, such as a combination of polyaspartic acid and polyacrylic acid, or a combination of polyaspartic acid and polymaleic acid; the mass fraction of the dispersant is preferably 0.1wt% to 5wt%, more preferably 1wt% to 4wt%, such as 0.1wt%, 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, preferably a range value with any of the above values ​​as the upper or lower limit.

[0040] The present invention also provides a cleaning process for a silicon carbide substrate, comprising the following steps:

[0041] A) placing the silicon carbide substrate in a cleaning tank filled with a cleaning solution for ultrasonic cleaning; the cleaning solution is a mixture of the cleaning agent for the silicon carbide substrate described above and water in a mass ratio of 1: (5-15);

[0042] B) placing the silicon carbide substrate cleaned in step A) in a water tank for heated ultrasonic cleaning;

[0043] C) Repeat steps A) and B) 1 to 2 times

[0044] D) placing the silicon carbide substrate cleaned in step C) in a water tank and performing ultrasonic cleaning at room temperature;

[0045] E) Drying the cleaned silicon carbide substrate in step D) to obtain a cleaned silicon carbide substrate.

[0046] In the present invention, the cleaning with the cleaning liquid in step A) is preferably carried out in a cleaning agent tank, and the heated ultrasonic cleaning in step B) is preferably carried out in an HQDR tank. The cleaning with the cleaning liquid and the heated ultrasonic cleaning are a combination. The present invention can repeat the combination 1 to 2 times. In each combination, the cleaning with the cleaning liquid can be carried out 1 to 3 times, and the heated ultrasonic cleaning can be carried out 1 to 2 times. In the same combination, the process parameters of the cleaning with the cleaning liquid can be the same or different, and the process parameters of the heated ultrasonic cleaning can be the same or different; in different combinations, the process parameters of the cleaning with the cleaning liquid can be the same or different, and the process parameters of the heated ultrasonic cleaning can be the same or different.

[0047] In the present invention, the cleaning process of the cleaning liquid in step A) is ultrasound + circulation + filtration + heating, and the frequency of the ultrasound is preferably 40-80KHz, more preferably 50-70KHz, such as 40KHz, 50KHz, 60KHz, 70KHz, 80KHz, preferably a range value with any of the above values ​​as the upper or lower limit; the cleaning temperature is preferably 40-80°C, such as 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, preferably a range value with any of the above values ​​as the upper or lower limit; the cleaning time is preferably 10-15min, such as 10min, 11min, 12min, 13min, 14min, 15min, preferably a range value with any of the above values ​​as the upper or lower limit.

[0048] In the present invention, the mass ratio of the cleaning agent to water in the cleaning solution is preferably 1:(5-15), more preferably 1:(10-15), such as 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, preferably a range value with any of the above values ​​as the upper or lower limit. In the same combination, the ratio of the cleaning agent to water used in each cleaning solution can be the same or different, preferably the same; in the different combinations, the ratio of the cleaning agent to water used in each cleaning solution can be the same or different, preferably decreasing in sequence, such as the ratio of the cleaning agent in the cleaning solution in the second combination is lower than the ratio of the cleaning agent in the cleaning solution in the first combination, and the ratio of the cleaning agent in the cleaning solution in the third combination is lower than the ratio of the cleaning agent in the cleaning solution in the first combination.

[0049] In the present invention, the process of heated ultrasonic cleaning in step B) is bottom water injection (overflow) + ultrasound + bubbling + heating + spraying, and the frequency of the ultrasound is preferably 40 to 80 KHz, more preferably 50 to 70 KHz, such as 40 KHz, 50 KHz, 60 KHz, 70 KHz, 80 KHz, preferably a range value with any of the above values ​​as the upper or lower limit; the temperature of the heated ultrasonic cleaning is preferably 50 to 60 ° C, and the time of the heated ultrasonic cleaning is preferably 5 to 15 min, such as 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, preferably a range value with any of the above values ​​as the upper or lower limit.

[0050] The present invention preferably repeats the above combination of "cleaning with cleaning liquid + heated ultrasonic cleaning" 1 to 2 times. After the cleaning is completed, the present invention places the cleaned silicon carbide substrate in a QRD tank and performs ultrasonic cleaning at room temperature.

[0051] In the present invention, the process of normal temperature ultrasonic cleaning includes bottom water injection (overflow) + ultrasound + bubbling, and the frequency of ultrasound in the normal temperature ultrasonic cleaning is preferably 40 to 80 KHz, more preferably 50 to 70 KHz, such as 40 KHz, 50 KHz, 60 KHz, 70 KHz, 80 KHz, preferably a range value with any of the above values ​​as the upper or lower limit; the time of normal temperature ultrasonic cleaning is preferably 1 to 10 min, more preferably 5 to 10 min.

[0052] After the normal temperature ultrasonic cleaning is completed, the present invention dries the cleaned silicon carbide substrate to obtain the cleaned silicon carbide substrate. The drying process includes spraying + drying + nitrogen drying, and the drying process is a commonly used drying process for silicon carbide substrates in the art, and the present invention will not repeat it here.

[0053] The present invention provides a cleaning agent for silicon carbide substrates, comprising the following components by mass fraction: sulfuric acid: 0.1wt% to 50wt%, hydrogen peroxide: 5wt% to 50wt%, metal ion chelating agent: 0.1wt% to 10wt%, cationic surfactant: 0.1wt% to 10wt%, nonionic surfactant: 0.1wt% to 10wt%, defoaming agent: 0.02wt% to 6wt%, dispersant: 0.1wt% to 5wt%, and the balance is water. The cleaning agent of the present invention can effectively solve the problem of residual stains on the surface of the silicon carbide substrate after aluminum oxide polishing, can effectively clean the polishing liquid, metal ions, inorganic particles and other dirt remaining on the surface of the silicon carbide substrate, and can effectively improve the apparent cleanliness of the silicon carbide substrate after CMP.

[0054] In order to further illustrate the present invention, a cleaning agent for silicon carbide substrate sheets and a cleaning process for silicon carbide substrate sheets provided by the present invention are described in detail below in combination with embodiments, but it should not be understood as limiting the scope of protection of the present invention.

[0055] Example 1

[0056] After the CMP process is completed, the wafer substrate is removed and placed in a cleaning plug, and then the plug is placed in a wafer cleaning machine for cleaning. The cleaning agent is used in a ratio of cleaning agent to water = 1:10 (the cleaning agent ratio is 50wt% sulfuric acid, 20wt% hydrogen peroxide, 3wt% sodium gluconate, 5wt% hexadecyltrimethylammonium bromide, 5wt% alkylphenol polyoxyethylene ether, 1wt% GP type glycerol polyether, and 0.01wt% polydimethylsiloxane.)

[0057] First, the substrate was placed in a 1# ultrasonic cleaning machine (30L volume) for cleaning for 10 minutes at a cleaning temperature of 70°C. The ultrasonic wave was turned on throughout the process and the ultrasonic frequency should be greater than 40KHZ.

[0058] After cleaning in the 1# ultrasonic cleaning machine, use a low-pressure water gun to rinse the substrate for 1 minute. After rinsing, place the substrate in the 2# ultrasonic cleaning machine (30L volume) filled with cleaning agent and clean it for 10 minutes. The cleaning temperature is 70°C. At the same time, turn on the ultrasonic wave throughout the process, and the ultrasonic frequency should be greater than 40KHZ. After completion, transfer the substrate to the 3# ultrasonic cleaning machine (the configuration conditions of 2# and 3# are the same). Repeat the operation once and then transfer the substrate to the 4# ultrasonic cleaning machine.

[0059] The 4# ultrasonic cleaning machine is a hot water circulating ultrasonic machine (80L volume), the cleaning temperature is 60°C, and the ultrasonic frequency should be greater than 40KHZ. After cleaning for 10 minutes, it is transferred to the 5# ultrasonic cleaning machine (the configuration conditions of 4# and 5# are the same). After repeating the operation once, the substrate is transferred to the 6# ultrasonic cleaning machine.

[0060] The 6# ultrasonic cleaning machine is at room temperature (30L volume), and the ultrasonic frequency should be greater than 40KHZ. Its water inlet and outlet are on two opposite sides of the ultrasonic cleaning machine. The water is filled and drained at the same time, so that the water in the tank is flowing water (1L / min-5L / min). After 15 minutes of 6# ultrasonic cleaning, the substrate is taken out and dried.

[0061] After cleaning, a substrate sheet with no dirt residue and meeting the requirements of macroscopic inspection is obtained.

[0062] Example 2

[0063] After the CMP process is completed, the wafer substrate is removed and placed in a cleaning plug, and then the plug is placed in a wafer cleaning machine for cleaning. The cleaning agent is used in a ratio of cleaning agent to water = 1:10 (the cleaning agent ratio is 50wt% sulfuric acid, 50wt% hydrogen peroxide, 10wt% sodium gluconate, 7wt% hexadecyltrimethylammonium bromide, 7wt% alkylphenol polyoxyethylene ether, 4wt% GP type glycerol polyether, 0.1wt% polydimethylsiloxane).

[0064] The process configuration of the wafer cleaning machine is:

[0065] Tank #1 is the feeding tank (without solution).

[0066] Tank 2# is a cleaning agent tank, and the process is ultrasound + circulation + filtration + heating, cleaning at 40℃ for 15 minutes.

[0067] Tank 3# is the cleaning agent tank, and the process is ultrasound + circulation + filtration + heating, cleaning at 40℃ for 15 minutes.

[0068] Tank 4# is a HQDR tank, and the process is bottom water injection (overflow) + ultrasound + bubbling + heating + spraying, and cleaning at 60℃ for 15min.

[0069] Tank 5# is a cleaning agent tank, and the process is ultrasound + circulation + filtration + heating, cleaning at 40℃ for 10 minutes.

[0070] Tank 6# is an HQDR tank, and the process is bottom water injection (overflow) + ultrasound + bubbling + heating + spraying, cleaning at 60℃ for 7min; the process is repeated once after changing the water.

[0071] For the 7# tank QDR tank, fill the bottom with water (overflow) + ultrasound + bubbling, and clean for 5 minutes at room temperature; repeat the process once after changing the water.

[0072] 8# drying tank, the function is spraying + drying + nitrogen drying, drying for 10 minutes.

[0073] After cleaning on the cleaning machine, a clean wafer substrate with no dirt residue and meeting the requirements of macro defect detection is obtained, and the rewashing rate is 0.2% to 0.6%.

[0074] Example 3

[0075] After the CMP process is completed, the wafer substrate is removed and placed in a cleaning plug, and then the plug is placed in an automatic wafer cleaning machine for cleaning. The cleaning agent is used in a ratio of 1:5 (the cleaning agent ratio is 40wt% sulfuric acid, 50wt% hydrogen peroxide, 10wt% sodium gluconate, 5wt% hexadecyltrimethylammonium bromide, 5wt% alkylphenol polyoxyethylene ether, 3wt% GP type glycerol polyether, and 0.1wt% polydimethylsiloxane.)

[0076] The automatic cleaning machine process settings are as follows:

[0077] Tank #1 is the feeding tank, containing 40℃ pure water.

[0078] Tank 2# is a cleaning agent tank, and the process is ultrasound + circulation + filtration + heating, cleaning at 80℃ for 15 minutes.

[0079] Tank 3# is a HQDR tank, and the process is ultrasound + spraying + bubbling + heating. It is cleaned at 50℃ for 10 minutes, and the water is changed after each cleaning.

[0080] Tank 4# is a cleaning agent tank, and the process is ultrasound + circulation + filtration + heating, cleaning at 80℃ for 15 minutes.

[0081] Tank 5# is a HQDR tank, and the process is ultrasound + spraying + bubbling + heating. It is cleaned at 50℃ for 10 minutes, and the water is changed after each cleaning.

[0082] Tank 6# is a cleaning agent tank, and the process is ultrasound + circulation + filtration + heating, cleaning at 80℃ for 15 minutes.

[0083] Tank 7# is an HQDR tank, and the process is ultrasound + spraying + bubbling + heating, cleaning at 50℃ for 7min; the process is repeated once after changing the water.

[0084] 8# tank QDR tank, the process is ultrasound + spray + bubbling + heating, cleaning at 50℃ for 7min; repeat the process once after changing the water.

[0085] 9# drying tank, the function is spraying + drying + nitrogen drying, drying for 10 minutes.

[0086] After macro defect detection and RCA cleaning, a commercial grade clean wafer substrate can be obtained. The particle test chart is as follows: Figure 4 As shown, the backwash rate is 0.1% to 0.5%.

[0087] Comparative Example 1

[0088] After completing the CMP process, remove the substrate and place it in a cleaning plug, then place it in a No. 1 ultrasonic cleaning machine (30L volume) filled with citric acid-hydrogen peroxide solution for pretreatment cleaning for 10 minutes. The cleaning temperature is room temperature, and the ultrasonic wave is turned on throughout the process. The ultrasonic frequency should be greater than 40KHZ.

[0089] After cleaning in the 1# ultrasonic cleaning machine, use a low-pressure water gun to rinse the substrate for 1 minute. After rinsing, place the substrate in the 2# ultrasonic cleaning machine (30L volume) filled with commercial cleaning agent for 10 minutes. The cleaning temperature is 70°C. At the same time, the ultrasonic wave is turned on throughout the process. The ultrasonic frequency should be greater than 40KHZ. After completion, transfer the substrate to the 3# ultrasonic cleaning machine (the configuration conditions of 2# and 3# are the same). Repeat the operation once and then transfer the substrate to the 4# ultrasonic cleaning machine.

[0090] The 4# ultrasonic cleaning machine is a hot water circulating ultrasonic machine (80L volume), the cleaning temperature is 60°C, and the ultrasonic frequency should be greater than 40KHZ. After cleaning for 10 minutes, it is transferred to the 5# ultrasonic cleaning machine (the configuration conditions of 4# and 5# are the same). After repeating the operation once, the substrate is transferred to the 6# ultrasonic cleaning machine.

[0091] The 6# ultrasonic cleaning machine is at room temperature (30L volume), and the ultrasonic frequency should be greater than 40KHZ. The water inlet and outlet are respectively on the two opposite sides of the ultrasonic cleaning machine. The method of filling water while draining water is adopted to make the water in the tank flowing water (1L / min-5L / min). After 15 minutes of 6# ultrasonic cleaning, the substrate sheet is taken out and spun dry. The substrate sheet obtained after drying has a backwash rate of about 3-7%. The reason for the backwash is that there are residual polishing liquid particles or white solid residues on the surface of the substrate. Specifically, Figures 1 to 3 shown.

[0092] The commercial cleaning agent used in Comparative Example 1 is a common alkaline water-based cleaning agent, the main component of which is potassium hydroxide or sodium hydroxide, and the concentration is cleaning agent: water = 1:5-1:20). In addition, the above situation also occurs when using an acidic water-based cleaning agent whose main component is citric acid-hydrogen peroxide (the concentration used is cleaning agent: water = 1:5-1:20). Analysis shows that the white dirt is the liquid component of the polishing liquid that has not been rinsed clean; the reason for the local residue of particles is mainly due to the weak local agglomeration of the polishing liquid, which leads to the situation that the agglomerated part of the solid abrasive is "embedded" in the substrate surface after processing.

[0093] The cleaning agent of the present invention can solve the above problems. As shown in Examples 1 and 2, the backwash rate is low, and there is no residual polishing liquid particles or white solid residue. At the same time, there is no need to use SC-1, SC-2, or DHF, and the use conditions are simpler and more convenient.

[0094] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A cleaning agent for a silicon carbide substrate, comprising the following components in mass fractions: Sulfuric acid: 0.1wt%-50wt%, hydrogen peroxide: 5wt%-50wt%, metal ion chelating agent: 0.1wt%-10wt%, cationic surfactant: 0.1wt%-10wt%, nonionic surfactant: 0.1wt%-10wt%, defoaming agent: 0.02wt%-6wt%, dispersant: 0.1wt%-5wt%.

2. The cleaning agent for silicon carbide substrate according to claim 1, characterized in that: The mass fraction of the sulfuric acid is 20wt% to 50wt%.

3. The cleaning agent for silicon carbide substrate according to claim 1, characterized in that: The mass fraction of the hydrogen peroxide is 10wt% to 50wt%.

4. The cleaning agent for silicon carbide substrate according to claim 1, characterized in that: The metal ion chelating agent includes one or more of sodium gluconate, sodium citrate, polymethacrylic acid and polymaleic acid; The mass fraction of the metal ion chelating agent is 1 wt% to 4 wt%.

5. The cleaning agent for silicon carbide substrate according to claim 1, characterized in that: The cationic surfactant includes hexadecyltrimethylammonium bromide and / or dodecyltrimethylammonium bromide; The mass fraction of the cationic surfactant is 3wt% to 8wt%.

6. The cleaning agent for silicon carbide substrate according to claim 1, characterized in that: The nonionic surfactant includes alkylphenol polyoxyethylene ether and / or polyoxyethylene fatty alcohol ether; The mass fraction of the nonionic surfactant is 3wt% to 8wt%.

7. The cleaning agent for silicon carbide substrate according to claim 1, characterized in that: The defoaming agent comprises GP type glycerol polyether and polydimethylsiloxane; the mass ratio of the GP type glycerol polyether to polydimethylsiloxane is 1:(0.005-0.04); The mass fraction of the defoaming agent is 0.1wt% to 5wt%.

8. A cleaning process for a silicon carbide substrate, comprising the following steps: A) placing the silicon carbide substrate in a cleaning tank filled with a cleaning solution and performing ultrasonic cleaning; the cleaning solution is a mixture of the cleaning agent for the silicon carbide substrate in claim 1 and water in a mass ratio of 1: (5-15); B) placing the silicon carbide substrate cleaned in step A) in a water tank for heated ultrasonic cleaning; C) Repeat steps A) and B) 1 to 2 times D) placing the silicon carbide substrate cleaned in step C) in a water tank and performing ultrasonic cleaning at room temperature; E) Drying the cleaned silicon carbide substrate in step D) to obtain a cleaned silicon carbide substrate.

9. The cleaning process according to claim 8, characterized in that: The temperature of ultrasonic cleaning in step A) is 40-80° C.; the time of ultrasonic cleaning is 10-15 minutes.

10. The cleaning process according to claim 8, characterized in that: The temperature of the heating ultrasonic cleaning in step B) is 50-60° C.; the time of the heating ultrasonic cleaning is 5-15 minutes.

Images