Composite cleaning agent for silicon carbide wafer, cleaning method and cleaned silicon carbide wafer

Abstract

The invention provides a composite cleaning agent for a silicon carbide wafer, a cleaning method and the cleaned silicon carbide wafer. The composite cleaning agent is composed of a first modified cleaning agent, a second modified cleaning agent and a surfactant. The first modified cleaning agent is obtained by carrying out condensation reaction on dihydroxy-terminated polysiloxane, a polyamine compound and an acid catalyst in a first solvent; the second modified cleaning agent is obtained by carrying out hydrosilylation reaction on diallyl terminated polyether, methyl hydrogen-containing siloxane and a platinum catalyst in a second solvent. Therefore, when the composite cleaning agent is used for cleaning the silicon carbide wafer, a good cleaning effect can be achieved under the condition that hydrofluoric acid is not used.

Description

Technical Field

[0001] The invention belongs to the technical field and relates to a composite cleaning agent for silicon carbide wafers, in particular to a composite cleaning agent for silicon carbide wafers, a cleaning method and a cleaned silicon carbide wafer. Background Art

[0002] Silicon carbide will be affected by many factors during the wafer processing, and contamination is inevitable. The media of contamination include environmental pollution during the processing, pollution introduced by metal parts of the equipment and metal workpiece fixtures, pollution brought by grinding and polishing liquids used in processing, and pollution introduced by cleaning chemical reagents. Trace metal ions and impurity particles on the surface of the single crystal substrate seriously affect the performance of the prepared device. Trace metal ions and impurity particles remaining in the device preparation process will remain in the epitaxial layer, which is easy to cause damage to the designed circuit function, such as short circuit and open circuit, and affect the long-term stability and reliability of device performance.

[0003] In order to solve the problem of contamination cleaning of SiC wafers, the industry mostly uses RCA wet chemical cleaning technology. In order to achieve better cleaning effect, it is usually necessary to add a certain amount of hydrofluoric acid in the cleaning process to remove the oxide film on the surface of the wafer and the particles and some metal ions adsorbed on the oxide film. However, according to the latest regulations on chemical emissions, strict restrictions will be imposed on the emission of fluorine elements. Therefore, effective cleaning of the silicon carbide surface without using hydrofluoric acid has become a technical problem that needs to be solved urgently.

[0004] CN118360109A discloses a cleaning agent for removing residues on the surface of silicon carbide, its application and cleaning method. The cleaning agent comprises a first component, a pH regulator and water; in terms of percentage of the mass of the cleaning agent, the first component comprises 6% to 8% of 3-methoxy-3-methylbutanol, 8% to 10% of isomeric alcohol ethers, 10% to 12% of surfactants and 4% to 6% of dispersants; the content of the pH regulator is the amount required to adjust the pH value of the cleaning agent to 9 to 10; the balance is water.

[0005] CN117660120A discloses a silicon carbide crystal cleaning agent and its application. The silicon carbide crystal cleaning agent comprises a nonionic surfactant, a metal ion chelating agent and water; the weight ratio of the nonionic surfactant, the metal ion chelating agent and the water is 1:(0.001-0.03):(0.001-0.03); the metal ion chelating agent is one or more selected from ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, aminotriacetic acid and sodium gluconate.

[0006] The cleaning agents for silicon carbide wafers disclosed in the prior art all have certain defects. There are problems such as the need to use hydrofluoric acid when cleaning silicon carbide wafers and poor cleaning effect. Therefore, it is very important to develop and design a new type of composite cleaning agent for silicon carbide wafers, a cleaning method and a cleaned silicon carbide wafer. Summary of the invention

[0007] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a composite cleaning agent, a cleaning method and a cleaned silicon carbide wafer for silicon carbide wafers. The composite cleaning agent provided by the present invention is rich in hydrophilic and lipophilic groups, which can be well dispersed on the surface of the silicon carbide wafer, thereby enhancing the cleaning effect; the first modified cleaning agent in the composite cleaning agent can enhance the cleaning of impurities and particles on the silicon surface of the silicon carbide wafer, and the second modified cleaning agent can enhance the impurities and particulate organic matter on the carbon surface of the silicon carbide wafer, thereby further enhancing the cleaning effect; the amino group in the composite cleaning agent can adsorb metal ions, thereby enhancing the cleaning effect of metal impurities. Therefore, when the composite cleaning agent is used for cleaning silicon carbide wafers, it can have a good cleaning effect without using hydrofluoric acid.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a composite cleaning agent for silicon carbide wafers, the composite cleaning agent consisting of a first modified cleaning agent, a second modified cleaning agent and a surfactant;

[0010] The first modified cleaning agent is obtained by condensing a dihydroxy-terminated polysiloxane, a polyamine compound and an acid catalyst in a first solvent;

[0011] The second modified cleaning agent is obtained by a hydrosilylation reaction of bisallyl-terminated polyether, methyl hydrogen-containing siloxane and a platinum catalyst in a second solvent.

[0012] On the one hand, the first modified cleaning agent and the second modified cleaning agent in the composite cleaning agent provided by the present invention are both rich in hydrophilic and lipophilic groups, and can be well dispersed on the surface of the silicon carbide wafer containing particulate pollutants and organic matter, thereby enhancing the cleaning effect on the surface of the silicon carbide wafer; on the other hand, the silicon carbide wafer has a silicon surface and a carbon surface, and the first modified cleaning agent has siloxane as the main chain, and has good wettability with the silicon surface of the silicon carbide wafer, and is easy to infiltrate the surface, and the end structure has relatively poor wettability. In combination with ultrasonic cleaning, the main chain infiltrates the silicon surface of the silicon carbide wafer to adsorb impurities, and the chain end has poor wetting, which facilitates the stripping of molecules from the end, thereby being able to efficiently The second modified cleaning agent has a polyoxyethylene group as the main chain, has good wettability with the carbon surface of the silicon carbide crystal, is easy to infiltrate the surface, and the end structure has relatively poor wettability. In conjunction with ultrasonic cleaning, the main chain infiltrates the carbon surface of the silicon carbide wafer to adsorb impurities, and the chain end has poor wetting, which facilitates the stripping of molecules from the end, thereby efficiently cleaning impurities and particulate organic matter on the surface of the silicon carbide wafer; in the third aspect, the composite cleaning agent provided by the present invention contains an amino group and has certain coordinated chelating properties. It can adsorb metal ions during ultrasonic cleaning and achieve the effect of cleaning metal impurities.

[0013] In summary, the composite cleaning agent provided by the present invention is rich in hydrophilic and lipophilic groups, which can be well dispersed on the surface of the silicon carbide wafer, thereby enhancing the cleaning effect; the first modified cleaning agent in the composite cleaning agent can enhance the cleaning of impurities and particles on the silicon surface of the silicon carbide wafer, and the second modified cleaning agent can enhance the impurities and particulate organic matter on the carbon surface of the silicon carbide wafer, thereby further enhancing the cleaning effect; the amino group in the composite cleaning agent can adsorb metal ions, thereby enhancing the cleaning effect of metal impurities. Therefore, when the composite cleaning agent is used for cleaning silicon carbide wafers, it can have a good cleaning effect without using hydrofluoric acid.

[0014] Preferably, based on the mass of the composite cleaning agent as 100%, the mass fraction of the first modified cleaning agent in the composite cleaning agent is 40-55wt%, the mass fraction of the second modified cleaning agent is 40-55wt%, and the remainder is a surfactant.

[0015] In the present invention, taking the mass of the composite cleaning agent as 100%, the mass fraction of the first modified cleaning agent in the composite cleaning agent is 40-55wt%, for example, it can be 40wt%, 41wt%, 42wt%, 43wt%, 44wt%, 45wt%, 50wt%, 51wt%, 52wt%, 53wt%, 54wt% or 55wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0016] In the present invention, taking the mass of the composite cleaning agent as 100%, the mass fraction of the second modified cleaning agent is 40-55wt%, for example, it can be 40wt%, 41wt%, 42wt%, 43wt%, 44wt%, 45wt%, 50wt%, 51wt%, 52wt%, 53wt%, 54wt% or 55wt%, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0017] Preferably, the chemical formula of the double-terminal hydroxyl polysiloxane is HOCH 2 [Si(CH 3 ) 2 ] n Si(CH 3 ) 2 CH 2 OH, wherein n is an integer from 3 to 10, for example, 3, 4, 5, 6, 7, 8, 9 or 10.

[0018] Preferably, the polyamine compound includes any one of ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, 1,2-butylenediamine, 1,4-butylenediamine, o-phenylenediamine, m-phenylenediamine or p-phenylenediamine, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of ethylenediamine and 1,2-propylenediamine, a combination of 1,3-propylenediamine and 1,2-butylenediamine, a combination of 1,4-butylenediamine and o-phenylenediamine, a combination of m-phenylenediamine and p-phenylenediamine, or a combination of ethylenediamine, 1,2-propylenediamine and 1,3-propylenediamine.

[0019] Preferably, the molar ratio of the hydroxyl group in the dihydroxylated polysiloxane to the amino group in the polyamine compound in the condensation reaction is 1:(1-2), for example, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] Preferably, the acid catalyst comprises any one of hydrochloric acid, sulfuric acid or acetic acid or a combination of at least two thereof. Typical but non-limiting combinations include a combination of hydrochloric acid and sulfuric acid, a combination of sulfuric acid and acetic acid, or a combination of hydrochloric acid, sulfuric acid and acetic acid.

[0021] Preferably, the mass of the acid catalyst in the condensation reaction is 0.1 to 1% of the total mass of the dihydroxylated polysiloxane and the polyamine compound, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.9%, 0.9% or 1%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0022] Preferably, the first solvent comprises tetrahydrofuran and / or dimethylformamide.

[0023] Preferably, the condensation reaction is carried out at a temperature of 10 to 60° C. and for a time of 1 to 4 hours.

[0024] The temperature of the condensation reaction in the present invention is 10-60°C, for example, it can be 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C or 60°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] The condensation reaction time of the present invention is 1 to 4 hours, for example, it can be 1h, 1.2h, 1.5h, 1.7h, 2h, 2.2h, 2.5h, 2.7h, 3h, 3.2h, 3.5h, 3.7h or 4h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] Preferably, the structural formula of the bisallyl terminated polyether is CH 2 =CH-CH 2 -(O-CH 2 CH 2 -O) m -CH 2 -CH=CH 2 , wherein m is an integer of 3 to 15, for example, 3, 5, 7, 9, 11 or 15, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0027] Preferably, the chemical formula of the methyl hydrogen siloxane is H(CH 3 ) 2 SiO-[SiO(CH 3 ) 2 ] x -Si(CH 3 ) 2 H, wherein x is an integer from 2 to 10, for example, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0028] Preferably, the platinum catalyst comprises any one of a platinum-alcohol complex, a platinum-olefin complex, a platinum-alkoxide complex, a platinum-ether complex, a platinum-ketone complex, a mixed solution of chloroplatinic acid and isopropanol, or a platinum-vinyl complex, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of a platinum-alcohol complex and a platinum-olefin complex, a combination of a platinum-alkoxide complex and a platinum-ether complex, a combination of a mixed solution of chloroplatinic acid and isopropanol and a platinum-vinyl complex, or a combination of a platinum-alcohol complex, a platinum-olefin complex, and a platinum-alkoxide complex.

[0029] Preferably, the second solvent comprises tetrahydrofuran and / or dimethylformamide.

[0030] Preferably, the molar ratio of the allyl groups in the bisallyl terminated polyether to the hydrogen groups in the methyl hydrogen siloxane in the hydrosilylation reaction is (1-1.5):1, for example, 1:1, 1.05:1, 1.1:1, 1.15:1, 1.2:1, 1.25:1, 1.3:1, 1.35:1, 1.4:1, 1.45:1 or 1.5:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] Preferably, the mass of the platinum catalyst in the hydrosilylation reaction is 0.08-0.2% of the total mass of the bisallyl-terminated polyether and the methyl hydrogen siloxane, for example, it can be 0.08%, 0.1%, 0.12%, 0.14%, 0.16%, 0.18% or 0.2%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0032] Preferably, the temperature of the hydrosilylation reaction is 60-100° C., and the time is 1-4 hours.

[0033] The temperature of the hydrosilylation reaction in the present invention is 60-100°C, for example, it can be 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or 100°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] The time of the hydrosilylation reaction in the present invention is 1 to 4 hours, for example, it can be 1h, 1.2h, 1.5h, 1.7h, 2h, 2.2h, 2.5h, 2.7h, 3h, 3.2h, 3.5h, 3.7h or 4h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0035] Preferably, the surfactant consists of a hydrophilic surfactant and a lipophilic surfactant.

[0036] Preferably, the hydrophilic surfactant comprises fatty alcohol polyoxyethylene ether and / or fatty acid polyoxyethylene ether.

[0037] Preferably, the lipophilic surfactant comprises sorbitan fatty acid ester.

[0038] Preferably, the mass ratio of the hydrophilic surfactant to the lipophilic surfactant in the surfactant is (60-70):(30-40), for example, it can be 60:40, 61:39, 62:38, 63:37, 64:36, 65:35, 66:34, 67:33, 68:32, 69:31 or 70:30, 60:40, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0039] In a second aspect, the present invention provides a method for cleaning a silicon carbide wafer, the cleaning method comprising:

[0040] The silicon carbide wafer is first cleaned in the solution of the composite cleaning agent in the first aspect, and then secondly cleaned and thirdly cleaned in the first cleaning agent and the second cleaning agent in sequence to obtain a cleaned silicon carbide wafer.

[0041] In the cleaning method provided by the present invention, a solution of a first composite cleaning agent is used for the first cleaning to remove larger particles of impurities, organic impurities and metal materials on the surface of the silicon carbide wafer; the first cleaning agent is then used for the second cleaning to remove fine particles and certain metal impurities on the surface of the silicon carbide wafer; the second cleaning agent is then used for the third cleaning to further remove metal impurities on the surface of the silicon carbide wafer, thereby obtaining a cleaned silicon carbide wafer.

[0042] Preferably, the solution of the composite cleaning agent is obtained by mixing the composite cleaning agent with a third solvent, and the mass ratio of the composite cleaning agent to the third solvent in the solution of the composite cleaning agent is 1:(10-100), for example, it can be 1:10, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90 or 1:100, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0043] Preferably, the third solvent in the solution of the composite cleaning agent includes water.

[0044] Preferably, the first cleaning includes first ultrasonic cleaning and first surface residue cleaning performed sequentially.

[0045] Preferably, the ultrasonic frequency in the first ultrasonic cleaning is 50-100 KHz, the time is 15-35 seconds, and the pore size of the circulation filter element is less than 0.5 μm.

[0046] The ultrasonic frequency in the first ultrasonic cleaning of the present invention is 50-100 KHz, for example, 50 KHz, 60 KHz, 70 KHz, 80 KHz, 90 KHz or 100 KHz, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0047] The first ultrasonic cleaning time of the present invention is 15 to 35 seconds, for example, it can be 15 seconds, 17 seconds, 20 seconds, 22 seconds, 25 seconds, 27 seconds, 30 seconds, 32 seconds or 35 seconds, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0048] The pore size of the circulating filter element in the first ultrasonic cleaning of the present invention is less than 0.5μm, for example, it can be 0.49μm, 0.45μm, 0.4μm, 0.35μm, 0.3μm, 0.25μm, 0.2μm, 0.15μm or 0.1μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0049] Preferably, the first surface residual cleaning is performed in a fast-drain rinsing tank, with a rinsing time of 3 to 6 minutes and a drainage time of 15 to 35 seconds.

[0050] The rinsing time for the first surface residual cleaning of the present invention in the quick-drain rinsing tank is 3 to 6 minutes, for example, it can be 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes, 5 minutes, 5.5 minutes or 6 minutes, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0051] The drainage time of the first surface residual cleaning in the quick drain rinsing tank of the present invention is 15 to 35 seconds, for example, it can be 15 seconds, 17 seconds, 20 seconds, 22 seconds, 25 seconds, 27 seconds, 30 seconds, 32 seconds or 35 seconds, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0052] Preferably, the first cleaning agent is NH 4 OH, H 2 O 2 , a cationic surfactant, a chelating agent and a fourth solvent.

[0053] In the cleaning method provided by the present invention, a cationic surfactant is introduced into the first cleaning agent, and the cationic surfactant can adsorb negatively charged particles to form particle precipitation, thereby better removing fine particles on the surface of the silicon carbide wafer; in addition, the introduction of a chelating agent into the first cleaning agent can further enhance the cleaning effect on metal impurities.

[0054] Preferably, the first cleaning agent contains NH 4 OH, H 2 O 2 , the mass ratio of cationic surfactant, chelating agent and the fourth solvent is (1-3):(1-3):(0.2-0.5):(0.2-0.5):(5-10).

[0055] The NH 4 OH and H 2 O 2 The mass ratio is (1-3):(1-3), for example, it can be 1:1, 1:2, 1:3, 2:1, 2:3, 3:1 or 3:2, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0056] The NH 4 The mass ratio of OH to cationic surfactant is (1-3):(0.2-0.5). For example, it can be 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1.5:0.2, 2:0.2 or 3:0.2, but it is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable.

[0057] The NH 4 The mass ratio of OH to chelating agent is (1-3):(0.2-0.5), for example, it can be 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1.5:0.2, 2:0.2 or 3:0.2, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0058] The NH 4 The mass ratio of OH to the fourth solvent is (1-3):(5-10), for example, it can be 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 3:5, 3:7, 3:9 or 3:10, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0059] Preferably, the cationic surfactant comprises tetradecyltrimethylammonium chloride and / or hexadecyltrimethylammonium chloride.

[0060] Preferably, the chelating agent comprises any one of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, ethylene glycol bis(2-hydroxyethyl)aminetriacetic acid or ethylenediaminetetrapropionic acid, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid, a combination of diethylenetriaminepentaacetic acid and ethylene glycol bis(2-hydroxyethyl)aminetriacetic acid, a combination of ethylene glycol bis(2-hydroxyethyl)aminetriacetic acid and ethylenediaminetetrapropionic acid, or a combination of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid and ethylene glycol bis(2-hydroxyethyl)aminetriacetic acid.

[0061] Preferably, the fourth solvent comprises water.

[0062] Preferably, the second cleaning includes a second ultrasonic cleaning and a second surface residue cleaning performed sequentially.

[0063] Preferably, the ultrasonic frequency in the second ultrasonic cleaning is 20-40 KHz, the time is 30-60 s, and the pore size of the circulation filter element is less than 0.5 μm.

[0064] The ultrasonic frequency in the second ultrasonic cleaning of the present invention is 20-40KHz, for example, it can be 20KHz, 22KHz, 24KHz, 26KHz, 28KHz, 30KHz, 32KHz, 34KHz, 36KHz, 38KHz or 40KHz, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0065] The second ultrasonic cleaning time of the present invention is 30 to 60 seconds, for example, 30 seconds, 35 seconds, 40 seconds, 45 seconds, 50 seconds, 55 seconds or 60 seconds, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0066] The pore size of the circulating filter element in the second ultrasonic cleaning of the present invention is less than 0.5μm, for example, it can be 0.49μm, 0.45μm, 0.4μm, 0.35μm, 0.3μm, 0.25μm, 0.2μm, 0.15μm or 0.1μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0067] Preferably, the second surface residual cleaning is carried out in a fast-drain rinsing tank, with a rinsing time of 3 to 6 minutes and a drainage time of 2 to 5 seconds.

[0068] The rinsing time for the second surface residual cleaning of the present invention in the quick-drain rinsing tank is 3 to 6 minutes, for example, it can be 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes, 5 minutes, 5.5 minutes or 6 minutes, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0069] The drainage time of the second surface residual cleaning of the present invention in the quick drain rinsing tank is 2 to 5 seconds, for example, it can be 2 seconds, 2.5 seconds, 3 seconds, 3.5 seconds, 4 seconds, 4.5 seconds or 5 seconds, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0070] Preferably, the second cleaning agent consists of hydrochloric acid, hydrogen peroxide and a fifth solvent.

[0071] Preferably, the mass ratio of hydrochloric acid, hydrogen peroxide and the fifth solvent in the second cleaning agent is (1-2):(1-2):(6-10).

[0072] The mass ratio of hydrochloric acid to hydrogen peroxide in the second cleaning agent of the present invention is (1-2):(1-2), for example, it can be 1:1, 1:1.5, 1:2, 2:1 or 2:1.5, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0073] Preferably, the fifth solvent comprises water.

[0074] Preferably, the third cleaning includes a third ultrasonic cleaning and a third surface residue cleaning performed sequentially.

[0075] Preferably, the ultrasonic frequency in the third ultrasonic cleaning is 50-100 KHz, the time is 10-30 seconds, and the pore size of the circulation filter element is less than 0.5 μm.

[0076] The ultrasonic frequency in the third ultrasonic cleaning described in the present invention is 50-100KHz, for example, it can be 50KHz, 55KHz, 60KHz, 65KHz, 70KHz, 75KHz, 80KHz, 85KHz, 90KHz, 95KHz or 100KHz, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0077] The time of the third ultrasonic cleaning in the present invention is 10 to 30 seconds, for example, it can be 10 seconds, 12 seconds, 15 seconds, 18 seconds, 20 seconds, 22 seconds, 25 seconds, 28 seconds or 30 seconds, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0078] Preferably, the third surface residual cleaning is carried out in a fast-drain rinsing tank, with a rinsing time of 3 to 6 minutes and a drainage time of 2 to 5 seconds.

[0079] The rinsing time for the third surface residual cleaning in the quick-drain rinsing tank of the present invention is 3 to 6 minutes, for example, it can be 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes, 5 minutes, 5.5 minutes or 6 minutes, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0080] The drainage time of the third surface residual cleaning in the quick drain rinsing tank of the present invention is 2 to 5 seconds, for example, it can be 2 seconds, 2.5 seconds, 3 seconds, 3.5 seconds, 4 seconds, 4.5 seconds or 5 seconds, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0081] In a third aspect, the present invention provides a cleaned silicon carbide wafer, wherein the cleaned silicon carbide wafer is obtained by the cleaning method described in the second aspect.

[0082] Compared with the prior art, the present invention has the following beneficial effects:

[0083] (1) The composite cleaning agent provided by the present invention is rich in hydrophilic and lipophilic groups, which can be well dispersed on the surface of the silicon carbide wafer, thereby enhancing the cleaning effect; the first modified cleaning agent in the composite cleaning agent can enhance the cleaning of impurities and particles on the silicon surface of the silicon carbide wafer, and the second modified cleaning agent can enhance the impurities and particulate organic matter on the carbon surface of the silicon carbide wafer, thereby further enhancing the cleaning effect; the amino group in the composite cleaning agent can adsorb metal ions, thereby enhancing the cleaning effect of metal impurities. Therefore, when the composite cleaning agent is used to clean silicon carbide wafers, it can have a good cleaning effect without using hydrofluoric acid;

[0084] (2) In the cleaning method provided by the present invention, a solution of a first composite cleaning agent is used for the first cleaning to remove larger particles of impurities, organic impurities and metal materials on the surface of the silicon carbide wafer; the first cleaning agent is then used for the second cleaning to remove fine particles and certain metal impurities on the surface of the silicon carbide wafer; the second cleaning agent is then used for the third cleaning to further remove metal impurities on the surface of the silicon carbide wafer, thereby obtaining a cleaned silicon carbide wafer;

[0085] (3) In the cleaning method provided by the present invention, a cationic surfactant is introduced into the first cleaning agent. The cationic surfactant can adsorb negatively charged particles to form particle precipitation, thereby better removing fine particles on the surface of the silicon carbide wafer; in addition, the introduction of a chelating agent into the first cleaning agent can further enhance the cleaning effect on metal impurities. DETAILED DESCRIPTION

[0086] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0087] Example 1

[0088] The present embodiment provides a composite cleaning agent for silicon carbide wafers, wherein the composite cleaning agent is composed of a first modified cleaning agent, a second modified cleaning agent and a surfactant; based on the mass of the composite cleaning agent as 100%, the mass fraction of the first modified cleaning agent in the composite cleaning agent is 45wt%, the mass fraction of the second modified cleaning agent is 45wt%, and the remainder is the surfactant.

[0089] The first modified cleaning agent is obtained by condensing dihydroxyl-terminated polysiloxane, ethylenediamine and hydrochloric acid in tetrahydrofuran; the chemical formula of the dihydroxyl-terminated polysiloxane is HOCH 2 [Si(CH 3 ) 2 ]n Si(CH 3 ) 2 CH 2 OH, wherein n is an integer of 5; the molar ratio of the hydroxyl group in the dihydroxy-terminated polysiloxane to the amino group in the ethylenediamine in the condensation reaction is 1:1.5; the mass of the hydrochloric acid in the condensation reaction is 0.5% of the total mass of the dihydroxy-terminated polysiloxane and the ethylenediamine; the temperature of the condensation reaction is 350° C. and the time is 2.5 h.

[0090] The second modified cleaning agent is obtained by hydrosilylation reaction of bisallyl-terminated polyether, methyl hydrogen-containing siloxane and platinum-alcohol complex in tetrahydrofuran; the structural formula of the bisallyl-terminated polyether is CH 2 =CH-CH 2 -(O-CH 2 CH 2 -O) m -CH 2 -CH=CH 2 , wherein m is an integer of 10; the chemical formula of the methyl hydrogen siloxane is H(CH 3 ) 2 SiO-[SiO(CH 3 ) 2 ] x -Si(CH 3 ) 2 H, wherein x is an integer of 5; the molar ratio of the allyl group in the bisallyl-terminated polyether to the hydrogen group in the methyl hydrogen siloxane in the hydrosilylation reaction is 1:1; the mass of the platinum-alcohol complex in the hydrosilylation reaction is 0.12% of the total mass of the bisallyl-terminated polyether and the methyl hydrogen siloxane; the temperature of the hydrosilylation reaction is 80° C. and the time is 2.5 h.

[0091] The surfactant is composed of fatty alcohol polyoxyethylene ether and sorbitan fatty acid ester in a mass ratio of 60:40;

[0092] This embodiment also provides a method for cleaning a silicon carbide wafer, the cleaning method comprising:

[0093] (1) The silicon carbide wafer is sequentially subjected to a first ultrasonic cleaning and a first surface residual cleaning in a solution of the above-mentioned composite cleaning agent;

[0094] The composite cleaning agent solution is obtained by mixing the composite cleaning agent with water, wherein the mass ratio of the composite cleaning agent to water in the composite cleaning agent solution is 1:50;

[0095] The ultrasonic frequency in the first ultrasonic cleaning is 80KHz, the time is 25s, and the pore size of the circulation filter element is 0.3μm;

[0096] The first surface residual cleaning is carried out in a fast-drain rinsing tank, with a rinsing time of 5 minutes and a drainage time of 25 seconds;

[0097] (2) subjecting the silicon carbide wafer obtained in step (1) to a first ultrasonic cleaning and a first surface residue cleaning in a first cleaning agent in sequence;

[0098] The first cleaning agent is composed of NH 4 OH, H 2 O 2 , tetradecyltrimethylammonium chloride, ethylenediaminetetraacetic acid and water;

[0099] The ultrasonic frequency in the second ultrasonic cleaning is 30KHz, the time is 45s, and the pore size of the circulation filter element is 0.3μm;

[0100] The second surface residual cleaning is carried out in a fast-drain rinsing tank with a rinsing time of 5 minutes and a drainage time of 4 seconds;

[0101] (3) subjecting the silicon carbide wafer obtained in step (2) to a first ultrasonic cleaning and a first surface residue cleaning in a second cleaning agent in sequence to obtain a cleaned silicon carbide wafer;

[0102] The second cleaning agent is composed of hydrochloric acid, hydrogen peroxide and water in a mass ratio of 1.5:1.5:8;

[0103] The ultrasonic frequency in the third ultrasonic cleaning is 80KHz, the time is 20s, and the pore size of the circulation filter element is 0.3μm;

[0104] The third surface residual cleaning is carried out in a fast-drain rinsing tank, with a rinsing time of 5 minutes and a drainage time of 4 seconds.

[0105] Example 2

[0106] The present embodiment provides a composite cleaning agent for silicon carbide wafers, wherein the composite cleaning agent is composed of a first modified cleaning agent, a second modified cleaning agent and a surfactant; based on the mass of the composite cleaning agent as 100%, the mass fraction of the first modified cleaning agent in the composite cleaning agent is 40wt%, the mass fraction of the second modified cleaning agent is 40wt%, and the remainder is the surfactant.

[0107] The first modified cleaning agent is obtained by condensing bihydroxyl-terminated polysiloxane, 1,2-propylenediamine and sulfuric acid in dimethylformamide; the chemical formula of the bihydroxyl-terminated polysiloxane is HOCH 2 [Si(CH 3 ) 2 ] n Si(CH3 ) 2 CH 2 OH, wherein n is an integer of 10; the molar ratio of the hydroxyl group in the dihydroxy-terminated polysiloxane to the amino group in the 1,2-propylenediamine in the condensation reaction is 1:1; the mass of the sulfuric acid in the condensation reaction is 1% of the total mass of the dihydroxy-terminated polysiloxane and the 1,2-propylenediamine; the temperature of the condensation reaction is 60° C. and the time is 1 hour.

[0108] The second modified cleaning agent is obtained by hydrosilylation reaction of bisallyl-terminated polyether, methyl hydrogen-containing siloxane and platinum-olefin complex in dimethylformamide; the structural formula of the bisallyl-terminated polyether is CH 2 =CH-CH 2 -(O-CH 2 CH 2 ) m -O-CH 2 -CH=CH 2 , wherein m is 15; the chemical formula of the methyl hydrogen siloxane is H(CH 3 ) 2 SiO-[SiO(CH 3 ) 2 ] x -Si(CH 3 ) 2 H, wherein x is 10; the molar ratio of the allyl group in the bis-allyl-terminated polyether to the hydrogen group in the methyl hydrogen siloxane in the hydrosilylation reaction is 1:1; the mass of the platinum-olefin complex in the hydrosilylation reaction is 0.2% of the total mass of the bis-allyl-terminated polyether and the methyl hydrogen siloxane; the temperature of the hydrosilylation reaction is 100° C. and the time is 1 hour.

[0109] The surfactant is composed of fatty acid polyoxyethylene ether and sorbitan fatty acid ester in a mass ratio of 65:35;

[0110] This embodiment also provides a method for cleaning a silicon carbide wafer, the cleaning method comprising:

[0111] (1) The silicon carbide wafer is sequentially subjected to a first ultrasonic cleaning and a first surface residual cleaning in a solution of the above-mentioned composite cleaning agent;

[0112] The composite cleaning agent solution is obtained by mixing the composite cleaning agent with water, wherein the mass ratio of the composite cleaning agent to water in the composite cleaning agent solution is 1:10;

[0113] The ultrasonic frequency in the first ultrasonic cleaning is 100 KHz, the time is 15 s, and the pore size of the circulation filter element is 0.4 μm;

[0114] The first surface residual cleaning is carried out in a fast-drain rinsing tank, with a rinsing time of 3 minutes and a drainage time of 15 seconds;

[0115] (2) subjecting the silicon carbide wafer obtained in step (1) to a first ultrasonic cleaning and a first surface residue cleaning in a first cleaning agent in sequence;

[0116] The first cleaning agent is composed of NH 4 OH, H 2 O 2 , hexadecyltrimethylammonium chloride, diethylenetriaminepentaacetic acid and a fourth solvent;

[0117] The ultrasonic frequency in the second ultrasonic cleaning is 40KHz, the time is 30s, and the pore size of the circulation filter element is 0.4μm;

[0118] The second surface residual cleaning is carried out in a fast-drain rinsing tank with a rinsing time of 3 minutes and a drainage time of 2 seconds;

[0119] (3) subjecting the silicon carbide wafer obtained in step (2) to a first ultrasonic cleaning and a first surface residue cleaning in a second cleaning agent in sequence to obtain a cleaned silicon carbide wafer;

[0120] The second cleaning agent is composed of hydrochloric acid, hydrogen peroxide and water in a mass ratio of 1:2:6;

[0121] The ultrasonic frequency in the third ultrasonic cleaning is 50KHz, the time is 30s, and the pore size of the circulation filter element is 0.4μm;

[0122] The third surface residual cleaning is carried out in a fast-drain rinsing tank, with a rinsing time of 3 minutes and a drainage time of 2 seconds.

[0123] Example 3

[0124] The present embodiment provides a composite cleaning agent for silicon carbide wafers, wherein the composite cleaning agent is composed of a first modified cleaning agent, a second modified cleaning agent and a surfactant; based on the mass of the composite cleaning agent as 100%, the mass fraction of the first modified cleaning agent in the composite cleaning agent is 55wt%, the mass fraction of the second modified cleaning agent is 55wt%, and the remainder is the surfactant.

[0125] The first modified cleaning agent is obtained by condensing dihydroxyl-terminated polysiloxane, 1,3-propylenediamine and acetic acid in tetrahydrofuran; the chemical formula of the dihydroxyl-terminated polysiloxane is HOCH 2 [Si(CH 3 ) 2 ] n Si(CH 3 ) 2 CH2 OH, wherein n is an integer of 3; the molar ratio of the hydroxyl group in the dihydroxy-terminated polysiloxane to the amino group in the 1,3-propylenediamine in the condensation reaction is 1:2; the mass of acetic acid in the condensation reaction is 0.1% of the total mass of the dihydroxy-terminated polysiloxane and the 1,3-propylenediamine; the temperature of the condensation reaction is 10° C. and the time is 4 hours.

[0126] The second modified cleaning agent is obtained by hydrosilylation reaction of bisallyl-terminated polyether, methyl hydrogen-containing siloxane and platinum-ether complex in tetrahydrofuran; the structural formula of the bisallyl-terminated polyether is CH 2 =CH-CH 2 -(O-CH 2 CH 2 -O) m -CH 2 -CH=CH 2 , wherein m is 3; the chemical formula of the methyl hydrogen siloxane is H(CH 3 ) 2 SiO-[SiO(CH 3 ) 2 ] x -Si(CH 3 ) 2 H, wherein x is 2; the molar ratio of the allyl group in the bis-allyl-terminated polyether to the hydrogen group in the methyl hydrogen siloxane in the hydrosilylation reaction is 1.5:1; the mass of the platinum-ether complex in the hydrosilylation reaction is 0.08% of the total mass of the bis-allyl-terminated polyether and the methyl hydrogen siloxane; the temperature of the hydrosilylation reaction is 60° C. and the time is 4 hours.

[0127] The surfactant is composed of fatty alcohol polyoxyethylene ether and sorbitan fatty acid ester in a mass ratio of 70:30;

[0128] This embodiment also provides a method for cleaning a silicon carbide wafer, the cleaning method comprising:

[0129] (1) The silicon carbide wafer is sequentially subjected to a first ultrasonic cleaning and a first surface residual cleaning in a solution of the above-mentioned composite cleaning agent;

[0130] The composite cleaning agent solution is obtained by mixing the composite cleaning agent with water, wherein the mass ratio of the composite cleaning agent to water in the composite cleaning agent solution is 1:10;

[0131] The ultrasonic frequency in the first ultrasonic cleaning is 50KHz, the time is 35s, and the pore size of the circulation filter element is 0.3μm;

[0132] The first surface residual cleaning is carried out in a fast-drain rinsing tank, with a rinsing time of 6 minutes and a drainage time of 35 seconds;

[0133] (2) subjecting the silicon carbide wafer obtained in step (1) to a first ultrasonic cleaning and a first surface residue cleaning in a first cleaning agent in sequence;

[0134] The first cleaning agent is composed of NH 4 OH, H 2 O 2 , tetradecyltrimethylammonium chloride, ethylene glycol bis(2-hydroxyethyl)amine triacetic acid and a fourth solvent;

[0135] The ultrasonic frequency in the second ultrasonic cleaning is 20KHz, the time is 60s, and the pore size of the circulation filter element is 0.3μm;

[0136] The second surface residual cleaning is carried out in a fast-drain rinsing tank with a rinsing time of 6 minutes and a drainage time of 5 seconds;

[0137] (3) subjecting the silicon carbide wafer obtained in step (2) to a first ultrasonic cleaning and a first surface residue cleaning in a second cleaning agent in sequence to obtain a cleaned silicon carbide wafer;

[0138] The second cleaning agent is composed of hydrochloric acid, hydrogen peroxide and water in a mass ratio of 2:1:10;

[0139] The ultrasonic frequency in the third ultrasonic cleaning is 100 KHz, the time is 10 s, and the pore size of the circulation filter element is 0.4 μm;

[0140] The third surface residual cleaning is carried out in a fast-drain rinsing tank, with a rinsing time of 6 minutes and a drainage time of 5 seconds.

[0141] Example 4

[0142] This embodiment provides a composite cleaning agent for silicon carbide wafers, which is the same as that of Embodiment 1 except that the mass fraction of the first modified cleaning agent in the composite cleaning agent is 30wt%, the mass fraction of the second modified cleaning agent is 45wt%, and the remainder is a surfactant.

[0143] This embodiment also provides a method for cleaning a silicon carbide wafer, which is the same as Embodiment 1 except that the composite cleaning agent in the cleaning method is replaced by the composite cleaning agent in this embodiment.

[0144] Example 5

[0145] This embodiment provides a composite cleaning agent for silicon carbide wafers, which is the same as that in Embodiment 1 except that the mass fraction of the first modified cleaning agent is 45wt%, the mass fraction of the second modified cleaning agent is 30wt%, and the remainder is a surfactant.

[0146] This embodiment also provides a method for cleaning a silicon carbide wafer, which is the same as Embodiment 1 except that the composite cleaning agent in the cleaning method is replaced by the composite cleaning agent in this embodiment.

[0147] Example 6

[0148] This embodiment provides a composite cleaning agent for silicon carbide wafers, except that the chemical formula of the bihydroxyl-terminated polysiloxane is HOCH 2 [Si(CH 3 ) 2 ] n Si(CH 3 ) 2 CH 2 OH, wherein n is 1, and the rest are the same as those in Example 1.

[0149] This embodiment also provides a method for cleaning a silicon carbide wafer, which is the same as Embodiment 1 except that the composite cleaning agent in the cleaning method is replaced by the composite cleaning agent in this embodiment.

[0150] Example 7

[0151] This embodiment provides a composite cleaning agent for silicon carbide wafers, except that the chemical formula of the bihydroxyl-terminated polysiloxane is HOCH 2 [Si(CH 3 ) 2 ] n Si(CH 3 ) 2 CH 2 OH, wherein n is 15, and the rest are the same as those in Example 1.

[0152] This embodiment also provides a method for cleaning a silicon carbide wafer, which is the same as Embodiment 1 except that the composite cleaning agent in the cleaning method is replaced by the composite cleaning agent in this embodiment.

[0153] Example 8

[0154] This embodiment provides a composite cleaning agent for silicon carbide wafers, which is the same as that of Embodiment 1 except that the molar ratio of the hydroxyl group in the dihydroxy-terminated polysiloxane to the amino group in the ethylenediamine in the condensation reaction is 1:0.5.

[0155] This embodiment also provides a method for cleaning a silicon carbide wafer, which is the same as Embodiment 1 except that the composite cleaning agent in the cleaning method is replaced by the composite cleaning agent in this embodiment.

[0156] Example 9

[0157] This embodiment provides a composite cleaning agent for silicon carbide wafers, which is the same as that of Embodiment 1 except that the molar ratio of the hydroxyl group in the dihydroxy-terminated polysiloxane to the amino group in the ethylenediamine in the condensation reaction is 1:3.

[0158] This embodiment also provides a method for cleaning a silicon carbide wafer, which is the same as Embodiment 1 except that the composite cleaning agent in the cleaning method is replaced by the composite cleaning agent in this embodiment.

[0159] Example 10

[0160] This embodiment provides a composite cleaning agent for silicon carbide wafers, except that the structure of the bisallyl terminated polyether is CH 2 =CH-CH 2 -(O-CH 2 CH 2 -O) m -CH 2 -CH=CH 2 , wherein m is 1, and the rest are the same as those in Example 1.

[0161] This embodiment also provides a method for cleaning a silicon carbide wafer, which is the same as Embodiment 1 except that the composite cleaning agent in the cleaning method is replaced by the composite cleaning agent in this embodiment.

[0162] Embodiment 11

[0163] This embodiment provides a composite cleaning agent for silicon carbide wafers, except that the structure of the bisallyl terminated polyether is CH 2 =CH-CH 2 -(O-CH 2 CH 2 -O) m -CH 2 -CH=CH 2 , wherein m is 20, and the rest are the same as those in Example 1.

[0164] This embodiment also provides a method for cleaning a silicon carbide wafer, which is the same as Embodiment 1 except that the composite cleaning agent in the cleaning method is replaced by the composite cleaning agent in this embodiment.

[0165] Example 12

[0166] This embodiment provides a composite cleaning agent for silicon carbide wafers, except that the chemical formula of the methyl hydrogen-containing siloxane is H(CH 3 ) 2 SiO-[SiO(CH 3 ) 2 ] x -Si(CH 3 ) 2 H, wherein x is 1, and the rest are the same as those in Example 1.

[0167] This embodiment also provides a method for cleaning a silicon carbide wafer, which is the same as Embodiment 1 except that the composite cleaning agent in the cleaning method is replaced by the composite cleaning agent in this embodiment.

[0168] Embodiment 13

[0169] This embodiment provides a composite cleaning agent for silicon carbide wafers, except that the chemical formula of the methyl hydrogen-containing siloxane is H(CH 3 ) 2 SiO-[SiO(CH 3 ) 2 ] x -Si(CH 3 ) 2 H, wherein x is 15, and the rest are the same as those in Example 1.

[0170] This embodiment also provides a method for cleaning a silicon carbide wafer, which is the same as Embodiment 1 except that the composite cleaning agent in the cleaning method is replaced by the composite cleaning agent in this embodiment.

[0171] Embodiment 14

[0172] This embodiment provides a composite cleaning agent for silicon carbide wafers, which is the same as that of Embodiment 1 except that the mass of the platinum-alcohol complex in the hydrosilylation reaction is 0.05% of the total mass of the bisallyl-terminated polyether and the methyl hydrogen-containing siloxane.

[0173] This embodiment also provides a method for cleaning a silicon carbide wafer, which is the same as Embodiment 1 except that the composite cleaning agent in the cleaning method is replaced by the composite cleaning agent in this embodiment.

[0174] Embodiment 15

[0175] This embodiment provides a composite cleaning agent for silicon carbide wafers, which is the same as that of Embodiment 1 except that the mass of the platinum-alcohol complex in the hydrosilylation reaction is 0.25% of the total mass of the bisallyl-terminated polyether and the methyl hydrogen-containing siloxane.

[0176] This embodiment also provides a method for cleaning a silicon carbide wafer, which is the same as Embodiment 1 except that the composite cleaning agent in the cleaning method is replaced by the composite cleaning agent in this embodiment.

[0177] Example 16

[0178] This embodiment provides a composite cleaning agent for silicon carbide wafers, which is the same as that of Embodiment 1 except that the surfactant only includes fatty alcohol polyoxyethylene ether, that is, sorbitan fatty acid ester is replaced with fatty alcohol polyoxyethylene ether of equal mass.

[0179] This embodiment also provides a method for cleaning a silicon carbide wafer, which is the same as Embodiment 1 except that the composite cleaning agent in the cleaning method is replaced by the composite cleaning agent in this embodiment.

[0180] Embodiment 17

[0181] This embodiment provides a composite cleaning agent for silicon carbide wafers, which is the same as that of Embodiment 1 except that the surfactant only includes sorbitan fatty acid ester, that is, fatty alcohol polyoxyethylene ether is replaced with sorbitan fatty acid ester of equal mass.

[0182] This embodiment also provides a method for cleaning a silicon carbide wafer, which is the same as Embodiment 1 except that the composite cleaning agent in the cleaning method is replaced by the composite cleaning agent in this embodiment.

[0183] Embodiment 18

[0184] This embodiment provides a method for cleaning a silicon carbide wafer, which is the same as that of Embodiment 1 except that tetradecyltrimethylammonium chloride in the first cleaning agent in step (2) is omitted.

[0185] Embodiment 19

[0186] This embodiment provides a method for cleaning a silicon carbide wafer, which is the same as that of Embodiment 1 except that the ethylenediaminetetraacetic acid in the first cleaning agent in step (2) is omitted.

[0187] Comparative Example 1

[0188] This comparative example provides a composite cleaning agent for silicon carbide wafers, which is the same as Example 1 except that the first modified cleaning agent in the composite cleaning agent is replaced with a second modified cleaning agent of equal quality.

[0189] This comparative example also provides a method for cleaning a silicon carbide wafer, which is the same as Example 1 except that the composite cleaning agent in the cleaning method is replaced by the composite cleaning agent in this example.

[0190] Comparative Example 2

[0191] This comparative example provides a composite cleaning agent for silicon carbide wafers, which is the same as Example 1 except that the second modified cleaning agent in the composite cleaning agent is replaced with the first modified cleaning agent of the same mass.

[0192] This comparative example also provides a method for cleaning a silicon carbide wafer, which is the same as Example 1 except that the composite cleaning agent in the cleaning method is replaced by the composite cleaning agent in this example.

[0193] Comparative Example 3

[0194] This comparative example provides a composite cleaning agent for silicon carbide wafers, which is the same as Example 1 except that the surfactant in the composite cleaning agent is replaced by a first modified cleaning agent and a second modified cleaning agent, and the total mass of the composite cleaning agent and the mass ratio of the first modified cleaning agent to the second modified cleaning agent are ensured to remain unchanged.

[0195] This comparative example also provides a method for cleaning a silicon carbide wafer, which is the same as Example 1 except that the composite cleaning agent in the cleaning method is replaced by the composite cleaning agent in this example.

[0196] The surface of the silicon carbide wafer is cleaned by the cleaning method of the silicon carbide wafer provided in the above embodiment and the comparative example, and then the number of particles on the surface of the silicon carbide wafer after cleaning is measured by surface defect detection equipment (particle size range 0.2 to 0.3 um), and the number of residual metal ions on the surface of the silicon carbide wafer after cleaning is tested by IPC detection means. The number of particles and the number of residual metal ions on the surface of the silicon carbide wafer after cleaning are tested as shown in Table 1.

[0197] Table 1

[0198]

[0199]

[0200] From Table 1, we can get:

[0201] (1) After the surface of the silicon carbide wafer is cleaned by the cleaning method provided in Examples 1 to 3, the number of particles on the surface of the silicon carbide wafer is small, the proportion of dirty area is low, and the number of residual metal ions is small;

[0202] (2) By comparing Example 1 with Examples 4 and 5, it can be seen that the mass fractions of the first modified cleaning agent and the second modified cleaning agent in the composite cleaning agent will affect the effect of the cleaning method; when the mass fraction of the first modified cleaning agent in the composite cleaning agent is 40-55wt%, and the mass fraction of the second modified cleaning agent is 40-55wt%, the cleaning method shows a better cleaning effect. This is because the first modified cleaning agent mainly cleans the silicon surface of the wafer, and the second cleaning agent mainly cleans the carbon surface of the wafer. The synergistic effect of the two can achieve the best cleaning effect;

[0203] (3) By comparing Example 1 with Examples 6 and 7, it can be seen that the chemical formula of the dihydroxylated polysiloxane affects the effect of the cleaning method; when the value of n in the chemical formula of the dihydroxylated polysiloxane is an integer of 3 to 10, the cleaning method exhibits a better cleaning effect. This is because -Si(CH 3 ) 2 The group within the appropriate range can provide the first modified cleaning agent with effective silicon-containing groups to form infiltration on the silicon surface of the wafer, achieving the effect of adsorption cleaning, -Si(CH 3 ) 2 Too many groups are over-infiltrated, making it difficult to peel off later, affecting the final cleaning effect;

[0204] (4) By comparing Example 1 with Examples 8 and 9, it can be seen that the molar ratio of the hydroxyl groups in the double-terminal hydroxyl polysiloxane to the amino groups in the polyamine compound in the condensation reaction affects the effect of the cleaning method; when the molar ratio of the hydroxyl groups in the double-terminal hydroxyl polysiloxane to the amino groups in the polyamine compound is 1:(1-2), the cleaning method exhibits a better cleaning effect. This is because the first modified cleaning agent has a molecular structure with siloxane as the main chain and amino groups grafted at the ends. An appropriate excess of amino groups is conducive to sufficient end grafting modification to form hydrophilic groups, which is conducive to improving the pollutant removal efficiency in the later cleaning process; an excess of amino groups will cause the wettability of the first modified cleaning agent to deteriorate, thereby reducing the pollutant cleaning efficiency;

[0205] (5) By comparing Example 1 with Examples 10 and 11, it can be seen that the structural formula of the bisallyl-terminated polyether will affect the effect of the cleaning method; when the value of m in the structural formula of the bisallyl-terminated polyether is an integer of 3 to 15, the cleaning method exhibits a better cleaning effect. This is because -OCH 2 CH 2 When the group is within an appropriate range, it can provide effective polyoxyethylene groups for the second modified cleaning agent to form infiltration on the carbon surface of the wafer, achieving the effect of adsorption cleaning. When the polyoxyethylene groups are too much, the infiltration is excessive and it is not easy to peel off in the later stage, which affects the final cleaning effect.

[0206] (6) By comparing Example 1 with Examples 12 and 13, it can be seen that the chemical formula of the methyl hydrogen siloxane affects the effect of the cleaning method; when x in the chemical formula of the methyl hydrogen siloxane is an integer of 2 to 10, the cleaning method exhibits a better cleaning effect. This is because -SiO(CH 3 ) 2 The group can provide an effective hydrophobic group for the second modified cleaning agent within an appropriate range, which facilitates effective stripping from the end during the cleaning process of the crystal carbon surface and improves the pollutant removal efficiency; SiO(CH 3 ) 2 Too many groups affect the wettability of the second modified cleaning agent during the carbon surface cleaning process, reducing the pollutant removal efficiency.

[0207] (7) By comparing Example 1 with Examples 14 and 15, it can be seen that the mass of the platinum catalyst in the hydrosilylation reaction of the present invention is a ratio of the total mass of the bis-allyl-terminated polyether and the methyl hydrogen-containing siloxane, which will affect the effect of the cleaning method; when the mass of the platinum catalyst in the hydrosilylation reaction is 0.08-0.2% of the total mass of the bis-allyl-terminated polyether and the methyl hydrogen-containing siloxane, the cleaning method shows a better cleaning effect. This is because the platinum catalyst can effectively promote the reaction to proceed fully within a suitable range, and too little catalytic effect cannot be achieved; too little causes waste of platinum catalyst and may introduce excess metal impurities;

[0208] (8) By comparing Example 1 with Examples 16 and 17, it can be seen that the surfactant of the present invention includes both a hydrophilic surfactant and a lipophilic surfactant, which is beneficial to improving the effect of the cleaning method. This is because the lipophilic surfactant helps to emulsify the pollutants on the silicon carbide wafer and improve the stripping efficiency of the pollutants, while the hydrophilic surfactant makes it easier for the emulsified pollutants to enter the cleaning medium to complete the final removal and cleaning of the pollutants.

[0209] (9) By comparing Example 1 with Example 18, it can be seen that the introduction of the cationic surfactant in the first cleaning agent in the cleaning method of the present invention is conducive to improving the cleaning effect. This is because the cationic surfactant introduced into the first cleaning agent can adsorb negatively charged particles to form particle precipitation, thereby better removing fine particles on the surface of the silicon carbide wafer;

[0210] (10) By comparing Example 1 with Example 19, it can be seen that the introduction of the chelating agent in the first cleaning agent in the cleaning method of the present invention is conducive to improving the cleaning effect, because the introduction of the chelating agent in the first cleaning agent can further improve the cleaning effect on metal impurities;

[0211] (11) By comparing Example 1 with Comparative Examples 1 to 3, it can be seen that the first modified cleaning agent and the second modified cleaning agent in the composite cleaning agent provided by the present invention are both rich in hydrophilic and lipophilic groups, and can be well dispersed on the surface of the silicon carbide wafer containing particulate pollutants and organic matter, thereby enhancing the cleaning effect on the surface of the silicon carbide wafer; secondly, the silicon carbide wafer has a silicon surface and a carbon surface, and the first modified cleaning agent has siloxane as the main chain, and has good wettability with the silicon surface of the silicon carbide wafer, and is easy to infiltrate the surface, and the end structure has relatively poor wettability. With ultrasonic cleaning, the main chain infiltrates the silicon surface of the silicon carbide wafer to adsorb impurities, and the chain end has poor infiltration, which facilitates the molecules to enter from the end. The second modified cleaning agent has a polyoxyethylene group as the main chain, has good wettability with the carbon surface of the silicon carbide crystal, is easy to infiltrate the surface, and the end structure has relatively poor wettability. In conjunction with ultrasonic cleaning, the main chain infiltrates the carbon surface of the silicon carbide wafer to adsorb impurities, and the chain end has poor wetting, which facilitates the stripping of molecules from the end, thereby efficiently cleaning impurities and particulate organic matter on the surface of the silicon carbide wafer; in the third aspect, the composite cleaning agent provided by the present invention contains an amino group and has certain coordinated chelating properties. It can adsorb metal ions during ultrasonic cleaning and achieve the effect of cleaning metal impurities.

[0212] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A composite cleaning agent for silicon carbide wafers, characterized in that: The composite cleaning agent is composed of a first modified cleaning agent, a second modified cleaning agent and a surfactant; The first modified cleaning agent is obtained by condensing a dihydroxy-terminated polysiloxane, a polyamine compound and an acid catalyst in a first solvent; The second modified cleaning agent is obtained by a hydrosilylation reaction of bisallyl-terminated polyether, methyl hydrogen-containing siloxane and a platinum catalyst in a second solvent.

2. The composite cleaning agent according to claim 1, characterized in that: Taking the mass of the composite cleaning agent as 100%, the mass fraction of the first modified cleaning agent in the composite cleaning agent is 40-55wt%, the mass fraction of the second modified cleaning agent is 40-55wt%, and the remainder is a surfactant.

3. The composite cleaning agent according to claim 1 or 2, characterized in that: The chemical formula of the double-terminal hydroxyl polysiloxane is HOCH2[Si(CH3)2] n Si(CH3)2CH2OH, wherein n is an integer from 3 to 10; Preferably, the polyamine compound includes any one or a combination of at least two of ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, 1,2-butylenediamine, 1,4-butylenediamine, o-phenylenediamine, m-phenylenediamine or p-phenylenediamine; Preferably, the molar ratio of the hydroxyl group in the dihydroxy-terminated polysiloxane to the amino group in the polyamine compound in the condensation reaction is 1:(1-2); Preferably, the acid catalyst comprises any one of hydrochloric acid, sulfuric acid or acetic acid or a combination of at least two thereof; Preferably, the mass of the acid catalyst in the condensation reaction is 0.1 to 1% of the total mass of the dihydroxy-terminated polysiloxane and the polyamine compound; Preferably, the first solvent comprises tetrahydrofuran and / or dimethylformamide; Preferably, the condensation reaction is carried out at a temperature of 10 to 60° C. and for a time of 1 to 4 hours.

4. The composite cleaning agent according to any one of claims 1 to 3, characterized in that: The structural formula of the bisallyl terminated polyether is CH2=CH-CH2-(O-CH2CH2-O) m -CH2-CH=CH2, wherein m is an integer from 3 to 15; Preferably, the chemical formula of the methyl hydrogen siloxane is H(CH3)2SiO-[SiO(CH3)2] x -Si(CH3)2H, wherein x is an integer from 2 to 10; Preferably, the platinum catalyst comprises any one or a combination of at least two of a platinum-alcohol complex, a platinum-olefin complex, a platinum-alkoxide complex, a platinum-ether complex, a platinum-ketone complex, a mixed solution of chloroplatinic acid and isopropanol, or a platinum-vinyl complex; Preferably, the second solvent comprises tetrahydrofuran and / or dimethylformamide; Preferably, in the hydrosilylation reaction, the molar ratio of the allyl group in the bisallyl-terminated polyether to the hydrogen group in the methyl hydrogen-containing siloxane is (1-1.5):1; Preferably, the mass of the platinum catalyst in the hydrosilylation reaction is 0.08 to 0.2% of the total mass of the bisallyl-terminated polyether and the methyl hydrogen-containing siloxane; Preferably, the temperature of the hydrosilylation reaction is 60-100° C., and the time is 1-4 hours.

5. The composite cleaning agent according to any one of claims 1 to 4, characterized in that: The surfactant is composed of a hydrophilic surfactant and a lipophilic surfactant; Preferably, the hydrophilic surfactant comprises fatty alcohol polyoxyethylene ether and / or fatty acid polyoxyethylene ether; Preferably, the lipophilic surfactant comprises sorbitan fatty acid ester; Preferably, the mass ratio of the hydrophilic surfactant to the lipophilic surfactant in the surfactant is (60-70):(30-40).

6. A method for cleaning a silicon carbide wafer, characterized in that: The cleaning method comprises: The silicon carbide wafer is first cleaned in the solution of the composite cleaning agent according to any one of claims 1 to 5, and then secondly cleaned and thirdly cleaned in the first cleaning agent and the second cleaning agent in sequence to obtain a cleaned silicon carbide wafer.

7. The cleaning method according to claim 6, characterized in that: The composite cleaning agent solution is obtained by mixing the composite cleaning agent with a third solvent, and the mass ratio of the composite cleaning agent to the third solvent in the composite cleaning agent solution is 1:(10-100); Preferably, the first cleaning comprises a first ultrasonic cleaning and a first surface residue cleaning performed sequentially; Preferably, the ultrasonic frequency in the first ultrasonic cleaning is 50-100 KHz, the time is 15-35 seconds, and the pore size of the circulation filter element is less than 0.5 μm; Preferably, the first surface residual cleaning is performed in a fast-drain rinsing tank, with a rinsing time of 3 to 6 minutes and a drainage time of 15 to 35 seconds.

8. The cleaning method according to claim 6 or 7, characterized in that: The first cleaning agent is composed of NH4OH, H2O2, a cationic surfactant, a chelating agent and a fourth solvent; Preferably, the mass ratio of NH4OH, H2O2, cationic surfactant, chelating agent and fourth solvent in the first cleaning agent is (1-3):(1-3):(0.2-0.5):(0.2-0.5):(5-10); Preferably, the cationic surfactant comprises tetradecyltrimethylammonium chloride and / or hexadecyltrimethylammonium chloride; Preferably, the chelating agent comprises any one of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, ethylene glycol bis(2-hydroxyethyl)aminetriacetic acid or ethylenediaminetetrapropionic acid, or a combination of at least two thereof; Preferably, the second cleaning comprises a second ultrasonic cleaning and a second surface residue cleaning performed sequentially; Preferably, the ultrasonic frequency in the second ultrasonic cleaning is 20-40 KHz, the time is 30-60 seconds, and the pore size of the circulation filter element is less than 0.5 μm; Preferably, the second surface residual cleaning is carried out in a fast-drain rinsing tank, with a rinsing time of 3 to 6 minutes and a drainage time of 2 to 5 seconds.

9. The cleaning method according to any one of claims 6 to 8, characterized in that: The second cleaning agent is composed of hydrochloric acid, hydrogen peroxide and a fifth solvent; Preferably, the mass ratio of hydrochloric acid, hydrogen peroxide and the fifth solvent in the second cleaning agent is (1-2):(1-2):(6-10); Preferably, the third cleaning comprises a third ultrasonic cleaning and a third surface residue cleaning performed sequentially; Preferably, the ultrasonic frequency in the third ultrasonic cleaning is 50-100 KHz, the time is 10-30 seconds, and the pore size of the circulation filter element is less than 0.5 μm; Preferably, the third surface residual cleaning is carried out in a fast-drain rinsing tank, with a rinsing time of 3 to 6 minutes and a drainage time of 2 to 5 seconds.

10. A cleaned silicon carbide wafer, characterized in that: The cleaned silicon carbide wafer is obtained by the cleaning method according to any one of claims 6 to 9.

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