Cleaning method of silicon carbide wafer and cleaned silicon carbide wafer

Abstract

The invention provides a silicon carbide wafer cleaning method and a cleaned silicon carbide wafer, and belongs to the technical field of semiconductor surface purification. The cleaning method comprises the following steps: placing a silicon carbide wafer to be cleaned in a composite cleaning solution, and carrying out organic cleaning; carrying out inorganic cleaning on the silicon carbide wafer after organic cleaning; wherein the composite cleaning solution comprises a main cleaning agent, a first auxiliary cleaning agent and a second auxiliary cleaning agent; the main cleaning agent comprises an organic alkaline cleaning agent, the first auxiliary cleaning agent comprises a Gemini anionic surfactant, and the second auxiliary cleaning agent comprises a polyhydroxy amide surfactant. According to the cleaning agent, the organic alkaline cleaning agent, the Gemini anionic surfactant and the polyhydroxy amide surfactant are synergistically matched, so that the surface hydrophilicity of the silicon carbide wafer is improved, and the subsequent cleaning effect and cleaning efficiency of the silicon carbide wafer are enhanced. In addition, the dual effects of organic cleaning and inorganic cleaning are combined, the cleaning process is simplified, and environmental friendliness is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor surface purification, and in particular relates to a method for cleaning a silicon carbide wafer and a cleaned silicon carbide wafer. Background Art

[0002] Silicon carbide wafers are a basic material that are widely used in the fields of electronics, optoelectronics, and semiconductors. To ensure the quality and performance of silicon carbide wafers, the wafer cleaning process is particularly important.

[0003] At present, there are many types of cleaning equipment for silicon carbide wafers on the market, but the main process principle is to remove surface pollutants through chemical reactions and physical effects. Among them, the RCA cleaning process is widely used. RCA is a common silicon wafer cleaning technology, including SPM (Sulfuric-Peroxide Mixture Cleaning), DHF (Diluted Hydrofluoric Acid), SC1, and SC2. SPM removes heavy organic matter and some metals on the surface of the wafer through strong oxidation, but it is difficult to remove when the organic pollution is serious; DHF removes the natural oxide film on the surface of the wafer, thereby dissolving the metal and particle contamination attached to the oxide film, while inhibiting the formation of a new oxide film.

[0004] The hydrophilicity of the wafer surface is mainly affected by organic pollutants and oxide films. The presence of organic pollutants will reduce the hydrophilicity of the wafer surface. When the organic pollution is serious, the traditional SPM cleaning cannot remove the organic matter on the wafer surface well, and the hydrophilicity of the wafer surface is poor, which affects the subsequent cleaning effect; the oxide film will increase the hydrophilicity of the wafer surface, but DHF cleaning will remove the natural oxide film on the silicon wafer surface, while inhibiting the formation of new oxide film, reducing the hydrophilicity of the wafer surface, and affecting the subsequent cleaning effect of the wafer.

[0005] Therefore, there is an urgent need to provide a cleaning method for making the surface of a silicon carbide wafer hydrophilic. Summary of the invention

[0006] In view of the deficiencies of the prior art, the object of the present invention is to provide a method for cleaning a silicon carbide wafer and a cleaned silicon carbide wafer. The present invention utilizes an organic alkaline cleaning agent, a Gemini anionic surfactant, and a polyhydroxyamide surfactant to cooperate with each other, significantly improving the surface hydrophilicity of the silicon carbide wafer and enhancing the subsequent cleaning effect and cleaning efficiency of the silicon carbide wafer. In addition, the present invention also combines the dual cleaning effects of organic cleaning and inorganic cleaning, which not only cleans thoroughly, but also simplifies the cleaning process, further improves the cleaning efficiency, and achieves the purpose of being environmentally friendly.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for cleaning a silicon carbide wafer, the cleaning method comprising the following steps:

[0009] placing the silicon carbide wafer to be cleaned in a composite cleaning solution for organic cleaning;

[0010] Performing inorganic cleaning on the silicon carbide wafer after organic cleaning;

[0011] The composite cleaning solution includes a main cleaning agent, a first auxiliary cleaning agent and a second auxiliary cleaning agent; the main cleaning agent includes an organic alkaline cleaning agent, the first auxiliary cleaning agent includes a Gemini anionic surfactant, and the second auxiliary cleaning agent includes a polyhydroxyamide surfactant.

[0012] The present invention utilizes organic alkaline cleaning agents, Gemini anionic surfactants and polyhydroxyamide surfactants to cooperate with each other, significantly improving the surface hydrophilicity of silicon carbide wafers, and enhancing the cleaning effect and cleaning efficiency of subsequent silicon carbide wafers. In addition, the present invention also combines the dual cleaning effects of organic cleaning and inorganic cleaning, which not only cleans thoroughly, but also simplifies the cleaning process, further improves the cleaning efficiency, and achieves the purpose of being environmentally friendly.

[0013] In the present invention, Gemini anionic surfactant is a type of surfactant with a special molecular structure, which is composed of two identical or different hydrophobic chains, two hydrophilic groups (usually anionic head groups) and a connecting group. Compared with traditional single-chain surfactants, its unique double hydrophobic chain and double hydrophilic group structure give it many advantages in performance. Gemini anionic surfactant itself has a certain ability to clean organic pollutants. At the same time, the hydrophilic group at one end can combine with the hydrophilic carbon surface of the silicon carbide wafer, and the hydrophilic group at the other end can improve the hydrophilicity of the carbon surface of the silicon carbide wafer, thereby improving the cleaning effect of the cleaning agent; at the same time, the negative charge property of the hydrophilic group in water can attract the positively charged metal impurities of the silicon carbide wafer, thereby facilitating the removal of metal impurities during the cleaning process.

[0014] In the present invention, the polyhydroxyamide surfactant is a surfactant containing multiple hydroxyl groups (-OH) and amide groups (-CONH-), and its molecular structure is generally composed of a hydrophobic part and a hydrophilic part containing hydroxyl groups and amide groups. Among them, the amide group of the hydrophobic part can be combined with the silicon surface of silicon carbide, and the hydrophilic groups of the polyhydroxyl groups are outward, which is conducive to improving the hydrophilicity of the silicon surface of silicon carbide and further improving the cleaning effect of the composite cleaning solution.

[0015] Preferably, the organic alkaline cleaning agent includes any one of N-methylpyrrolidone, polyvinylpyrrolidone or polyoxyethylene alkylamine, or a combination of at least two thereof.

[0016] Preferably, the Gemini anionic surfactant comprises dicarboxylates and / or disulfonates.

[0017] Preferably, the dicarboxylate salt comprises sodium dioctyl succinate and / or sodium behenyl succinate.

[0018] Preferably, the bissulfonate comprises sodium bis(dodecyl)benzenesulfonate and / or sodium bis(hexadecyl)benzenesulfonate.

[0019] Preferably, the polyhydroxyamide surfactant includes any one of cocoylglyceramide, N-stearoyl glucosamine or N-lauroyl glucosamine, or a combination of at least two thereof.

[0020] Preferably, the mass ratio of the main cleaning agent, the first auxiliary cleaning agent and the second auxiliary cleaning agent is 1:(0.1-1):(0.1-1), wherein the mass ratio of the main cleaning agent and the first auxiliary cleaning agent can be, for example, 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9 or 1:1, and the mass ratio of the main cleaning agent and the second auxiliary cleaning agent can be, for example, 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9 or 1:1. The mass ratio of the first cleaning agent to the second cleaning agent can be, for example, 0.1:0.1, 0.1:0.3, 0.1:0.5, 0.1:0.7, 0.1:0.9, 0.1:1, 0.3:0.1, 0.5:0.1, 0.7:0.1, 0.9:0.1 or 1:0.1, etc.

[0021] In the present invention, the main cleaning agent, the first auxiliary cleaning agent and the second auxiliary cleaning agent in an appropriate mass ratio cooperate with each other to fully remove heavy organic matter and metal impurities on the surface of the wafer.

[0022] Preferably, the cleaning temperature of the organic cleaning is 50-100°C, for example, it can be 50°C, 60°C, 70°C, 80°C, 90°C or 90°C.

[0023] In the present invention, a suitable cleaning temperature helps to accelerate the chemical reaction and improve the removal efficiency of pollutants.

[0024] Preferably, the cleaning time of the organic cleaning is 10-30 min, for example, 10 min, 15 min, 20 min, 25 min or 30 min.

[0025] Preferably, the organic cleaning process is accompanied by ultrasound.

[0026] In the present invention, ultrasound helps to remove large contaminants and particle contaminants on the wafer surface.

[0027] Preferably, the frequency of the ultrasound is 30-80 KHz, for example, it may be 30 KHz, 40 KHz, 50 KHz, 60 KHz, 70 KHz or 80 KHz.

[0028] Preferably, a pH regulator is also added during the organic cleaning process.

[0029] In the present invention, the purpose of adding a pH regulator is to adjust the pH of the cleaning system and improve the cleaning efficiency.

[0030] Preferably, the pH adjuster comprises any one of potassium hydroxide solution, sodium bicarbonate solution or sodium phosphate solution, or a combination of at least two thereof.

[0031] Preferably, the specific steps of the inorganic cleaning include:

[0032] The silicon carbide wafer after organic cleaning is placed in an inorganic cleaning solution for inorganic cleaning.

[0033] Preferably, the inorganic cleaning solution comprises inorganic acid and hydrogen peroxide.

[0034] In the present invention, inorganic acid and hydrogen peroxide are used in combination for inorganic cleaning, which can effectively remove the remaining organic pollutants on the surface of the wafer.

[0035] Preferably, based on the mass of the inorganic cleaning liquid, the mass fraction of the inorganic acid is 50-80wt%, for example, 50wt%, 60wt%, 70wt% or 80wt%, etc., and the mass fraction of the hydrogen peroxide is 20-50wt%, for example, 20wt%, 30wt%, 40wt% or 50wt%, etc.

[0036] Preferably, the inorganic acid comprises H2SO4 and HNO3.

[0037] In the present invention, H2SO4 and HNO3 are selected as inorganic acids to improve the removal rate of organic matter on the surface of the wafer.

[0038] Preferably, the mass ratio of H2SO4 to HNO3 is 1:(0.2-0.5), for example, it can be 1:0.2, 1:0.3, 1:0.4 or 1:0.5, etc.

[0039] In the present invention, H2SO4 and HNO3 in a suitable mass ratio are beneficial to the removal of residual organic pollutants on the surface of the wafer after ultrasonic cleaning, thereby improving the hydrophilicity of the wafer.

[0040] Preferably, the cleaning method comprises the following steps:

[0041] (1) An organic alkaline cleaning agent, a Gemini anionic surfactant and a polyhydroxyamide surfactant are mixed in a mass ratio of 1:(0.1-1):(0.1-1) to obtain a composite cleaning solution.

[0042] (2) placing the polished silicon carbide wafer to be cleaned in an organic cleaning solution composed of the composite cleaning solution and a pH regulator, controlling the pH value of the organic cleaning solution to be 9-14 (for example, 9, 10, 11, 12, 13 or 14, etc.), and performing organic cleaning, wherein the cleaning temperature of the organic cleaning is 50-100° C. and the cleaning time is 10-30 min; wherein the organic cleaning process is accompanied by ultrasound, and the frequency of the ultrasound is 30-80 KHz.

[0043] (3) placing the polished silicon carbide wafer after organic cleaning in an inorganic cleaning liquid for inorganic cleaning, wherein the time of the inorganic cleaning is 15-30 min (for example, 15 min, 20 min, 25 min or 30 min, etc.) and the temperature is 80-120° C. (for example, 80° C., 90° C., 100° C., 110° C. or 120° C., etc.); wherein the inorganic cleaning liquid comprises an inorganic acid and hydrogen peroxide, and based on the mass of the inorganic cleaning liquid, the mass fraction of the inorganic acid is 50-80wt%, the mass fraction of the hydrogen peroxide is 20-50wt%, and the inorganic acid comprises H2SO4 and HNO3 in a mass ratio of 1:(0.2-0.5).

[0044] (4) After inorganic cleaning, the polished silicon carbide wafer is immersed in ultrapure water for water washing, and then dried (for example, by spin drying) to complete the cleaning.

[0045] In a second aspect, the present invention provides a cleaned silicon carbide wafer obtained by cleaning using the cleaning method described in the first aspect, wherein the water contact angle of the cleaned silicon carbide wafer is 10-25°, for example, it can be 10°, 15°, 20° or 25°.

[0046] It should be noted that hydrophilicity refers to the formation of hydrogen bonds between chemical groups and water. The high surface hydrophilicity of the silicon carbide wafer will make the wafer better wetted and contacted with the cleaning liquid during the subsequent cleaning process, thereby improving the cleaning effect of the wafer. The water contact angle of the cleaned silicon carbide wafer obtained by the cleaning method provided by the present invention is 10-25°, indicating that the silicon carbide wafer has excellent surface hydrophilicity.

[0047] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The present invention utilizes organic alkaline cleaning agents, Gemini anionic surfactants and polyhydroxyamide surfactants to cooperate with each other, significantly improving the surface hydrophilicity of silicon carbide wafers, and enhancing the cleaning effect and cleaning efficiency of subsequent silicon carbide wafers. In addition, the present invention also combines the dual cleaning effects of organic cleaning and inorganic cleaning, which not only cleans thoroughly, but also simplifies the cleaning process, further improves the cleaning efficiency, and achieves the purpose of being environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a process flow chart of the cleaning method provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0051] 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.

[0052] Example 1

[0053] This embodiment provides a method for cleaning a silicon carbide wafer, and its process flow chart is as follows: Figure 1 As shown, the cleaning method comprises the following steps:

[0054] (1) Preparation of a composite cleaning solution: an organic alkaline cleaning agent, a Gemini anionic surfactant, and a polyhydroxyamide surfactant were mixed in a mass ratio of 1:0.3:0.6 to obtain a composite cleaning solution.

[0055] Among them, the organic alkaline cleaning agent is N-methylpyrrolidone, the Gemini anionic surfactant is dioctyl sodium succinate, and the polyhydroxyamide surfactant is coconut oil acylglyceramide.

[0056] (2) Organic cleaning: placing the polished silicon carbide wafer to be cleaned in an ultrasonic cleaning machine containing an organic cleaning solution composed of the composite cleaning solution and a pH adjuster, controlling the pH value of the organic cleaning solution to 13, and performing organic cleaning at a cleaning temperature of 80° C. for 30 minutes; wherein the frequency of the ultrasonic cleaning machine is 80 kHz; and the pH adjuster is a potassium hydroxide solution.

[0057] (3) Inorganic cleaning: placing the polished silicon carbide wafer after organic cleaning in a quartz tank containing an inorganic cleaning liquid for inorganic cleaning, wherein the time for the inorganic cleaning is 30 minutes and the temperature is 120° C.; wherein the inorganic cleaning liquid comprises an inorganic acid and hydrogen peroxide, and based on the mass of the inorganic cleaning liquid, the mass fraction of the inorganic acid is 65wt%, the mass fraction of the hydrogen peroxide is 35wt%, and the inorganic acid comprises H2SO4 and HNO3 in a mass ratio of 1:0.35;

[0058] (4) Water washing and drying: The polished silicon carbide wafer after inorganic cleaning is immersed in ultrapure water in the HQDR tank for water washing, and then dried using a spin dryer to obtain a cleaned silicon carbide wafer.

[0059] Example 2

[0060] This embodiment provides a method for cleaning a silicon carbide wafer, the cleaning method comprising the following steps:

[0061] (1) An organic alkaline cleaning agent, a Gemini anionic surfactant, and a polyhydroxyamide surfactant are mixed in a mass ratio of 1:0.6:0.3 to obtain a composite cleaning solution.

[0062] The organic alkaline cleaning agent is polyvinyl pyrrolidone, the Gemini anionic surfactant is sodium bis(dodecyl)benzene sulfonate, and the polyhydroxyamide surfactant is N-stearoyl glucosamine.

[0063] (2) placing the polished silicon carbide wafer to be cleaned in an ultrasonic cleaning machine containing an organic cleaning solution composed of the composite cleaning solution and a pH adjuster, controlling the pH value of the organic cleaning solution to 12, and performing organic cleaning, wherein the cleaning temperature of the organic cleaning is 100° C. and the cleaning time is 30 min; wherein the frequency of the ultrasonic cleaning machine is 80 KHz; and the pH adjuster is a sodium bicarbonate solution.

[0064] (3) placing the polished silicon carbide wafer after organic cleaning in a quartz tank containing an inorganic cleaning liquid for inorganic cleaning, wherein the inorganic cleaning time is 30 minutes and the temperature is 110° C.; wherein the inorganic cleaning liquid comprises an inorganic acid and hydrogen peroxide, and based on the mass of the inorganic cleaning liquid, the mass fraction of the inorganic acid is 50wt%, the mass fraction of the hydrogen peroxide is 50wt%, and the inorganic acid comprises H2SO4 and HNO3 in a mass ratio of 1:0.2;

[0065] (4) The polished silicon carbide wafer after inorganic cleaning is immersed in ultrapure water in a HQDR tank for immersion water washing, and then dried using a spin dryer to obtain a cleaned silicon carbide wafer.

[0066] Example 3

[0067] This embodiment provides a method for cleaning a silicon carbide wafer, the cleaning method comprising the following steps:

[0068] (1) An organic alkaline cleaning agent, a Gemini anionic surfactant, and a polyhydroxyamide surfactant are mixed in a mass ratio of 1:0.4:0.8 to obtain a composite cleaning solution.

[0069] Among them, the organic alkaline cleaning agent is polyoxyethylene alkylamine, the Gemini anionic surfactant is sodium dodecyl succinate, and the polyhydroxyamide surfactant is N-lauroyl glucosamine.

[0070] (2) placing the polished silicon carbide wafer to be cleaned in an ultrasonic cleaning machine containing an organic cleaning solution composed of the composite cleaning solution and a pH adjuster, controlling the pH value of the organic cleaning solution to 14, and performing organic cleaning, wherein the cleaning temperature of the organic cleaning is 80° C. and the cleaning time is 30 min; wherein the frequency of the ultrasonic cleaning machine is 80 KHz; and the pH adjuster is a potassium hydroxide solution.

[0071] (3) placing the polished silicon carbide wafer after organic cleaning in a quartz tank containing an inorganic cleaning liquid for inorganic cleaning, wherein the time of the inorganic cleaning is 30 minutes and the temperature is 120° C.; wherein the inorganic cleaning liquid comprises an inorganic acid and hydrogen peroxide, and based on the mass of the inorganic cleaning liquid, the mass fraction of the inorganic acid is 80wt%, the mass fraction of the hydrogen peroxide is 20wt%, and the inorganic acid comprises H2SO4 and HNO3 in a mass ratio of 1:0.5;

[0072] (4) The polished silicon carbide wafer after inorganic cleaning is immersed in ultrapure water in a HQDR tank for immersion water washing, and then dried using a spin dryer to obtain a cleaned silicon carbide wafer.

[0073] Example 4

[0074] The difference between this embodiment and embodiment 1 is that the mass ratio of the main cleaning agent to the first auxiliary cleaning agent is 1:1.5.

[0075] The rest of the cleaning methods and parameters were the same as those in Example 1.

[0076] Example 5

[0077] The difference between this embodiment and embodiment 1 is that the mass ratio of the main cleaning agent to the first auxiliary cleaning agent is 1:0.05.

[0078] The rest of the cleaning methods and parameters were the same as those in Example 1.

[0079] Example 6

[0080] The difference between this embodiment and embodiment 1 is that the mass ratio of the main cleaning agent to the second auxiliary cleaning agent is 1:1.5.

[0081] The rest of the cleaning methods and parameters were the same as those in Example 1.

[0082] Example 7

[0083] The difference between this embodiment and embodiment 1 is that the mass ratio of the main cleaning agent to the second auxiliary cleaning agent is 1:0.05.

[0084] The rest of the cleaning methods and parameters were the same as those in Example 1.

[0085] Example 8

[0086] The difference between this embodiment and embodiment 1 is that the mass ratio of the first cleaning aid to the second cleaning aid is 0.1:1.5.

[0087] The rest of the cleaning methods and parameters were the same as those in Example 1.

[0088] Example 9

[0089] The difference between this embodiment and embodiment 1 is that the mass ratio of the first cleaning aid to the second cleaning aid is 1.5:0.1.

[0090] The rest of the cleaning methods and parameters were the same as those in Example 1.

[0091] Example 10

[0092] The difference between this embodiment and embodiment 1 is that the inorganic acid is H2SO4.

[0093] The rest of the cleaning methods and parameters were the same as those in Example 1.

[0094] Embodiment 11

[0095] The difference between this embodiment and embodiment 1 is that the inorganic acid is HNO3.

[0096] The rest of the cleaning methods and parameters were the same as those in Example 1.

[0097] Comparative Example 1

[0098] The difference between this comparative example and Example 1 is that the composite cleaning liquid does not contain the first cleaning aid.

[0099] The rest of the cleaning methods and parameters were the same as those in Example 1.

[0100] Comparative Example 2

[0101] The difference between this comparative example and Example 1 is that the composite cleaning liquid does not contain the second cleaning aid.

[0102] The rest of the cleaning methods and parameters were the same as those in Example 1.

[0103] Comparative Example 3

[0104] The difference between this comparative example and Example 1 is that step (3) is not performed.

[0105] The rest of the cleaning methods and parameters were the same as those in Example 1.

[0106] Performance Testing

[0107] The water contact angle of the cleaned silicon carbide wafer obtained by cleaning the cleaning methods provided in the above embodiments and comparative examples is tested. The specific testing method includes:

[0108] 1) Ensure that the wafer surface is free of dust and dirt after cleaning.

[0109] 2) Take a 5 μL drop of ultrapure water and collect the liquid through the rising sample platform.

[0110] 3) Use a camera to capture images of the droplet and the sample surface.

[0111] 4) Use analysis software to measure the contact angle between the droplet and the solid surface.

[0112] The above test results are statistically analyzed, as shown in Table 1.

[0113] Table 1

[0114] Water contact angle Example 1 10° Example 2 13° Example 3 12° Example 4 15° Example 5 14° Example 6 16° Example 7 15° Example 8 19° Example 9 18° Example 10 17° Embodiment 11 19° Comparative Example 1 22° Comparative Example 2 23° Comparative Example 3 25°

[0115] analyze:

[0116] The present invention utilizes organic alkaline cleaning agents, Gemini anionic surfactants and polyhydroxyamide surfactants to cooperate with each other, significantly improving the surface hydrophilicity of silicon carbide wafers, and enhancing the cleaning effect and cleaning efficiency of subsequent silicon carbide wafers. In addition, the present invention also combines the dual cleaning effects of organic cleaning and inorganic cleaning, which not only cleans thoroughly, but also simplifies the cleaning process, further improves the cleaning efficiency, and achieves the purpose of being environmentally friendly.

[0117] By comparing Example 1 with Examples 4-5, it can be seen that if the mass ratio of the main cleaning agent to the first auxiliary cleaning agent is too small, the concentration of the main cleaning agent will be diluted, and the concentration of the first auxiliary cleaning agent will increase, the viscosity of the mixed solution will increase, and the fluidity of the cleaning solution will deteriorate, which is not conducive to the removal of organic pollutants on the chip surface; if the mass ratio of the main cleaning agent to the first auxiliary cleaning agent is too large, the content of the first auxiliary cleaning agent is relatively small, and the auxiliary cleaning effect is relatively low, which is not conducive to the main cleaning agent playing a role and affects the cleaning effect.

[0118] By comparing Example 1 with Examples 6-7, it can be seen that if the mass ratio of the main cleaning agent to the second auxiliary cleaning agent is too small, the concentration of the main cleaning agent is diluted, which is not conducive to the removal of organic pollutants on the chip surface. At the same time, the introduction of a large number of hydrophobic amide groups will reduce the hydrophilicity of the chip surface and affect the subsequent cleaning effect; if the mass ratio of the main cleaning agent to the second auxiliary cleaning agent is too large, the content of the second auxiliary cleaning agent is relatively small, and the auxiliary cleaning effect is relatively low, which is not conducive to the main cleaning agent to play a role and affects the cleaning effect.

[0119] By comparing Example 1 with Examples 8-9, it can be seen that if the mass ratio of the first cleaning agent to the second cleaning agent is too small, the content of the first cleaning agent is relatively small, the content of the hydrophilic group in the solution is relatively low, the hydrophilicity of the wafer surface is relatively poor, the cleaning effect is reduced, and it is not conducive to the removal of organic pollutants on the wafer surface; if the mass ratio of the first cleaning agent to the second cleaning agent is too large, the content of the first cleaning agent in the solution is too high, the fluidity of the solution deteriorates, the cleaning effect is reduced, and it is not conducive to the cleaning effect of the solution.

[0120] By comparing Example 1 with Examples 10-11, it can be seen that if the inorganic acid is H2SO4, the removal effect of organic matter on the wafer surface is lower than that of the mixed acid solution; if the inorganic acid is HNO3, the removal effect of organic matter on the wafer surface is lower than that of the mixed acid solution and the single sulfuric acid solution.

[0121] By comparing Example 1 with Comparative Examples 1-2, it can be seen that if the composite cleaning liquid does not contain the first auxiliary cleaning agent, it is not conducive to the main cleaning agent to play a role, affecting the cleaning effect; if the composite cleaning liquid does not contain the second auxiliary cleaning agent, it is not conducive to the main cleaning agent to play a role, affecting the cleaning effect.

[0122] By comparing Example 1 with Comparative Example 3, it can be seen that if step (3) is not performed, the organic matter on the wafer surface is not completely removed, the hydrophilicity of the wafer deteriorates, and the cleaning effect is affected.

[0123] The applicant declares that the present invention illustrates the process method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned process steps, that is, it does not mean that the present invention must rely on the above-mentioned process steps to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for cleaning a silicon carbide wafer, characterized in that: The cleaning method comprises the following steps: placing the silicon carbide wafer to be cleaned in a composite cleaning solution for organic cleaning; Performing inorganic cleaning on the silicon carbide wafer after organic cleaning; The composite cleaning solution includes a main cleaning agent, a first auxiliary cleaning agent and a second auxiliary cleaning agent; the main cleaning agent includes an organic alkaline cleaning agent, the first auxiliary cleaning agent includes a Gemini anionic surfactant, and the second auxiliary cleaning agent includes a polyhydroxyamide surfactant.

2. The cleaning method according to claim 1, characterized in that: The organic alkaline cleaning agent includes any one of N-methylpyrrolidone, polyvinylpyrrolidone or polyoxyethylene alkylamine or a combination of at least two thereof; and / or, the Gemini anionic surfactant comprises dicarboxylates and / or disulfonates; and / or, the dicarboxylate comprises sodium dioctyl succinate and / or sodium behenyl succinate; And / or, the bissulfonate comprises sodium bis(dodecyl)benzenesulfonate and / or sodium bis(hexadecyl)benzenesulfonate; And / or, the polyhydroxyamide surfactant includes any one or a combination of at least two of cocoylglyceramide, N-stearoyl glucosamine or N-lauroyl glucosamine; And / or, the mass ratio of the main cleaning agent, the first auxiliary cleaning agent and the second auxiliary cleaning agent is 1:(0.1-1):(0.1-1).

3. The cleaning method according to claim 1, characterized in that: The cleaning temperature of the organic cleaning is 50-100°C; And / or, the cleaning time of the organic cleaning is 10-30 minutes.

4. The cleaning method according to claim 1, characterized in that: The organic cleaning process is accompanied by ultrasound; And / or, the frequency of the ultrasound is 30-80 KHz.

5. The cleaning method according to claim 1, characterized in that: During the organic cleaning process, a pH regulator is also added; And / or, the pH adjuster includes any one of potassium hydroxide solution, sodium bicarbonate solution or sodium phosphate solution, or a combination of at least two thereof.

6. The cleaning method according to claim 1, characterized in that: The specific steps of the inorganic cleaning include: The silicon carbide wafer after organic cleaning is placed in an inorganic cleaning solution for inorganic cleaning.

7. The cleaning method according to claim 6, characterized in that: The inorganic cleaning solution includes inorganic acid and hydrogen peroxide; And / or, based on the mass of the inorganic cleaning solution, the mass fraction of the inorganic acid is 50-80wt%, and the mass fraction of the hydrogen peroxide is 20-50wt%.

8. The cleaning method according to claim 7, characterized in that: The inorganic acid includes H2SO4 and HNO3; And / or, the mass ratio of H2SO4 and HNO3 is 1:(0.2-0.5).

9. The cleaning method according to claim 1, characterized in that: The cleaning method comprises the following steps: (1) mixing an organic alkaline cleaning agent, a Gemini anionic surfactant and a polyhydroxyamide surfactant in a mass ratio of 1:(0.1-1):(0.1-1) to obtain a composite cleaning solution; (2) placing the polished silicon carbide wafer to be cleaned in an organic cleaning solution composed of the composite cleaning solution and a pH adjuster, controlling the pH value of the organic cleaning solution to be 9-14, and performing organic cleaning, wherein the cleaning temperature of the organic cleaning is 50-100° C., and the cleaning time is 10-30 min; wherein the organic cleaning process is accompanied by ultrasound, and the frequency of the ultrasound is 30-80 KHz; (3) placing the polished silicon carbide wafer after organic cleaning in an inorganic cleaning solution for inorganic cleaning, wherein the time of the inorganic cleaning is 15-30 minutes and the temperature is 80-120° C.; wherein the inorganic cleaning solution comprises an inorganic acid and hydrogen peroxide, and based on the mass of the inorganic cleaning solution, the mass fraction of the inorganic acid is 50-80wt%, the mass fraction of the hydrogen peroxide is 20-50wt%, and the inorganic acid comprises H2SO4 and HNO3 in a mass ratio of 1:(0.2-0.5); (4) After inorganic cleaning, the polished silicon carbide wafer is immersed in ultrapure water for water washing, and then dried to complete the cleaning.

10. A cleaned silicon carbide wafer obtained by cleaning using the cleaning method according to any one of claims 1 to 9, characterized in that: The water contact angle of the cleaned silicon carbide wafer is 10-25°.

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