A method for preparing a self-supporting silicon carbide film

Abstract

The present invention provides a method for preparing a self-supporting silicon carbide film. The method of the present invention comprises: introducing carbosilane and reducing gas into a growth chamber for the first time, and maintaining the temperature of the glassy carbon substrate at 900°C-1200°C, the pressure at 8000-20000Pa, growing for 60min-120min, and forming a silicon carbide peeling layer; introducing carbosilane and reducing gas into the growth chamber for the second time, and maintaining the temperature of the glassy carbon substrate at 1100°C-1300°C, the pressure at 8000-20000Pa, growing for 240min-560min, and forming a silicon carbide support layer on the surface of the silicon carbide peeling layer. The present invention improves the method for preparing a silicon carbide film, so that the generated silicon carbide film can achieve complete self-stripping and self-support from the surface of the glassy carbon substrate, thereby improving the appearance morphology and structural performance of the silicon carbide film, and after continued deposition, the silicon carbide film is tightly combined with the silicon carbide coating product to form a silicon carbide semiconductor product with good integrity.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon carbide semiconductors, in particular to a method for preparing a self-supporting silicon carbide film. Background Art

[0002] In the silicon carbide semiconductor industry, conventional silicon carbide film deposition methods easily cause the substrate and the CVD deposited product to tightly bond together during the deposition process. At this time, the film-substrate interface has strong bonding strength, making it impossible to achieve self-stripping. Physical methods are required to separate the substrate from the CVD deposited silicon carbide film. Furthermore, since the peeled silicon carbide film cannot achieve self-support after peeling, it is difficult to maintain the appearance, surface morphology, and structural properties of the silicon carbide film product after peeling. Therefore, there is an urgent need for a silicon carbide film that can achieve rapid peeling and is self-supporting. Summary of the Invention

[0003] Based on the problems existing in the above-mentioned prior art, the present invention provides a method for preparing a self-supporting silicon carbide film. By improving the method for preparing the silicon carbide film, the present invention can enable the generated silicon carbide film to achieve complete self-stripping and self-support from the surface of the glassy carbon substrate, thereby improving the appearance, morphology and structural performance of the silicon carbide film.

[0004] Specifically, in order to achieve the above-mentioned object, a first aspect of the present invention provides a method for preparing a self-supporting silicon carbide film, the method comprising: performing a surface cleaning treatment on a glassy carbon substrate;

[0005] placing a glassy carbon substrate in a growth chamber and evacuating the chamber to a vacuum state, and heating the glassy carbon substrate by microwave radiation, wherein the output power of the microwave radiation is 1000W-1500W;

[0006] introducing carbosilane and reducing gas into the growth chamber for the first time, maintaining the temperature of the glassy carbon substrate at 900° C.-1200° C. and the pressure at 8000-20000 Pa, and growing the substrate for 60 min-120 min to form a silicon carbide exfoliation layer;

[0007] introducing carbosilane and reducing gas into the growth chamber for a second time, maintaining the temperature of the glassy carbon substrate at 1100° C.-1300° C. and the pressure at 8000-20000 Pa, and growing the substrate for 240 min-560 min to form a silicon carbide support layer on the surface of the silicon carbide exfoliation layer;

[0008] Annealing the silicon carbide peeling layer and the silicon carbide support layer, and reducing the temperature of the glassy carbon substrate to 20° C.-30° C. at a cooling rate of 10° C. / h-20° C. / h;

[0009] The annealing treatment includes reducing the output power of microwave radiation to 500W-800W at a rate of 100W / h-300W / h, and the annealing time is 3-8h;

[0010] When the carbosilane and the reducing gas are introduced into the growth chamber for the first time, a gas flow ratio between the carbosilane and the reducing gas is 1:(1.5-1.8);

[0011] When the carbosilane and the reducing gas are introduced into the growth chamber for the second time, the gas flow ratio between the carbosilane and the reducing gas is 1:(0.8-1.2).

[0012] A second aspect of the present invention provides a self-supporting silicon carbide film, which is prepared by the method for preparing a self-supporting silicon carbide film according to the first aspect of the present invention.

[0013] Through the above technical solution, the present invention has at least the following advantages compared with the prior art:

[0014] (1) The method for preparing a self-supporting silicon carbide film provided by the present invention first generates a silicon carbide peeling layer by microwave chemical vapor deposition. The reducing gas in the deposition growth atmosphere can continuously perform plasma etching on the interface layer between the glassy carbon substrate and the silicon carbide peeling layer, thereby continuously weakening the interface bonding force between the glassy carbon substrate and the silicon carbide peeling layer by reaction, so that the bonding strength of the film-substrate interface becomes smaller after the growth of the silicon carbide film is completed, thereby improving the integrity of the silicon carbide film after peeling and obtaining a more excellent appearance, morphology and structural performance;

[0015] (2) The method for preparing a self-supporting silicon carbide film provided by the present invention, after generating a silicon carbide peeling layer that is easy to peel off, continues to deposit and generate a silicon carbide support layer. The reducing gas in the continuously introduced microwave atmosphere will generate plasma, which can continue to rapidly etch the interface layer between the glassy carbon substrate and the silicon carbide peeling layer, thereby preventing the silicon carbide film from sticking to the glassy carbon substrate during the deposition of the silicon carbide support layer;

[0016] (3) The method for preparing a self-supporting silicon carbide film provided by the present invention finally requires annealing the silicon carbide peeling layer and the silicon carbide support layer. This process enables the silicon carbide film to achieve self-stripping and self-support at the same time, so that a silicon carbide film with a complete film layer and capable of achieving self-support can be quickly obtained after the deposition is completed, thereby improving the appearance, morphology and structural performance of the silicon carbide film.

[0017] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein. DETAILED DESCRIPTION

[0018] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0019] Based on the problems and analysis existing in the above-mentioned prior art, the present invention provides a peelable multilayer material with excellent performance and a preparation method thereof. This peelable multilayer material improves the glassy carbon substrate material so that the thermal expansion coefficients of the glassy carbon substrate in the peelable multilayer material and the silicon carbide film deposited on its surface are closer, and the silicon carbide film with a thickness of only microns can be completely self-peeled from the surface of the glassy carbon substrate, thereby improving the appearance, morphology and structural performance of the silicon carbide film in the peelable multilayer material after peeling.

[0020] Specifically, in order to achieve the above-mentioned object, a first aspect of the present invention provides a method for preparing a self-supporting silicon carbide film, the method comprising: performing a surface cleaning treatment on a glassy carbon substrate;

[0021] Placing a glassy carbon substrate in a growth chamber and evacuating the chamber to a vacuum state, heating the glassy carbon substrate using microwave radiation, wherein the output power of the microwave radiation is 1000W-1500W (for example, 1000W, 1100W, 1200W, 1300W, 1400W, 1500W);

[0022] introducing carbosilane and reducing gas into the growth chamber for the first time, maintaining the temperature of the glassy carbon substrate at 900° C. to 1200° C. (e.g., 900° C., 1000° C., 1100° C., 1200° C.), maintaining the pressure at 8000 Pa to 20000 Pa, and growing for 60 min to 120 min to form a silicon carbide exfoliation layer;

[0023] Introducing carbosilane and reducing gas into the growth chamber for a second time, maintaining the temperature of the glassy carbon substrate at 1100° C. to 1300° C. (e.g., 1100° C., 1200° C., 1300° C.), and the pressure at 8000 Pa to 20000 Pa, and growing for 240 min to 560 min to form a silicon carbide support layer on the surface of the silicon carbide exfoliation layer;

[0024] Annealing the silicon carbide peeling layer and the silicon carbide support layer, and reducing the temperature of the glassy carbon substrate to 20° C.-30° C. at a cooling rate of 10° C. / h-20° C. / h;

[0025] The annealing treatment includes reducing the output power of microwave radiation at a rate of 100W / h-300W / h (for example, 100W / h, 200W / h, 300W / h) to 500W-800W (for example, 500W, 600W, 700W, 800W), and the annealing time is 3-8h.

[0026] Since microwave chemical vapor deposition facilitates the formation of reducing gas plasma, the method for preparing a self-supporting silicon carbide film provided by the present invention, during the process of first generating a silicon carbide peeling layer by microwave chemical vapor deposition, the plasma formed by the reducing gas in the deposition growth atmosphere can continuously perform plasma etching on the interface layer between the glassy carbon substrate and the silicon carbide peeling layer, thereby continuously weakening the interfacial bonding force between the glassy carbon substrate and the silicon carbide peeling layer through reaction, resulting in a decrease in the bonding strength of the film-substrate interface after the silicon carbide film is finally grown, thereby improving the integrity of the silicon carbide film after peeling and obtaining more excellent appearance, morphology and structural performance;

[0027] After forming a silicon carbide peeling layer that is easy to peel off, the silicon carbide support layer is deposited and formed. The reducing gas in the continuously introduced microwave atmosphere will continue to generate plasma, which can continue to rapidly etch the interface layer between the glassy carbon substrate and the silicon carbide peeling layer, thereby preventing the silicon carbide film from sticking to the glassy carbon substrate during the deposition of the silicon carbide support layer.

[0028] Finally, the silicon carbide peeling layer and the silicon carbide supporting layer need to be annealed. This process enables the silicon carbide film to achieve self-stripping and self-support at the same time. This is because the silicon carbide peeling layer and the silicon carbide self-supporting layer can quickly obtain a complete and self-supporting silicon carbide film after the deposition is completed, thereby improving the appearance, morphology and structural performance of the silicon carbide film.

[0029] In the present invention, the thickness of the silicon carbide exfoliation layer may be 20 nm to 200 nm, for example, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, or 200 nm. In one embodiment, the thickness of the silicon carbide exfoliation layer is 50 nm to 180 nm.

[0030] In the present invention, the thickness of the silicon carbide supporting layer needs to be ≥500nm, for example, 500nm, 510nm, 520nm, 530nm, 540nm, 550nm, 560nm, 570nm, 580nm, 590nm, 600nm, 620nm, 640nm, 660nm, 680nm, 700nm, 800nm, 900nm, or 1000nm.

[0031] The different thicknesses of the SiC support layer and the SiC peeling layer allow the SiC self-supporting layer to have different internal stresses than the SiC peeling layer. Furthermore, when the thickness is ≥500 nm, internal stress is more easily generated during annealing, allowing the SiC peeling layer to peel off from the glassy carbon substrate along with the SiC support layer, thereby facilitating self-peeling of the SiC film. However, an excessively thick SiC support layer may cause delamination between the SiC peeling layer and the SiC support layer. Therefore, in one embodiment, the SiC support layer has a thickness of 500 nm to 700 nm.

[0032] In the present invention, the carbosilane includes at least one of monosilane, disilane, trisilane, methylchlorosilane, dimethylchlorosilane or trichloromethylsilane, preferably trichloromethylsilane.

[0033] In the present invention, the reducing gas includes at least one of hydrogen, methane, ethylene or acetylene, preferably hydrogen.

[0034] In the present invention, when the carbosilane and the reducing gas are introduced into the growth chamber for the first time, the gas flow ratio between the carbosilane and the reducing gas is 1:(1.5-1.8), for example: 1:1.5, 1:1.6, 1:1.7, 1:1.8.

[0035] In the present invention, when the carbosilane and the reducing gas are introduced into the growth chamber for the first time, the gas flow rate of the carbosilane is 50L / min-90L / min, for example: 50L / min, 55L / min, 60L / min, 65L / min, 70L / min, 75L / min, 80L / min, 85L / min, 90L / min; the gas flow rate of the reducing gas is 70L / min-170L / min, for example: 70L / min, 80L / min, 90L / min, 100L / min, 110L / min, 120L / min, 130L / min, 140L / min, 150L / min, 160L / min, 170L / min.

[0036] In the present invention, when the carbosilane and the reducing gas are introduced into the growth chamber for the second time, the gas flow ratio between the carbosilane and the reducing gas is 1:(0.8-1.2), for example: 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2.

[0037] In the present invention, when the carbosilane and the reducing gas are introduced into the growth chamber for the second time, the gas flow rate of the carbosilane is 70L / min-140L / min, for example: 70L / min, 80L / min, 90L / min, 100L / min, 110L / min, 120L / min, 130L / min, 140L / min; the gas flow rate of the reducing gas is 60L / min-120L / min, for example: 60L / min, 70L / min, 80L / min, 90L / min, 100L / min, 110L / min, 120L / min.

[0038] Different silicon carbide layers use different gas flow ratios and different gas flow rates, which can further control the internal stress of the two silicon carbide layers with different functions, thereby achieving better self-stripping and self-support.

[0039] In the present invention, the surface of the glassy carbon substrate is cleaned by sequentially cleaning the glassy carbon substrate with acetone, anhydrous ethanol, and deionized water to remove impurities on the surface. Cleaning the impurities before deposition is more conducive to the stripping of the silicon carbide film.

[0040] In the present invention, the glassy carbon substrate comprises carbon particles, linear phenolic resin, phenolic resin curing agent, glass fiber and viscose fiber;

[0041] Based on the total weight of the glassy carbon substrate, the content of the carbon particles is 50 wt%-60 wt% (for example, 50 wt%, 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, 56 wt%, 57 wt%, 58 wt%, 59 wt%, and 60 wt%), the content of the linear phenolic resin is 5 wt%-12 wt% (for example, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, and 12 wt%), the content of the phenolic resin curing agent is 25 wt%-35 wt% (for example, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, and 35 wt%), the content of the glass fiber is 1 wt%-5 wt% (for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, and 5 wt%), and the content of the viscose fiber is 1 wt%-2 wt% (for example, 1 wt%, and 2 wt%).

[0042] Glass fiber is used in the raw materials of the glassy carbon substrate to prepare glassy carbon. The thermal expansion coefficient of glass fiber is low. As one of the raw material components, it can reduce the expansion coefficient of the surface of the glassy carbon substrate, making it closer to the thermal expansion coefficient of the silicon carbide film. After the annealing process, it is conducive to the complete self-peeling of the silicon carbide film with a thickness of only microns from the surface of the glassy carbon substrate, thereby further improving the self-peeling and self-supporting properties of the silicon carbide film, and further improving the appearance, morphology and structural performance of the silicon carbide film.

[0043] In the present invention, the glassy carbon substrate is prepared by the following method:

[0044] The method comprises the following steps:

[0045] S1. mixing carbon particles, linear phenolic resin, phenolic resin curing agent, glass fiber and viscose fiber to form a premix;

[0046] S2, impregnating the preform mixture prepared in step S1 into a substrate mold, and performing hot pressing molding to form a composite structure having the shape of the substrate;

[0047] S3. The material obtained in step S2 is further subjected to thermal curing treatment to prepare the glassy carbon substrate.

[0048] In a specific embodiment, the carbon particles include at least one of graphite chips, carbon fibers, glassy carbon chips, and natural graphite powder.

[0049] In one embodiment, the linear phenolic resin is liquid. It is understood that the liquid linear phenolic resin can evenly mix the other materials introduced to form a uniform slurry, which is more conducive to solidification and molding when poured into a mold.

[0050] In a specific embodiment, the phenolic resin curing agent includes at least one of benzenesulfonyl chloride, p-toluenesulfonyl chloride, and ethyl sulfate.

[0051] In step S2, the hot press molding process is performed under conditions including a hot press temperature of 50°C to 100°C and a hot press pressure of 0.5 MPa to 2 MPa. For example, the hot press temperature may be 50°C, 60°C, 70°C, 80°C, 90°C, or 100°C. For example, the hot press pressure may be 0.5 MPa, 1 MPa, 1.5 MPa, or 2 MPa.

[0052] In step S3, the conditions of the heat curing treatment include: using microwave radiation equipment to quickly heat the material obtained in step S2, the power of the microwave radiation equipment is 800W-1200W, the heating time is 100min-240min, the heating rate is 5℃ / min-10℃ / min, and the temperature range is 800℃-1200℃.

[0053] A second aspect of the present invention provides a self-supporting silicon carbide film, which is prepared by the method for preparing a self-supporting silicon carbide film according to the first aspect of the present invention.

[0054] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0055] Unless otherwise specified, the materials and instruments used in the following examples are commercially available.

[0056] Example 1

[0057] 1. Preparation of glassy carbon substrate, specifically including the following steps:

[0058] Graphite crumbs + linear phenolic resin liquid + phenolic resin curing agent are used as raw materials, wherein graphite crumbs: linear phenolic resin: phenolic resin curing agent = 54%wt: 11%wt: 30%wt; the raw materials also contain 3.6%wt of glass fiber and 1.4%wt of viscose fiber. The above raw materials are first mixed and kneaded into a paste;

[0059] The preform mixture is impregnated into a support rod mold and compression molded or hot pressed under the conditions of a hot pressing temperature of 80° C. and a hot pressing pressure of 1 MPa to form an integral composite structure.

[0060] Place the container containing the raw materials in a microwave irradiation device. Depending on the device and experimental conditions, set the appropriate power, time, and temperature (power: 1000W, heating time: 150 minutes, heating rate: 8°C / min, temperature range: 1000°C) for microwave heating. Microwave radiation heats the raw materials, raising their temperature and ultimately forming a glassy carbon substrate in the shape of a support rod.

[0061] 2. Preparation of self-supporting silicon carbide film, specifically including the following steps:

[0062] The glassy carbon substrate obtained in step 1 is cleaned of other impurities on its surface using acetone, anhydrous ethanol and deionized water in sequence;

[0063] The glassy carbon substrate was placed in a growth chamber of a microwave chemical vapor deposition device and evacuated to a vacuum. The glassy carbon substrate was heated by microwave radiation. The output power of the microwave radiation was 1500W. Trichloromethylsilane and hydrogen were introduced at a gas flow ratio of 1:1.6 to deposit a silicon carbide peeling layer. The thickness of the silicon carbide peeling layer was 100 nm. The specific microwave chemical vapor deposition process parameters were set as follows: deposition temperature: 1000°C; MTS (trichloromethylsilane): 80 L / min; hydrogen: 130 L / min; argon: 80 L / min; pressure: 10,000 Pa; and deposition time: 100 min. The silicon carbide peeling layer was obtained.

[0064] Trichloromethylsilane and hydrogen were introduced again with a gas flow ratio of 1:1 to deposit a silicon carbide support layer having a thickness of 500 nm. The specific parameters of the microwave chemical vapor deposition process were set as follows: deposition temperature: 1200° C.; MTS (trichloromethylsilane): 120 L / min; hydrogen: 120 L / min; argon: 80 L / min; pressure: 10,000 Pa; and deposition time: 500 min. The silicon carbide support layer was obtained.

[0065] Annealing the obtained silicon carbide peeling layer and silicon carbide support layer, reducing the output power of microwave radiation from 300 W / h to 500 W, annealing for 3.5 hours, and cooling the glassy carbon substrate to 20°C-30°C at a cooling rate of 10°C / h-20°C / h, to finally obtain a completely peeled self-supporting silicon carbide film;

[0066] The silicon carbide film prepared in this embodiment can be easily self-peeled from the glassy carbon substrate, and the surface of the silicon carbide film will not be damaged. It can continue to be tightly bonded with the silicon carbide coating product to form a silicon carbide semiconductor product with good integrity.

[0067] Example 2

[0068] The preparation process of the glassy carbon substrate of Example 2 is carried out with reference to Example 1, and the preparation method of the self-supporting silicon carbide film is modified as follows:

[0069] The glassy carbon substrate was placed in a growth chamber of a microwave chemical vapor deposition device and evacuated to a vacuum. The glassy carbon substrate was heated by microwave radiation. The output power of the microwave radiation was 1300 W. Trichloromethylsilane and hydrogen were introduced at a gas flow ratio of 1:1.5 to deposit a silicon carbide peeling layer. The thickness of the silicon carbide peeling layer was 50 nm. The specific microwave chemical vapor deposition process parameters were set as follows: deposition temperature: 900° C.; MTS (trichloromethylsilane): 50 L / min; hydrogen: 75 L / min; argon: 80 L / min; pressure: 10,000 Pa; and deposition time: 60 min. The silicon carbide peeling layer was obtained.

[0070] Trichloromethylsilane and hydrogen were introduced again with a gas flow ratio of 1:0.85 to deposit a silicon carbide support layer. The thickness of the silicon carbide support layer was 800 nm. The specific parameters of the microwave chemical vapor deposition process were set as follows: deposition temperature: 1200°C; MTS (trichloromethylsilane): 140 L / min; hydrogen: 120 L / min; argon: 80 L / min; pressure: 10,000 Pa; and deposition time: 500 min to obtain the silicon carbide support layer.

[0071] Example 3

[0072] The preparation process of the glassy carbon substrate of Example 3 is carried out with reference to Example 1, and the preparation method of the self-supporting silicon carbide film is modified as follows:

[0073] The glassy carbon substrate was placed in a growth chamber of a microwave chemical vapor deposition device and evacuated to vacuum. The glassy carbon substrate was heated by microwave radiation with an output power of 1000 W. Trichloromethylsilane and hydrogen were introduced with a gas flow ratio of 1:1.8 to deposit a silicon carbide peeling layer. The thickness of the silicon carbide peeling layer was 200 nm. The specific parameters of the microwave chemical vapor deposition process were set as follows: deposition temperature: 900°C; MTS (trichloromethylsilane): 90 L / min; hydrogen: 165 L / min; argon: 80 L / min; pressure: 10,000 Pa; deposition time: 120 min to obtain a silicon carbide peeling layer.

[0074] Example 4

[0075] The preparation process of the glassy carbon substrate of Example 4 is carried out with reference to Example 1, and the preparation method of the self-supporting silicon carbide film is modified as follows:

[0076] The silicon carbide peeling layer and silicon carbide support layer obtained above were annealed, the output power of the microwave radiation was reduced to 800 W at a rate of 100 W / h, the annealing time was 7 hours, and the temperature of the glassy carbon substrate was reduced to 20°C-30°C at a cooling rate of 10°C / h-20°C / h, and finally a completely peeled self-supporting silicon carbide film was obtained.

[0077] Example 5

[0078] The preparation process of the glassy carbon substrate of Example 5 is carried out with reference to Example 1, and the preparation method of the self-supporting silicon carbide film is modified as follows:

[0079] The silicon carbide peeling layer and silicon carbide support layer obtained above were annealed, the output power of the microwave radiation was reduced to 700 W at a rate of 200 W / h, the annealing time was 4 h, and the temperature of the glassy carbon substrate was reduced to 20°C-30°C at a cooling rate of 10°C / h-20°C / h, and finally a completely peeled self-supporting silicon carbide film was obtained.

[0080] Comparative Example 1

[0081] The preparation process of the glassy carbon substrate of Comparative Example 1 was carried out with reference to Example 1, and the method for preparing the self-supporting silicon carbide film was changed as follows: carbon silane and reducing gas were introduced only once, specifically, it was placed in the growth chamber of the microwave chemical vapor deposition equipment, evacuated to vacuum, and the glassy carbon substrate was heated by microwave radiation. The output power of the microwave radiation was 1500W, and trichloromethylsilane and hydrogen were introduced with a gas flow ratio of 1:1.6 to deposit a silicon carbide film. The thickness of the silicon carbide release film was 600nm. The specific parameters of the microwave chemical vapor deposition process were set as: deposition temperature: 1200°C; MTS (trichloromethylsilane): 80L / min; hydrogen: 130L / min; argon: 80L / min; pressure: 10000Pa; deposition time: 600min; and a silicon carbide film was obtained.

[0082] Comparative Example 2

[0083] The preparation process of the glassy carbon substrate of Comparative Example 2 was carried out with reference to Example 1, and the preparation method of the self-supporting silicon carbide film was changed as follows: a conventional chemical vapor deposition process was adopted, and microwave radiation was not used to heat the glassy carbon substrate.

[0084] Comparative Example 3

[0085] The preparation process of the glassy carbon substrate of Comparative Example 3 is carried out with reference to Example 1, and the preparation method of the self-supporting silicon carbide film is changed as follows: the silicon carbide film generated by the silicon carbide peeling layer and the silicon carbide support layer is not annealed.

[0086] Silicon carbide films were prepared according to the preparation steps of the above-mentioned groups of embodiments and comparative examples, and the silicon carbide films that could be completely peeled off and had no damage on the surface of the silicon carbide films were considered qualified. Each group of embodiments and comparative examples was tested 10 times, among which, embodiment 1 could easily self-peel off from the glass carbon substrate, and the surface of the silicon carbide film would not be damaged. The 10 tests all ensured the self-peeling of the silicon carbide film and that it could be self-supporting: in embodiment 2, due to the thin thickness of the silicon carbide peeling layer, the silicon carbide film was damaged during the peeling process 3 times in 10 tests; embodiments 3-5 could also easily self-peel off from the glass carbon substrate, and the surface of the silicon carbide film would not be damaged. The 10 tests all showed that the silicon carbide film In the comparison example 1, since no silicon carbide peeling layer is deposited, the bonding strength between the glass carbon substrate and the silicon carbide film is strong, and the silicon carbide film is damaged during the manual stripping process more than 5 times in 10 tests; in the comparison example 2, since no microwave process is used, hydrogen plasma cannot be generated to quickly etch and strip the silicon carbide film, and therefore the silicon carbide film is damaged during the manual stripping process more than 5 times in 10 tests; in the comparison example 3, since no annealing treatment is performed, the self-stripping and self-support of the silicon carbide film cannot be achieved, and therefore, manual stripping of the silicon carbide film is required. In the 10 tests, due to the difficulty of manual stripping, more than 5 times of damage will occur.

[0087] In summary, the present invention improves the method for preparing silicon carbide film, so that the generated silicon carbide film can achieve complete self-stripping and self-support from the surface of the glassy carbon substrate, thereby improving the appearance, morphology and structural performance of the silicon carbide film.

[0088] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing a self-supporting silicon carbide film, characterized in that: The method comprises: performing surface cleaning treatment on a glassy carbon substrate; placing a glassy carbon substrate in a growth chamber and evacuating the chamber to a vacuum state, and heating the glassy carbon substrate by microwave radiation, wherein the output power of the microwave radiation is 1000W-1500W; introducing carbosilane and reducing gas into the growth chamber for the first time, maintaining the temperature of the glassy carbon substrate at 900° C.-1200° C. and the pressure at 8000-20000 Pa, and growing the substrate for 60 min-120 min to form a silicon carbide exfoliation layer; introducing carbosilane and reducing gas into the growth chamber for a second time, maintaining the temperature of the glassy carbon substrate at 1100° C.-1300° C. and the pressure at 8000-20000 Pa, and growing the substrate for 240 min-560 min to form a silicon carbide support layer on the surface of the silicon carbide exfoliation layer; Annealing the silicon carbide peeling layer and the silicon carbide support layer, and reducing the temperature of the glassy carbon substrate to 20° C.-30° C. at a cooling rate of 10° C. / h-20° C. / h; The annealing treatment includes reducing the output power of microwave radiation to 500W-800W at a rate of 100W / h-300W / h, and the annealing time is 3-8h; The thickness of the silicon carbide peeling layer is 20nm~200nm; The thickness of the silicon carbide support layer is ≥500nm; When the carbosilane and the reducing gas are introduced into the growth chamber for the first time, a gas flow ratio between the carbosilane and the reducing gas is 1:(1.5-1.8); When the carbosilane and the reducing gas are introduced into the growth chamber for the second time, the gas flow ratio between the carbosilane and the reducing gas is 1:(0.8-1.2).

2. The method for preparing a self-supporting silicon carbide film according to claim 1, wherein: The carbosilane hydrocarbon includes at least one of monosilane, disilane, trisilane, methylchlorosilane, dimethylchlorosilane or trichloromethylsilane; And / or, the reducing gas includes at least one of hydrogen, methane, ethylene or acetylene.

3. The method for preparing a self-supporting silicon carbide film according to claim 1, wherein: The gas flow rate of the carbosilane is 50 L / min-90 L / min; the gas flow rate of the reducing gas is 70 L / min-170 L / min.

4. The method for preparing a self-supporting silicon carbide film according to claim 1, wherein: The gas flow rate of the carbosilane is 70 L / min-140 L / min; the gas flow rate of the reducing gas is 60 L / min-120 L / min.

5. The method for preparing a self-supporting silicon carbide film according to claim 1, wherein: The glassy carbon substrate is subjected to a surface cleaning treatment, comprising: The glassy carbon substrate is cleaned of other impurities on its surface using acetone, anhydrous ethanol and deionized water in sequence.

6. The method for preparing a self-supporting silicon carbide film according to claim 1, wherein: The glassy carbon substrate comprises carbon particles, linear phenolic resin, phenolic resin curing agent, glass fiber and viscose fiber; Based on the total weight of the glassy carbon substrate, the content of the carbon particles is 50 wt%-60 wt%, the content of the linear phenolic resin is 5 wt%-12 wt%, the content of the phenolic resin curing agent is 25 wt%-35 wt%, the content of the glass fiber is 1 wt%-5 wt%, and the content of the viscose fiber is 1 wt%-2 wt%.

7. A self-supporting silicon carbide film, characterized in that The self-supporting silicon carbide film is prepared by the method for preparing a self-supporting silicon carbide film according to any one of claims 1 to 6.