Method for preparing self-supporting silicon carbide film

Abstract

The invention provides a method for preparing a self-supporting silicon carbide film. The method comprises the following steps: introducing carbosilane alkane and reducing gas into a growth chamber for the first time, maintaining the temperature of a glassy carbon substrate at 900-1200 DEG C, maintaining the pressure at 8000-20000 Pa, and growing for 60-120 minutes to form a silicon carbide stripping layer; and introducing carbosilane alkane and reducing gas into the growth chamber for the second time, maintaining the temperature of the glassy carbon substrate at 1100-1300 DEG C, maintaining the pressure at 8000-20000 Pa, growing for 240-560 minutes, and forming a silicon carbide support layer on the surface of the silicon carbide stripping layer. By improving the method for preparing the silicon carbide film, the generated silicon carbide film can be completely self-stripped and self-supported from the surface of the glassy carbon substrate, so that the appearance and the structural performance of the silicon carbide film are improved, the silicon carbide film is tightly combined with a silicon carbide coating product after continuous deposition, and the performance of the silicon carbide coating product is improved. And a silicon carbide semiconductor product with good integrity can be formed.

Description

Technical Field

[0001] The 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 be tightly bonded together during the deposition process. At this time, the film-substrate interface bonding force is strong and cannot be self-stripped. It is necessary to separate the substrate from the CVD deposited product silicon carbide film by physical methods. And because the peeled silicon carbide film cannot be self-supporting, it is difficult to ensure the appearance, surface morphology and structural performance of the silicon carbide film product after peeling. Therefore, there is an urgent need for a silicon carbide film that can be quickly peeled and self-supporting. Summary of the invention

[0003] Based on the above-mentioned problems existing in the 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., maintaining the pressure at 8000-20000 Pa, growing for 60 min-120 min, and forming a silicon carbide peeling layer;

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

[0008] Annealing the silicon carbide peeling layer and the silicon carbide supporting 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, wherein the self-supporting silicon carbide film 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, and 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, so that the interface bonding force between the glassy carbon substrate and the silicon carbide peeling layer is continuously weakened by the 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, and 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 supporting 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 and any values ​​of the ranges disclosed in this article 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 endpoint values ​​of each range, the endpoint values ​​of each range and the 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 as specifically disclosed in this article. DETAILED DESCRIPTION

[0018] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0019] Based on the problems and analysis existing in the above-mentioned prior art, the present invention provides a strippable multilayer material with excellent performance and a preparation method thereof. The strippable multilayer material improves the glassy carbon substrate material so that the thermal expansion coefficients of the glassy carbon substrate in the strippable 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 properties of the silicon carbide film in the strippable 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 by 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.-1200° C. (e.g., 900° C., 1000° C., 1100° C., 1200° C.), maintaining the pressure at 8000-20000 Pa, and growing for 60 min-120 min to form a silicon carbide peeling layer;

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

[0024] Annealing the silicon carbide peeling layer and the silicon carbide supporting 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] Wherein, 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 is conducive to the formation of reducing gas plasma, in the method for preparing a self-supporting silicon carbide film provided by the present invention, in 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, so that the interface bonding force between the glassy carbon substrate and the silicon carbide peeling layer is continuously weakened by the reaction, so that the bonding strength of the film-base interface after the growth of the silicon carbide film is finally completed becomes smaller, thereby improving the integrity of the silicon carbide film after peeling, and obtaining a more excellent appearance morphology and structural performance;

[0027] After a silicon carbide peeling layer that is easy to peel off is generated, the silicon carbide support layer is continuously deposited, and the reducing gas in the continuously introduced microwave atmosphere will continue to generate plasma, which can continue to quickly 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 can make the silicon carbide film self-stripping and self-supporting 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 peeling 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, 200 nm. In one example, the thickness of the silicon carbide peeling 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 silicon carbide support layer and the silicon carbide peeling layer can make the silicon carbide self-supporting layer obtain different internal stress from the silicon carbide peeling layer, and its thickness is ≥500nm. During the annealing process, it is easier to generate internal stress so that the silicon carbide peeling layer peels off along with the silicon carbide support layer and the glassy carbon substrate, thereby making it easier for the silicon carbide film to self-peel off. However, an overly thick silicon carbide support layer may cause the silicon carbide peeling layer and the silicon carbide support layer to delaminate. Therefore, in one example, the thickness of the silicon carbide support layer is 500nm to 700nm.

[0032] In the present invention, the carbosilane hydrocarbon 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 cleaning treatment of the silicon carbide substrate includes: cleaning other impurities on the surface of the silicon carbide substrate with acetone, anhydrous ethanol and deionized water in sequence. Cleaning impurities first 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%, 60 wt%), and 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%, 12 wt%), The content of the phenolic resin curing agent is 25 weight %-35 weight % (for example: 25 weight %, 26 weight %, 27 weight %, 28 weight %, 29 weight %, 30 weight %, 31 weight %, 32 weight %, 33 weight %, 34 weight %, 35 weight %), the content of the glass fiber is 1 weight %-5 weight % (for example: 1 weight %, 2 weight %, 3 weight %, 4 weight %, 5 weight %), and the content of the viscose fiber is 1 weight %-2 weight % (for example: 1 weight %, 2 weight %).

[0042] Glass fiber is used in the raw materials of the glassy carbon substrate to prepare glassy carbon. The glass fiber has a low thermal expansion coefficient. 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 beneficial for the silicon carbide film with a thickness of only microns to achieve complete self-peeling 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 properties 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, kneading carbon particles, linear phenolic resin, phenolic resin curing agent, glass fiber and viscose fiber into 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 a substrate shape;

[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 a specific embodiment, the linear phenolic resin is liquid. It is understood that the liquid linear phenolic resin can evenly mix the other introduced materials to form a uniform slurry, which is more conducive to curing 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 conditions of the hot pressing molding process include: the hot pressing temperature is 50°C-100°C, and the hot pressing pressure is 0.5MPa-2MPa. Exemplarily, the hot pressing temperature can be 50°C, 60°C, 70°C, 80°C, 90°C, 100°C. Exemplarily, the hot pressing pressure is 0.5MPa, 1MPa, 1.5MPa, 2MPa.

[0052] In step S3, the conditions for the heat curing treatment include: using microwave radiation equipment to quickly heat up 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, wherein the self-supporting silicon carbide film 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 described embodiments 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 creative work 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, and the above raw materials are firstly mixed and kneaded into a paste;

[0059] The preform mixture is impregnated into a support rod mold and compression molded or hot pressed at 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 radiation device. According to different equipment and experimental conditions, set appropriate power, time and temperature (power is 1000W, heating time is 150min, heating rate is 8℃ / min, temperature range is 1000℃) to perform microwave heating: the raw materials are heated by microwave radiation to increase their temperature, and finally a glassy carbon substrate in the shape of a support rod is prepared;

[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 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 100nm. The specific parameters of the microwave chemical vapor deposition process were set as follows: deposition temperature: 1000°C; MTS (trichloromethylsilane): 80L / min; hydrogen: 130L / min; argon: 80L / min; pressure: 10000Pa; deposition time: 100min; and a silicon carbide peeling layer was obtained.

[0064] Trichloromethylsilane and hydrogen were introduced again, and the gas flow ratio was 1:1, and a silicon carbide support layer was deposited. The thickness of the silicon carbide support layer was 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: 10000 Pa; deposition time: 500 min; and a silicon carbide support layer was obtained;

[0065] Annealing the silicon carbide peeling layer and the silicon carbide supporting layer obtained above, reducing the output power of the microwave radiation at a rate of 300 W / h to 500 W, the annealing time is 3.5 h, and the temperature of the glassy carbon substrate is reduced to 20°C-30°C at a cooling rate of 10°C / h-20°C / h, and finally obtaining 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 combined 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 method for preparing the self-supporting silicon carbide film is changed as follows:

[0069] The 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 parameters of the microwave chemical vapor deposition process were set as follows: deposition temperature: 900° C.; MTS (trichloromethylsilane): 50 L / min; hydrogen: 75 L / min; argon: 80 L / min; pressure: 10000 Pa; deposition time: 60 min; and a 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: 10000 Pa; deposition time: 500 min to obtain a 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 method for preparing the self-supporting silicon carbide film is changed as follows:

[0073] 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 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: 10000 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 method for preparing the self-supporting silicon carbide film is changed as follows:

[0076] The silicon carbide peeling layer and silicon carbide supporting layer obtained above were annealed, the output power of 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 method for preparing the self-supporting silicon carbide film is changed as follows:

[0079] The silicon carbide peeling layer and silicon carbide supporting layer obtained above were annealed, the output power of 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 is carried out with reference to Example 1, and the method for preparing the self-supporting silicon carbide film is changed as follows: carbon silane hydrocarbon and reducing gas are introduced only once, specifically, it is placed in the growth chamber of the microwave chemical vapor deposition equipment, evacuated to vacuum, and the glassy carbon substrate is heated by microwave radiation. The output power of the microwave radiation is 1500W, and trichloromethylsilane and hydrogen are introduced with a gas flow ratio of 1:1.6 to deposit a silicon carbide film. The thickness of the silicon carbide peeling film is 600nm. The specific parameters of the microwave chemical vapor deposition process are 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 is obtained.

[0082] Comparative Example 2

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

[0086] According to the preparation steps of the above-mentioned groups of embodiments and comparative examples, silicon carbide films were prepared respectively, and complete peeling could be achieved. The silicon carbide films without 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 achieve self-peeling from the glassy 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 achieved self-support: 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 out of 10 tests; embodiments 3-5 could also easily achieve self-peeling from the glassy carbon substrate, and the surface of the silicon carbide film would not be damaged. The 10 tests all showed The silicon carbide film was damaged twice during the stripping process; in Comparative Example 1, since no silicon carbide stripping layer was deposited, the bonding strength between the glass carbon substrate and the silicon carbide film was strong, and the silicon carbide film was damaged more than 5 times in 10 tests during the manual stripping process; in Comparative Example 2, since no microwave process was used, hydrogen plasma could not be generated to quickly etch and strip the silicon carbide film, and therefore, the silicon carbide film was damaged more than 5 times in 10 tests during the manual stripping process; in Comparative Example 3, since no annealing treatment was performed, the silicon carbide film could not achieve self-stripping and self-support, and therefore, manual stripping of the silicon carbide film was required. In 10 tests, the film was damaged more than 5 times due to the difficulty of manual stripping.

[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-peeling 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 are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope 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., maintaining the pressure at 8000-20000 Pa, growing for 60 min-120 min, and forming a silicon carbide peeling layer; Introducing carbosilane and reducing gas into the growth chamber for the second time, maintaining the temperature of the glassy carbon substrate at 1100° C.-1300° C., maintaining the pressure at 8000-20000 Pa, growing for 240 min-560 min, and forming a silicon carbide support layer on the surface of the silicon carbide peeling layer; Annealing the silicon carbide peeling layer and the silicon carbide supporting 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 to 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, characterized in that: 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, characterized in that: The gas flow rate of the carbosilane is 50L / min-90L / min; the gas flow rate of the reducing gas is 70L / min-170L / min.

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

5. The method for preparing a self-supporting silicon carbide film according to claim 1, characterized in that: The silicon carbide substrate is subjected to a surface cleaning treatment, comprising: The silicon carbide 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, characterized in that: 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 weight %-60 weight %, the content of the linear phenolic resin is 5 weight %-12 weight %, the content of the phenolic resin curing agent is 25 weight %-35 weight %, the content of the glass fiber is 1 weight %-5 weight %, and the content of the viscose fiber is 1 weight %-2 weight %.

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.