Method for preparing silicon carbide epitaxial wafer for chips using alkylsilane

Abstract

The present application relates to the field of electronic components and electronic special materials manufacturing, and in particular to a method for preparing a silicon carbide epitaxial wafer for chips using an alkylsilane. When an alkylsilane precursor is used for CVD deposition of SiC, a decomposition temperature is moderate, decomposition products are simple, deposition efficiency is high, use safety is high, there is no spontaneous combustion in air, and storage stability is good. Using an alkylsilane precursor can form stable single crystal SiC crystals and thin films at 100°C-200°C lower than conventional materials, and has high crystal growth and film formation efficiency with few defects, making a good semi-insulating SiC raw material. In addition, as an SiC precursor for CVD / CVI, an alkylsilane precursor is a non-corrosive, single-source silicon-carbon compound having the lowest molecular weight. Due to the high SiC content in precursor molecules, the deposition rate is faster and the deposition temperature is lower, and nearly stoichiometric SiC can be obtained. It is the optimal solution for growing SiC crystals in high-temperature chemical vapor deposition processes.

Description

Method for preparing silicon carbide epitaxial wafer for chip using alkylsilane Technical Field

[0001] The present invention relates to the technical field of manufacturing electronic special materials, in particular to a method for preparing silicon carbide epitaxial wafers for chips using alkylsilane. Background Art

[0002] Power semiconductor devices are semiconductor components designed to carry high currents at high withstand voltages, and those using silicon (Si) substrates dominate. However, in recent years, third-generation semiconductor materials, represented by single-crystal silicon carbide (SiC), have become one of the most promising semiconductor materials after silicon. The insulation breakdown voltage of single-crystal silicon carbide material itself is one order of magnitude higher than that of silicon-based material. It has the advantages of high power, high voltage resistance, high temperature resistance, high frequency, low energy consumption, and strong radiation resistance. It can be widely used in new energy vehicles, 5G communications, photovoltaic power generation, rail transportation, smart grids, aerospace and other modern industrial fields; the technology of using precursors to prepare SiC using high-temperature chemical vapor deposition process has been studied abroad. The precursors used are silane, propane, propylene, ethylene, methane, etc., and the combined gases such as silane + propane, silane + propylene, silane + ethylene, silane + methane are used to control the flow of silane and alkane (propane, propylene, ethylene, methane) respectively, so that the two precursors react in proportion at a temperature of 2200℃-2500℃ to generate SiC.

[0003] Based on the above reasons, the inventors believe that: Using silane + alkanes (propane, propylene, ethylene, methane) as a mixed precursor, due to the significant differences in the thermal decomposition parameters of the two gaseous raw materials, makes the control of process parameters such as feed gas flow rate, ratio, and pyrolysis temperature extremely complicated, and many by-products are unstable, product purity is difficult to control, and product consistency is poor. At the same time, silane has a low decomposition temperature (it can decompose at 600°C), which is very easy to nucleate in the air phase within the crystal growth furnace, which can easily cause an unstable Si / C ratio, the formation of "silicon droplets" on the SiC crystal surface, and the resulting SiC crystal form to be variable. In addition, when depositing an epitaxial layer on silicon carbide, defects or surface roughness may be caused on the wafer, and the defects or surface roughness of the wafer will reduce the quality of the silicon carbide epitaxial wafer. Therefore, there is a need for silicon carbide epitaxial wafers and methods for manufacturing the same that can overcome wafer defects or surface roughness. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing silicon carbide epitaxial wafers for chips using alkylsilane, so as to solve the technical problems of low purity, unstable growth and low quality of silicon carbide epitaxy in the above-mentioned background technology. To this end, the method for preparing silicon carbide epitaxial wafers for semiconductor chips using alkylsilane disclosed in this application adopts alkylsilane (especially methylsilane) as a precursor for preparing single-crystal silicon carbide and adopts chemical vapor deposition process.

[0005] To achieve the above objectives, the present invention provides the following technical solutions: A method for preparing silicon carbide epitaxial wafers for chips using alkylsilanes, comprising preparing silicon carbide epitaxial wafers by chemical vapor deposition of a precursor, wherein the precursor is selected from one or more of methylsilane, dimethylsilane, and trimethylsilane of the alkylsilane class;

[0006] The preparation of the silicon carbide epitaxial wafer comprises the following steps:

[0007] S1: SiC substrate cleaning;

[0008] S2: Play film:

[0009] S3: in-situ etching;

[0010] S4: epitaxial growth;

[0011] S5: Cooling step.

[0012] Furthermore, the SiC substrate cleaning is to use anhydrous ethanol to perform closed ultrasonic cleaning on the SiC substrate, and then use deionized water to perform ultrasonic cleaning on the SiC substrate. When the SiC substrate is ultrasonically cleaned, the growth surface of the SiC substrate should face down, and the time for each ultrasonic cleaning should be 5 minutes to 10 minutes. After cleaning, the surface of the silicon carbide substrate is completely dried with high-purity argon gas and quickly placed in the sampling chamber.

[0013] Furthermore, the reaction chamber is filled with argon, and the cleaned SiC substrate is placed in the reaction chamber to make the internal pressure of the reaction chamber reach 0.05-0.1 MPa, and then the reaction chamber is evacuated to a background vacuum of 0.1-10x10 -7 mbar.

[0014] Furthermore, the in-situ etching includes introducing high-purity hydrogen gas into the reaction chamber at a pressure of 10-10000 Pa, slowly raising the temperature to 1000-1800° C., introducing high-purity HCl gas for in-situ etching for 5 minutes, and introducing hydrogen gas after the etching is completed to ensure that the HCl is completely discharged.

[0015] Furthermore, the epitaxial growth includes stabilizing the growth temperature at 600-1400° C. and the pressure at 0.01-400 Pa, introducing the precursor methylsilane into the reaction chamber, and starting the epitaxial growth for 30-60 minutes.

[0016] Furthermore, the temperature accuracy of the substrate should be controlled within ±0.5-1°C.

[0017] Furthermore, the flow rate control accuracy of the alkylsilane should be within ±0.5% FS.

[0018] Furthermore, the cooling process includes continuously introducing hydrogen gas into the reaction chamber, initially maintaining the pressure at 10-10000 mbar, cooling the temperature for 25 minutes until the substrate temperature drops to 600-800°C, increasing the hydrogen pressure to 100-10000 mbar, and dropping the substrate temperature to 200-600°C. The reaction chamber is evacuated and the vacuum reaches 0.01-10x10 -4 After mba, introduce protective gas Ar to normal pressure.

[0019] Furthermore, the precursor further includes alkanes and / or silanes.

[0020] Furthermore, the alkane is selected from methane, propane, ethylene, and propylene, and the silane is selected from silane, trichlorosilane, dichlorosilane, and silicon tetrachloride.

[0021] The above technical solution has the following advantages or beneficial effects:

[0022] The method disclosed in this application for preparing silicon carbide epitaxial wafers for semiconductor chips using alkylsilanes produces dense, extremely high-purity silicon carbide with few crystal defects. Using the CVD method, the apparatus is simple and the controllability is excellent, resulting in epitaxial wafers with high uniformity and reproducibility. Using alkylsilane precursors, stable single-crystal SiC crystals and thin films can be formed at temperatures 100°C-200°C lower than conventional materials, with high crystal growth and film formation efficiency and few defects, making them excellent semi-insulating SiC raw materials. Furthermore, as SiC precursors for CVD / CVI, alkylsilane precursors are non-corrosive, single-source silicon-carbon compounds with the smallest molecular weight. Due to the high SiC content in the precursor molecules, the deposition rate is faster and the deposition temperature is lower, resulting in near-stoichiometric SiC. This method is the optimal solution for growing SiC crystals using high-temperature chemical vapor deposition processes.

[0023] BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 is a schematic diagram showing the principle of preparing silicon carbide epitaxial wafers for chips using alkylsilane according to one embodiment of the present application;

[0025] FIG2 is a schematic flow chart of a method for preparing silicon carbide epitaxial wafers for chips using alkylsilane according to one embodiment of the present application;

[0026] FIG3 is a schematic diagram of waste gas treatment for preparing silicon carbide epitaxial wafers for chips using alkylsilane according to one embodiment of the present application.

[0027] DETAILED DESCRIPTION

[0028] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0029] Semiconductor chips are divided into integrated circuits and discrete devices, and their basic structure can be categorized as a "substrate-epitaxial-device" structure. The silicon carbide disclosed in this application primarily serves as a substrate and epitaxial material in semiconductor chips. Silicon carbide wafers are categorized as conductive or semi-insulating based on their resistivity. Conductive silicon carbide wafers are primarily used in the manufacture of high-temperature and high-voltage power devices, while semi-insulating silicon carbide substrates are primarily used in microwave and radio frequency devices.

[0030] The alkylsilanes referred to in this application primarily refer to methylsilane, dimethylsilane, or trimethylsilane. Alkylsilane precursors (particularly methylsilane), as single-source materials containing both Si and C in a 1:1 Si / C ratio, are used for CVD deposition of SiC. They offer advantages such as a moderate decomposition temperature, simple decomposition products, high deposition efficiency, high safety, no spontaneous combustion in air, and excellent storage stability. Alkylsilane precursors can form stable single-crystal SiC crystals and thin films at temperatures 100°C-200°C lower than conventional materials, with high crystal growth and film formation efficiency and minimal defects. Furthermore, as SiC precursors for CVD / CVI, alkylsilane precursors are non-corrosive, single-source silicon-carbon compounds with the smallest molecular weight. Due to the high SiC content in the precursor molecule, they offer faster deposition rates and lower deposition temperatures, resulting in near-stoichiometric SiC. This makes them an optimal solution for growing SiC crystals using high-temperature chemical vapor deposition (HTVD) processes.

[0031] The crystal thickness of SiC epitaxial wafers prepared by the chemical vapor deposition process (CVD) in this application is generally 20-100um. The epitaxial furnace of this application adopts a horizontal low-pressure hot wall CVD system, which is fully enclosed, and the reaction chamber includes an induction coil, a quartz tube, an insulating layer, and graphite. A layer of SiC coating is covered on the surface of the graphite to isolate impurities in the graphite and prevent impurities from invading the growth layer. During the operation of the reaction chamber, the coil is loaded with a certain frequency of alternating current. Due to the skin effect of the electromagnetic field, eddy currents are formed on the surface of the graphite substrate, generating Joule heat. Through heat conduction, heat is transferred from the graphite surface to the inside, forming thermal radiation between the various surfaces of the inner wall of the graphite substrate, providing reaction energy to the reaction gas and substrate in the cavity. The principles of preparing silicon carbide epitaxial wafers for semiconductor chips in this application include: (1) In-situ etching reaction principle:

[0032] In-situ etching reaction principle: SiC(s)→Si(l)+C(s); 2C(s)+H2(g)→C2H4(g) Si+3HCl(g)→SiHCl3(g)+H2(g);

[0033] (2) Crystal epitaxial wafer principle: H3C-SiH3→ SiC+3H2.

[0034] With reference to Figures 1 and 2, a specific embodiment of the present application proposes a method for preparing silicon carbide epitaxial wafers for chips using alkylsilane, which specifically includes the following steps. S1, cleaning of the SiC substrate: first, use anhydrous ethanol to perform a closed ultrasonic cleaning on the SiC substrate to remove impurities that may remain on the surface of the substrate; then use deionized water to perform an ultrasonic cleaning on the SiC substrate to remove the ethanol remaining on the surface of the substrate. When ultrasonically cleaning the SiC substrate, the growth surface of the SiC substrate should face downward, and the time for each ultrasonic cleaning should be 5min-10min. After completing all the above cleaning steps, the surface of the SiC substrate is completely dried with high-purity argon gas, and quickly placed in a sample injection chamber under a high-purity argon atmosphere to prevent it from being oxidized again.

[0035] S2, placing the wafer and evacuating: The computer controls the opening of the argon valve of the equipment, fills the reaction chamber with argon, and uses the automatic robot arm to load the SiC substrate into the reaction chamber, so that the pressure inside the reaction chamber reaches 0.01-0.1MPa. Then, the computer is operated to evacuate the reaction chamber until the background vacuum reaches 0.2-10x10 -7 mbar.

[0036] S3, In-situ Etching: Operate the computer to introduce high-purity hydrogen gas into the reaction chamber, maintaining a pressure of 10-10,000 Pa. Adjust the RF heating coil and slowly increase the temperature at 100-300°C / min. Using power control or temperature control, control the temperature within the reaction chamber to 1100-1450°C. Then, introduce 7N pure HCl gas and perform in-situ etching for 5-10 minutes to remove surface damage and scratches on the substrate. The hydrogen etching process increases the surface roughness of the silicon carbide substrate and forms steps on the surface. After etching, introduce hydrogen gas to ensure complete removal of the HCl.

[0037] S4, Epitaxial Growth: The growth temperature is stabilized at 600-1400°C, preferably 1050°C, and the pressure is 0.01-400 Pa. Precursors (methylsilane and hydrogen (including nitrogen)) are introduced into the reaction chamber at set flow rates: 10-10,000 sccm, preferably 50 sccm, of methylsilane and 10-100 sccm of nitrogen, diluted with 50-300 sccm of high-purity hydrogen. The gas source flow rates are controlled to maintain a stable ratio of alkylsilane to hydrogen of 1:15-200. Epitaxial growth is initiated for approximately 30-60 minutes, with an epitaxial thickness of 20-100 mm. Preferably, argon or helium can be used as carrier gases in addition to hydrogen.

[0038] S5, Cooling: After the preset CVD growth time has elapsed, close the methylsilane inlet valve, turn off the heating RF power supply, and stop heating. Continue to introduce hydrogen into the reaction chamber, initially maintaining a pressure of 10-1000 mbar. Cool the reaction chamber for 25 minutes until the substrate temperature drops to 600-800°C. Increase the hydrogen pressure to 300-2000 mbar and lower the substrate temperature to 300-600°C. Evacuate the reaction chamber. Once the vacuum reaches 0.05-0.1 x 10-4 mbar, introduce protective Ar gas to atmospheric pressure.

[0039] S6, take out the sample: After the reaction chamber and substrate cool down naturally, open the reaction chamber door, take out the epitaxial wafer, and inspect the packaging.

[0040] Referring to Figures 2 and 3, a specific embodiment of the present application proposes a method for treating waste gas from silicon carbide epitaxial wafers used in the preparation of chips using alkylsilane. (1) SiC substrate ultrasonic cleaning waste gas G13: The SiC substrate needs to be placed in an ultrasonic cleaning instrument containing ethanol for cleaning. The process is fully sealed, and only a very small amount of ethanol gas is recycled when the cover is opened. (2) Ar purge tail gas G14: A small amount of anhydrous ethanol remains on the surface of the SiC substrate after ultrasonic cleaning with anhydrous ethanol. It will be purged with Ar gas. The tail gas is collected and sent to the replacement gas sealing tank, and then sent to the alkali spray and then emptied. After collection, the waste gas first enters the paraffin sealing tank, and then undergoes alkali spraying. Ethanol and water are miscible, and the removal rate is 80%. (3) In-situ etching waste gas G16: In-situ etching mainly uses HCl, accompanied by hydrogen. In this process of etching SiC, acetylene, trichlorosilane, and HCl will be generated. The waste gas will also be discharged after being treated by the paraffin sealing tank + alkali spraying. (4) Epitaxial growth tail gas G17: Methylsilane, nitrogen, and hydrogen are introduced during epitaxial wafer growth. After high-temperature growth, the tail gas is mainly nitrogen, a small amount of hydrogen, and a very small amount of unreacted methylsilane. This component is sent to the paraffin sealing tank + alkali spray and then discharged. (5) Workshop unorganized waste gas: The products are semiconductor materials such as silicon carbide and electronic specialty gases. The production environment cleanliness requirements are extremely high. The production process is fully enclosed. Inert gases such as nitrogen, helium, and argon are used for protection in various production processes. At the same time, the tail gas is sent to the paraffin sealing tank + alkali spray + water seal and then discharged.

[0041] The main component of the waste gas related to epitaxial wafer production is a very small amount of methylsilane, which easily reacts with sodium hydroxide to eventually produce salt (sodium metasilicate), carbon dioxide, and hydrogen. It can be properly disposed of by pre-treatment condensation, end paraffin sealing tank + alkali spraying + water seal. The waste gas treatment principles are as follows: (1) Alkali spray waste gas treatment main reaction principle: SiHCH spray waste gas treatment side reaction principle: SiHCH3Cl2+2NaOH+2H2O = SiO2+2NaCl+CO2+5H2, 2) Alkali spray waste gas treatment side reaction principle: SiH2(CH3)2+2NaOH+5H2O = Na2SiO3+2CO2+7H2, SiH2CH 32 +2NaOH+3H2O = Na2SiO3+CO2+7H2

[0042] Example 1 Cleaning of SiC substrate: Power on the system, perform various pre-startup inspections, vacuumize and detect leaks, replace the system with argon, and maintain the circulating cooling water temperature at 26°C and the pressure at 320KPa. Turn on the PLC control panel of the SiC epitaxial furnace system and perform a self-test on the entire system. The pH of the alkali solution in the tail gas treatment system is ≥12, the spray tower circulation pump is turned on, and the tail gas recovery system is put into normal operation. Use anhydrous ethanol to ultrasonically clean the SiC substrate for 10 minutes, then use deionized water to ultrasonically clean the SiC substrate for 5 minutes, and use high-purity argon to completely dry the surface of the SiC substrate and place it in the sample injection chamber.

[0043] Place the wafer and evacuate: Set the argon valve opening to 26%, fill the reaction chamber with argon, start the automatic robot arm to load the SiC substrate into the reaction chamber, and evacuate the reaction chamber to 0.5X10 -7 mbar.

[0044] In-situ etching: Set the epitaxial chamber vacuum to 100 Pa, turn on the RF heating coil, and increase the temperature at 180°C / min until the reaction chamber reaches 1100°C. Then, introduce 7N HCl gas at 50 L / min for in-situ etching for 5 minutes. After etching, introduce hydrogen at 100 L / min to replace the HCl.

[0045] Epitaxial growth: The reaction chamber temperature was set at 1100°C, the vacuum degree was 0.1 Pa, the methylsilane flow rate was controlled at 100 sccm, the nitrogen flow rate was 20 sccm (diluted by 50 sccm of hydrogen), and epitaxial growth was started for about 300 min.

[0046] Cooling: Close the methylsilane inlet valve, turn off the heating RF power supply, and stop heating. Continue to introduce hydrogen into the reaction chamber at 5L / min. Maintain the hydrogen pressure at 100mbar for the first 25 minutes. Lower the substrate temperature to 600℃, then to 300mbar and 30℃. Evacuate the reaction chamber. When the vacuum reaches 0.5x10 -4 After mba, Ar was introduced to normal pressure.

[0047] Remove the sample: After the reaction chamber and substrate cool down naturally, open the reaction chamber door, remove the epitaxial wafer, and inspect the packaging. Example

[0048] Cleaning the SiC substrate: Power on the system, perform pre-startup checks, vacuum and detect leaks, replace the system with argon, and maintain the circulating cooling water temperature at 28°C and pressure at 350 kPa. Open the SiC epitaxial furnace system PLC control panel and perform a self-test of the entire system. Ensure the pH of the alkaline solution in the exhaust gas treatment system is ≥11, start the spray tower circulation pump, and operate the exhaust gas recovery system. Ultrasonic clean the 8-inch SiC substrate with anhydrous ethanol for 15 minutes, followed by ultrasonic cleaning with deionized water for 10 minutes. Completely dry the SiC substrate surface with high-purity argon and place it in the sample chamber.

[0049] Place the wafer and evacuate: Set the argon valve opening to 32%, fill the reaction chamber with argon, start the automatic robot arm to load the SiC substrate into the reaction chamber, and evacuate the reaction chamber to 0.3X10 -7 mbar.

[0050] In-situ etching: Set the epitaxial chamber vacuum to 80 Pa, turn on the RF heating coil, and raise the temperature at 200°C / min until the reaction chamber reaches 1050°C. Then, introduce 7N HCl gas at 60 L / min for in-situ etching for 10 minutes. After etching, introduce hydrogen at 120 L / min to replace the HCl.

[0051] Epitaxial growth: The reaction chamber temperature was set at 1050°C, the vacuum was 0.2 Pa, the flow rates of methylsilane were controlled to 80 sccm, dimethylsilane to 40 sccm, and nitrogen to 40 sccm (diluted with 60 scm hydrogen), and epitaxial growth was started for approximately 260 min.

[0052] Cooling: Close the methylsilane and trimethylsilane inlet valves, turn off the heating RF power supply, and stop heating. Continue to introduce hydrogen into the reaction chamber at 10L / min, maintain the hydrogen pressure at 120mbar for the first 30 minutes, and reduce the substrate temperature to 560℃. When the hydrogen pressure reaches 500mbar, the substrate temperature drops to 32℃. Evacuate the reaction chamber and, when the vacuum reaches 1.5x10 -4 After mba, Ar was introduced to normal pressure.

[0053] Remove the sample: After the reaction chamber and substrate cool down naturally, open the reaction chamber door, remove the epitaxial wafer, and inspect the packaging.

[0054] The embodiments of the present invention are presented for purposes of illustration and description and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. The embodiments are chosen and described in order to better illustrate the principles of the invention and its practical application and to enable those skilled in the art to understand the invention and design various embodiments with various modifications as suited for specific applications.

Claims

1. A method for preparing silicon carbide epitaxial wafers for chips using alkylsilane, comprising preparing silicon carbide epitaxial wafers using a precursor alkylsilane by chemical vapor deposition, characterized in that: The precursor is selected from one or more of methylsilane, dimethylsilane and trimethylsilane of the alkylsilane class; The preparation of the silicon carbide epitaxial wafer comprises the following steps: S1: SiC substrate cleaning; S2: Play film: S3: in-situ etching; S4: epitaxial growth; S5: Cooling step.

2. The method for preparing silicon carbide epitaxial wafer for chip using alkylsilane according to claim 1, characterized in that: The SiC substrate cleaning is to use anhydrous ethanol to perform closed ultrasonic cleaning on the SiC substrate, and then use deionized water to perform ultrasonic cleaning on the SiC substrate. When the SiC substrate is ultrasonically cleaned, the growth surface of the SiC substrate should face downward, and the time for each ultrasonic cleaning should be 5min-10min. After cleaning, the surface of the silicon carbide substrate is completely dried with high-purity argon gas and quickly placed in the sample injection chamber.

3. The method for preparing silicon carbide epitaxial wafer for chip using alkylsilane according to claim 2, characterized in that: The reaction chamber is filled with argon gas, and then the cleaned SiC substrate is placed in the reaction chamber to make the internal pressure of the reaction chamber reach 0.05-0.1MPa, and then the reaction chamber is evacuated to a background vacuum degree of to 0.1-10x10 -7 mbar.

4. The method for preparing silicon carbide epitaxial wafer for chip using alkylsilane according to claim 3, characterized in that: The in-situ etching includes introducing high-purity hydrogen gas into the reaction chamber at a pressure of 10-10000Pa, slowly heating to 1000-1800°C, introducing high-purity HCl gas for 5 minutes of in-situ etching, and introducing hydrogen gas after the etching is completed to ensure that the HCl is completely discharged.

5. The method for preparing silicon carbide epitaxial wafers for chips using alkylsilane according to claim 4, characterized in that the epitaxial growth includes stabilizing the growth temperature at 600-1400° C. and the pressure at 0.01-400 Pa, introducing the precursor alkylsilane and into the reaction chamber, and starting the epitaxial growth for 30-60 minutes.

6. The method for preparing silicon carbide epitaxial wafer for chip using alkylsilane according to claim 5, characterized in that: The temperature accuracy of the substrate should be controlled within ±0.5-1°C.

7. The method for preparing silicon carbide epitaxial wafer for chip using alkylsilane according to claim 6, characterized in that: The flow control accuracy of the alkylsilane should be within ±0.5%FS.

8. The method for preparing silicon carbide epitaxial wafer for chip using alkylsilane according to claim 7, characterized in that: Cooling includes continuously introducing hydrogen gas into the reaction chamber, initially maintaining the pressure at 10-10000 mbar, cooling for 25 minutes until the substrate temperature drops to 600-800°C, increasing the hydrogen pressure to 100-10000 mbar, dropping the substrate temperature to 200-600°C, and evacuating the reaction chamber. -4 After mba, introduce protective gas Ar to normal pressure.

9. The method for preparing silicon carbide epitaxial wafer for chip using alkylsilane according to claim 8, characterized in that: The precursor also includes alkanes and / or silanes.

10. The method for preparing silicon carbide epitaxial wafer for chip using alkylsilane according to claim 9, characterized in that: The alkane is selected from methane, propane, ethylene, and propylene, and the silane is selected from silane, trichlorosilane, dichlorosilane, and silicon tetrachloride.

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