Method for preparing silicon carbide epitaxial wafer for chip by using alkylsilane

Abstract

The invention relates to the field of manufacturing of electronic elements and electronic special materials, in particular to a method for preparing a silicon carbide epitaxial wafer for a chip from alkylsilane. The alkylsilane precursor is used for CVD deposition of SiC, the decomposition temperature is moderate, the decomposition product is simple, the deposition efficiency is high, the use safety is high, spontaneous combustion in air is avoided, and the storage stability is good. By adopting the alkylsilane precursor, stable single-crystal SiC crystals and thin films can be formed at the temperature 100-200 DEG C lower than that of a conventional material, the crystal growth and film forming efficiency is high, the defects are few, and the alkylsilane precursor is a good semi-insulating SiC raw material. In addition, as the SiC precursor for CVD / CVI, the alkyl silane precursor is a non-corrosive single-source silicon carbon compound with the minimum molecular weight, SiC with a near stoichiometric ratio can be obtained due to the fact that the SiC component content in precursor molecules is high, the deposition rate is higher and the deposition temperature is lower, and the method is an optimal scheme for growing SiC crystals through a high-temperature chemical vapor deposition process.

Description

Technical Field

[0001] The 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 that are used to pass strong currents under high withstand voltages, and power semiconductor devices using silicon (Si) substrates dominate. However, in recent years, third-generation semiconductor materials represented by single-crystal silicon carbide (SiC) are one of the most promising semiconductor materials after silicon materials. The insulation breakdown voltage of single-crystal silicon carbide materials themselves is an order of magnitude higher than that of silicon-based materials. 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 modern industrial fields such as new energy vehicles, 5G communications, photovoltaic power generation, rail transportation, smart grids, aerospace, etc.

[0003] There have been studies abroad on the technology of preparing SiC using precursors using high-temperature chemical vapor deposition technology. The precursors used are silane, propane, propylene, ethylene, methane, etc., and a combination of gases such as silane + propane, silane + propylene, silane + ethylene, and silane + methane are used to control the flow rates of silane and alkanes (propane, propylene, ethylene, methane) respectively, so that the two precursors react in proportion at a temperature of 2200°C - 2500°C to generate SiC.

[0004] Based on the above reasons, the inventors believe that:

[0005] With silane + alkane (propane, propylene, ethylene, methane) as a mixed precursor, due to the great difference in the thermal decomposition parameters of the two gas raw materials, the regulation of process parameters such as feed gas flow velocity, ratio, pyrolysis temperature becomes extremely complicated, and the by-products are mostly unstable, the product purity is not easy to control, and the product consistency is poor. At the same time, the decomposition temperature of silane is low (600°C can be decomposed), and it is very easy to nucleate in the space gas phase in the crystal growth furnace, which is easy to cause the Si / C ratio to be unstable, form "silicon droplets" on the surface of the SiC crystal, and the resulting SiC crystal form is variable. In addition, when an epitaxial layer is deposited 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, it is necessary to be able to overcome the defects or surface roughness of the wafer. Silicon carbide epitaxial wafers and methods for manufacturing the same. Summary of the invention

[0006] 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 of silicon carbide crystals, 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 the present application adopts alkylsilane (especially methylsilane) as a precursor for preparing single crystal silicon carbide, and adopts a chemical vapor deposition process.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A method for preparing a silicon carbide epitaxial wafer for a chip using an alkylsilane comprises preparing a silicon carbide epitaxial wafer 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;

[0009] The preparation of the silicon carbide epitaxial wafer comprises the following steps:

[0010] S1: SiC substrate cleaning;

[0011] S2: Play film:

[0012] S3: in-situ etching;

[0013] S4: epitaxial growth;

[0014] S5: Cooling step.

[0015] Furthermore, the SiC substrate is cleaned by using anhydrous ethanol to perform closed ultrasonic cleaning on the SiC substrate, and then using 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 injection chamber.

[0016] Furthermore, the reaction chamber is filled with argon gas, and then the cleaned SiC substrate is loaded into 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.

[0017] Furthermore, the in-situ etching includes introducing high-purity hydrogen gas into the reaction chamber at a pressure of 10-10000 Pa, slowly heating to 1000-1800° C., introducing high-purity HCl gas for 5 minutes of in-situ etching, and introducing hydrogen after the etching is completed to ensure that the HCl is completely discharged.

[0018] 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.

[0019] Furthermore, the temperature accuracy of the substrate should be controlled within ±0.5-1°C.

[0020] Furthermore, the flow rate control accuracy of the alkylsilane should be within ±0.5% FS.

[0021] Further, the cooling process includes continuously introducing hydrogen gas into the reaction chamber, initially maintaining the gas 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, dropping the substrate temperature to 200-600°C, and evacuating the reaction chamber until the vacuum reaches 0.01-10x10 -4 After mba, the protective gas Ar was introduced to normal pressure.

[0022] Furthermore, the precursor also includes alkanes and / or silanes.

[0023] Furthermore, the alkane is selected from methane, propane, ethylene, and propylene, and the silane is selected from silane, trichlorosilane, dichlorosilane, and silicon tetrachloride.

[0024] The above technical solution has the following advantages or beneficial effects:

[0025] The method for preparing silicon carbide epitaxial wafers for semiconductor chips using alkylsilane disclosed in the present application has dense crystals, extremely high purity and few crystal defects in the deposited silicon carbide. Since the CVD method is used, the device is simple and the controllability is excellent, so epitaxial wafers with high uniformity and reproducibility can be obtained. The use of alkylsilane precursors can form stable single-crystal SiC crystals and thin films at a temperature 100°C-200°C lower than that of conventional materials, and the crystal growth and film formation efficiency are high and the defects are few. It is a good semi-insulating SiC raw material. In addition, as a SiC precursor for CVD / CVI, the alkylsilane precursor is a non-corrosive, single-source silicon-carbon compound with the smallest molecular weight. Since the SiC component content in the precursor molecule is high, the deposition rate is faster and the deposition temperature is lower, and a nearly stoichiometric SiC can be obtained. It is the optimal solution for growing SiC crystals by high-temperature chemical vapor deposition process. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the principle of preparing a silicon carbide epitaxial wafer for a chip using alkylsilane according to an embodiment of the present application;

[0027] Figure 2 This is a schematic flow chart of a method for preparing a silicon carbide epitaxial wafer for a chip using alkylsilane according to an embodiment of the present application;

[0028] Figure 3 It is a schematic diagram of waste gas treatment for preparing silicon carbide epitaxial wafers for chips using alkylsilane according to an embodiment of the present application. DETAILED DESCRIPTION

[0029] The following embodiments of the present invention are described in further detail in conjunction with 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.

[0030] Semiconductor chips are divided into integrated circuits and discrete devices, and their basic structures can be divided into "substrate-epitaxial-device" structures. The main form of silicon carbide disclosed in this application in semiconductor chips is as a substrate and epitaxial material. According to different resistivities, silicon carbide wafers are divided into conductive and semi-insulating types. Among them, conductive silicon carbide wafers are mainly used to manufacture high-temperature and high-voltage resistant power devices; semi-insulating silicon carbide substrates are mainly used in microwave radio frequency devices and other fields.

[0031] The alkylsilane in this application mainly refers to methylsilane, dimethylsilane or trimethylsilane. Alkylsilane precursors (especially methylsilane) are single-source substances containing both Si and C elements in the molecule and Si / C is 1:1. They are used for CVD deposition of SiC, and have the advantages of moderate decomposition temperature, simple decomposition products, high deposition efficiency, high safety in use, no spontaneous combustion in the air, and good storage stability. The use of alkylsilane precursors can form stable single-crystal SiC crystals and thin films at 100°C-200°C lower than conventional materials, and the crystal growth and film formation efficiency are high and the defects are few. In addition, as a SiC precursor for CVD / CVI, alkylsilane precursors are non-corrosive, single-source silicon-carbon compounds with the smallest molecular weight. Because the SiC content in the precursor molecule is high, the deposition rate is faster and the deposition temperature is lower, and a nearly stoichiometric SiC can be obtained, which is the optimal solution for growing SiC crystals in a high-temperature chemical vapor deposition process. The present application adopts chemical vapor deposition (CVD) process to prepare SiC epitaxial wafers, and the crystal thickness is generally 20-100um.

[0032] The epitaxial furnace of the present 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 alternating current of a certain frequency. 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 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 of the present application include: (a) in-situ etching reaction principle:

[0033] Principle of in-situ etching reaction: SiC(s)→Si(l)+C(s); 2C(s)+H2(g)→C2H2(g); Si+3HCl(g)→SiHCl3(g)+H2(g); (ii) Principle of crystal epitaxial wafer: H3C-SiH3→SiC+3H2.

[0034] refer to Figure 1 and Figure 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 SiC substrate: first, use anhydrous ethanol to perform 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 ultrasonic cleaning on the SiC substrate to remove residual ethanol 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, use high-purity argon to completely dry the surface of the SiC substrate, and quickly put it into the injection chamber under a high-purity argon atmosphere to prevent it from being oxidized again.

[0035] S2, place the wafer and evacuate: the argon valve opening of the equipment is controlled by computer, argon is filled into the reaction chamber, the SiC substrate is loaded into the reaction chamber by the automatic robot arm, the pressure inside the reaction chamber reaches 0.01-0.1MPa, and 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 to maintain a pressure of 10-10000Pa in the chamber. Adjust the RF heating coil and slowly increase the temperature at 100-300℃ / min. Use power control or temperature control to control the temperature ramp rate to control the temperature in the reaction chamber to 1100-1450℃. Introduce 7N pure HCl gas for 5-10min in-situ etching to remove surface damage and scratches on the substrate. During the hydrogen etching process, the surface roughness of the silicon carbide substrate will increase and steps will be formed on the surface. After the etching is completed, hydrogen is introduced to ensure that the HCl is completely discharged.

[0037] S4, epitaxial growth: stabilize the growth temperature at 600-1400°C, preferably 1050°C, and the pressure at 0.01-400Pa. According to the set flow rate, i.e., methylsilane 10-10000sccm, preferably 50sccm, nitrogen 10-100sccm and diluted by high-purity hydrogen 50-300scm, the precursor methylsilane and hydrogen (including nitrogen) are introduced into the reaction chamber, and the stable gas source flow rate is controlled. The ratio of alkylsilane to hydrogen is 1:15-200, and the epitaxial growth starts for about 30-60min, and the epitaxial thickness is 20-100mm. Preferably, the carrier gas can be argon or helium in addition to hydrogen.

[0038] S5, cooling down: When the preset CVD growth time is reached, close the methylsilane inlet valve, turn off the heating RF power supply, and stop heating. Continue to introduce hydrogen gas into the reaction chamber, and maintain the pressure at 10-1000mbar at the beginning. Cool down for 25 minutes to reduce the substrate temperature to 600-800℃, increase the hydrogen pressure to 300-2000mbar, and reduce the substrate temperature to 300-600℃. Evacuate the reaction chamber, and when the vacuum reaches 0.05-0.1x10 -4 After mba, the protective gas Ar was introduced to normal 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 package.

[0040] refer to Figure 2 and Figure 3A specific embodiment of the present application proposes a method for treating waste 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 the waste gas is collected, it 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. Acetylene, trichlorosilane, and HCl will be generated in the process of etching SiC. The waste gas will also be discharged after being treated with 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 spraying and then discharged. (5) Unorganized waste gas in the workshop: The products are semiconductor materials silicon carbide and electronic special gases. The cleanliness of the production environment is 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 spraying + 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 is very easy to react with sodium hydroxide to eventually generate salt (sodium metasilicate), carbon dioxide, and hydrogen. It can be properly treated by pre-treatment condensation, end paraffin sealing tank + alkali spray + water seal. The waste gas treatment principle is as follows: (1) Alkaline spray waste gas treatment main reaction principle: SiHCH3Cl2+2NaOH+2H2O=SiO2+2NaCl+CO2+5H2, (2) Alkaline spray waste gas treatment side reaction principle: SiH2(CH3)2+2NaOH+5H2O=Na2SiO3+2CO2+7H2, SiH3CH3+2NaOH+3H2O=Na2SiO3+CO2+7H2.

[0042] Example 1

[0043] Cleaning of SiC substrate: Power on the system, conduct various inspections before starting up, vacuum 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-check on the entire system. The pH of the alkali solution in the tail gas treatment system is ≥12, turn on the spray tower circulation pump, and put the tail gas recovery system 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, use high-purity argon to completely dry the surface of the SiC substrate and put it into the injection chamber.

[0044] 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.

[0045] In-situ etching: Set the vacuum of the epitaxial chamber to 100Pa, turn on the RF heating coil, and heat up at 180℃ / min until the temperature in the reaction chamber reaches 1100℃. Then, introduce 7N HCl gas at 50L / min for in-situ etching for 5min. After etching, introduce hydrogen at 100L / min to replace HCl.

[0046] 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, and the nitrogen flow rate was 20 sccm (diluted by 50 scm hydrogen), and epitaxial growth was started for about 300 minutes.

[0047] 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 25min, and drop the substrate temperature to 600℃, then to 300mbar and 30℃. Evacuate the reaction chamber and keep the vacuum at 0.5x10 -4 After mba, Ar was introduced to normal pressure.

[0048] 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.

[0049] Example 2

[0050] Cleaning of SiC substrate: Power on the system, conduct various inspections before starting up, vacuum and detect leaks, replace the system with argon, and maintain the circulating cooling water temperature at 28°C and the pressure at 350KPa. Turn on the PLC control panel of the SiC epitaxial furnace system and perform a self-check on the entire system. The pH of the alkaline solution in the tail gas treatment system is ≥11, turn on the spray tower circulation pump, and put the tail gas recovery system into normal operation. Use anhydrous ethanol to ultrasonically clean the 8-inch SiC substrate for 15 minutes, then use deionized water to ultrasonically clean the SiC substrate for 10 minutes, use high-purity argon to completely dry the surface of the SiC substrate and put it into the injection chamber.

[0051] 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.

[0052] In-situ etching: Set the vacuum of the epitaxial chamber to 80Pa, turn on the RF heating coil, and heat up at 200℃ / min until the temperature in the reaction chamber reaches 1050℃. Then, introduce 7N HCl gas at 60L / min for in-situ etching for 10min. After etching, introduce hydrogen at 120L / min to replace HCl.

[0053] Epitaxial growth: set the reaction chamber temperature to 1050°C, the vacuum degree to 0.2 Pa, control the flow rates of methylsilane to 80 sccm, dimethylsilane to 40 sccm, and nitrogen to 40 sccm (diluted by 60 scm hydrogen), and start epitaxial growth for about 260 min.

[0054] 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 30min, and drop the substrate temperature to 560℃. When the hydrogen pressure reaches 500mbar, the substrate temperature drops to 32℃. Evacuate the reaction chamber and keep the vacuum at 1.5x10 -4 After mba, Ar was introduced to normal pressure.

[0055] 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.

[0056] The embodiments of the present invention are given for the purpose 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 of ordinary skill in the art. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present invention and to enable those of ordinary skill in the art to understand the present invention and thereby design various embodiments with various modifications suitable for specific uses.

Claims

1. A method for preparing silicon carbide epitaxial wafers for chips using alkylsilane, comprising preparing silicon carbide epitaxial wafers from a precursor 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 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 0.05-0.1 MPa, and then the reaction chamber is evacuated to a background vacuum of 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 10-10000 Pa, 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 wafer for chip using alkylsilane according to claim 4, characterized in that: The epitaxial growth comprises 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.

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 rate 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 gas 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, the protective gas Ar was introduced 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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