Silicon carbide epitaxial growth method with chlorine-silicon ratio region controllable and silicon carbide epitaxial wafer

Abstract

The invention provides a silicon carbide epitaxial growth method with a chlorine-silicon ratio region controllable and a silicon carbide epitaxial wafer. The method comprises the following steps: putting a silicon carbide substrate into a reaction cavity of silicon carbide epitaxial equipment, and sequentially carrying out etching and buffer layer growth on the silicon carbide substrate; after the buffer layer grows, silicon source gas and carbon source gas are introduced into the reaction cavity through the first gas path, hydrogen chloride gas is introduced into the edge area of the reaction cavity through the second gas path, and drift layer growth is carried out; and obtaining the silicon carbide epitaxial wafer after the growth of the drift layer is completed. The doping concentration and the doping concentration uniformity of the silicon carbide epitaxial wafer can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of silicon carbide epitaxial wafers, and in particular to a silicon carbide epitaxial growth method with regionally controllable chlorine-silicon ratio and a silicon carbide epitaxial wafer. Background Art

[0002] Silicon carbide is a typical representative of the third generation of semiconductors. It has the advantages of large bandgap, high saturated carrier velocity, and good thermal conductivity. It is the core material of power devices such as new energy vehicle drivers, high-speed rail tractors, and photovoltaic inverters. In the entire processing technology of silicon carbide devices, the epitaxial process is one of the core steps. This is because the epitaxial layer is the key to silicon carbide materials, and all functional structures are realized in the epitaxial layer.

[0003] The market is dominated by 6-inch silicon carbide epitaxial products. Carrier doping concentration uniformity is one of the key parameters for measuring epitaxial wafer quality, which directly determines the consistency of device voltage resistance and the consistency of on-resistance. At present, production mainly relies on adjusting the flow rate of edge and center dopants (nitrogen, aluminum, etc.) to control the concentration of the edge and center, and the obtained concentration uniformity is about 3%. However, this adjustment method currently has the following problems:

[0004] 1) The adjustment method is relatively rough. When adjusting the dopant flow rate at the edge (or center), the dopant flow rate in the area adjacent to the edge (or center) will also be affected, making it difficult to accurately control the doping concentration and further reduce the uniformity of the doping concentration;

[0005] 2) During the epitaxial growth process, only the growth reaction gases of the silicon source and the carbon source are introduced, but the hydrogen chloride gas with etching effect and doping efficiency adjustment is not introduced. At the same time, due to the limitations of the current equipment, the chlorine-silicon ratio in the central area and the chlorine-silicon ratio in the edge area always remain the same and cannot be adjusted independently, resulting in a single concentration adjustment method, and it is impossible to adjust the doping efficiency and doping concentration of the dopant by adjusting the chlorine-silicon ratio. Summary of the invention

[0006] The present application provides a silicon carbide epitaxial growth method and a silicon carbide epitaxial wafer with regionally controllable chlorine-silicon ratio, so as to solve the problem of poor uniformity of carrier concentration of silicon carbide epitaxial wafers in the prior art.

[0007] In a first aspect, the present application provides a method for epitaxial growth of silicon carbide with a regionally controllable chlorine-silicon ratio, comprising:

[0008] Placing a silicon carbide substrate into a reaction chamber of a silicon carbide epitaxial device, and sequentially performing etching and buffer layer growth on the silicon carbide substrate;

[0009] After the buffer layer is grown, silicon source gas and carbon source gas are introduced into the reaction chamber through a first gas path, and hydrogen chloride gas is introduced into an edge region of the reaction chamber through a second gas path to grow a drift layer;

[0010] After the drift layer is grown, a silicon carbide epitaxial wafer is obtained.

[0011] In a possible implementation, after the buffer layer is grown, silicon source gas and carbon source gas are introduced into the reaction chamber through a first gas path, and hydrogen chloride gas is introduced into an edge region of the reaction chamber through a second gas path to grow a drift layer, including:

[0012] After the buffer layer is grown, silicon source gas and carbon source gas are introduced into the reaction chamber at a first flow rate through a first gas path, and hydrogen chloride gas is introduced into the edge area of ​​the reaction chamber at a second flow rate through a second gas path to grow a drift layer.

[0013] In a possible implementation, the flow rate of the first flow rate is in a range of 300-500 sccm;

[0014] The flow rate of the second flow rate is in the range of 10-50 sccm.

[0015] In a possible implementation, the silicon source gas includes trichlorosilane and silane;

[0016] The carbon source gas includes ethylene and methane.

[0017] In a possible implementation, placing the silicon carbide substrate in a reaction chamber of a silicon carbide epitaxial device, and sequentially etching and growing a buffer layer on the silicon carbide substrate includes:

[0018] Placing the silicon carbide substrate into a reaction chamber of the silicon carbide epitaxial device, evacuating the reaction chamber, setting the pressure in the evacuated reaction chamber to a predetermined pressure, and raising the temperature of the evacuated reaction chamber to a first preset temperature;

[0019] introducing hydrogen chloride gas into the reaction chamber at a third flow rate through the first gas path, and raising the temperature of the reaction chamber to a second preset temperature to etch the silicon carbide substrate for a first period of time;

[0020] After the etching of the silicon carbide substrate is completed, the silicon source gas and the carbon source gas are introduced into the reaction chamber through the first gas path at a fourth flow rate to grow a buffer layer on the etched silicon carbide substrate.

[0021] In a possible implementation, the predetermined pressure ranges from 50 to 500 mbar.

[0022] In a possible implementation, the first preset temperature has a temperature range of 1500° C.-1700° C.;

[0023] The second preset temperature ranges from 1600°C to 1700°C.

[0024] In a possible implementation, the flow rate of the third flow rate is in a range of 100-500 sccm;

[0025] The flow rate of the fourth flow rate ranges from 100 to 400 sccm.

[0026] In a possible implementation, the first time period ranges from 5 to 15 minutes.

[0027] In a second aspect, the present application provides a silicon carbide epitaxial wafer, which is prepared using the above-mentioned silicon carbide epitaxial growth method with regionally controllable chlorine-silicon ratio.

[0028] The present application provides a silicon carbide epitaxial growth method and a silicon carbide epitaxial wafer with a regionally controllable chlorine-silicon ratio, by placing a silicon carbide substrate into a reaction chamber of a silicon carbide epitaxial device, and etching and growing a buffer layer on the silicon carbide substrate in sequence; after the growth of the buffer layer, silicon source gas and carbon source gas are introduced into the reaction chamber through a first gas path, and hydrogen chloride gas is introduced into the edge region of the reaction chamber through a second gas path to grow a drift layer; after the growth of the drift layer is completed, a silicon carbide epitaxial wafer is obtained. The present application is based on the principle that the higher the chlorine-silicon ratio in the edge region, the lower the growth rate of the epitaxial layer and the higher the doping efficiency. By using a second gas path to introduce additional hydrogen chloride gas into the edge region of the reaction chamber, the independent control capability of the chlorine-silicon ratio in the edge region and the chlorine-silicon ratio in the central region of the reaction chamber is achieved. By precisely controlling the chlorine-silicon ratio in the edge region and the central region, precise control of the doping efficiency of each region and precise control of the doping concentration are achieved, thereby effectively improving the doping concentration and uniformity of the silicon carbide epitaxial wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0030] Figure 1 It is a flow chart for realizing the method for epitaxial growth of silicon carbide with controllable silicon ratio in sections provided in the embodiment of the present application;

[0031] Figure 2It is a structural schematic diagram of the first gas path operation provided in an embodiment of the present application;

[0032] Figure 3 It is a schematic diagram of the structure of the second gas path provided in the embodiment of the present application;

[0033] Figure 4 is a curve diagram of carrier doping concentration uniformity of the first silicon carbide epitaxial wafer provided in an embodiment of the present application;

[0034] Figure 5 is a curve diagram of carrier doping concentration uniformity of a second silicon carbide epitaxial wafer provided in an embodiment of the present application;

[0035] Figure 6 It is a schematic diagram of the structure of the silicon carbide epitaxial wafer provided in the embodiment of the present application. DETAILED DESCRIPTION

[0036] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0037] In order to make the purpose, technical solutions and advantages of the present application clearer, specific embodiments will be described below in conjunction with the accompanying drawings.

[0038] Since carrier doping concentration uniformity is one of the key parameters for measuring epitaxial wafer quality, it directly determines the consistency of device withstand voltage and the consistency of on-resistance. At present, production mainly relies on adjusting the flow rate of edge and center dopants (nitrogen, aluminum, etc.) to control the concentration of the edge and center, and the obtained concentration uniformity is about 3%. However, this adjustment method currently has the following problems:

[0039] 1) The adjustment method is relatively rough. When adjusting the dopant flow rate at the edge (or center), the dopant flow rate in the area adjacent to the edge (or center) will also be affected, making it difficult to accurately control the doping concentration and further reduce the uniformity of the doping concentration;

[0040] 3) During the epitaxial growth process, only the growth reaction gases of the silicon source and the carbon source were introduced, but the hydrogen chloride gas with etching effect and doping efficiency adjustment was not introduced. At the same time, due to the limitations of the current equipment, the chlorine-silicon ratio in the central area and the chlorine-silicon ratio in the edge area always remain the same and cannot be adjusted independently, resulting in a single concentration adjustment method, and the doping efficiency and doping concentration of the dopant cannot be adjusted by adjusting the chlorine-silicon ratio.

[0041] In order to solve the problem of poor uniformity of carrier concentration of silicon carbide epitaxial wafers in the prior art mentioned above, the embodiment of the present application provides a silicon carbide epitaxial growth method with regionally controllable chlorine-silicon ratio based on the principle that the higher the chlorine-silicon ratio in the edge area, the lower the growth rate of the epitaxial layer and the higher the doping effect. By independently adjusting the chlorine-silicon ratio in the edge area and the central area of ​​the reaction chamber of the silicon carbide epitaxial equipment, the doping efficiency of the dopant can be accurately adjusted, the carrier concentration of the silicon carbide epitaxial wafer can be accurately controlled, and the quality of the silicon carbide epitaxial wafer can be improved.

[0042] Compared with the current method of simply controlling the dopant flow rate, the embodiment of the present application has higher control accuracy and better uniformity of doping concentration; and the embodiment of the present application requires less modification to the equipment, has low modification cost, and is more adaptable.

[0043] Figure 1 The implementation flow chart of the method for epitaxial growth of silicon carbide with regionally controllable chlorine-silicon ratio provided in the embodiment of the present application is described in detail as follows:

[0044] In step 101, a silicon carbide substrate is placed in a reaction chamber, and etching and buffer layer growth are performed on the silicon carbide substrate in sequence.

[0045] The silicon carbide growth includes a temperature rise stage, a substrate etching stage, a buffer layer growth stage, a drift layer growth stage and a substrate removal stage.

[0046] In an embodiment of the present application, a silicon carbide substrate is placed in a reaction chamber of a silicon carbide epitaxial device using a robot, and the silicon carbide substrate is sequentially subjected to a heating stage, a substrate etching stage, and a buffer layer growth stage to obtain a buffer layer based on the silicon carbide substrate.

[0047] In a possible implementation, a silicon carbide substrate is placed in a reaction chamber of a silicon carbide epitaxial device, and etching and buffer layer growth are performed on the silicon carbide substrate in sequence, including:

[0048] Placing the silicon carbide substrate into a reaction chamber of a silicon carbide epitaxial device, evacuating the reaction chamber, setting the pressure in the evacuated reaction chamber to a predetermined pressure, and raising the temperature of the evacuated reaction chamber to a first preset temperature;

[0049] Introducing hydrogen chloride gas into the reaction chamber at a third flow rate through the first gas path, and raising the temperature of the reaction chamber to a second preset temperature, and etching the silicon carbide substrate for a first period of time;

[0050] After the etching of the silicon carbide substrate is completed, silicon source gas and carbon source gas are introduced into the reaction chamber through the first gas path at a fourth flow rate to grow a buffer layer on the etched silicon carbide substrate.

[0051] Optionally, after the silicon carbide substrate is placed in a reaction chamber of a silicon carbide epitaxial device, the reaction chamber is evacuated, and the pressure in the evacuated reaction chamber is set to a predetermined pressure, and the temperature in the reaction chamber is increased to a first preset temperature.

[0052] The predetermined pressure has a pressure range of 50-500 mbar.

[0053] The temperature range of the first preset temperature is 1500°C-1700°C.

[0054] Then enter the substrate etching stage, refer to Figure 2 The first gas path includes a first sub-gas path, a second sub-gas path and a third sub-gas path. Different gases are introduced into the mixing chamber through the first sub-gas path, the second sub-gas path and the third sub-gas path for mixing, and then the mixed gas is introduced into the reaction chamber, that is, hydrogen chloride gas is introduced into the reaction chamber at a third flow rate through the first gas path, and the temperature in the reaction chamber is increased to a second preset temperature. Etching is continued within the first time period to obtain a high-quality silicon carbide surface and ensure the step flow growth.

[0055] The flow rate of the third flow rate ranges from 100 to 500 sccm.

[0056] Since the temperature in the substrate etching stage is slightly higher than the temperature in the heating stage, that is, the second preset temperature is slightly higher than the first preset temperature, the temperature range of the second preset temperature is 1600°C-1700°C.

[0057] The etching time, i.e. the first time period, ranges from 5 to 15 minutes.

[0058] After the etching of the silicon carbide substrate is completed, the buffer layer growth stage is then entered. The silicon source gas and the carbon source gas are introduced into the reaction chamber at a fourth flow rate through the first gas path to grow the buffer layer. At this time, the silicon source gas and the carbon source gas in the edge area and the central area of ​​the reaction chamber are both from the first gas path. Therefore, the chlorine-silicon ratio of the edge area is the same as that of the central area, that is, Figure 2 The chlorine-silicon ratio in the edge area and the center area is uniform.

[0059] The flow rate of the fourth flow rate ranges from 100 to 400 sccm.

[0060] In the embodiment of the present application, the silicon source gas introduced may include but is not limited to trichlorosilane and silane.

[0061] Accordingly, the carbon source gas introduced may include, but is not limited to, ethylene and methane.

[0062] In step 102, after the buffer layer is grown, silicon source gas and carbon source gas are introduced into the reaction chamber through the first gas path, and hydrogen chloride gas is introduced into the edge area of ​​the reaction chamber through the second gas path to grow the drift layer.

[0063] In an embodiment of the present application, after the buffer layer is grown, the drift layer growth stage is entered, and silicon source gas and carbon source gas of the same composition as above are introduced into the reaction chamber through the first gas path, and hydrogen chloride gas is introduced into the edge area of ​​the reaction chamber through the second gas path to grow the drift layer.

[0064] In a possible implementation, after the buffer layer is grown, silicon source gas and carbon source gas are introduced into the reaction chamber through the first gas path, and hydrogen chloride gas is introduced into the edge region of the reaction chamber through the second gas path to grow the drift layer, which may include:

[0065] After the buffer layer is grown, silicon source gas and carbon source gas are introduced into the reaction chamber at a first flow rate through the first gas path, and hydrogen chloride gas is introduced into the edge area of ​​the reaction chamber at a second flow rate through the second gas path to grow the drift layer.

[0066] Optionally, the principle of regulating the doping efficiency of the dopant by the chlorine-silicon ratio is used (i.e., the change of the local chlorine-silicon ratio directly affects the doping efficiency of the dopant in the local area. For N-type doping such as nitrogen, the higher the chlorine-silicon ratio, the higher the doping efficiency; the lower the chlorine-silicon ratio, the lower the doping efficiency). After the buffer layer is grown, the present embodiment enters the drift layer growth stage. Figure 3 , a silicon source gas and a carbon source gas are introduced into the reaction chamber at a first flow rate through a first gas path, wherein the silicon source gas may include but is not limited to trichlorosilane and silane, and the carbon source gas may include but is not limited to ethylene and methane. At this time, the chlorine-silicon ratio in the central area of ​​the reaction chamber is a chlorine-silicon ratio a.

[0067] At the same time, hydrogen chloride gas is introduced into the edge region of the reaction chamber at a second flow rate through the second gas path to grow the drift layer. At this time, the chlorine-silicon ratio in the edge region of the reaction chamber is chlorine-silicon ratio b, which is different from chlorine-silicon ratio a in the central region.

[0068] At this time, the hydrogen chloride gas introduced into the edge area of ​​the reaction chamber will lead to an increase in the chlorine-silicon ratio in the edge area. The change in the chlorine-silicon ratio in the edge area directly affects the doping efficiency of the dopant in the edge area, thereby determining the doping concentration in the edge area. The embodiment of the present application can independently adjust the chlorine-silicon ratio of the edge area and the central area of ​​the reaction chamber by controlling the flow rate of the independent hydrogen chloride gas path, thereby achieving precise control of the chlorine-silicon ratio and the doping concentration, thereby improving the quality of the silicon carbide epitaxial wafer.

[0069] The flow rate of the first flow rate is in the range of 300-500 sccm.

[0070] The second flow rate of the hydrogen chloride gas introduced into the edge region of the reaction chamber is in the range of 10-50 sccm.

[0071] Since the hydrogen chloride gas is introduced into only the edge region of the reaction chamber through the second gas path during the drift layer growth stage, the flow rate of the hydrogen chloride in the central region of the reaction chamber is zero.

[0072] In step 103, after the drift layer is grown, a silicon carbide epitaxial wafer is obtained.

[0073] In an embodiment of the present application, after the drift layer growth is completed, the substrate removal stage is entered, that is, after the reaction is completed, all reaction gases entering the reaction chamber are turned off, and the temperature of the reaction chamber is lowered. After the temperature is lowered, the silicon carbide substrate is removed using a robot to obtain a silicon carbide epitaxial wafer.

[0074] For example, Figure 4 is a curve diagram of carrier doping concentration uniformity of a first silicon carbide epitaxial wafer, that is, a curve diagram of carrier doping concentration uniformity of a silicon carbide epitaxial wafer prepared by using the prior art, Figure 5 is a curve trend of carrier doping uniformity of the second silicon carbide epitaxial wafer, that is, a curve trend of carrier doping concentration uniformity of the silicon carbide epitaxial wafer prepared in the embodiment of the present application, Figure 4 4.33% of Figure 5 The 0.78% in the figure are the average values ​​of the concentration differences between the carrier doping concentrations of the silicon carbide epitaxial wafers obtained in the prior art and the embodiments of the present application. Figure 4 and Figure 5 It can be seen that the silicon carbide epitaxial wafer prepared in the embodiment of the present application has better uniformity of dopant concentration, so that the performance of the device prepared from the silicon carbide epitaxial wafer obtained in the embodiment of the present application can be better.

[0075] The present application provides a method for epitaxial growth of silicon carbide with regionally controllable chlorine-silicon ratio, by placing a silicon carbide substrate into a reaction chamber of a silicon carbide epitaxial device, and etching and growing a buffer layer on the silicon carbide substrate in sequence; after the growth of the buffer layer, silicon source gas and carbon source gas are introduced into the reaction chamber through a first gas path, and hydrogen chloride gas is introduced into the edge region of the reaction chamber through a second gas path to grow a drift layer; after the growth of the drift layer is completed, a silicon carbide epitaxial wafer is obtained. The present application is based on the principle that the higher the chlorine-silicon ratio in the edge region, the lower the growth rate of the epitaxial layer and the higher the doping efficiency. By using a second gas path to introduce additional hydrogen chloride gas into the edge region of the reaction chamber, the independent control capability of the chlorine-silicon ratio in the edge region and the chlorine-silicon ratio in the central region of the reaction chamber is achieved. By precisely controlling the chlorine-silicon ratio in the edge region and the central region, precise control of the doping efficiency of each region and precise control of the doping concentration are achieved, thereby effectively improving the doping concentration and uniformity of the silicon carbide epitaxial wafer.

[0076] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0077] The following is an embodiment of the device of the present application. For details not described in detail, please refer to the corresponding method embodiment described above.

[0078] Figure 6 A schematic structural diagram of a silicon carbide epitaxial wafer provided in an embodiment of the present application is shown, and the silicon carbide epitaxial wafer is prepared using the steps in the above-mentioned embodiments of the silicon carbide epitaxial growth method with controllable chlorine-silicon ratio regions.

[0079] Reference Figure 6 The silicon carbide epitaxial wafer includes a silicon carbide substrate 61, a buffer layer 62 and a drift layer 63. The buffer layer 62 is located above the silicon surface 611 of the silicon carbide substrate 61, and the drift layer 63 is located above the buffer layer 62.

[0080] The present application provides a silicon carbide epitaxial wafer, which is prepared by the above-mentioned silicon carbide epitaxial growth method with controllable chlorine-silicon ratio. The specific preparation process is: by placing a silicon carbide substrate in the reaction chamber of a silicon carbide epitaxial device, and etching and growing a buffer layer on the silicon carbide substrate in sequence; after the growth of the buffer layer, silicon source gas and carbon source gas are introduced into the reaction chamber through a first gas path, and hydrogen chloride gas is introduced into the edge area of ​​the reaction chamber through a second gas path to grow a drift layer; after the growth of the drift layer is completed, a silicon carbide epitaxial wafer is obtained. The present application is based on the principle that the higher the chlorine-silicon ratio in the edge area, the lower the growth rate of the epitaxial layer and the higher the doping efficiency. By using the second gas path to introduce additional hydrogen chloride gas into the edge area of ​​the reaction chamber, the independent control capability of the chlorine-silicon ratio in the edge area and the chlorine-silicon ratio in the central area of ​​the reaction chamber is achieved. By accurately controlling the chlorine-silicon ratio in the edge area and the central area, the precise control of the doping efficiency of each area and the precise control of the doping concentration are achieved, thereby effectively improving the doping concentration and doping concentration uniformity of the silicon carbide epitaxial wafer.

[0081] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for epitaxial growth of silicon carbide with regionally controllable chlorine-silicon ratio, characterized in that: include: Placing a silicon carbide substrate into a reaction chamber of a silicon carbide epitaxial device, and sequentially performing etching and buffer layer growth on the silicon carbide substrate; After the buffer layer is grown, silicon source gas and carbon source gas are introduced into the reaction chamber through a first gas path, and hydrogen chloride gas is introduced into an edge region of the reaction chamber through a second gas path to grow a drift layer; After the drift layer is grown, a silicon carbide epitaxial wafer is obtained.

2. The method for epitaxial growth of silicon carbide with regionally controllable chlorine-silicon ratio according to claim 1, characterized in that: After the buffer layer is grown, silicon source gas and carbon source gas are introduced into the reaction chamber through a first gas path, and hydrogen chloride gas is introduced into the edge region of the reaction chamber through a second gas path to grow the drift layer, including: After the buffer layer is grown, silicon source gas and carbon source gas are introduced into the reaction chamber at a first flow rate through a first gas path, and hydrogen chloride gas is introduced into the edge area of ​​the reaction chamber at a second flow rate through a second gas path to grow a drift layer.

3. The method for epitaxial growth of silicon carbide with regionally controllable chlorine-silicon ratio according to claim 2, characterized in that: The flow rate range of the first flow rate is 300-500 sccm; The flow rate of the second flow rate is in the range of 10-50 sccm.

4. The method for epitaxial growth of silicon carbide with regionally controllable chlorine-silicon ratio according to claim 1, characterized in that: The silicon source gas includes trichlorosilane and silane; The carbon source gas includes ethylene and methane.

5. The method for epitaxial growth of silicon carbide with regionally controllable chlorine-silicon ratio according to claim 1, characterized in that: The step of placing the silicon carbide substrate into a reaction chamber of a silicon carbide epitaxial device and sequentially etching and growing a buffer layer on the silicon carbide substrate comprises: Placing the silicon carbide substrate into a reaction chamber of the silicon carbide epitaxial device, evacuating the reaction chamber, setting the pressure in the evacuated reaction chamber to a predetermined pressure, and raising the temperature of the evacuated reaction chamber to a first preset temperature; introducing hydrogen chloride gas into the reaction chamber at a third flow rate through the first gas path, and raising the temperature of the reaction chamber to a second preset temperature, and etching the silicon carbide substrate for a first period of time; After the etching of the silicon carbide substrate is completed, the silicon source gas and the carbon source gas are introduced into the reaction chamber through the first gas path at a fourth flow rate to grow a buffer layer on the etched silicon carbide substrate.

6. The method for epitaxial growth of silicon carbide with regionally controllable chlorine-silicon ratio according to claim 5, characterized in that: The predetermined pressure ranges from 50 to 500 mbar.

7. The method for epitaxial growth of silicon carbide with regionally controllable chlorine-silicon ratio according to claim 5, characterized in that: The temperature range of the first preset temperature is 1500°C-1700°C; The second preset temperature ranges from 1600°C to 1700°C.

8. The method for epitaxial growth of silicon carbide with regionally controllable chlorine-silicon ratio according to claim 5, characterized in that: The flow rate of the third flow rate is in the range of 100-500 sccm; The flow rate of the fourth flow rate ranges from 100 to 400 sccm.

9. The method for epitaxial growth of silicon carbide with regionally controllable chlorine-silicon ratio according to claim 5, characterized in that: The first time period ranges from 5 to 15 minutes.

10. A silicon carbide epitaxial wafer, characterized in that: The silicon carbide epitaxial wafer is prepared by using the silicon carbide epitaxial growth method with regionally controllable chlorine-silicon ratio according to any one of claims 1 to 9.

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