P-type silicon carbide epitaxial wafer, preparation method thereof and semiconductor device

Abstract

The invention relates to a p-type silicon carbide epitaxial wafer, a preparation method thereof and a semiconductor device. The preparation method of the p-type silicon carbide epitaxial wafer comprises the following steps: placing a substrate in a reaction chamber; introducing source gas and diluent gas into the reaction chamber; applying radio frequency power to generate plasma in the reaction chamber; introducing a p-type doping source and carrier gas into the reaction chamber, wherein the p-type doping source comprises trimethylaluminum and triethyl boron; and growing a p-type silicon carbide epitaxial layer on one side of the substrate to obtain the p-type silicon carbide epitaxial wafer. According to the preparation method of the p-type silicon carbide epitaxial wafer, the trimethylaluminum and the triethyl boron are jointly used as the p-type doping source, the p-type silicon carbide epitaxial wafer is grown through the plasma enhanced chemical vapor deposition (PECVD) technology, and the doping efficiency can be improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a p-type silicon carbide epitaxial wafer and a preparation method thereof, and a semiconductor device. Background Art

[0002] Silicon carbide (SiC), as a wide-bandgap semiconductor material, is widely considered to be suitable for electronic devices working in harsh environments due to its excellent electrical and chemical properties. P-type silicon carbide epitaxial wafers are silicon carbide epitaxial layers grown on conductive silicon carbide substrates, which are achieved by introducing p-type dopants. Due to its excellent physical properties, this material has broad application prospects in power electronics, microwave radio frequency devices, new energy vehicles and other industries.

[0003] In traditional technology, the industry generally uses trimethylaluminum (TMA) as a dopant and grows p-type silicon carbide epitaxial layers through chemical vapor deposition (CVD) technology. However, this method has limitations in preparing highly doped p-type silicon carbide epitaxial wafers. The actual utilization rate of trimethylaluminum (TMA) is less than 1%, and even more than 99.9% of the raw materials are wasted when high doping is used. Summary of the invention

[0004] Based on this, it is necessary to provide a p-type silicon carbide epitaxial wafer and a preparation method thereof and a semiconductor device in order to improve the doping efficiency.

[0005] A method for preparing a p-type silicon carbide epitaxial wafer comprises the following steps:

[0006] placing a substrate in a reaction chamber;

[0007] Introducing source gas and dilution gas into the reaction chamber;

[0008] applying radio frequency power to generate a plasma within the reaction chamber;

[0009] Introducing a p-type doping source and a carrier gas into the reaction chamber, wherein the p-type doping source includes trimethylaluminum and triethylboron; and

[0010] A p-type silicon carbide epitaxial layer is grown on one side of the substrate to obtain a p-type silicon carbide epitaxial wafer.

[0011] The preparation method of the p-type silicon carbide epitaxial wafer adopts trimethylaluminum and triethylboron as p-type doping sources, and grows the p-type silicon carbide epitaxial wafer by plasma enhanced chemical vapor deposition (PECVD) technology, which can improve the doping efficiency. Specifically, on the one hand, by adopting the B-Al co-doping method, according to the first principle calculation, the carrier concentration of the p-type silicon carbide epitaxial wafer can reach more than 3 times that of Al doping alone, which significantly improves the carrier concentration of the p-type silicon carbide epitaxial layer, so that the required electrical properties can be achieved at a lower doping concentration, thereby reducing the demand for high doping concentration. On the other hand, compared with the traditional CVD technology, the plasma enhanced chemical vapor deposition (PECVD) technology has higher synthesis efficiency, which not only improves the utilization efficiency of the source gas, but also improves the utilization efficiency of the dopant, while operating at a lower temperature saves energy consumption, and the lower growth rate is conducive to the precise control of the thickness of the ultra-high doped p-type epitaxial layer, which provides a practical solution for the preparation of highly doped p-type silicon carbide epitaxial layer.

[0012] In a feasible implementation, the ratio of the carrier gas flow rate of the trimethylaluminum to the carrier gas flow rate of the triethylboron is 0.95-5.

[0013] In a feasible implementation, the carrier gas flow rate of trimethylaluminum is 5 sccm to 100 sccm, and the carrier gas flow rate of triethylboron is 2 sccm to 50 sccm;

[0014] The carrier gas is hydrogen.

[0015] In a feasible implementation, the substrate is selected from an n-type substrate, an epitaxial wafer having grown an n-type epitaxial layer, an epitaxial wafer having grown a p-type epitaxial layer, or an epitaxial wafer having grown an n-type and p-type composite epitaxial layer.

[0016] In a feasible implementation, the source gas includes a carbon source and a silicon source, the carbon source is selected from at least one of alkanes, alkenes and chlorine-containing alkanes, and the silicon source is selected from at least one of silanes and chlorosilanes;

[0017] The source gas further includes a chlorine source, and the chlorine source is selected from at least one of HCl gas, chlorine-containing alkanes and chlorine-containing silanes.

[0018] In a feasible implementation, the dilution gas is selected from at least one of hydrogen and argon, and the flow rate of the dilution gas is 3 to 10 times the flow rate of the source gas;

[0019] The flow rate of the source gas is 10 sccm to 100 sccm, and the flow rate of the dilution gas is 300 sccm to 500 sccm.

[0020] In a feasible implementation, the radio frequency power is 20W to 200W.

[0021] In a feasible implementation, in the operation of growing the p-type silicon carbide epitaxial layer on one side of the substrate: the chamber pressure is 50Pa to 200Pa, and the growth temperature is 100°C to 200°C;

[0022] After the p-type silicon carbide epitaxial layer is grown on one side of the substrate, an annealing step is also included; the annealing temperature is 1000°C to 1200°C.

[0023] A p-type silicon carbide epitaxial wafer is prepared by using any of the above-mentioned methods for preparing a p-type silicon carbide epitaxial wafer.

[0024] The method for preparing the p-type silicon carbide epitaxial wafer adopts trimethylaluminum and triethylboron as p-type doping sources and grows the p-type silicon carbide epitaxial wafer by plasma enhanced chemical vapor deposition (PECVD) technology, which can improve the doping efficiency. Therefore, the p-type silicon carbide epitaxial wafer prepared by the preparation method has a high doping efficiency.

[0025] A semiconductor device comprises a p-type silicon carbide epitaxial wafer prepared by any of the above-mentioned methods for preparing a p-type silicon carbide epitaxial wafer.

[0026] The semiconductor device of the technical solution of the present invention includes the above-mentioned p-type silicon carbide epitaxial wafer, has the advantage of high doping efficiency, and is conducive to wide application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a flowchart of a method for preparing a p-type silicon carbide epitaxial wafer according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0030] See also Figure 1 A method for preparing a p-type silicon carbide epitaxial wafer according to an embodiment of the present invention comprises the following steps:

[0031] S10, placing a substrate in a reaction chamber.

[0032] In a feasible implementation, the substrate is selected from an n-type substrate, an epitaxial wafer having grown an n-type epitaxial layer, an epitaxial wafer having grown a p-type epitaxial layer, or an epitaxial wafer having grown an n-type and p-type composite epitaxial layer. The selection of these substrate materials provides flexibility for realizing the epitaxial layers required for preparing devices with different electrical characteristics, indicating strong adaptability. Further, the substrate of an embodiment can adopt a 3C-SiC, 4H-SiC or 6H-SiC substrate with a tilt angle (2° to 6°).

[0033] S20, introducing source gas and dilution gas into the reaction chamber.

[0034] In a feasible implementation, the source gas includes a carbon source and a silicon source, and the carbon source is selected from alkanes (such as C 3 H 8 ), at least one of alkenes and chlorine-containing alkanes, and the silicon source is selected from at least one of silanes and chlorosilanes. The selection of these source materials is crucial to the growth of the silicon carbide epitaxial layer. Their ratio and purity directly affect the quality and doping concentration of the epitaxial layer. The atomic ratio of the carbon source to the silicon source is controlled between 0.5 and 2, and the specific ratio value is determined according to the growth rate and surface quality.

[0035] In a feasible implementation, the source gas further includes a chlorine source, and the chlorine source is selected from at least one of HCl gas, chlorine-containing alkanes and chlorine-containing silanes. Chlorine atoms are introduced through the chlorine source to control the atomic ratio of chlorine to silicon between 0 and 5, and the specific ratio value is determined according to the growth rate and surface quality.

[0036] In a feasible implementation, the dilution gas is selected from at least one of hydrogen and argon, and the flow rate of the dilution gas is 3 to 10 times the flow rate of the source gas.

[0037] In a feasible implementation, the flow rate of the source gas is 10 sccm to 100 sccm, and the flow rate of the dilution gas is 300 sccm to 500 sccm. Further, the flow rate of the source gas may be, but is not limited to, 10 sccm, 20 sccm, 30 sccm, 40 sccm, 50 sccm, 60 sccm, 70 sccm, 80 sccm, 90 sccm or 100 sccm, and the flow rate of the dilution gas may be, but is not limited to, 300 sccm, 350 sccm, 400 sccm, 450 sccm or 500 sccm.

[0038] S30, applying radio frequency power to generate plasma in the reaction chamber.

[0039] In a feasible implementation, the radio frequency (RF) power is 20W to 200W. Plasma is generated in the reaction chamber by applying radio frequency (RF) power to excite gas molecules to form electrons, ions and neutral free radicals. This step is critical in the epitaxial growth of silicon carbide. The generation and control of plasma has a significant impact on the growth rate and the quality of the epitaxial layer.

[0040] Furthermore, the RF power may be, but is not limited to, 20W, 30W, 40W, 50W, 60W, 70W, 80W, 90W, 100W, 110W, 120W, 130W, 140W, 150W, 160W, 170W, 180W, 190W or 200W.

[0041] S40, introducing a p-type doping source and a carrier gas into the reaction chamber, wherein the p-type doping source includes trimethylaluminum (TMA) and triethylboron (TEB).

[0042] Among them, trimethylaluminum (TMA) and triethylboron (TEB) are both brought into the cavity by the carrier gas using the bubbling method.

[0043] In a feasible implementation, the ratio of the carrier gas flow of trimethylaluminum to the carrier gas flow of triethylboron is 0.95 to 5. Further, the ratio of the carrier gas flow of trimethylaluminum to the carrier gas flow of triethylboron can be, but is not limited to, 0.95, 1, 2, 3, 4 or 5.

[0044] In a feasible implementation, the carrier gas flow rate of trimethylaluminum is 5 sccm to 100 sccm, and the carrier gas flow rate of triethylboron is 2 sccm to 50 sccm. Further, the carrier gas flow rate of methylaluminum can be, but not limited to, 5 sccm, 10 sccm, 20 sccm, 30 sccm, 40 sccm, 50 sccm, 60 sccm, 70 sccm, 80 sccm, 90 sccm or 100 sccm, and the carrier gas flow rate of triethylboron can be, but not limited to, 2 sccm, 10 sccm, 20 sccm, 30 sccm, 40 sccm or 50 sccm.

[0045] In one possible implementation, the carrier gas is hydrogen.

[0046] S50, growing a p-type silicon carbide epitaxial layer on one side of the substrate to obtain a p-type silicon carbide epitaxial wafer.

[0047] In a feasible implementation, in the operation of growing a p-type silicon carbide epitaxial layer on one side of the substrate: the chamber pressure is 50Pa-200Pa, and the growth temperature is 100°C-200°C. Further, the chamber pressure may be, but is not limited to, 50Pa, 60Pa, 70Pa, 80Pa, 90Pa, 100Pa, 110Pa, 120Pa, 130Pa, 140Pa, 150Pa, 160Pa, 170Pa, 180Pa, 190Pa or 200Pa, and the growth temperature may be, but is not limited to, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C or 200°C.

[0048] In a feasible implementation, after the p-type silicon carbide epitaxial layer is grown on one side of the substrate, an annealing step is also included. Annealing the silicon carbide epitaxial layer can improve crystallinity and eliminate stress, and after annealing, the epitaxial wafer is transferred out of the reaction chamber.

[0049] In a feasible implementation, the temperature of the annealing treatment is 1000° C. to 1200° C. The annealing treatment is usually performed in the above-mentioned high temperature environment, so as to ensure the quality and performance of the silicon carbide epitaxial layer. Further, the temperature of the annealing treatment can be, but is not limited to, 1000° C., 1050° C., 1100° C., 1150° C. or 1200° C.

[0050] The preparation method of the p-type silicon carbide epitaxial wafer adopts trimethylaluminum and triethylboron as p-type doping sources, and grows the p-type silicon carbide epitaxial wafer by plasma enhanced chemical vapor deposition (PECVD) technology, which can improve the doping efficiency. Specifically, on the one hand, by adopting the B-Al co-doping method, according to the first principle calculation, the carrier concentration of the p-type silicon carbide epitaxial wafer can reach more than 3 times that of Al doping alone, which significantly improves the carrier concentration of the p-type silicon carbide epitaxial layer, so that the required electrical properties can be achieved at a lower doping concentration, thereby reducing the demand for high doping concentration. On the other hand, compared with the traditional CVD technology, the plasma enhanced chemical vapor deposition (PECVD) technology has higher synthesis efficiency, which not only improves the utilization efficiency of the source gas, but also improves the utilization efficiency of the dopant, while operating at a lower temperature saves energy consumption, and the lower growth rate is conducive to the precise control of the thickness of the ultra-high doped p-type epitaxial layer, which provides a practical solution for the preparation of highly doped p-type silicon carbide epitaxial layer.

[0051] Furthermore, the method for preparing a p-type silicon carbide epitaxial wafer using the technical solution of the present invention also has the following advantages:

[0052] 1. Reduce costs: Since B-Al co-doping can increase the carrier concentration, the use of expensive dopants such as trimethylaluminum (TMA) and triethylboron (TEB) is reduced, thereby reducing production costs;

[0053] 2. Energy saving and consumption reduction: PECVD technology operates at a lower temperature, which can save a lot of energy consumption compared to traditional CVD technology;

[0054] 3. Improve crystallinity and eliminate stress: Through annealing, the crystallinity of the epitaxial layer can be improved and stress can be eliminated, thereby improving the performance and reliability of the device;

[0055] 4. Environmentally friendly: Due to the reduction of chemical gas usage and the improvement of utilization efficiency, this technical solution has less impact on the environment and is in line with the trend of green manufacturing.

[0056] A p-type silicon carbide epitaxial wafer according to an embodiment is prepared by using any of the above-mentioned methods for preparing a p-type silicon carbide epitaxial wafer.

[0057] The p-type silicon carbide epitaxial wafer prepared by the above preparation method has a wide range of applications, including but not limited to the following applications:

[0058] 1. Power electronic devices: Highly doped p-type silicon carbide epitaxial wafers are key materials for manufacturing high-performance power electronic devices such as MOSFETs, IGBTs and SBDs, which are widely used in electric vehicles, solar inverters, wind power generation, smart grids and other fields;

[0059] 2. Microwave RF devices: In microwave RF fields such as 5G communications, satellite communications, and radar systems, highly doped p-type silicon carbide epitaxial wafers can be used to manufacture high-frequency, high-power RF devices such as power amplifiers, low-noise amplifiers, and switches;

[0060] 3. New energy vehicles: With the rapid development of new energy vehicles, the demand for high-efficiency and high-reliability power electronic devices is increasing. This technical solution can provide high-performance semiconductor materials for key components such as battery management systems and motor controllers of new energy vehicles;

[0061] 4. Industrial automation: In the field of industrial automation, highly doped p-type silicon carbide epitaxial wafers can be used to manufacture high-temperature and high-voltage resistant sensors and actuators, improving the stability and reliability of industrial systems.

[0062] The method for preparing the p-type silicon carbide epitaxial wafer adopts trimethylaluminum and triethylboron as p-type doping sources and grows the p-type silicon carbide epitaxial wafer by plasma enhanced chemical vapor deposition (PECVD) technology, which can improve the doping efficiency. Therefore, the p-type silicon carbide epitaxial wafer prepared by the preparation method has a high doping efficiency.

[0063] A semiconductor device according to one embodiment includes a p-type silicon carbide epitaxial wafer prepared by any of the above-mentioned methods for preparing a p-type silicon carbide epitaxial wafer.

[0064] The semiconductor device of the technical solution of the present invention includes the above-mentioned p-type silicon carbide epitaxial wafer, has the advantage of high doping efficiency, and is conducive to wide application.

[0065] With reference to the above implementation contents, in order to make the technical solution of the present invention more specific, clear and easy to understand, the technical solution of the present invention is now exemplified. However, it should be noted that the contents to be protected by the present invention are not limited to the following embodiments.

[0066] Example 1

[0067] 1. Place the substrate in a pe-CVD furnace. The substrate is a 4H-SiC conductive substrate with a tilt angle of 4°.

[0068] 2. Source gas and dilution gas are introduced into the PE-CVD furnace, wherein ethylene is used as the carbon source with a flow rate of 22 sccm; silane is used as the silicon source with a flow rate of 50 sccm; and hydrogen is used as the dilution gas with a flow rate of 450 sccm.

[0069] 3. Apply RF power to generate plasma in the PE-CVD furnace, and the RF power is controlled at 90W.

[0070] 4. A p-type doping source and a carrier gas are introduced into the pe-CVD furnace. The p-type doping source includes trimethylaluminum (TMA) and triethylboron (TEB). Both trimethylaluminum and triethylboron are brought into the cavity by hydrogen using a bubbling method; the trimethylaluminum bubbling hydrogen flow rate is 20 sccm, and the triethylboron bubbling hydrogen flow rate is 8 sccm.

[0071] 5. Control the chamber pressure at about 110 Pa and the growth temperature at 180 ° C to grow a p-type silicon carbide epitaxial layer on one side of the substrate.

[0072] 6. After the epitaxial growth is completed, the epitaxial wafer is taken out from the pe-CVD furnace and placed in an annealing furnace for annealing at a temperature of 1200° C. After annealing, the p-type silicon carbide epitaxial wafer of Example 1 is obtained.

[0073] Example 2

[0074] 1. Place the substrate in a pe-CVD furnace. The substrate is an epitaxial wafer on which two n-type epitaxial layers, n+ and n-, have been grown.

[0075] 2. Introduce source gas and dilution gas into the PE-CVD furnace, wherein ethylene is used as the carbon source with a flow rate of 18 sccm; silane is used as the silicon source with a flow rate of 40 sccm; and hydrogen is used as the dilution gas with a flow rate of 400 sccm.

[0076] 3. Apply RF power to generate plasma in the PE-CVD furnace, and the RF power is controlled at 100W.

[0077] 4. A p-type doping source and a carrier gas are introduced into the pe-CVD furnace. The p-type doping source includes trimethylaluminum (TMA) and triethylboron (TEB). Both trimethylaluminum and triethylboron are brought into the cavity by hydrogen using a bubbling method; the trimethylaluminum bubbling hydrogen flow rate is 30 sccm, and the triethylboron bubbling hydrogen flow rate is 15 sccm.

[0078] 5. Control the chamber pressure at about 110 Pa and the growth temperature at 180 ° C to grow a p-type silicon carbide epitaxial layer on one side of the substrate.

[0079] 6. After the epitaxial growth is completed, the epitaxial wafer is taken out from the pe-CVD furnace and placed in an annealing furnace for annealing at a temperature of 1200° C. After annealing, the p-type silicon carbide epitaxial wafer of Example 2 is obtained.

[0080] Comparative Example 1

[0081] This comparative example provides a p-type silicon carbide epitaxial wafer and a preparation method thereof, which is different from Example 1 only in that the p-type doping source is trimethylaluminum, and the trimethylaluminum bubbling hydrogen flow rate is 28 sccm.

[0082] Comparative Example 2

[0083] This comparative example provides a p-type silicon carbide epitaxial wafer and a preparation method thereof, which is different from Example 2 only in that the p-type doping source is trimethylaluminum, and the trimethylaluminum bubbling hydrogen flow rate is 100 sccm.

[0084] Comparative Example 3

[0085] This comparative example provides a p-type silicon carbide epitaxial wafer and a preparation method thereof, which is different from Example 1 in that:

[0086] A p-type silicon carbide epitaxial wafer was grown using a CVD furnace, wherein ethylene was used as a carbon source with a flow rate of 200 sccm; trichlorosilane TCS was used as a silicon source, which was brought out by hydrogen using a bubbling method with a flow rate of 340 sccm; and hydrogen was used as a diluent gas with a flow rate of 100 slm. A p-type doping source was introduced into the CVD furnace and brought into the cavity by hydrogen using a bubbling method, wherein the p-type doping source was trimethylaluminum (TMA) and triethylboron (TEB), and the flow rate of hydrogen bubbling with trimethylaluminum was 2000 sccm, and the flow rate of hydrogen bubbling with triethylboron was 1000 sccm. The growth temperature was 1620°C and the cavity pressure was 10 kPa.

[0087] Performance Testing:

[0088] The carrier concentration of the p-type silicon carbide epitaxial wafers of Examples 1 to 2 and Comparative Examples 1 to 3 was measured using MCV. The test standard adopted the ten-point method commonly used in the industry. The test results are shown in Table 1.

[0089] Table 1 Carrier concentration test results of p-type silicon carbide epitaxial wafers of Examples 1 to 2 and Comparative Examples 1 to 3

[0090]

[0091] According to the data in Table 1, the mean values ​​of the carrier concentrations of Examples 1 to 2 and Comparative Examples 1 to 3 are 5.99E+17, 1.06E+18, 4.12E+17, 8.60E+17, and 4.122E+17, respectively. Since it is difficult to quantitatively test the doping concentration of highly doped epitaxial wafers, before the doping concentration approaches the doping limit, it is proportional to the amount of doping source used. Therefore, by comparing Example 1 with Comparative Example 1, Example 1 uses less trimethylaluminum source and has a lower doping concentration, but its carrier concentration is much higher than that of Comparative Example 1. Similarly, by comparing Example 2 with Comparative Example 2, it can be seen that at higher doping concentrations, this phenomenon will be more obvious. The doping concentration of trimethylaluminum in Example 2 is much lower than that of trimethylaluminum in Comparative Example 2, but its carrier concentration is much higher than that of Comparative Example 2. In addition, by comparing Example 1 with Comparative Example 3, it can be seen that the use of PE-CVD greatly improves the utilization efficiency of the doping source compared to the conventional CVD method, which is presumably due to the reduction of the dilution gas. The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0092] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a p-type silicon carbide epitaxial wafer, characterized in that: The steps include: placing a substrate in a reaction chamber; Introducing source gas and dilution gas into the reaction chamber; applying radio frequency power to generate a plasma within the reaction chamber; Introducing a p-type doping source and a carrier gas into the reaction chamber, wherein the p-type doping source includes trimethylaluminum and triethylboron; and A p-type silicon carbide epitaxial layer is grown on one side of the substrate to obtain a p-type silicon carbide epitaxial wafer.

2. The method for preparing a p-type silicon carbide epitaxial wafer according to claim 1, characterized in that: The ratio of the carrier gas flow rate of the trimethylaluminum to the carrier gas flow rate of the triethylboron is 0.95-5.

3. The method for preparing a p-type silicon carbide epitaxial wafer according to claim 1 or 2, characterized in that: The carrier gas flow rate of trimethylaluminum is 5 sccm to 100 sccm, and the carrier gas flow rate of triethylboron is 2 sccm to 50 sccm; The carrier gas is hydrogen.

4. The method for preparing a p-type silicon carbide epitaxial wafer according to claim 1, characterized in that: The substrate is selected from an n-type substrate, an epitaxial wafer having grown an n-type epitaxial layer, an epitaxial wafer having grown a p-type epitaxial layer, or an epitaxial wafer having grown an n-type and p-type composite epitaxial layer.

5. The method for preparing a p-type silicon carbide epitaxial wafer according to claim 1, characterized in that: The source gas includes a carbon source and a silicon source, wherein the carbon source is selected from at least one of alkanes, alkenes and chlorine-containing alkanes, and the silicon source is selected from at least one of silanes and chlorosilanes; The source gas further includes a chlorine source, and the chlorine source is selected from at least one of HCl gas, chlorine-containing alkanes and chlorine-containing silanes.

6. The method for preparing a p-type silicon carbide epitaxial wafer according to claim 1, characterized in that: The dilution gas is selected from at least one of hydrogen and argon, and the flow rate of the dilution gas is 3 to 10 times the flow rate of the source gas; The flow rate of the source gas is 10 sccm to 100 sccm, and the flow rate of the dilution gas is 300 sccm to 500 sccm.

7. The method for preparing a p-type silicon carbide epitaxial wafer according to claim 1, characterized in that: The radio frequency power is 20W to 200W.

8. The method for preparing a p-type silicon carbide epitaxial wafer according to claim 1, characterized in that: In the operation of growing a p-type silicon carbide epitaxial layer on one side of the substrate: the chamber pressure is 50Pa to 200Pa, and the growth temperature is 100°C to 200°C; After the p-type silicon carbide epitaxial layer is grown on one side of the substrate, an annealing step is also included; the annealing temperature is 1000°C to 1200°C.

9. A p-type silicon carbide epitaxial wafer, characterized in that: The p-type silicon carbide epitaxial wafer is prepared by the method for preparing the p-type silicon carbide epitaxial wafer according to any one of claims 1 to 8.

10. A semiconductor device, characterized in that: The invention comprises a p-type silicon carbide epitaxial wafer prepared by the method for preparing a p-type silicon carbide epitaxial wafer according to any one of claims 1 to 8.

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