A method for treating a silicon carbide substrate

Abstract

The present invention provides a method for treating a silicon carbide substrate. The silicon carbide substrate is passivated by a plasma processing device; the passivated silicon carbide substrate is subjected to high-temperature annealing using an annealing furnace; an oxide layer is grown on the surface of the silicon carbide substrate after high-temperature annealing; performing high-temperature annealing on the silicon carbide substrate can improve the surface morphology of the silicon carbide substrate, reduce the introduction of impurities at the interface between the silicon carbide substrate and the oxide layer, avoid the introduction of new impurities during the annealing process, reduce the defects in the oxide layer, improve the quality of the oxide layer, and at the same time, the junction depth of phosphorus atom diffusion can be precisely controlled by temperature and time; in the present invention, residual carbon on the surface of the silicon carbide substrate is eliminated by oxygen plasma in a chalcogen gas, and the surface of the silicon carbide substrate is passivated by nitrogen plasma in a pnictogen gas and phosphorus plasma in a pnictide gas, greatly reducing the interface state density.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to a method for processing a silicon carbide substrate. Background Art

[0002] In recent years, based on the statistical data analysis of domestic power devices, the market scale of high-voltage silicon carbide power devices has increased significantly year by year. The main market applications of silicon carbide devices include photovoltaic, power supply, uninterruptible power supply, electric / hybrid vehicles, wind power generation, rail transit, motor drive, and charging piles, etc. Silicon carbide materials are expected to gradually replace silicon devices in power electronic devices with their characteristics such as wide bandgap and high critical breakdown field strength, so as to improve the working efficiency of existing power electronic equipment. In short, the continuous progress of silicon carbide power electronic devices will play a revolutionary role in promoting the development of the power electronics technology field.

[0003] Silicon carbide (SiC) has advantages that cannot be compared with traditional silicon and gallium arsenide in terms of bandgap width, maximum field strength, doping concentration, and thermal conductivity, and is particularly suitable for high-voltage, high-frequency, high-power, high-irradiation, and optoelectronic detection technology fields of certain wavelengths. Therefore, silicon carbide materials have received extensive attention from researchers in power microwave and optoelectronic devices.

[0004] Among them, in the preparation process of silicon carbide power devices, the high-temperature oxidation process is one of the core processes that determine the performance of silicon carbide power devices. Silicon carbide has its own advantages compared with other wide-bandgap semiconductors such as gallium nitride. Silicon carbide forms an oxide film through a thermal oxidation process without introducing other impurity elements, making it easy for silicon carbide to be compatible with the preparation process of silicon power devices.

[0005] Currently, the treatment of silicon carbide is to grow an oxide layer and then anneal the silicon carbide containing the oxide layer in a nitrogen group atmosphere. The interface state density between silicon carbide and the oxide layer is relatively high, resulting in a low inversion channel electron mobility of silicon carbide power devices, seriously affecting the performance of silicon carbide power devices. Summary of the Invention

[0006] In order to overcome the deficiency of the relatively high interface state density between silicon carbide and the oxide layer in the above-mentioned prior art, the present invention provides a method for processing a silicon carbide substrate, including:

[0007] Passivating the silicon carbide substrate through a plasma processing device;

[0008] Performing high-temperature annealing on the passivated silicon carbide substrate using an annealing furnace;

[0009] Growing an oxide layer on the surface of the silicon carbide substrate after high-temperature annealing.

[0010] The passivation of the silicon carbide substrate through the plasma includes:

[0011] Clean the silicon carbide substrate using the RCA standard;

[0012] Passivate the silicon carbide substrate using a plasma processing device based on one or more of chalcogen gases, pnictogen gases, and / or pnictide gases.

[0013] Passivating the silicon carbide substrate through a plasma processing device includes:

[0014] When using a chalcogen gas, place the silicon carbide substrate in the plasma processing device and evacuate the plasma processing device;

[0015] Adjust the internal temperature of the plasma processing device to 200°C - 400°C, then adjust the power of the plasma processing device to 10W - 1000W, and then introduce the chalcogen gas at a flow rate of 10 SCCM - 1000 SCCM and maintain for 1s - 5 min.

[0016] Passivating the silicon carbide substrate through a plasma processing device includes:

[0017] When using a pnictogen gas, place the silicon carbide substrate in the plasma processing device and evacuate the plasma processing device;

[0018] Adjust the internal temperature of the plasma processing device to 200°C - 400°C, then adjust the power of the plasma processing device to 10W - 1000W, and then introduce the pnictogen gas at a flow rate of 10 SCCM - 1000 SCCM and maintain for 1s - 5 min.

[0019] Passivating the silicon carbide substrate through a plasma processing device includes:

[0020] When using a pnictide gas, place the silicon carbide substrate in the plasma processing device and evacuate the plasma processing device;

[0021] Adjust the internal temperature of the plasma processing device to 200°C - 400°C, then adjust the power of the plasma processing device to 10W - 1000W, and then introduce the pnictide gas at a flow rate of 10 SCCM - 2000 SCCM and maintain for 1s - 5 min.

[0022] Performing high-temperature annealing on the passivated silicon carbide substrate using an annealing furnace includes:

[0023] Place the passivated silicon carbide substrate in the annealing furnace and evacuate the annealing furnace to 1 torr - 30 torr;

[0024] Raise the internal temperature of the annealing furnace to 800°C - 1000°C at a heating rate of 10°C / min - 200°C / min, then introduce H2 at a flow rate of 5 SCCM - 60 SCCM and maintain for 2 min - 20 min;

[0025] While introducing H2, continue to introduce HCL at a flow rate of 20 SCCM - 200 SCCM and maintain for 0.5 min - 5 min;

[0026] Lower the internal temperature of the true annealing furnace to room temperature.

[0027] Grow an oxide layer on the surface of the silicon carbide substrate after high-temperature annealing, including:

[0028] Place the silicon carbide substrate after high-temperature annealing into an oxidation furnace, and raise the internal temperature of the oxidation furnace to 900°C - 1200°C at a heating rate of 10°C / min - 200°C / min, and introduce O2, NO, and / or N2O at a flow rate of 1 SLM - 10 SLM;

[0029] Raise the internal temperature of the oxidation furnace to 1200°C - 1500°C at a heating rate of 10°C / min - 200°C / min, maintain for 1 min - 5 h, then stop introducing O2, NO, and / or N2O to obtain an oxide layer.

[0030] Grow an oxide layer on the surface of the silicon carbide substrate after high-temperature annealing, including:

[0031] Place the silicon carbide substrate after high-temperature annealing into an oxidation furnace, and raise the internal temperature of the oxidation furnace to 900°C - 1200°C at a heating rate of 10°C / min - 200°C / min, and introduce H2 and O2 at a flow rate of 1 SLM - 10 SLM;

[0032] Raise the internal temperature of the oxidation furnace to 1200°C - 1500°C at a heating rate of 10°C / min - 200°C / min, maintain for 1 min - 5 h, then stop introducing H2 and O2 to obtain an oxide layer.

[0033] Grow an oxide layer on the surface of the silicon carbide substrate after high-temperature annealing, including:

[0034] Place the silicon carbide substrate after high-temperature annealing into an oxidation furnace, and raise the internal temperature of the oxidation furnace to 900°C - 1200°C at a heating rate of 10°C / min - 200°C / min, and introduce O2, NO, and / or N2O at a flow rate of 1 SLM - 10 SLM;

[0035] Raise the internal temperature of the oxidation furnace to 1200°C - 1500°C at a heating rate of 10°C / min - 200°C / min, maintain for 1 min - 5 h, and stop introducing O2, NO, and / or N2O;

[0036] Maintain the internal temperature of the oxidation furnace, introduce H2 and O2 at a flow rate of 1 SLM - 10 SLM, maintain for 1 min - 5 h, and then stop introducing H2 and O2 to obtain an oxide layer.

[0037] The chalcogen gas includes O2 and / or O3;

[0038] The pnictogen gas includes one or more of N2O, NO, NH3, and N2;

[0039] The pnictogen gas includes one or more of PH3, POCl3, TBP, and TMP.

[0040] The thickness of the oxide layer is 2 nm - 50 nm.

[0041] The silicon carbide substrate is an N-type silicon carbide substrate or a P-type silicon carbide substrate;

[0042] The ion doping concentration of the silicon carbide substrate is 1×10 13 ~10 21 cm -3 , and its thickness is 0.1 μm - 500 μm.

[0043] The technical solution provided by the present invention has the following beneficial effects:

[0044] In the method for treating a silicon carbide substrate provided by the present invention, the silicon carbide substrate is passivated by a plasma processing device; the passivated silicon carbide substrate is subjected to high-temperature annealing using an annealing furnace; an oxide layer is grown on the surface of the silicon carbide substrate after high-temperature annealing, greatly reducing the interface state density between the silicon carbide and the oxide layer and eliminating the residual carbon on the surface of the silicon carbide substrate;

[0045] The technical solution provided by the present invention performs high-temperature annealing on the silicon carbide substrate, which can improve the surface morphology of the silicon carbide substrate, reduce the introduction of impurities at the interface between the silicon carbide substrate and the oxide layer, avoid the introduction of new impurities during the annealing process, reduce the defects in the oxide layer, improve the quality of the oxide layer, and at the same time, the junction depth of phosphorus atom diffusion can be accurately controlled by temperature and time;

[0046] The present invention eliminates the residual carbon on the surface of the silicon carbide substrate through oxygen plasma in the chalcogen gas, and passivates the surface of the silicon carbide substrate using nitrogen plasma in the pnictogen gas and phosphorus plasma in the pnictogen gas, greatly reducing the interface state density. Brief Description of the Drawings

[0047] Figure 1 It is a flowchart of the method for treating a silicon carbide substrate in an embodiment of the present invention. Detailed Description of the Embodiments

[0048] The present invention will be further described in detail below with reference to the accompanying drawings.

[0049] An embodiment of the present invention provides a method for treating a silicon carbide substrate. The specific flowchart is as Figure 1 shown, and the specific process is as follows:

[0050] S101: Passivate the silicon carbide substrate through a plasma processing device;

[0051] S102: Perform high-temperature annealing on the passivated silicon carbide substrate using an annealing furnace;

[0052] S103: Grow an oxide layer on the surface of the silicon carbide substrate after high-temperature annealing.

[0053] In the embodiment of the present invention, the silicon carbide substrate to be treated is an N-type silicon carbide substrate or a P-type silicon carbide substrate; the ion doping concentration of the silicon carbide substrate is 1×10 13 ~10 21 cm -3 , and its thickness is 0.1 μm to 500 μm. In the embodiment of the present invention, the selected thickness of the silicon carbide substrate is 360 μm, and the silicon carbide substrate material is an n-type SiC epitaxial material with a doping concentration of 1×10 18 cm-3.

[0054] Passivating the silicon carbide substrate through plasma includes:

[0055] Clean the silicon carbide substrate using the RCA standard. The specific cleaning process is as follows:

[0056] (1) Prepare a hydrofluoric acid solution (HF:H2O = 1:10);

[0057] (2) Clean and dry the sample holder for later use;

[0058] (3) Place the above silicon carbide sample on the holder and arrange it in order;

[0059] (4) Prepare Solution 3 (sulfuric acid:H2O2 = 3:1), add sulfuric acid last, and boil water in another container at the same time;

[0060] (5) Boil and wash with Solution 3 for 15 min, heat to 250 °C, lift the holder and let it cool for a while;

[0061] (6) Place the holder in hot water and rinse;

[0062] (7) Prepare Solution 1 (ammonia:H2O2:H2O = 1:1:5 - 1:1:7), pour the first two into hot water, and heat to 75 - 85 °C,

[0063] Time: 10 - 20 min (removing heavy metal impurities by complexation), take out the sample holder, put it into Solution 1 for 15 min, take it out and put it into hot water, then rinse with water;

[0064] (8) Prepare Solution 2 (HCl:H₂O₂:H₂O = 1:1:5), pour the first two into hot water;

[0065] (9) Take out the silicon wafer, put it into Solution 2 for 15 min, take it out and put it into hot water, then rinse with water;

[0066] (10) 1% hydrofluoric acid for 5 - 120 s to remove the oxide layer on the surface of the above silicon carbide sample;

[0067] (11) Rinse with deionized water for 20 min, and the surface after ultrasonic treatment has hydroxyl groups.

[0068] Based on one or more of chalcogen gases, pnictogen gases, and pnictide gases, the silicon carbide substrate is passivated by using a plasma processing device. That is, any one of the chalcogen gas, pnictogen gas, and pnictide gas can be selected to passivate the silicon carbide substrate, or any two or three of the chalcogen gas, pnictogen gas, and pnictide gas can be used to passivate the silicon carbide substrate. When using two gases of chalcogen gas and pnictogen gas, first passivate the silicon carbide substrate based on the chalcogen gas, and then passivate the silicon carbide substrate based on the pnictogen gas; when using two gases of chalcogen gas and pnictide gas, first passivate the silicon carbide substrate based on the chalcogen gas, and then passivate the silicon carbide substrate based on the pnictide gas; when using two gases of pnictogen gas and pnictide gas, first passivate the silicon carbide substrate based on the pnictogen gas, and then passivate the silicon carbide substrate based on the pnictide gas; when using three gases of chalcogen gas, pnictogen gas, and pnictide gas, first passivate the silicon carbide substrate based on the chalcogen gas, then passivate the silicon carbide substrate based on the pnictogen gas, and finally passivate the silicon carbide substrate based on the pnictide gas.

[0069] Specifically, passivating the silicon carbide substrate by using a plasma processing device includes:

[0070] When using a chalcogen gas, put the silicon carbide substrate into the plasma processing device, and evacuate the plasma processing device. In the embodiment of the present invention, the vacuum degree of the plasma processing device after evacuation is 8 torr;

[0071] Adjust the internal temperature of the plasma processing equipment to 200°C - 400°C, then adjust the power of the plasma processing equipment to 10W - 1000W, and then introduce a chalcogen gas at a flow rate of 10 SCCM - 1000 SCCM and maintain for 1s - 5min. In the embodiment of the present invention, the internal temperature of the plasma processing equipment is adjusted to 250°C, the power of the plasma processing equipment is adjusted to 800W, and the flow rate of the introduced chalcogen gas is 500 SCCM;

[0072] Specifically, passivating the silicon carbide substrate through a plasma processing equipment includes:

[0073] When using a pnictogen gas, place the silicon carbide substrate in the plasma processing equipment and evacuate the plasma processing equipment. In the embodiment of the present invention, the vacuum degree of the plasma processing equipment after evacuation is 6 torr;

[0074] Adjust the internal temperature of the plasma processing equipment to 200°C - 400°C, then adjust the power of the plasma processing equipment to 10W - 1000W, and then introduce a pnictogen gas at a flow rate of 10 SCCM - 1000 SCCM and maintain for 1s - 5min. In the embodiment of the present invention, the internal temperature of the plasma processing equipment is adjusted to 250°C, the power of the plasma processing equipment is adjusted to 600W, and the flow rate of the introduced chalcogen gas is 1000 SCCM;

[0075] Specifically, passivating the silicon carbide substrate through a plasma processing equipment includes:

[0076] When using a phosphorous group gas, place the silicon carbide substrate in the plasma processing equipment and evacuate the plasma processing equipment. In the embodiment of the present invention, the vacuum degree of the plasma processing equipment after evacuation is 1 torr - 10 torr;

[0077] Adjust the internal temperature of the plasma processing equipment to 200°C - 400°C, then adjust the power of the plasma processing equipment to 10W - 1000W, and then introduce a phosphorous group gas at a flow rate of 10 SCCM - 2000 SCCM and maintain for 1s - 5min. In the embodiment of the present invention, the internal temperature of the plasma processing equipment is adjusted to 250°C, the power of the plasma processing equipment is adjusted to 700W, and the flow rate of the introduced chalcogen gas is 1500 SCCM;

[0078] The chalcogen gas includes O2 and / or O3; the pnictogen gas includes one or more of N2O, NO, NH3, and N2; the phosphorous group gas includes one or more of PH3, POCl3, TBP, and TMP.

[0079] Perform high-temperature annealing on the passivated silicon carbide substrate using an annealing furnace, including:

[0080] Place the passivated silicon carbide substrate into an annealing furnace, and evacuate the annealing furnace to a vacuum of 1 torr - 30 torr. In the embodiment of the present invention, the vacuum degree of the annealing furnace after evacuation is 15 torr;

[0081] Raise the internal temperature of the annealing furnace to 800°C - 1000°C at a heating rate of 10°C / min - 200°C / min, and then introduce H2 at a flow rate of 5 SCCM - 60 SCCM for 2 min - 20 min. In the embodiment of the present invention, the internal temperature of the annealing furnace is raised to 850°C, the flow rate of H2 introduced is 40 SCCM, and the introduction time of H2 is 10 min;

[0082] While introducing H2, continue to introduce HCl at a flow rate of 20 SCCM - 200 SCCM for 0.5 min - 5 min. When the introduction time of HCl gas is 0.5 min, the corresponding total introduction time of H2 is 2 min. When the introduction time of HCl gas is 5 min, the corresponding total introduction time of H2 is 20 min. In the embodiment of the present invention, the flow rate of HCl gas introduced is 30 SCCM, and the introduction time of HCl gas is 3 min.

[0083] Finally, lower the internal temperature of the annealing furnace to room temperature.

[0084] Grow an oxide layer on the surface of the silicon carbide substrate after high-temperature annealing, specifically as follows:

[0085] 1. Grow an oxide layer on the surface of the silicon carbide substrate through a dry oxidation process, including:

[0086] Place the silicon carbide substrate into an oxidation furnace, and raise the internal temperature of the oxidation furnace to 900°C - 1200°C at a heating rate of 10°C / min - 200°C / min, and introduce O2, NO, and / or N2O at a flow rate of 1 SLM - 10 SLM. In the embodiment of the present invention, select a heating rate of 20°C / min to raise the internal temperature of the oxidation furnace to 1000°C, and the gas introduced is N2O;

[0087] Raise the internal temperature of the oxidation furnace to 1200°C - 1500°C at a heating rate of 10°C / min - 200°C / min, maintain for 1 min - 5 h, and then stop introducing O2, NO, and / or N2O to obtain an oxide layer. In the embodiment of the present invention, raise the internal temperature of the oxidation furnace to 1300°C at a heating rate of 50°C / min, and the thickness of the obtained oxide layer is 20 nm.

[0088] 2. Grow an oxide layer on the surface of the silicon carbide substrate through a wet oxidation process, including:

[0089] Place the silicon carbide substrate in an oxidation furnace, and increase the internal temperature of the oxidation furnace from room temperature to 900°C - 1200°C at a heating rate of 10°C / min - 200°C / min, and introduce H2 and O2 at a flow rate of 1SLM - 10SLM;

[0090] Increase the internal temperature of the oxidation furnace from room temperature to 1200°C - 1500°C at a heating rate of 10°C / min - 200°C / min, maintain for 1min - 5h, and then stop introducing H2 and O2 to obtain an oxide layer.

[0091] 3. Grow an oxide layer on the surface of the silicon carbide substrate through dry oxidation process and wet oxidation process, including:

[0092] Place the silicon carbide substrate in an oxidation furnace, and increase the internal temperature of the oxidation furnace from room temperature to 900°C - 1200°C at a heating rate of 10°C / min - 200°C / min, and introduce O2, NO, and / or N2O at a flow rate of 1SLM - 10SLM; In the embodiments of the present invention, the heating rate of 20°C / min is selected to increase the internal temperature of the oxidation furnace to 1000°C, and the gas introduced is N2O;

[0093] Increase the internal temperature of the oxidation furnace from room temperature to 1200°C - 1500°C at a heating rate of 10°C / min - 200°C / min, maintain for 1min - 5h, and stop introducing O2, NO, and / or N2O;

[0094] Maintain the internal temperature of the oxidation furnace (i.e., keep the internal temperature of the oxidation furnace at 1200°C - 1500°C), introduce H2 and O2 at a flow rate of 1SLM - 10SLM, maintain for 1min - 5h, and then stop introducing H2 and O2 to obtain an oxide layer with a thickness of 2nm - 50nm. In the embodiments of the present invention, the heating rate of 50°C / min is selected to increase the internal temperature of the oxidation furnace to 1300°C, and the thickness of the obtained oxide layer is 20nm.

[0095] For the convenience of description, each part of the above device is described separately as various modules or units according to its function. Of course, when implementing the present application, the functions of each module or unit can be realized in the same or multiple software or hardware.

[0096] Those skilled in the art should understand that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0097] This application is described with reference to the flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processors of general-purpose computers, special-purpose computers, embedded processors, or other programmable data processing devices to generate a machine, such that the instructions executed by the processors of the computer or other programmable data processing devices generate means for implementing the functions specified in the Figure 1 one or more flows and / or blocks Figure 1 one or more blocks.

[0098] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including instruction means that implement the functions specified in the Figure 1 one or more flows and / or blocks Figure 1 one or more blocks.

[0099] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in the Figure 1 one or more flows and / or blocks Figure 1 one or more blocks.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Those of ordinary skill in the art can still modify or equivalently replace the specific implementation manners of the present invention with reference to the above embodiments. Any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention are within the protection scope of the present invention pending approval of the application.

Claims

1. A processing method for a silicon carbide substrate, characterized in that, Including: Passivating the silicon carbide substrate through a plasma processing device; Performing high-temperature annealing on the passivated silicon carbide substrate using an annealing furnace; Growing an oxide layer on the surface of the silicon carbide substrate after high-temperature annealing; Cleaning the silicon carbide substrate using the RCA standard; Based on one or more of chalcogen gases, pnictogen gases, and pnictide gases, passivating the silicon carbide substrate using a plasma processing device; When using three gases of chalcogen gas, pnictogen gas, and pnictide gas, first passivate the silicon carbide substrate based on the chalcogen gas, then passivate the silicon carbide substrate based on the pnictogen gas, and finally passivate the silicon carbide substrate based on the pnictide gas; The passivation of the silicon carbide substrate through the plasma processing device includes: When using a chalcogen gas, place the silicon carbide substrate in the plasma processing device and evacuate the plasma processing device; adjust the internal temperature of the plasma processing device to 200°C - 400°C, then adjust the power of the plasma processing device to 10W - 1000W, and then introduce the chalcogen gas at a flow rate of 10 SCCM - 1000 SCCM and maintain for 1s - 5min; The passivation of the silicon carbide substrate through the plasma processing device includes: When using a pnictogen gas, place the silicon carbide substrate in the plasma processing device and evacuate the plasma processing device; adjust the internal temperature of the plasma processing device to 200°C - 400°C, then adjust the power of the plasma processing device to 10W - 1000W, and then introduce the pnictogen gas at a flow rate of 10 SCCM - 1000 SCCM and maintain for 1s - 5min; The passivation of the silicon carbide substrate through the plasma processing device includes: When using a pnictide gas, place the silicon carbide substrate in the plasma processing device and evacuate the plasma processing device; adjust the internal temperature of the plasma processing device to 200°C - 400°C, then adjust the power of the plasma processing device to 10W - 1000W, and then introduce the pnictide gas at a flow rate of 10 SCCM - 2000 SCCM and maintain for 1s - 5min; The high-temperature annealing of the passivated silicon carbide substrate using the annealing furnace includes: Place the passivated silicon carbide substrate in the annealing furnace and evacuate the annealing furnace to 1 torr - 30 torr; Raise the internal temperature of the annealing furnace to 800°C - 1000°C at a heating rate of 10°C / min - 200°C / min, and then introduce H2 at a flow rate of 5 SCCM - 60 SCCM and maintain for 2min - 20min; While introducing H2, continue to introduce HCl at a flow rate of 20 SCCM - 200 SCCM and maintain for 0.5min - 5min; Lower the internal temperature of the annealing furnace to room temperature; Put the silicon carbide substrate after high-temperature annealing into an oxidation furnace, and raise the internal temperature of the oxidation furnace to 900°C - 1200°C at a heating rate of 10°C / min - 200°C / min, and introduce O2, NO, and / or N2O at a flow rate of 1 SLM - 10 SLM; Raise the internal temperature of the oxidation furnace to 1200°C - 1500°C at a heating rate of 10°C / min - 200°C / min, maintain for 1 min - 5 h, and stop introducing O2, NO, and / or N2O; Maintain the internal temperature of the oxidation furnace, introduce H2 and O2 at a flow rate of 1 SLM - 10 SLM, maintain for 1 min - 5 h, and then stop introducing H2 and O2 to obtain an oxide layer; Raise the internal temperature of the oxidation furnace to 1300°C at a heating rate of 50°C / min, and the thickness of the obtained oxide layer is 20 nm.

2. The processing method of the silicon carbide substrate according to claim 1, wherein, Growing an oxide layer on the surface of the silicon carbide substrate after high-temperature annealing includes: Put the silicon carbide substrate after high-temperature annealing into an oxidation furnace, and raise the internal temperature of the oxidation furnace to 900°C - 1200°C at a heating rate of 10°C / min - 200°C / min, and introduce O2, NO, and / or N2O at a flow rate of 1 SLM - 10 SLM; Raise the internal temperature of the oxidation furnace to 1200°C - 1500°C at a heating rate of 10°C / min - 200°C / min, maintain for 1 min - 5 h, and then stop introducing O2, NO, and / or N2O to obtain an oxide layer.

3. The processing method of the silicon carbide substrate according to claim 1, wherein Growing an oxide layer on the surface of the silicon carbide substrate after high-temperature annealing includes: Put the silicon carbide substrate after high-temperature annealing into an oxidation furnace, and raise the internal temperature of the oxidation furnace to 900°C - 1200°C at a heating rate of 10°C / min - 200°C / min, and introduce H2 and O2 at a flow rate of 1 SLM - 10 SLM; Raise the internal temperature of the oxidation furnace to 1200°C - 1500°C at a heating rate of 10°C / min - 200°C / min, maintain for 1 min - 5 h, and then stop introducing H2 and O2 to obtain an oxide layer.

4. The processing method of the silicon carbide substrate according to claim 1, characterized in that, The chalcogen gas includes O2 and / or O3; The nitrogen group gas includes one or more of N2O, NO, NH3, and N2; The phosphorus group gas includes one or more of PH3, POCl3, TBP, and TMP.

5. The processing method of the silicon carbide substrate according to claim 1, characterized in that, The silicon carbide substrate is an N-type silicon carbide substrate or a P-type silicon carbide substrate; The ion doping concentration of the silicon carbide substrate is 1×10 13 ~10 21 cm -3 , and its thickness is 0.1 μm to 500 μm.

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