N-type 4H silicon carbide single crystal growth equipment and growth method thereof

Abstract

The invention relates to the technical field of silicon carbide single crystal growth, in particular to n-type 4H silicon carbide single crystal growth equipment and a growth method thereof.The growth equipment comprises an equipment frame platform, an operation platform, a power system, a control system, an elevator assembly and a vacuum cavity assembly; the operating platform, the power system and the control system are all arranged on one side of the equipment frame platform, the vacuum cavity assembly is arranged on the equipment frame platform, the elevator assembly corresponding to the vacuum cavity assembly is arranged on the equipment frame platform, and the power system and the control system are both electrically connected with the vacuum cavity assembly. The vacuum furnace further comprises a gas circuit panel assembly, a circulating cooling water supply system, a vacuum detection device and a temperature field lifting and rotating assembly. The vacuum cavity assembly comprises a vacuum chamber, a vacuum furnace cover, a low vacuum pumping device, a high vacuum pumping device, an infrared thermometer and a deflation valve. The wafer size of the silicon carbide single crystal material can be continuously increased, and the defect density is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of silicon carbide single crystal growth, and in particular to n-type 4H silicon carbide single crystal growth equipment and a growth method thereof. Background Art

[0002] Modern electronic systems or equipment have an increasing demand for power electronic devices, requiring not only higher power density and higher energy efficiency, but also high extreme characteristics and resistance to harsh environments. Silicon carbide power electronic devices have excellent characteristics that surpass those of single-crystal silicon devices, and can meet the new needs of the new infrastructure of 5G information technology, solve the huge energy consumption bottleneck faced by information infrastructure such as data centers and wireless base stations, and support IT mobile smart terminals to achieve miniaturization, lightweight, and improve endurance, and support the urgent needs of industrial development in new infrastructure advantage application fields such as new energy vehicles, smart energy, rail transportation, and smart manufacturing.

[0003] Semiconductor materials and equipment are the core foundation of information technology. One generation of materials, one generation of equipment, one generation of technology, one generation of industry. In terms of the cost of silicon carbide devices, due to the difficulty of material preparation process, low yield and expensive equipment, the substrate accounts for up to 50% of the device price. High-quality, large-size silicon carbide single crystal materials are the first problem to be solved in the development of silicon carbide technology. Continuously increasing the wafer size and reducing the defect density (micropipes, dislocations, stacking faults, etc.) are its key development directions. Summary of the invention

[0004] In order to solve the problems in the background technology, the present invention proposes an n-type 4H silicon carbide single crystal growth equipment and a growth method thereof. The present invention can continuously increase the wafer size of the silicon carbide single crystal material and reduce the defect density.

[0005] To solve the above problems, the present invention adopts the following technical solution: an n-type 4H silicon carbide single crystal growth equipment, including an equipment frame platform, an operating platform, a power system, a control system, a hoist assembly and a vacuum chamber assembly, wherein the operating platform, the power system and the control system are all arranged on one side of the equipment frame platform, the vacuum chamber assembly is arranged on the equipment frame platform, the hoist assembly is arranged on the equipment frame platform corresponding to the vacuum chamber assembly, the power system and the control system are both electrically connected to the vacuum chamber assembly, and further comprising:

[0006] An air circuit panel assembly, the air circuit panel assembly being arranged outside the vacuum chamber assembly and used for filling the vacuum chamber assembly with an inert gas;

[0007] A circulating cooling water supply system, which is arranged on the equipment frame platform and is used to cool the power system, the hoist assembly and the vacuum chamber assembly;

[0008] A vacuum detection device, the vacuum detection device comprising a detection pipeline, a Pirani vacuum gauge and an ionization gauge vacuum gauge, the detection pipeline is connected and arranged on the vacuum chamber assembly, and the Pirani vacuum gauge and the ionization gauge vacuum gauge are installed on the detection pipeline;

[0009] The vacuum chamber assembly comprises a vacuum chamber, a vacuum furnace cover, a low vacuum device, a high vacuum device, an infrared thermometer and a venting valve. The vacuum furnace cover is arranged on the top of the vacuum chamber. The lifting machine assembly is connected with the vacuum furnace cover. An induction heater for providing heating is arranged in the vacuum chamber. The infrared thermometer is arranged on the vacuum furnace cover and is used to measure the temperature in the vacuum chamber. The low vacuum device and the high vacuum device are respectively arranged on the outer wall of the vacuum chamber and communicated with the vacuum chamber. The venting valve is arranged on the outer side wall of the vacuum chamber.

[0010] A temperature field lifting and rotating assembly is arranged in the vacuum chamber and is used to rotate and lift a graphite crucible placed in the vacuum chamber, wherein the graphite crucible is used to store silicon carbide raw materials.

[0011] Furthermore, the low vacuum device includes a rotary vane vacuum pump, a vacuum exhaust pipe, a high vacuum pneumatic angle valve and a pressure control butterfly valve. The outer side of the vacuum chamber is connected to the vacuum exhaust pipe, the inner end of the vacuum exhaust pipe extends into the vacuum chamber, the outer end of the vacuum exhaust pipe is connected to the rotary vane vacuum pump, the high vacuum pneumatic angle valve is arranged on the vacuum exhaust pipe, and the pressure control butterfly valve is arranged on the vacuum exhaust pipe between the high vacuum pneumatic angle valve and the vacuum chamber.

[0012] Furthermore, the high vacuum device includes a molecular pump, a vacuum right-angle elbow and an ultra-high vacuum plug valve, the inner end of the vacuum right-angle elbow is connected to the vacuum chamber, the outer end of the vacuum right-angle elbow is connected to the molecular pump, and the ultra-high vacuum plug valve is arranged on the vacuum right-angle elbow.

[0013] Furthermore, the air path panel assembly includes multiple groups of air intake structures arranged in parallel, and the multiple groups of air intake structures each include a gas filter, a diaphragm valve, a gas mass flow meter and a one-way valve arranged in sequence. The air inlet end of the gas filter is used to fill with inert gas, and the air outlet end of the one-way valve is used to connect to the vacuum chamber.

[0014] Furthermore, the circulating cooling water supply system includes an inlet pipe assembly and a return pipe assembly, the inlet pipe assembly is circulated with the return pipe assembly, the inlet pipe assembly and the return pipe assembly both include a water flow pipeline and a water pressure gauge, a plurality of ball valves, a plurality of water flow meters and a plurality of water temperature sensors arranged on the water flow pipeline, and the plurality of ball valves are connected one-to-one with the power supply system, the hoist assembly and the vacuum chamber assembly.

[0015] Furthermore, the control system is a PLC programmed automatic control, and an alarm for water, electricity and gas outages is provided in the control system.

[0016] Furthermore, the vacuum furnace cover is provided with a sapphire glass window for observing the reaction inside the vacuum chamber.

[0017] Furthermore, a method for growing an n-type 4H silicon carbide crystal is provided, using the above-mentioned n-type 4H silicon carbide single crystal growth equipment, the method comprising the following steps:

[0018] Step 1: Put the silicon carbide raw material into a graphite crucible, put the graphite crucible into a vacuum chamber and close the vacuum furnace cover;

[0019] Step 2: Turn on the vacuum pumping device to pump a low vacuum into the vacuum chamber;

[0020] Step 3: When the vacuum inside the vacuum chamber is less than 5×10-4Pa, the high vacuum device is turned on; when the vacuum inside the vacuum chamber is less than 5×10-4Pa, the high vacuum device is turned off;

[0021] Step 4: Inert gas is filled into the vacuum chamber through the gas path panel assembly and the induction heater is turned on for heating. The flow rate is 5 liters / minute and the pressure is controlled to be 50000Pa. The temperature is raised to 2050°C after 3 hours, and then the temperature is kept constant for 4 hours. After 8 hours, the pressure is reduced from 50000Pa to 600Pa.

[0022] Step 5: Heating at a constant temperature for 120 hours, starting the temperature field lifting and rotating assembly to rotate and lift the graphite crucible, the rotation speed is 0.5 rpm, the pulling speed is 0.15 mm / h, and the pressure in the vacuum chamber is controlled to be constant at 600 Pa and the temperature is constant at 2200°C;

[0023] Step 6: After the crystal growth is completed, inert gas is filled into the vacuum chamber to increase the pressure in the vacuum chamber to 60000Pa, with a flow rate of 5 liters / minute;

[0024] Step 7: After cooling for 12 hours, open the vent valve, open the vacuum furnace cover through the lifting machine assembly and take out the graphite crucible.

[0025] Furthermore, the inert gas filled in step 4 is nitrogen or argon, and the inert gas filled in step 6 is argon.

[0026] Furthermore, the temperature inside the vacuum chamber measured in step 4 is obtained by measuring the power of the power supply system in cooperation with the infrared thermometer.

[0027] Beneficial effects of the present invention: The present invention realizes low vacuum and high vacuum of the vacuum chamber by superimposing the low vacuum pumping device and the high vacuum pumping device, and respectively measures the low vacuum and high vacuum by using the Pirani vacuum gauge and the ionization gauge vacuum gauge and accurately controls the pressure in the vacuum chamber, and sets a circulating cooling water supply system to cool the vacuum chamber assembly, the power supply system and various parts of the elevator assembly to ensure the normal operation of the equipment, and accurately measures the temperature in the vacuum chamber by using an infrared thermometer in combination with the power of the power supply system. Compared with the traditional silicon carbide growth device, the present invention realizes the precise control of the temperature, pressure and cooling and heat dissipation in the vacuum chamber, so that the crystal growth process is more stable, and the wafer size of the silicon carbide single crystal material can be continuously increased and the defect density can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0029] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0030] Figure 2 It is a structural schematic diagram of the vacuum chamber assembly;

[0031] Figure 3 It is a structural schematic diagram of the gas path panel assembly;

[0032] Figure 4 This is a structural diagram of the circulating cooling water supply system.

[0033] 1. Equipment frame platform; 2. Operating platform; 3. Power supply system; 4. Control system; 5. Hoist assembly; 6. Vacuum chamber assembly; 7. Gas path panel assembly; 8. Circulating cooling water supply system; 9. Vacuum detection device; 10. Detection pipeline; 11. Pirani vacuum gauge; 12. Vacuum chamber; 13. Vacuum furnace cover; 14. Low vacuum device; 15. High vacuum device; 16. Infrared thermometer; 17. Air release valve; 18. , rotary vane vacuum pump; 19. Vacuum exhaust pipeline; 20. High vacuum pneumatic angle valve; 21. Pressure control butterfly valve; 22. Molecular pump; 23. Vacuum right-angle elbow; 24. Ultra-high vacuum plug valve; 25. Gas filter; 26. Diaphragm valve; 27. Gas mass flow meter; 28. Check valve; 29. ​​Water flow pipeline; 30. Water pressure gauge; 31. Ball valve; 32. Water flow meter; 33. Water temperature sensor; 34. Sapphire glass window. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] The present invention realizes low vacuum and high vacuum of the vacuum chamber 12 by superimposing the low vacuum pumping device 14 and the high vacuum pumping device 15, and respectively measures the low vacuum and high vacuum by the Pirani vacuum gauge 11 and the ionization gauge vacuum gauge and accurately controls the pressure in the vacuum chamber 12, and sets a circulating cooling water supply system 8 to cool the vacuum chamber assembly 6, the power supply system 3 and the various parts of the elevator assembly 5 to ensure the normal operation of the equipment, and accurately measures the temperature in the vacuum chamber 12 by the infrared thermometer 16 in coordination with the power of the power supply system 3. Compared with the traditional silicon carbide growth device, the present invention realizes the precise control of the temperature, pressure and cooling and heat dissipation in the vacuum chamber 12, so that the crystal growth process is more stable, and the wafer size of the silicon carbide single crystal material can be continuously increased and the defect density can be reduced.

[0036] Specifically, Figures 1 to 4 As shown, an n-type 4H silicon carbide single crystal growth equipment includes an equipment frame platform 1, an operating platform 2, a power system 3, a control system 4, a hoist assembly 5 and a vacuum chamber assembly 6, wherein the operating platform 2, the power system 3 and the control system 4 are all arranged on one side of the equipment frame platform 1, the vacuum chamber assembly 6 is arranged on the equipment frame platform 1, the hoist assembly 5 is arranged on the equipment frame platform 1 corresponding to the vacuum chamber assembly 6, the power system 3 and the control system 4 are both electrically connected to the vacuum chamber assembly 6, and further includes:

[0037] An air circuit panel assembly 7, wherein the air circuit panel assembly 7 is arranged outside the vacuum chamber assembly 6 and is used to fill the vacuum chamber assembly 6 with an inert gas;

[0038] A circulating cooling water supply system 8, which is arranged on the equipment frame platform 1 and is used to cool the power system 3, the hoist assembly 5 and the vacuum chamber assembly 6;

[0039] A vacuum detection device 9, the vacuum detection device 9 comprises a detection pipeline 10, a Pirani vacuum gauge 11 and an ionization gauge vacuum gauge, the detection pipeline 10 is connected to the vacuum chamber assembly 6, and the Pirani vacuum gauge 11 and the ionization gauge vacuum gauge are installed on the detection pipeline 10;

[0040] The vacuum chamber assembly 6 includes a vacuum chamber 12, a vacuum furnace cover 13, a low vacuum device 14, a high vacuum device 15, an infrared thermometer 16 and a venting valve 17. The vacuum furnace cover 13 is arranged on the top of the vacuum chamber 12. The lifting machine assembly 5 is connected with the vacuum furnace cover 13. An induction heater for providing heating is arranged in the vacuum chamber 12. The infrared thermometer 16 is arranged on the vacuum furnace cover 13 and is used to measure the temperature in the vacuum chamber 12. The low vacuum device 14 and the high vacuum device 15 are respectively arranged on the outer wall of the vacuum chamber 12 and communicated with the vacuum chamber 12. The venting valve 17 is arranged on the outer wall of the vacuum chamber 12.

[0041] A temperature field lifting and rotating assembly is provided in the vacuum chamber 12 and is used to rotate and lift a graphite crucible placed in the vacuum chamber 12, wherein the graphite crucible is used to store silicon carbide raw materials.

[0042] Furthermore, the low vacuum device 14 includes a rotary vane vacuum pump 18, a vacuum exhaust pipe 19, a high vacuum pneumatic angle valve 20 and a pressure control butterfly valve 21. The outer side of the vacuum chamber 12 is connected to the vacuum exhaust pipe 19, the inner end of the vacuum exhaust pipe 19 extends into the vacuum chamber 12, the outer end of the vacuum exhaust pipe 19 is connected to the rotary vane vacuum pump 18, the high vacuum pneumatic angle valve 20 is arranged on the vacuum exhaust pipe 19, and the pressure control butterfly valve 21 is arranged on the vacuum exhaust pipe 19 between the high vacuum pneumatic angle valve 20 and the vacuum chamber 12.

[0043] Furthermore, the high vacuum device 15 includes a molecular pump 22, a vacuum right-angle elbow 23 and an ultra-high vacuum plug valve 24, the inner end of the vacuum right-angle elbow 23 is connected to the vacuum chamber 12, the outer end of the vacuum right-angle elbow 23 is connected to the molecular pump 22, and the ultra-high vacuum plug valve 24 is arranged on the vacuum right-angle elbow 23.

[0044] Furthermore, the air path panel assembly 7 includes multiple groups of air intake structures arranged in parallel, and the multiple groups of air intake structures each include a gas filter 25, a diaphragm valve 26, a gas mass flow meter 27 and a one-way valve 28 that are arranged in sequence. The air inlet end of the gas filter 25 is used to fill with inert gas, and the air outlet end of the one-way valve 28 is used to connect to the vacuum chamber 12.

[0045] Furthermore, the circulating cooling water supply system 8 includes an inlet pipe assembly and a return pipe assembly, the inlet pipe assembly is cyclically connected to the return pipe assembly, and the inlet pipe assembly and the return pipe assembly both include a water flow pipeline 29 and a water pressure gauge 30, a plurality of ball valves 31, a plurality of water flow meters 32 and a plurality of water temperature sensors 33 arranged on the water flow pipeline 29, and the plurality of ball valves 31 are connected one by one to the power supply system 3, the hoist assembly 5 and the vacuum chamber assembly 6.

[0046] Furthermore, the control system 4 is a PLC programmed automatic control, and an alarm for water, electricity and gas outages is provided in the control system 4.

[0047] Furthermore, a sapphire glass window 34 for observing the reaction inside the vacuum chamber 12 is provided on the vacuum furnace cover 13 .

[0048] Furthermore, a method for growing an n-type 4H silicon carbide crystal is provided, using the above-mentioned n-type 4H silicon carbide single crystal growth equipment, the method comprising the following steps:

[0049] Step 1: Put the silicon carbide raw material into a graphite crucible, put the graphite crucible into the vacuum chamber 12 and close the vacuum furnace cover 13;

[0050] Step 2: Open the vacuum pumping device 14 to pump a low vacuum into the vacuum chamber 12;

[0051] Step 3: When the vacuum inside the vacuum chamber 12 is less than 5×100Pa, the high vacuum device 15 is turned on; when the vacuum inside the vacuum chamber 12 is less than 5×10-4Pa, the high vacuum device 15 is turned off;

[0052] Step 4: Inert gas is filled into the vacuum chamber 12 through the gas path panel assembly 7 and the induction heater is turned on for heating. The flow rate is 5 liters / minute and the pressure is controlled to be 50000Pa. The temperature is raised to 2050°C after 3 hours, and then the temperature is kept constant for 4 hours. After 8 hours, the pressure is reduced from 50000Pa to 600Pa.

[0053] Step 5: Heating at a constant temperature for 120 hours, starting the temperature field lifting and rotating assembly to rotate and lift the graphite crucible, the rotation speed is 0.5 rpm, the pulling speed is 0.15 mm / h, and the pressure in the vacuum chamber 12 is controlled to be constant at 600 Pa and the temperature is constant at 2200°C;

[0054] Step 6: After the crystal growth is completed, inert gas is filled into the vacuum chamber 12 to increase the pressure in the vacuum chamber 12 to 60000Pa, with a flow rate of 5 liters / minute;

[0055] Step 7: After cooling for 12 hours, open the vent valve 17, open the vacuum furnace cover 13 through the elevator assembly 5 and take out the graphite crucible.

[0056] Furthermore, the inert gas filled in step 4 is nitrogen or argon, and the inert gas filled in step 6 is argon.

[0057] Furthermore, the temperature in the vacuum chamber 12 measured in step 4 is obtained by measuring the power of the power supply system 3 in cooperation with the infrared thermometer 16 .

[0058] When the present invention is in use, the low vacuum and high vacuum of the vacuum chamber 12 are realized by superimposing the low vacuum device 14 and the high vacuum device 15, and the low vacuum and high vacuum are measured respectively by the Pirani vacuum gauge 11 and the ionization gauge vacuum gauge to accurately control the pressure in the vacuum chamber 12, and the circulating cooling water supply system 8 is set to cool the vacuum chamber assembly 6, the power system 3 and the various parts of the elevator assembly 5 to ensure the normal operation of the equipment, and the temperature in the vacuum chamber 12 is accurately measured by the infrared thermometer 16 in conjunction with the power of the power system 3. The present invention realizes the precise control of the temperature, pressure and cooling and heat dissipation in the vacuum chamber 12, making the crystal growth process more stable, and can continuously increase the wafer size of the silicon carbide single crystal material and reduce the defect density.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An n-type 4H silicon carbide single crystal growth equipment, comprising an equipment frame platform (1), an operating platform (2), a power system (3), a control system (4), a hoist assembly (5) and a vacuum chamber assembly (6), wherein the operating platform (2), the power system (3) and the control system (4) are all arranged on one side of the equipment frame platform (1), the vacuum chamber assembly (6) is arranged on the equipment frame platform (1), the hoist assembly (5) is arranged on the equipment frame platform (1) corresponding to the vacuum chamber assembly (6), the power system (3) and the control system (4) are both electrically connected to the vacuum chamber assembly (6), and characterized in that: Also includes: An air path panel assembly (7), wherein the air path panel assembly (7) is arranged outside the vacuum chamber assembly (6) and is used to fill the vacuum chamber assembly (6) with an inert gas; a circulating cooling water supply system (8), the circulating cooling water supply system (8) being arranged on the equipment frame platform (1) and being used for cooling the power supply system (3), the hoist assembly (5) and the vacuum chamber assembly (6); A vacuum detection device (9), the vacuum detection device (9) comprising a detection pipeline (10), a Pirani vacuum gauge (11) and an ionization gauge vacuum gauge, the detection pipeline (10) being connected to the vacuum chamber assembly (6), and the Pirani vacuum gauge (11) and the ionization gauge vacuum gauge being installed on the detection pipeline (10); The vacuum chamber assembly (6) comprises a vacuum chamber (12), a vacuum furnace cover (13), a low vacuum device (14), a high vacuum device (15), an infrared thermometer (16) and a venting valve (17); the vacuum furnace cover (13) is arranged on the top of the vacuum chamber (12); the lifting machine assembly (5) is connected to the vacuum furnace cover (13); an induction heater for providing heating is arranged in the vacuum chamber (12); the infrared thermometer (16) is arranged on the vacuum furnace cover (13) and is used to measure the temperature in the vacuum chamber (12); the low vacuum device (14) and the high vacuum device (15) are respectively arranged on the outer wall of the vacuum chamber (12) and are in communication with the vacuum chamber (12); the venting valve (17) is arranged on the outer wall of the vacuum chamber (12); A temperature field lifting and rotating assembly is provided in the vacuum chamber (12) and is used to rotate and lift a graphite crucible placed in the vacuum chamber (12), wherein silicon carbide raw materials are stored in the graphite crucible.

2. The n-type 4H silicon carbide single crystal growth equipment according to claim 1, characterized in that: The low vacuum device (14) comprises a rotary vane vacuum pump (18), a vacuum exhaust pipe (19), a high vacuum pneumatic angle valve (20) and a pressure control butterfly valve (21); the outer side of the vacuum chamber (12) is connected to the vacuum exhaust pipe (19); the inner end of the vacuum exhaust pipe (19) extends into the vacuum chamber (12); the outer end of the vacuum exhaust pipe (19) is connected to the rotary vane vacuum pump (18); the high vacuum pneumatic angle valve (20) is arranged on the vacuum exhaust pipe (19); and the pressure control butterfly valve (21) is arranged on the vacuum exhaust pipe (19) between the high vacuum pneumatic angle valve (20) and the vacuum chamber (12).

3. The n-type 4H silicon carbide single crystal growth equipment according to claim 1, characterized in that: The high vacuum device (15) comprises a molecular pump (22), a vacuum right-angle elbow (23) and an ultra-high vacuum plug valve (24); the inner end of the vacuum right-angle elbow (23) is connected to the vacuum chamber (12); the outer end of the vacuum right-angle elbow (23) is connected to the molecular pump (22); and the ultra-high vacuum plug valve (24) is arranged on the vacuum right-angle elbow (23).

4. The n-type 4H silicon carbide single crystal growth equipment according to claim 1, characterized in that: The gas path panel assembly (7) comprises a plurality of groups of air intake structures arranged in parallel, each of the plurality of groups of air intake structures comprises a gas filter (25), a diaphragm valve (26), a gas mass flow meter (27) and a one-way valve (28) arranged in sequence, the air intake end of the gas filter (25) being used for filling inert gas, and the air outlet end of the one-way valve (28) being used for connecting to the vacuum chamber (12).

5. The n-type 4H silicon carbide single crystal growth equipment according to claim 1, characterized in that: The circulating cooling water supply system (8) comprises a water inlet pipe assembly and a water return pipe assembly, wherein the water inlet pipe assembly is cyclically connected to the water return pipe assembly, and the water inlet pipe assembly and the water return pipe assembly both comprise a water flow pipeline (29) and a water pressure gauge (30), a plurality of ball valves (31), a plurality of water flow meters (32) and a plurality of water temperature sensors (33) arranged on the water flow pipeline (29), wherein the plurality of ball valves (31) are connected one by one to the power supply system (3), the hoist assembly (5) and the vacuum chamber assembly (6).

6. The n-type 4H silicon carbide single crystal growth equipment according to claim 1, characterized in that: The control system (4) is a PLC programmed automatic control, and an alarm for water, electricity and gas outages is provided in the control system (4).

7. The n-type 4H silicon carbide single crystal growth equipment according to claim 1, characterized in that: The vacuum furnace cover (13) is provided with a sapphire glass window (34) for observing the reaction inside the vacuum chamber (12).

8. A method for growing n-type 4H silicon carbide crystals, characterized in that: Using the n-type 4H silicon carbide single crystal growth equipment as described in any one of claims 1 to 7, the method comprises the following steps: Step 1: Place silicon carbide raw materials into a graphite crucible, place the graphite crucible into a vacuum chamber (12) and close the vacuum furnace cover (13); Step 2: Open the low vacuum device (14) to draw a low vacuum on the vacuum chamber (12); Step 3: When the vacuum inside the vacuum chamber (12) is less than 5×100 Pa, the high vacuum device (15) is turned on; when the vacuum inside the vacuum chamber (12) is less than 5×10-4 Pa, the high vacuum device (15) is turned off; Step 4: Inert gas is filled into the vacuum chamber (12) through the gas path panel assembly (7) and the induction heater is turned on for heating. The flow rate is 5 liters / minute and the pressure is controlled to be 50000Pa. The temperature is raised to 2050°C after 3 hours, and then the temperature is kept constant for 4 hours. After 8 hours, the pressure is reduced from 50000Pa to 600Pa. Step 5: heating at a constant temperature for 120 hours, starting the temperature field lifting and rotating assembly to rotate and lift the graphite crucible, the rotation speed is 0.5 rpm, the pulling speed is 0.15 mm / h, and the pressure in the vacuum chamber (12) is controlled to be constant at 600 Pa and the temperature is controlled to be constant at 2200° C.; Step 6: After the crystal growth is completed, an inert gas is filled into the vacuum chamber (12) to increase the pressure in the vacuum chamber (12) to 60,000 Pa, with a flow rate of 5 liters / minute; Step 7: After cooling for 12 hours, open the vent valve (17), open the vacuum furnace cover (13) through the elevator assembly (5) and take out the graphite crucible.

9. The method for growing n-type 4H silicon carbide crystal according to claim 8, characterized in that: The inert gas filled in step 4 is nitrogen or argon, and the inert gas filled in step 6 is argon.

10. The method for growing n-type 4H silicon carbide crystal according to claim 8, characterized in that: The temperature inside the vacuum chamber (12) measured in step 4 is obtained by measuring the power of the power supply system (3) in cooperation with the infrared thermometer (16).

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