A thermal field structure for growing silicon carbide of large diameter, a silicon carbide growing device and a growing method

Abstract

The present application relates to the technical field of silicon carbide growth, in particular to a thermal field structure for growing large-diameter silicon carbide, a silicon carbide growth device and a growth method. In the present application, the convexity of the silicon carbide single crystal is reduced by canceling the heat preservation center hole of the top heat preservation part of the heat preservation unit and reducing the thickness of the second side heat preservation section. In addition, the convexity of the silicon carbide single crystal is also reduced by adjusting the cooling water temperature and flow rate to adjust the thermal field.

Description

Technical Field

[0001] This invention relates to the field of silicon carbide growth technology, specifically to a thermal field structure, silicon carbide growth apparatus, and growth method for growing large-diameter silicon carbide. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Silicon carbide (SiC) is a third-generation semiconductor material with strong radiation resistance, high critical electric field and high saturation mobility. It has great advantages in the field of power devices and is widely used in new energy vehicles, photovoltaic power generation, railway transportation and power systems.

[0004] Currently, the most mature method for silicon carbide crystal growth is the physical vapor transport (PVT) method. Its principle involves using a specific temperature gradient to allow silicon carbide powder to sublimate and crystallize on the seed crystal surface in a sealed environment. Induction coil heating is the mainstream heating method due to its high heating efficiency and rapid heating rate. During silicon carbide growth, heat is transferred horizontally from the crucible wall into the crucible, while heat inside the crucible dissipates vertically through the crucible lid and the central insulation hole. This creates a convex temperature field within the crucible and crystal, especially for the growth of large-diameter silicon carbide single crystals. As the crucible diameter increases, the temperature field within the single crystal area becomes even more convex, leading to a rapid increase in thermal stress within the large-diameter crystal. When the thermal stress exceeds the material's fracture threshold, it directly causes single crystal cracking and wafer splitting, significantly impacting the yield of usable wafers. Simultaneously, excessive thermal stress within the crystal increases the applied shear stress σ acting on the crystal slip system. RS Exceeding the critical shear stress σ CRS The lattice undergoes slip plastic deformation, introducing a large number of dislocation defects, resulting in numerous structural defects in the single-crystal substrate, which severely affects the performance and reliability of SiC power devices. Therefore, for the growth of large-diameter, high-quality silicon carbide crystals, it is necessary to construct a near-flat, micro-convex temperature field structure.

[0005] Furthermore, different temperature gradients are required for different stages of silicon carbide crystal growth. In the early stage of crystal growth, a large radial temperature gradient needs to be constructed at the edge of the seed crystal to suppress polymorphic inclusions caused by edge polycrystalline nucleation, while achieving a certain degree of edge diameter expansion. When the crystal diameter expansion ends and the constant diameter growth stage begins, crystal growth needs to be carried out under a flat temperature field to reduce stress and improve crystal quality. After the crystal growth is completed, a small temperature gradient needs to be constructed for crystal annealing to eliminate stress in the crystal as much as possible. Summary of the Invention

[0006] To overcome the above problems, the present invention provides a thermal field structure, silicon carbide growth apparatus and growth method for growing large-diameter silicon carbide.

[0007] To achieve the above technical objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a thermal field structure for growing large-diameter silicon carbide, comprising a heat preservation unit, a crucible, a cooling unit, and a heating unit; The insulation unit includes a top insulation component, a side insulation component, and a bottom insulation component; the top insulation component, the side insulation component, and the bottom insulation component are sealed to form a cavity, and the crucible is located inside the cavity; The side insulation components are, from bottom to top, a first side insulation section and a second side insulation section. The height of the first side insulation section is the same as the height of the crucible, and the thickness of the second side insulation section is less than that of the first side insulation section. A cooling unit and a heating unit are arranged sequentially on the outside of the insulation unit.

[0008] In one or more embodiments, the diameter of silicon carbide is 8 to 12 inches.

[0009] In one or more embodiments, the top insulation component, the side insulation component, and the bottom insulation component are all made of graphite felt.

[0010] In one or more embodiments, the thickness of the top insulation component and the bottom insulation component is 30~60mm.

[0011] In one or more embodiments, the thickness of the first side insulation section is 30-60 mm, and the thickness of the second side insulation section is 15-30 mm.

[0012] In one or more embodiments, the cooling unit consists of two quartz tubes, which are arranged around the outer periphery of the side insulation component, with a spacing of 12 to 20 mm, preferably 16 mm. Preferably, the inlet of the quartz tube is connected to an inlet pipe, and the inlet pipe is sequentially equipped with a water temperature regulating switch, a water flow rate regulating switch, and a first water temperature monitoring meter. The outlet of the quartz tube is connected to an outlet pipe, and a second water temperature monitoring meter is installed on the outlet pipe. Preferably, the gap between the quartz tube and the side insulation component is 18~22 mm, more preferably 20 mm.

[0013] In one or more embodiments, the heating unit is an induction heating coil; the induction heating coil is arranged around the outer periphery of the cooling unit.

[0014] Preferably, the gap between the quartz tube and the induction heating coil is 8~12 mm, more preferably 10 mm.

[0015] A second aspect of the present invention provides a silicon carbide growth apparatus, comprising the thermal field structure for growing large-diameter silicon carbide as described in the first aspect.

[0016] A third aspect of the present invention provides a method for growing large-diameter silicon carbide, wherein the growth method employs the thermal field structure for growing large-diameter silicon carbide described in the first aspect.

[0017] In one or more embodiments, the growth method includes the following steps: (1) Place the silicon carbide raw material in the crucible and place the seed crystal at the top of the inner cavity of the crucible; (2) Seal the crucible in the thermal field structure for growing large-diameter silicon carbide, evacuate and introduce protective gas; (3) Turn on the heating unit to raise the temperature, and at the same time turn on the cooling unit to regulate the temperature.

[0018] Preferably, in the early stage of crystal growth, the heating power during the diameter expansion stage is set between 5 and 16 kW, the heating time is 15 to 24 h, the cooling water temperature is 35 to 40 °C, the water flow rate is 0.16 to 0.2 L / s, and the final heating temperature is above 2000 °C. During the constant diameter growth stage, the power is controlled between 15 and 17 kW during heat preservation, the cooling water temperature is 20 to 25℃, the water flow rate is 0.25 to 0.3 L / s, and the growth temperature is controlled between 2050 and 2200℃. After crystal growth is complete, the cooling water temperature is set to 45~55℃ and the water flow rate is 0.12~0.15 L / s.

[0019] The beneficial effects of this invention are as follows: (1) In this invention, the convexity of silicon carbide single crystal is reduced by adjusting the central hole of the top insulation component of the insulation unit and reducing the thickness of the second side insulation section. This is because: reducing the diameter of the central hole of the top insulation component of the insulation unit or eliminating the central hole can reduce the heat dissipation of the seed crystal center, reduce the temperature difference between the seed crystal edge and the seed crystal center, thereby reducing the radial temperature gradient of the temperature field and reducing the crystal convexity; however, eliminating the central hole will reduce the overall heat dissipation, thereby reducing the axial temperature gradient and reducing the crystal growth rate; therefore, by reducing the thickness of the second side insulation section, the heat dissipation is increased, the axial gradient is maintained, and the temperature of the seed crystal edge is reduced, further reducing the temperature difference between the seed crystal edge and the seed crystal center, reducing the radial temperature gradient, and the axial temperature gradient of the seed crystal edge is also relatively increased. The synergistic effect of the radial temperature gradient and the axial temperature gradient has a positive effect on the diameter expansion in the early stage of crystal growth and the reduction of the final crystal convexity.

[0020] (2) In addition, the thermal field is adjusted by adjusting the cooling water temperature and flow rate in this invention. In the early stage of crystal growth, the diameter needs to be expanded rapidly and stably to establish the macroscopic geometric shape of the single crystal. For this purpose, a relatively large radial temperature gradient is needed to drive the diameter expansion and suppress polycrystalline growth. A relatively high cooling water temperature is set so that the heat dissipation at the edge of the crucible is relatively slow, increasing the temperature difference between the seed crystal edge and the seed crystal center, thereby increasing the radial temperature gradient. This makes the gas components in the growth chamber transport to the seed crystal center faster, which can effectively promote the diameter expansion in the early stage of crystal growth. After the crystal diameter expansion is completed, the constant diameter growth stage begins. As the growth time increases, the material source is gradually consumed. Under the condition that the power remains unchanged, the temperature in the growth chamber gradually increases. At this time, the grown crystal gradually becomes thicker, and the leading edge surface gradually approaches the high temperature convex temperature field, which will increase the crystal convexity. The cooling water temperature is reduced by a cooling rate of 0~2℃ / 10 h, thereby adjusting the radial temperature gradient of the crystal surface, reducing the convexity, and also accelerating the heat dissipation in the crucible to maintain the temperature field in the crucible in a steady state. When in-situ annealing is carried out after crystal growth, the cooling water temperature is increased and the cooling water flow rate is decreased, thereby reducing the heat dissipation rate, reducing the radial and axial temperature gradients, and reducing the thermal stress generated during annealing. Attached Figure Description

[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0022] Figure 1 This is a schematic diagram of the thermal field structure for growing large-diameter silicon carbide, where 1-top insulation component, 2-side insulation component, 3-bottom insulation component, 4-first side insulation section, 5-second side insulation section, 6-quartz tube, 7-induction heating coil, 8-crucible, 9-silicon carbide crystal, 10-silicon carbide raw material. Figure 2 This is the thermal field structure for conventional silicon carbide production in Comparative Example 1; Figure 3 The thermal field structure for silicon carbide production is shown in Comparative Example 2, which is the first improvement of the structure. Figure 4 This is a thermal field distribution diagram of the thermal field structure for growing large-diameter silicon carbide in Example 1; Figure 5 This is a thermal field distribution diagram of the conventional silicon carbide production thermal field structure in Comparative Example 1; Figure 6 This is a thermal field distribution diagram of the first improved thermal field structure for silicon carbide production in Comparative Example 2. Figure 7 This is a photograph of an 8-inch crystal with low conductivity convexity obtained in Example 2; Figure 8This is a physical image of a 12-inch crystal with low conductivity convexity obtained in Example 3. Detailed Implementation

[0023] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0025] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0026] Example 1 Figure 1 This is a schematic diagram of the thermal field structure for growing large-diameter silicon carbide, for reference. Figure 1 A thermal field structure for growing large-diameter silicon carbide includes a heat preservation unit, a crucible 8, a cooling unit, and a heating unit. The insulation unit includes a top insulation component 1, a side insulation component 2, and a bottom insulation component 3; the top insulation component 1, the side insulation component 2, and the bottom insulation component 3 are sealed to form a cavity, and the crucible 8 is located inside the cavity; The side insulation component 2 consists of a first side insulation section 4 and a second side insulation section 5 from bottom to top. The height of the first side insulation section 4 is the same as the height of the crucible, and the thickness of the second side insulation section 5 is less than that of the first side insulation section 4. The top insulation component 1, the side insulation component 2, and the bottom insulation component 3 are all made of graphite felt.

[0027] The thickness of the top insulation component 1 and the bottom insulation component 2 is 40 mm.

[0028] The thickness of the first side insulation section 4 is 40 mm and the height is 290 mm, while the thickness of the second side insulation section 5 is 20 mm and the height is 60 mm. Sealing the top insulation component 1 of the insulation unit and eliminating the upper insulation center hole reduces heat dissipation from the seed crystal center, decreases the temperature difference between the seed crystal edge and the seed crystal center, and thus reduces the radial temperature gradient of the temperature field, reducing crystal convexity. However, eliminating the insulation center hole reduces overall heat dissipation, thereby reducing the axial temperature gradient and decreasing the crystal growth rate. Therefore, compared to Comparative Example 1, reducing the thickness of the second side insulation section 5 to 20 mm and increasing its height to 60 mm increases heat dissipation, maintains axial ladder stability, and simultaneously reduces the temperature at the seed crystal edge, further reducing the temperature difference between the seed crystal edge and the seed crystal center, decreasing the radial temperature gradient, and reducing crystal convexity.

[0029] A cooling unit and a heating unit are arranged sequentially on the outside of the insulation unit.

[0030] The cooling unit consists of two quartz tubes 6, which are arranged around the outer periphery of the side insulation component, with a spacing of 16 mm between the two tubes. The inlet of the quartz tube 3 is connected to an inlet pipe, on which a water temperature regulating switch, a water flow rate regulating switch, and a first water temperature monitoring meter are sequentially installed. The outlet of the quartz tube 3 is connected to an outlet pipe, on which a second water temperature monitoring meter is installed. Cooling water enters from the inlet at the bottom of the quartz tube and flows out through the outlet at the top. The flow rate and temperature of the cooling water at the inlet are adjusted to regulate the heat dissipation rate of the crucible sidewall. The inlet water temperature is observed in real time using the first water temperature monitoring meter, and the outlet water temperature is observed in real time using the second water temperature monitoring meter. Monitoring the outlet water temperature allows for the inference of temperature fluctuations within the growth chamber, thereby determining whether an abnormality has occurred in the temperature field within the growth chamber.

[0031] The gap between the quartz tube and the side insulation component is 20 mm.

[0032] The heating unit is an induction heating coil; the induction heating coil is wound around the outer periphery of the cooling unit. The gap between the quartz tube and the induction heating coil is 10 mm.

[0033] Comparative Example 1 Figure 2 The thermal field structure is a traditional one for silicon carbide production. Compared to Example 1, the central insulation hole of the top insulation component is retained, with a diameter of 40 mm. Meanwhile, the side insulation components have the same thickness of 40 mm, and the total height is 310 mm. There is no distinction between the first and second side insulation sections.

[0034] Comparative Example 2 Figure 3For the first improved thermal field structure in silicon carbide production, compared to Example 1, the central insulation hole of the top insulation component is retained, but its diameter is reduced to 20 mm. Meanwhile, the side insulation components are divided into a first side insulation section and a second side insulation section. Side insulation component 2 is the same as in Example 1; the thickness of side insulation component 5 is the same as in Example 1, and its height is 20 mm.

[0035] Figure 4 This is a thermal field distribution diagram of the thermal field structure for growing large-diameter silicon carbide in Example 1; Figure 5 This is a thermal field distribution diagram of the conventional silicon carbide production thermal field structure in Comparative Example 1; Figure 6 This is a thermal field distribution diagram of the first improved thermal field structure for silicon carbide production in Comparative Example 2. The radial temperature gradient in the simulated temperature field of the thermal field structure in Example 1 and Comparative Examples 1-2 during the initial growth stage is shown in Table 1.

[0036] Table 1 Radial temperature gradient during the initial growth stage in the simulated temperature field type <![CDATA[Seed crystal edge to center diameter gradient / °C·mm -1 > <![CDATA[Seed crystal edge and 20 mm diameter gradient below the center / °C·mm -1 > Traditional temperature field 0.23 0.16 First Improvement 0.096 0.091 Final Improvement 0.059 0.081 contrast Figure 5 and Figure 6 It can be seen that by reducing the diameter of the central insulation hole and thinning the thickness of the second side insulation section of the side insulation component, the temperature field lines in the growth chamber become gentler, and the isotherms in the growth chamber become looser, indicating a reduction in the temperature gradient. Furthermore, from the perspective of the grown crystal, the crystal convexity is significantly improved, effectively addressing the problem of high convexity in SiC single crystals grown under traditional temperature field conditions.

[0037] contrast Figures 4-6 It can be seen that removing the upper insulation center hole reduces heat dissipation from the crucible center while increasing the height of the middle insulation layer 5 by 40 mm and reducing its thickness by half. This enhances heat dissipation at the crucible edge, ensuring that the overall heat dissipation within the growth chamber remains essentially consistent with Comparative Example 2. Consequently, it reduces the radial temperature gradient difference between the seed crystal edge and the center, thereby reducing the convexity of the grown crystal. (Comparison) Figures 4-6 The isotherms inside the crystal growth chamber and the grown crystal show that... Figure 4 The isotherms in the model are relatively gentler, and the radial gradient decreases from the traditional thermal field to the final improved thermal field, as shown in Table 1, and this trend is still present 20 mm below the seed crystal; in contrast... Figures 4-6 Based on the crystal growth simulation results, from the traditional temperature field to the initial improvement and finally to the final improvement, the convexity of the crystal center has been decreasing, indicating that Example 1 has a greater advantage in reducing the convexity of the grown crystal during the actual crystal growth process.

[0038] Example 2 Silicon carbide with a diameter of 8 feet was produced using the thermal field structure for growing large-diameter silicon carbide shown in Example 1.

[0039] Specific steps: (1) Place the silicon carbide raw material in the crucible and place the seed crystal at the top of the inner cavity of the crucible, keeping the source crystal distance at 70 mm; (2) Seal the crucible in the thermal field structure for growing large-diameter silicon carbide and evacuate it (vacuum degree is 10). -4 Pa, maintained for 8 h) and argon gas was introduced as a protective gas; (3) Turn on the heating unit to raise the temperature, and at the same time turn on the cooling unit to regulate the temperature.

[0040] In step (3), the growth pressure inside the furnace is adjusted to 70 mbar and the temperature is raised. The initial stage of crystal growth includes the heating stage and the diameter expansion stage after reaching the maximum power. When heating, the heating power gradient is set to 5 kW, 8 kW, and 12 kW, with corresponding holding times of 5 h, 4 h, and 4 h. Finally, the temperature is raised to 15 kW to start diameter expansion growth, which takes about 15~20 h. The inlet cooling water temperature is set to about 35℃ and the water flow rate is about 0.18 L / s. During the constant diameter growth stage, the growth pressure inside the furnace is adjusted to 10 mbar, the power is kept constant at 15 kW, the temperature is between 2050 and 2070℃, the cooling water temperature is 25℃, and the water flow rate is about 0.28 L / s. As the growth time increases, the grown crystal gradually becomes thicker, and the leading edge surface gradually approaches the high temperature convex field, increasing the radial temperature gradient and thus increasing the crystal convexity. Therefore, during the growth process, the inlet cooling water temperature is reduced at a cooling rate of 0.2~0.5℃ / 10 h to adjust the temperature gradient. After crystal growth is complete, cooling begins. The cooling water temperature is set to approximately 48°C, the water flow rate is 0.15 L / s, and the highest temperature at the outlet is monitored to not exceed 65°C. The cooling rate is maintained at 2-4°C / min. Slow cooling is used to fully release thermal stress and prevent excessive defects or even crystal cracking. When the temperature drops below 1000°C, the inlet cooling water temperature can be reduced, and the cooling rate can be increased to 4-6°C / min.

[0041] The physical image of the 8-inch crystal with low conductivity convexity obtained in this embodiment is shown below. Figure 7 As shown.

[0042] Example 3 Silicon carbide with a diameter of 12 feet was produced using the thermal field structure for growing large-diameter silicon carbide shown in Example 1.

[0043] Specific steps: (1) Place the silicon carbide raw material in the crucible and place the seed crystal at the top of the inner cavity of the crucible, keeping the source crystal distance at 70 mm; (2) Seal the crucible in the thermal field structure for growing large-diameter silicon carbide and evacuate it (vacuum degree is 10). -4 Pa, maintained for 8 h) and argon gas was introduced as a protective gas; (3) Turn on the heating unit to raise the temperature, and at the same time turn on the cooling unit to regulate the temperature.

[0044] In step (3), the growth pressure inside the furnace is adjusted to 70 mbar. The initial stage of crystal growth includes the heating stage and the diameter expansion stage after reaching the maximum power. When heating, the heating power gradient is set to 5 kW, 8 kW, and 13 kW, with corresponding holding times of 6 h, 5 h, and 6 h. Finally, the diameter expansion growth begins at 16 kW, which takes about 15 to 20 hours. The cooling water temperature is 37 to 40°C, the water flow rate is 0.18 to 0.2 L / s, and the growth temperature is between 2100 and 2120°C. During the constant diameter growth stage, after initial heating and diameter expansion, the growth pressure inside the furnace is adjusted to 8 mbar, the power is kept constant at 16 kW, the cooling water temperature is 22℃, and the water flow rate is 0.3 L / s. As the growth time increases, the grown crystal gradually becomes thicker, and the leading edge surface gradually approaches the high-temperature convex temperature field, increasing the radial temperature gradient and thus increasing the crystal convexity. Therefore, during the growth process, the cooling water temperature is reduced at a cooling rate of 0.2~0.5℃ / 10 h to adjust the temperature gradient. After crystal growth is complete, cooling begins. The cooling water temperature is set to 55℃, the water flow rate is 0.12 L / s, and the highest temperature at the outlet is monitored to not exceed 65℃. The cooling rate is maintained at 2~4℃ / min. Slow cooling is used to fully release thermal stress and prevent excessive defects or even crystal cracking. When the temperature is below 1000℃, the inlet cooling water temperature can be reduced, and the cooling rate can be increased to 4~6℃ / min.

[0045] The physical image of the 12-inch crystal with low conductivity convexity obtained in this embodiment is shown below. Figure 8 As shown.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A thermal field structure for growing large-diameter silicon carbide, characterized in that, It includes a heat preservation unit, a crucible, a cooling unit, and a heating unit; The insulation unit includes a top insulation component, a side insulation component, and a bottom insulation component; the top insulation component, the side insulation component, and the bottom insulation component are sealed to form a cavity, and the crucible is located inside the cavity; The side insulation components are, from bottom to top, a first side insulation section and a second side insulation section. The height of the first side insulation section is the same as the height of the crucible, and the thickness of the second side insulation section is less than that of the first side insulation section. A cooling unit and a heating unit are arranged sequentially on the outside of the insulation unit.

2. The thermal field structure for growing large-diameter silicon carbide as described in claim 1, characterized in that, The top insulation component, side insulation component, and bottom insulation component are all made of graphite felt.

3. The thermal field structure for growing large-diameter silicon carbide as described in claim 1, characterized in that, The thickness of the top and bottom insulation components is 30~60 mm; The thickness of the first insulation section is 30~60 mm, and the thickness of the second insulation section is 15~30 mm.

4. The thermal field structure for growing large-diameter silicon carbide as described in claim 1, characterized in that, The cooling unit consists of two quartz tubes, which are arranged around the outer periphery of the side insulation component.

5. The thermal field structure for growing large-diameter silicon carbide as described in claim 4, characterized in that, The inlet of the quartz tube is connected to an inlet pipe, on which a water temperature regulating switch, a water flow rate regulating switch, and a first water temperature monitoring meter are installed in sequence. The outlet of the quartz tube is connected to an outlet pipe, and a second water temperature monitoring meter is installed on the outlet pipe. Alternatively, the gap between the quartz tube and the side insulation component is 18~22 mm, preferably 20 mm.

6. The thermal field structure for growing large-diameter silicon carbide as described in claim 1, characterized in that, The heating unit is an induction heating coil; the induction heating coil is arranged around the outer periphery of the cooling unit; Preferably, the gap between the quartz tube and the induction heating coil is 8~12mm, and more preferably 10mm.

7. A silicon carbide growth apparatus, characterized in that, Includes the thermal field structure for growing large-diameter silicon carbide as described in any one of claims 1 to 6.

8. A method for growing large-diameter silicon carbide, characterized in that, The growth method employs the thermal field structure for growing large-diameter silicon carbide as described in any one of claims 1 to 6.

9. The method for growing large-diameter silicon carbide as described in claim 8, characterized in that, The growth method includes the following steps: (1) Place the silicon carbide raw material in the crucible and place the seed crystal at the top of the inner cavity of the crucible; (2) Seal the crucible in the thermal field structure for growing large-diameter silicon carbide, evacuate and introduce protective gas; (3) Turn on the heating unit to raise the temperature, and at the same time turn on the cooling unit to regulate the temperature.

10. The method for growing large-diameter silicon carbide as described in claim 9, characterized in that, In the early stage of crystal growth, the heating power during the diameter expansion stage is set between 5 and 16 kW, the heating time is 15 to 24 h, the cooling water temperature is 35 to 40℃, the water flow rate is 0.16 to 0.2 L / s, and the final heating temperature is above 2000℃. During the constant diameter growth stage, the power is controlled between 15 and 17 kW during heat preservation, the cooling water temperature is 20 to 25℃, the water flow rate is 0.25 to 0.3 L / s, and the growth temperature is controlled between 2050 and 2200℃. After crystal growth is complete, the cooling water temperature is set to 45~55℃ and the water flow rate is 0.12~0.15 L / s.

Images