Crystal growth furnace and crystal growth method for improving silicon carbide crystal quality
By introducing a silicon-containing gas during the later stages of silicon carbide crystal growth, the problems of carbon particle inclusions and unstable carbon-silicon ratio were solved, thus achieving stable growth of high-quality silicon carbide crystals and protection of the crystal growth furnace.
Patent Information
- Application Number
- CN202511111309.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-08
- Publication Date
- 2025-11-18
AI Technical Summary
In existing silicon carbide crystal growth processes, carbon particle inclusions lead to reduced crystal quality, dynamic changes in the carbon-silicon ratio affect the stability of the crystal growth composition, and insufficient silicon content leads to changes in crystal form and the risk of crystal carbonization.
In the later stages of crystal growth, a silicon-containing gas is introduced along the bottom of the crucible. By stably controlling its flow direction, the gas reacts with the excess carbon components, reducing the free carbon content, balancing the carbon-silicon ratio, and avoiding the risk of insufficient silicon components.
This method achieves stable crystal growth with low inclusions, improves silicon carbide crystal quality, prevents gas from blowing directly into the seed crystal region, and reduces the corrosion and deposition effects on the crystal growth furnace structure.
Smart Images
Figure CN120967494A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the field of silicon carbide crystal growth, and relates to a crystal growing furnace and a crystal growing method for improving the quality of silicon carbide crystals. BACKGROUND
[0002] As a high-performance semiconductor material, 4H-type silicon carbide (4H-SiC) has advantages such as a wide band gap, a high breakdown field strength, a high thermal conductivity, a high electron saturation drift speed, excellent chemical stability, and a low defect density, and thus performs well in high-power, high-temperature, and high-frequency applications and is widely used in the fields of power electronics, radio frequency communication, and high-temperature sensors. With the maturity of production technology and the gradual reduction of costs, 4H-SiC has become an important development direction of future semiconductor technology.
[0003] At present, the physical vapor transport method (PVT) is generally used for growing silicon carbide crystals. In the PVT growth process, the silicon component of the silicon carbide powder is preferentially sublimated, and the remaining residual carbon particles are in a solid state and have a small density. In particular, a part of the small-diameter carbon particles will enter the crystal along with the gas flow and form inclusions, causing the quality of the crystal to decrease. Since the carbon-silicon ratio dynamically changes, the stability of the crystal growing component will also be affected. If the method of introducing a silicon component-containing gas is directly used for silicon replenishment, the gas utilization rate is low, the powder cannot be fully contacted, the gas flow direction in the crucible cannot be stably controlled, and the silicon component-containing gas that has not been fully reacted will corrode the internal structure of the crystal growing furnace and form deposits in the high-temperature environment, thereby increasing equipment wear and tear.
[0004] Therefore, there is a need to develop a crystal growing furnace and a crystal growing method for improving the quality of silicon carbide crystals, which can stably control the silicon component-containing gas in the process and avoid the risk of increasing crystal type changes and carbonization of the crystal due to a lack of silicon component in the later stage of crystal growing. SUMMARY
[0005] The technical problem to be solved by the present application is to solve the above-mentioned problems of the prior art, and to provide a crystal growing furnace and a crystal growing method for improving the quality of silicon carbide crystals. In this scheme, a silicon component-containing gas is introduced along the bottom of the crucible in the middle and late stages of crystal growing, and the flow direction of the silicon component-containing gas in the crucible is stably controlled, so that the silicon component-containing gas and the excess carbon component fully react to reduce the content of free carbon and reduce the risk of inclusions. At the same time, due to the introduction of the silicon component, the carbon-silicon ratio in the crystal growing process is effectively balanced, and the growth environment is stabilized. Furthermore, the risk of increasing crystal type changes and carbonization of the crystal due to a lack of silicon component in the later stage of crystal growing is avoided.
[0006] To solve the above-mentioned technical problems, the technical scheme adopted by the present application is as follows:
[0007] The application provides a crystal growing furnace for improving the quality of silicon carbide crystals, which comprises a crystal growing furnace body, a heat preservation assembly, a heating assembly, a crucible assembly and a support ring, a central gas inlet is arranged at the bottom center of the crystal growing furnace body, and the heat preservation assembly, the heating assembly and the crucible assembly are sequentially arranged on the inner side of the crystal growing furnace body from outside to inside.
[0008] The heat preservation assembly comprises a side heat preservation cylinder, which is arranged above the bottom inner side of the crystal growing furnace body and surrounds the outer side of the heating assembly, the inner wall surface of the side heat preservation cylinder is horizontally provided with an annular boss, the bottom outer side of the support ring is arranged above the annular boss, a plurality of L-shaped channels are circumferentially arranged at the inner ring of the support ring, each L-shaped channel is respectively provided with a top flow guide opening and a side flow guide opening, the top flow guide opening is arranged at the top annular surface of the support ring, the side flow guide opening is arranged at the inner ring wall surface of the support ring, and the top flow guide opening and the side flow guide opening of each L-shaped channel are communicated with each other.
[0009] The heat preservation assembly further comprises an upper heat preservation cover and a heat preservation base, the upper heat preservation cover is coaxially arranged above the side heat preservation cylinder, and a gas guide channel is arranged at the axis of the upper heat preservation cover; the heat preservation base is arranged above the bottom center of the inner side of the crystal growing furnace body, a vertical through hole is arranged at the axis of the heat preservation base, and the crucible body is coaxially arranged above the heat preservation base.
[0010] The heating assembly comprises a plurality of lower heating resistors and resistor support bases, the lower heating resistors are arranged in a plurality of groups, the lower heating resistors are arranged around the outer side of the crucible assembly, the lower heating resistors are all located below the support ring, and each lower heating resistor is slidably arranged on the bottom inner side of the crystal growing furnace body through a corresponding resistor support base.
[0011] The heating assembly further comprises a plurality of upper heating resistors, the upper heating resistors are arranged around the outer side of the crucible assembly, and the upper heating resistors are all located below the upper heat preservation cover; each lower heating resistor is correspondingly provided with a heat preservation piece.
[0012] The crucible assembly comprises a crucible body, a charging cylinder, a blocking ring, a seed crystal base, an upper crucible cover and a flow guide cover, the crucible body is arranged above the bottom center of the inner side of the crystal growing furnace body, the inner ring of the support ring is arranged around the outer side of the crucible body, a gas inlet through hole is arranged at the bottom center of the crucible body, and the gas inlet through hole is coaxially arranged above the central gas inlet.
[0013] The charging cylinder is used for providing an annular loading space for silicon carbide powder, the charging cylinder is annularly arranged on the inner side of the crucible body, the hollow part of the inner ring of the charging cylinder is coaxial with the gas inlet through hole, and the blocking ring is horizontally arranged in the hollow part of the inner ring of the charging cylinder.
[0014] The inner ring wall surface of the charging cylinder is a stepped type gradually narrowing in diameter from top to bottom along the axial direction, and the corresponding steps of the inner ring wall surface due to the change in diameter are not less than two, and the blocking ring is provided with a plurality of blocking rings which are sequentially and horizontally arranged on different steps of the inner ring wall surface of the charging cylinder from bottom to top.
[0015] The blocking ring includes a first blocking ring and a second group of blocking rings, the first and second blocking rings are sequentially and horizontally arranged on the two steps of the inner ring wall surface of the charging cylinder from bottom to top, and the center of the second blocking ring is arc-shaped and concave downward. The material of the first blocking ring is preferably high-purity graphite, the material of the central concave region of the second group of blocking rings is preferably a silicon carbide substrate coated with pyrolytic graphite, and the material of the peripheral horizontal region is preferably isostatic pressed graphite processed into a porous structure.
[0016] The seed crystal holder is arranged at the top end of the crucible body and is arranged on the top of the inner ring side of the support ring. The upper crucible cover is arranged above the seed crystal holder, a plurality of gas guide grooves are arranged on the side wall surface near the bottom of the upper crucible cover, a gas guide channel is arranged above the center of the top end of the upper crucible cover, and the top end of the gas guide channel is sealingly arranged on the top of the crystal growing furnace body. The flow guide cover is arranged outside the upper crucible cover, the bottom of the flow guide cover is arranged above the top surface of the support ring, the contact surface between the bottom of the flow guide cover and the support ring is located on the side away from the center of the support ring, and the contact surface between the top of the flow guide cover and the upper crucible cover is located above the gas guide groove.
[0017] A plurality of support blocks are circumferentially arranged at the radial edge of the seed crystal holder, and the seed crystal holder is lapped on the top of the inner ring side of the support ring through the support blocks.
[0018] The radius from the center of the crucible body to the inner wall is R1, and the radius from the center of the crucible body to the outer wall is R2. The radius from the center of the seed crystal holder to the arc-shaped outer edge thereof is R3, and the radius from the center of the seed crystal holder to the outer edge of the support block is R4. The bottom of the upper crucible cover and the bottom of the seed crystal holder are both arranged above the annular top surface of the crucible body, and the bottom of the upper crucible cover is provided with an annular groove, which reduces the contact area between the bottom of the upper crucible cover and the crucible body. The radius from the center of the upper crucible cover to the inner side edge of the bottom thereof is R5, and the radius from the center of the upper crucible cover to the outer side edge of the bottom thereof is R6. The radius from the center of the support ring to the inner ring wall surface is R7. The assembly size between the crucible body, the seed crystal holder, the upper crucible cover and the support ring should satisfy R1
[0019] A crystal growing method for improving the quality of silicon carbide crystals, comprising the following steps:
[0020] Step one, fill the silicon carbide powder into the annular area of the charging cylinder, complete the assembly and sealing of the internal structure of the crystal growing furnace body, gradually heat the inside of the crystal growing furnace body from room temperature to 800-1000℃, and at the same time, introduce argon gas into the furnace as a protective gas at a flow rate of 500sccm, and control the pressure to be 50Torr.
[0021] Step two, after the preheating stage, gradually heat the crystal growth furnace body to 2000-2150 DEG C at a rate of 3 DEG C / min, after temperature rising, the seed crystal region temperature reaches 2100-2150 DEG C, the crucible body bottom charge region temperature reaches 2250-2300 DEG C, at this time, the center inlet path injects silicon component gas, the flow rate is kept at 200 sccm, and the control pressure is 10-50Torr.
[0022] Step three, after the temperature rising stage, keep injecting the silicon component gas, and open the resistance support seat and drive the lower heating resistance upwards along the vertical direction, at this time, the lower heating resistance drives the support ring to move upwards synchronously through the heat preservation part, at this time, due to the reason that the outer end of the seed crystal seat is arranged on the top of the inner ring side of the support ring, the seed crystal seat will gradually move upwards away from the upper end of the crucible body, due to the reason that the gap between the seed crystal seat and the crucible body, the L-shaped channel in the support ring close to the outer wall of the crucible body connects the inner space of the crucible body with the inner space of the upper crucible cover; after the lower heating resistance reaches the target height, the temperature of the crucible body bottom charge region is stabilized at 2250-2300 DEG C, and the temperature of the seed crystal region is stabilized at 2100-2150 DEG C.
[0023] Step four, after the crystal growth stage, stop injecting the silicon component gas, increase the argon flow rate to 1000 sccm, gradually reduce the crystal growth furnace body to 1000 DEG C at a rate of 2 DEG C / min, and then naturally cool down, open the resistance support seat and lower the lower heating resistance to complete the reset, and open the furnace when the temperature in the furnace is less than 50 DEG C to take out the crystal.
[0024] Compared with the prior art, the present application has at least the following beneficial effects:
[0025] 1. The present application realizes stable crystal growth of low inclusions, by injecting the gas containing silicon components along the bottom of the crucible in the later stage of crystal growth, so that it fully reacts with the excess carbon components to reduce the content of free carbon and reduce the risk of generating inclusions; at the same time, due to the injection of the silicon component, the carbon-silicon ratio in the crystal growth process is effectively balanced, the growth environment is stabilized, and the risk of increasing crystal form and carbonization of the crystal due to the lack of silicon component in the later stage of crystal growth is avoided.
[0026] 2. In the path design of the silicon component gas, on the one hand, it prevents the gas from directly blowing the seed crystal growth area, on the other hand, it improves the contact efficiency with the powder area, and reduces the corrosion and deposition of the silicon component gas on the structure of the crystal growth furnace. BRIEF DESCRIPTION OF DRAWINGS
[0027] Figure 1 is a cross-sectional view of a crystal growth furnace for improving the quality of silicon carbide crystal Figure 1 .
[0028] Figure 2 shows the cross-sectional view of the seed holder and the support ring after being lifted by the heating assembly lifting belt Figure 2 .
[0029] Figure 3 shows the cross-sectional view of the structure shown in Figure 1 rotated 45° around the axis Figure 2 .
[0030] Figure 4 shows the perspective view of the structure shown in Figure 1 .
[0031] Figure 5 shows the perspective view of the structure shown in Figure 2 .
[0032] Figure 6 shows the perspective view of the structure shown in Figure 3 .
[0033] wherein:
[0034] 10. the crystal growing furnace body;
[0035] 11. the central air inlet;
[0036] 20. the heat preservation assembly;
[0037] 21. the side heat preservation cylinder; 211. the annular boss; 22. the upper heat preservation cover; 23. the heat preservation base;
[0038] 30. the heating assembly;
[0039] 31. the lower heating resistor; 311. the heat preservation member; 32. the resistor support base; 33. the upper heating resistor;
[0040] 40. the crucible assembly;
[0041] 41. the crucible body; 411. the air inlet through hole; 42. the charging cylinder; 43. the blocking ring; 431. the first blocking ring; 432. the second blocking ring; 44. the seed holder; 441. the support block; 442. the seed crystal; 45. the upper crucible cover; 451. the air guide groove; 452. the air guide channel; 453. the annular groove; 46. the flow guide cover;
[0042] 50. the support ring;
[0043] 51. the L-shaped channel; 511. the top flow guide opening; 512. the side flow guide opening;
[0044] 60. the silicon carbide powder. DETAILED DESCRIPTION
[0045] The application will be described in further detail below with reference to the drawings and specific preferred embodiments.
[0046] In the description of the present application, it should be understood that the terms "left side", "right side", "upper part", "lower part", "top", "bottom" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and "first", "second" and the like do not represent the importance of the parts, and therefore cannot be understood as a limitation on the present application. The specific dimensions used in the embodiments are only for the purpose of illustrating the technical solutions and do not limit the protection scope of the present application. Those skilled in the art should understand that the embodiments are only to help understand the present application and should not be regarded as a specific limitation on the present application.
[0047] As shown in Figure 1 A crystal growing furnace for improving the quality of silicon carbide crystals includes a crystal growing furnace body 10, a heat preservation assembly 20, a heating assembly 30, a crucible assembly 40 and a support ring 50. The bottom center of the crystal growing furnace body 10 is provided with a central gas inlet 11, and the inside of the crystal growing furnace body 10 is sequentially provided with the heat preservation assembly 20, the heating assembly 30 and the crucible assembly 40 from outside to inside. The bottom of the crystal growing furnace body is also provided with a plurality of gas inlets, and the top of the crystal growing furnace body is provided with a plurality of gas outlets. The central gas inlet 11 is mainly used to introduce silicon-containing component gas into the inside of the crucible body 41 during the later growth stage, and the remaining gas inlets continuously and stably introduce protective gas into the inside of the crystal growing furnace body 10 to ensure the stability of the growth environment and growth pressure in the entire growth chamber.
[0048] The heat preservation assembly 20 includes a side heat preservation cylinder 21, which is arranged above the bottom center of the inside of the crystal growing furnace body 10 and surrounds the outside of the heating assembly 30. The inner wall surface of the side heat preservation cylinder 21 is horizontally provided with an annular boss 211. The heat preservation assembly 20 further includes an upper heat preservation cover 22 and a heat preservation base 23. The upper heat preservation cover 22 is coaxially arranged above the side heat preservation cylinder 21, and a gas guide channel 452 is inserted at the axis of the upper heat preservation cover 22. The heat preservation base 23 is arranged above the bottom center of the inside of the crystal growing furnace body 10, and a vertical through hole is formed at the axis of the heat preservation base 23.
[0049] The outer ring side bottom of the support ring 50 is arranged above the annular boss 211, and a plurality of L-shaped channels 51 are circumferentially arranged at the inner ring of the support ring 50. Each L-shaped channel 51 is respectively provided with a top flow guide port 511 and a side flow guide port 512. The top flow guide port 511 is arranged on the top circular surface of the support ring 50, and the side flow guide port 512 is arranged on the inner ring wall surface of the support ring 50. The top flow guide port 511 and the side flow guide port 512 of each L-shaped channel 51 are in communication with each other.
[0050] The heating assembly 30 comprises a plurality of lower heating resistors 31 and resistor support seats 32. The lower heating resistors 31 are arranged around the outside of the crucible assembly 40 and are located below the support ring 50. The bottom of each lower heating resistor 31 is slidably arranged on the inside bottom of the crystal growing furnace body 10 through the corresponding resistor support seat 32. The heating assembly 30 further comprises a plurality of upper heating resistors 33 arranged around the outside of the crucible assembly 40 and located below the upper heat preservation cover 22. The top of each lower heating resistor 31 is provided with a heat preservation piece 311 corresponding to the lower heating resistor 31, which is used to reduce the heat loss when the lower heating resistor 31 is lifted upward and contacts the support ring 50.
[0051] The crucible assembly 40 comprises a crucible body 41, a charging cylinder 42, a blocking ring 43, a seed crystal seat 44, an upper crucible cover 45 and a flow guide cover 46. The crucible body 41 is arranged above the center of the inside bottom of the crystal growing furnace body 10 and coaxially above the heat preservation base 23. The inner ring of the support ring 50 is arranged around the outside of the crucible body 41. A gas inlet hole 411 is formed in the center of the bottom of the crucible body 41, which is coaxially arranged above the central gas inlet 11.
[0052] The charging cylinder 42 is used to provide an annular loading space for the silicon carbide powder 60. The charging cylinder 42 is annularly arranged inside the crucible body 41. The inner ring hollow part of the charging cylinder 42 is coaxial with the gas inlet hole 411, and the blocking ring 43 is horizontally arranged in the inner ring hollow part of the charging cylinder 42. The inner wall surface of the inner ring of the charging cylinder 42 is a stepped type with the inner diameter gradually narrowing from top to bottom along the axis direction. The charging cylinder 42 is provided with not less than two steps 421 corresponding to the change of the inner diameter. The blocking ring 43 is arranged in several groups, and the blocking rings 43 are sequentially and horizontally arranged on different steps 421 of the inner wall surface of the charging cylinder 42 from bottom to top.
[0053] As shown in Figures 1 to 3 , two blocking rings 43 are arranged in the embodiment. The blocking ring 43 comprises a first blocking ring 431 and a second blocking ring 432. The first blocking ring 431 and the second blocking ring 432 are sequentially and horizontally arranged on two steps of the inner wall surface of the charging cylinder 42 from bottom to top. The center of the second blocking ring 432 is arc-shaped and concave downward. The material of the first blocking ring 431 is preferably high-purity graphite. The material of the concave region in the center of the second blocking ring 432 is preferably a silicon carbide substrate coated with pyrolytic graphite coating. The material of the peripheral horizontal region is preferably isostatic pressed graphite processed into a porous structure.
[0054] The seed crystal seat 44 is arranged at the top end of the crucible body 41, and the outer end of the seed crystal seat 44 is arranged on the top of the inner ring side of the support ring 50. Figure 4 and Figure 5As shown, the seed seat 44 is provided with a plurality of support blocks 441 at the radial edge, and the seed seat 44 is lapped in the inner ring side top of the support ring 50 through the support blocks 441.
[0055] The upper crucible cover 45 is arranged above the seed seat 44, and the upper crucible cover 45 is provided with a plurality of gas guide grooves 451 at the circumferential direction near the bottom side wall surface. The upper crucible cover 45 is provided with a gas guide passage 452 above the top center, and the top end of the gas guide passage 452 is sealingly arranged on the top of the crystal growing furnace body 10.
[0056] In the above, since the upper crucible cover 45 is connected to the top of the crystal growing furnace body 10 through the gas guide passage 452, it cannot change the vertical height in the axial direction during the growth process. Therefore, it is necessary to ensure that the seed seat 44 is lifted upwards under the driving of the support ring 50 without changing the position of the upper crucible cover 45 and the crucible body 41. The radius from the center of the crucible body 41 to the inner wall is R1, and the radius from the center of the crucible body 41 to the outer wall is R2. The radius from the center of the seed seat 44 to the arc-shaped outer edge is R3, and the radius from the center of the seed seat 44 to the outer edge of the support block is R4. The bottom of the upper crucible cover 45 and the bottom of the seed seat 44 are both arranged above the annular top surface of the crucible body 41, and the bottom of the upper crucible cover 45 is also provided with an annular groove 453, which reduces the contact area between the bottom of the upper crucible cover 45 and the crucible body 41. The radius from the center of the upper crucible cover 45 to the bottom inner side edge is R5, and the radius from the center of the upper crucible cover 45 to the bottom outer side edge is R6. The radius from the center of the support ring 50 to the inner ring wall surface is R7, and the assembly size between the crucible body 41, the seed seat 44, the upper crucible cover 45 and the support ring 50 should satisfy: R1 < R3 = R5 < R2 = R6 = R7 < R4.
[0057] The flow guide cover 46 is arranged around the outside of the upper crucible cover 45, the bottom of the flow guide cover 46 is arranged above the top surface of the support ring 50, and the contact surface between the bottom of the flow guide cover 46 and the support ring 50 is located on the side away from the center of the support ring 50 of the top flow guide port 511. The contact surface between the top of the flow guide cover 46 and the upper crucible cover 45 is located above the gas guide groove 451.
[0058] Based on the above-mentioned crystal growing furnace for improving the quality of silicon carbide crystals, a method for improving the quality of silicon carbide crystals is provided, which specifically includes the following steps:
[0059] Step one, fill the silicon carbide powder 60 into the annular area of the charging cylinder 42, complete the assembly and sealing of the internal structure of the crystal growing furnace body 10, gradually heat the inside of the crystal growing furnace body 10 from room temperature to 800-1000℃, and at the same time, introduce argon gas into the furnace as a protective gas at a flow rate of 500sccm, and control the pressure to be 50Torr;
[0060] Step two, after the preheating stage, the temperature in the furnace body 10 is gradually increased to 2000-2150 °C at a rate of 3 °C / min. After the temperature is increased, the temperature of the seed crystal 442 region reaches 2100-2150 °C, and the temperature of the bottom of the crucible body 41 reaches 2250-2300 °C. At this time, the silicon-containing component gas is injected into the crucible body 41 through the central gas inlet 11, the flow rate is maintained at 200 sccm, and the control pressure is 10-50 Torr.
[0061] Step three, after the temperature increasing stage, the silicon-containing component gas is still injected, the resistance support seat 32 is turned on, and the lower heating resistance 31 is driven upward along the vertical direction. At this time, the lower heating resistance 31 drives the support ring 50 to move upward synchronously through the heat preservation part 311. At this time, due to the fact that the outer end of the seed crystal seat 44 is arranged on the top of the inner ring side of the support ring 50, the seed crystal seat 44 will gradually move upward away from the upper end of the crucible body 41. Due to the gap between the seed crystal seat 44 and the crucible body 41, the L-shaped channel 51 in the support ring 50 that is close to the outer wall of the crucible body 41 is connected to the space inside the crucible body 41, the upper flow guide cover 46, and the space inside the upper crucible cover 45. After the lower heating resistance 31 reaches the target height, the temperature of the bottom of the crucible body 41 is stabilized at 2250-2300 °C, and the temperature of the seed crystal 442 region is stabilized at 2100-2150 °C.
[0062] The silicon-containing component gas is injected from the central gas inlet 11 at the bottom center of the crystal growing furnace body 10, enters the inside of the crucible body 41 through the vertical through hole in the center of the heat preservation base 23 at the bottom of the crucible body 41, and passes through the first blocking ring 431 and the second blocking ring 432 in sequence, wherein the first blocking ring 431 is preferably a mesh structure, which can convert the bottom jet into uniform laminar flow and filter free particles with a particle size greater than 10 μm, thereby reducing the risk of blockage and deposition in the powder area; when the gas flows through the second blocking ring 432, it will be guided outward when passing through the concave arc surface, and then pass through the porous area at the edge of the second blocking ring 432 and rise, so that the vertically rising gas bypasses to the outer edge silicon carbide powder area 60, increases the contact time with the powder, and the high-temperature powder area will attract the silicon-containing component gas to migrate to the inner wall of the crucible body 41, avoiding the gas directly rising to the seed crystal crystallization area, maintaining the stability of the Si / C stoichiometric ratio at the seed crystal interface, and inhibiting the carbon inclusion defects; at the same time, during the crystal growth stage, the rising of the support ring 50 and the seed crystal seat 44 makes the inside of the crucible communicate with the inside area of the upper crucible cover 45 through the L-shaped channel 51, and the silicon-containing component gas that is not fully reacted will escape from the L-shaped channel 51, enter the area between the flow guide cover 46 and the upper crucible cover 45, and then enter the inside area of the upper crucible cover through the gas guide groove 451 corresponding to the upper crucible cover, and finally leave the crystal growing furnace through the gas guide channel 452. The gas path design effectively reduces the local pressure in the crucible, attracts the silicon-containing component gas to quickly pass through the powder area, increases the contact frequency of the silicon-containing gas and the powder, and at the same time, the designed path of the silicon-containing component gas avoids its corrosion and deposition on the remaining structure inside the crystal growing furnace, effectively protecting the service life of the resistance furnace.
[0063] Step four, after the end of the crystal growth stage, stop injecting the silicon-containing component gas, increase the argon flow to 1000 sccm, gradually reduce the temperature in the crystal growing furnace body 10 to 1000℃ at a rate of 2℃ / min, and then naturally cool down, open the resistance support seat 32 and lower the lower heating resistance 31 to complete the reset, and when the temperature in the furnace is less than 50℃, open the furnace and take out the crystal.
[0064] The above describes the preferred embodiments of the present application, but the present application is not limited to the specific details in the above embodiments, and various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, and these simple modifications all belong to the protection scope of the present application.
[0065] In addition, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction, and in order to avoid unnecessary repetition, the present application will not further describe various possible combinations.
[0066] Furthermore, the various embodiments of the present application can be combined with each other, as long as it does not violate the spirit of the present application, and it should be considered as disclosed in the present application.
Claims
1. A crystal growth furnace for improving the quality of silicon carbide crystals, characterized in that: The furnace includes a crystal growth furnace body (10), a heat preservation component (20), a heating component (30), a crucible component (40), and a support ring (50). A central air inlet (11) is provided at the bottom center of the crystal growth furnace body (10). The heat preservation component (20), the heating component (30), and the crucible component (40) are arranged sequentially from the outside to the inside of the crystal growth furnace body (10). The heat insulation component (20) includes a side heat insulation cylinder (21), which is located above the center of the bottom of the inner side of the crystal growth furnace body (10). The side heat insulation cylinder (21) is arranged around the outside of the heating component (30). The inner wall of the side heat insulation cylinder (21) is horizontally provided with an annular boss (211). The bottom of the outer ring side of the support ring (50) is placed above the annular boss (211). The inner ring of the support ring (50) is provided with multiple L-shaped channels (51) circumferentially. Each L-shaped channel (51) is provided with a top guide port (511) and a side guide port (512). The top guide port (511) is located on the top annular surface of the support ring (50), and the side guide port (512) is located on the inner ring wall of the support ring (50). The top guide port (511) and the side guide port (512) of each L-shaped channel (51) are interconnected. The heating assembly (30) includes a lower heating resistor (31) and a resistor support (32). There are several lower heating resistors (31). The lower heating resistors (31) are arranged around the outside of the crucible assembly (40). The lower heating resistors (31) are all located below the ring body of the support ring (50). The bottom of each lower heating resistor (31) is slidably arranged on the bottom of the inner side of the crystal growth furnace body (10) through the corresponding resistor support (32). The crucible assembly (40) includes a crucible body (41), a loading cylinder (42), a baffle ring (43), a seed crystal seat (44), an upper crucible cover (45), and a flow guide (46). The crucible body (41) is located above the center of the bottom inside the crystal growth furnace body (10). The inner ring of the support ring (50) is arranged around the outside of the crucible body (41). An air inlet hole (411) is opened at the center of the bottom of the crucible body (41), and the air inlet hole (411) is coaxially arranged above the central air inlet (11). The loading cylinder (42) is used to provide an annular loading space for silicon carbide powder (60). The loading cylinder (42) is arranged annularly inside the crucible body (41). The hollow part of the inner ring of the loading cylinder (42) is coaxial with the air inlet hole. The baffle ring (43) is horizontally arranged in the hollow part of the inner ring of the loading cylinder (42). The seed crystal seat (44) is located in the center of the inner ring of the crucible body (41). The top of the crucible body (41) and the outer end of the seed crystal seat (44) are placed on the top of the inner ring side of the support ring (50); the upper crucible cover (45) is placed above the seed crystal seat (44), and multiple gas guide grooves (451) are circumferentially opened near the bottom side wall of the upper crucible cover (45). A gas guide channel (452) is set above the center of the top of the upper crucible cover (45), and the top of the gas guide channel (452) is sealed on the top of the crystal growth furnace body (10); the flow guide hood (46) is arranged around the outside of the upper crucible cover (45), and the bottom of the flow guide hood (46) is set above the top surface of the support ring (50). The contact surface between the bottom of the flow guide hood (46) and the support ring (50) is located on the side away from the center of the support ring (50) from the top flow guide port (511), and the contact surface between the top of the flow guide hood (46) and the upper crucible cover (45) is located above the gas guide groove (451).
2. The crystal growth furnace for improving silicon carbide crystal quality according to claim 1, characterized in that: The inner ring wall of the loading cylinder (42) is a stepped type with the inner diameter gradually narrowing from top to bottom along the axial direction. The inner ring wall of the loading cylinder (42) has at least two steps (421) corresponding to the change in inner diameter. The blocking rings (43) are provided in a number of ways. The blocking rings (43) are horizontally installed on different steps (421) of the inner ring wall of the loading cylinder (42) from bottom to top.
3. The crystal growth furnace for improving silicon carbide crystal quality according to claim 2, characterized in that: The blocking ring (43) includes a first blocking ring (431) and a second set of blocking rings (432). The first blocking ring (431) and the second blocking ring (432) are horizontally installed on two steps on the inner ring wall of the loading cylinder (42) from bottom to top. The center of the second blocking ring (432) is concave in an arc shape.
4. The crystal growth furnace for improving silicon carbide crystal quality according to claim 1, characterized in that: The seed crystal seat (44) is provided with a plurality of support blocks (441) circumferentially arranged at the radial edge, and the seed crystal seat (444) overlaps the top of the inner ring side of the support ring (50) through the support blocks (441).
5. The crystal growth furnace for improving silicon carbide crystal quality according to claim 4, characterized in that: The radius from the center of the crucible body (41) to the inner wall is R1, and the radius from the center of the crucible body (41) to the outer wall is R2; the radius from the center of the seed crystal seat (44) to the arc-shaped outer edge is R3, and the radius from the center of the seed crystal seat (44) to the outer edge of the support block is R4; the bottom of the upper crucible cover (45) and the bottom of the seed crystal seat (44) are both in contact above the annular top surface of the crucible body (41), and an annular groove (453) is provided at the bottom of the upper crucible cover (45), the annular groove (453) reduces the upper The contact area between the bottom of the crucible cover (45) and the crucible body (41) is R5, the radius from the center of the upper crucible cover (45) to the inner edge of the bottom is R6, and the radius from the center of the upper crucible cover (45) to the outer edge of the bottom is R7. The radius from the center of the support ring (50) to the inner ring wall is R7. The assembly dimensions between the crucible body (41), the seed crystal seat (44), the upper crucible cover (45) and the support ring (50) should satisfy: R1 < R3 = R5 < R2 = R6 = R7 < R4.
6. The crystal growth furnace for improving silicon carbide crystal quality according to claim 1, characterized in that: The heat preservation component (20) also includes an upper heat preservation cover (22) and a heat preservation base (23). The upper heat preservation cover (22) is coaxially arranged above the side heat preservation cylinder (21), and a gas guide channel (452) is inserted at the center of the upper heat preservation cover (22). The heat preservation base (23) is arranged above the center of the bottom of the inner side of the crystal growth furnace body (10), and a vertical through hole is opened at the center of the heat preservation base (23). The crucible body (41) is coaxially arranged above the heat preservation base (23).
7. The crystal growth furnace for improving silicon carbide crystal quality according to claim 1, characterized in that: The heating assembly (30) also includes several upper heating resistors (33), which are arranged around the outside of the crucible assembly (40). The upper heating resistors (33) are all located below the upper heat preservation cover (22); each lower heating resistor (31) has a corresponding heat preservation component (311) on its top.
8. A method for improving the quality of silicon carbide crystals based on any one of claims 1 to 7, characterized in that, Includes the following steps: Step 1: Fill the annular area of the charging cylinder (42) with silicon carbide powder (60) to complete the internal structure assembly and sealing of the crystal growth furnace body (10). Gradually heat the inside of the crystal growth furnace body (10) from room temperature to 800~1000℃, and at the same time, introduce argon gas into the furnace at a flow rate of 500sccm as a protective gas, and control the pressure to 50Torr. Step 2: After the preheating stage, the crystal growth furnace (10) is gradually heated to 2000~2150℃ at a rate of 3℃ / min. After the temperature rises, the temperature of the seed crystal (442) area reaches 2100~2150℃, and the temperature of the bottom loading area of the crucible body (41) reaches 2250~2300℃. At this time, silicon-containing gas is injected into the crucible body (41) through the central gas inlet (11) passage, with a flow rate of 200 sccm and a pressure of 10~50 Torr. Step 3: After the heating stage is completed, while continuing to introduce silicon-containing gas, turn on the resistor support base (32) and drive the lower heating resistor (31) upward in the vertical direction. At this time, the lower heating resistor (31) drives the support ring (50) to move upward synchronously through the heat insulation element (311). At this time, because the outer end of the seed crystal base (44) is placed on the top of the inner ring side of the support ring (50), the seed crystal base (44) will gradually move upward away from the upper end of the crucible body (41). Because of the gap in the crucible body (41), the L-shaped channel (51) opened in the support ring (50) close to the outer wall of the crucible body (41) connects the internal space of the crucible body (41) with the internal space of the upper guide shroud (46) and the upper crucible cover (45); after the lower heating resistor (31) reaches the target height, the temperature of the bottom loading area of the crucible body (41) is stabilized at 2250~2300℃, and the temperature of the seed crystal (442) area is stabilized at 2100~2150℃; Step 4: After the crystal growth stage is completed, stop injecting silicon-containing gas, increase the argon flow rate to 1000 sccm, and gradually lower the temperature inside the crystal growth furnace (10) to 1000℃ at a rate of 2℃ / min, and then allow it to cool naturally. Open the resistor support base (32) and lower the lower heating resistor (31) to complete the reset. When the temperature inside the furnace is less than 50℃, open the furnace and take out the crystal.