Polycrystalline silicon carbide vapor phase growth device

Abstract

The invention relates to the technical field of silicon carbide production, and discloses a polycrystalline silicon carbide vapor phase growth device, the bottom of a crucible is used for placing silicon carbide powder, the upper end of the crucible is provided with a seed crystal cover for installation, and the lower end of the seed crystal cover is uniformly provided with a plurality of seed crystals; a plurality of heat conduction channels used for transferring heat are installed on the side, close to the outer side, in the thermal resistance block in a surrounding mode, a heat conduction column used for conducting heat is fixedly installed at the center of the thermal resistance block, it is ensured that heat can be evenly and efficiently transferred to a seed crystal area according to a preset path through a heat conduction mechanism, temperature fluctuation caused by disordered heat transfer is reduced, and the heat conduction efficiency is improved. According to the heat conduction column, heat can be stably conveyed to a seed crystal area, the spiral shape of the upper end and the lower end of the heat conduction column optimizes the heat transfer path, the thermal stress in the seed crystal growth process is reduced, a more stable and concentrated heat source is provided for crystal growth, and then the spiral dislocation forming probability is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of silicon carbide production, in particular to a polycrystalline silicon carbide vapor phase growth device. Background Art

[0002] Silicon carbide (SiC) is a high-performance semiconductor material. With its excellent physical and chemical properties, such as high hardness, high wear resistance, high thermal conductivity, good chemical stability and wide bandgap characteristics, it shows great application potential in power electronics, high-temperature structural materials, optoelectronics and microwave devices. In particular, its excellent thermal conductivity and high-temperature resistance make silicon carbide an ideal material for manufacturing high-power density and high-efficiency electronic devices. Silicon carbide crystals mainly exist in two forms: single crystal and polycrystalline. Among them, polycrystalline silicon carbide occupies an important position in many industrial applications due to its relatively simple preparation process and low cost.

[0003] The vapor growth technology of polycrystalline silicon carbide is one of the key means to prepare high-quality silicon carbide materials. Its core lies in the precise control of heating, sublimation, transmission and condensation crystallization processes to make silicon carbide powder sublime at high temperature to form a gas, and then condense and crystallize in a certain orientation on the surface of the seed crystal to gradually accumulate and form polycrystalline silicon carbide crystals. This process not only requires a high degree of process precision, but also relies on the fine control of multiple factors such as temperature, pressure, gas composition, seed crystal quality and growth environment. The vapor growth technology has become the mainstream method for preparing polycrystalline silicon carbide in the current industry due to its fast growth rate, large-area crystals with controllable composition.

[0004] Although polycrystalline silicon carbide vapor growth technology has made remarkable progress in improving material properties and broadening application fields, it still faces a series of complex problems in practical applications. Screw dislocations have become a key obstacle to improving crystal quality. Due to various structural and functional defects, screw dislocations have a high probability of occurring in traditional polycrystalline silicon carbide vapor growth devices. It is difficult to effectively suppress the formation of screw dislocations, which has a serious impact on the production of high-quality polycrystalline silicon carbide crystals. In response to the problem of screw dislocations, the present invention proposes a polycrystalline silicon carbide vapor growth device. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a polycrystalline silicon carbide vapor phase growth device to solve the above-mentioned problems.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a polycrystalline silicon carbide vapor phase growth device, comprising a crucible, the bottom of the crucible is used to place silicon carbide powder, the upper end of the crucible is equipped with a seed crystal cover for installation, and the lower end of the seed crystal cover is evenly equipped with multiple seed crystals, and also includes: The heat conduction mechanism comprises a heat resistance block, a plurality of heat conduction channels for transferring heat are installed around the outer side of the heat resistance block, and a heat conduction column for heat conduction is fixedly installed at the center of the heat resistance block.

[0007] Preferably, the crucible is conical in shape, with a wider bottom and gradually narrowing upwards. The crucible is made of gradient material as a whole, with the inner layer of the crucible made of material with low thermal conductivity, high temperature resistance and good affinity with silicon carbide, and the outer layer made of high thermal conductivity material to assist heat dissipation.

[0008] Preferably, the heat conduction channel is connected to the inside of the heat resistance block by brazing, the multiple heat conduction channels are installed at an angle, the heat resistance block is arranged in a close fit with the inner wall of the crucible, a second gap is arranged at the lower end of the heat resistance block, and silicon carbide powder is placed inside the second gap.

[0009] Preferably, the heat-conducting channels are arranged in an array around the inside of the thermal resistance block with the heat-conducting column as the center point, eight heat-conducting channels are provided, and the angle between adjacent heat-conducting channels is 45°.

[0010] Preferably, the lower half of the thermally conductive column is set to a spiral shape to increase the contact area between the thermally conductive column and the surrounding thermal environment. The middle of the thermally conductive column is set to a straight column, and the middle straight column part smoothly transports the heat collected by the lower half upward. The upper half of the thermally conductive column is set to an inward spiral shape, and the spiral of the upper part guides the heat to gather in the central area.

[0011] Preferably, a thermal buffer layer for thermal buffering is fixedly installed on the upper end of the heat-conducting mechanism inside the crucible. The thermal buffer layer is made of a gradient material as a whole, and the overall gradient process of the thermal buffer layer decreases exponentially from bottom to top. The overall material of the thermal buffer layer is adhered to the inner material of the crucible. A plurality of heat channels for guiding are arranged on the surface of the thermal buffer layer. The plurality of heat channels are uniformly arranged in tiny shapes on the surface of the thermal buffer layer, and a gap for buffering is arranged between the upper end of the heat-conducting mechanism and the thermal buffer layer.

[0012] Preferably, a coating is provided on the inner wall surface of the crucible to prevent the impurities of the crucible from seeping out and to keep the inner surface clean, and the coating is made of a ceramic coating.

[0013] A metal shell for protection is installed on the outside of the crucible, a groove is arranged on the upper end of the metal shell, a metal cover is installed inside the groove, and a fixing bolt for fixing is movably installed at the side end of the metal shell corresponding to the position of the metal cover.

[0014] Preferably, a fixing ring for fixing is fixedly installed inside the metal shell, a center hole is arranged at the center of the fixing ring, a fixing cylinder for supporting is fixedly installed inside the fixing ring, a limiting groove for sliding is arranged inside the fixing cylinder, a limiting block is slidably installed inside the limiting groove, a guide rod for guiding is fixedly installed near the inner end of the limiting block, and the other end of the guide rod is connected to the inner clamping block, a high temperature resistant spring is installed around the surface of the guide rod, one end of the high temperature resistant spring is fixedly installed to the limiting block, and the other end of the high temperature resistant spring is fixedly connected to the inner wall of the fixing cylinder, the inner clamping block fits with the outer surface of the crucible, a rough surface is arranged on the inner end surface of the inner clamping block, and a second rough surface is arranged on the outer surface of the corresponding crucible.

[0015] Preferably, a plurality of heat pipes for heat dissipation are fixedly installed on the surface of the crucible corresponding to the lower end of the fixing ring, the heat pipes are square in shape, a thermal insulation layer is arranged at the connection between the outer end of the heat pipe and the metal shell, a plurality of heat dissipation fins for heat dissipation are arranged on the outer surface of the metal shell corresponding to the position of the heat pipe, and the heat pipes penetrate the plurality of heat dissipation fins.

[0016] Compared with the prior art, the present invention provides a polycrystalline silicon carbide vapor phase growth device, which has the following beneficial effects: 1. In the polycrystalline silicon carbide vapor growth device, the crucible adopts a structure with a wide bottom and gradually narrowing upwards, which not only promotes the uniform heating of the raw materials, but also effectively prevents the accumulation of heat at the bottom of the crucible, thereby avoiding the concentration of thermal stress caused by excessive temperature gradient, thereby reducing the probability of screw dislocation. The crucible is made of gradient material, and the inner layer of the crucible is made of a material with low thermal conductivity, high temperature resistance and good affinity with silicon carbide, which ensures that the silicon carbide powder will not chemically react with the inner wall of the crucible during the sublimation process, prevents crystal contamination caused by chemical reaction, maintains the purity of the crystal, and also helps to reduce the thermal stress caused by material mismatch, further reducing the risk of screw dislocation.

[0017] 2. In this polycrystalline silicon carbide vapor growth device, the combination of thermal resistance blocks, thermal conduction channels and thermal conduction columns in the heat conduction mechanism ensures that heat can be evenly and efficiently transferred to the seed crystal area along a predetermined path, reduces temperature fluctuations caused by disordered heat transfer, enables heat to be smoothly transported to the seed crystal area, and provides a stable thermal environment for the seed crystal. The spiral shape of the upper and lower ends of the thermal conduction column optimizes the heat transfer path, enables heat to be smoothly transported to the seed crystal area, reduces thermal stress during seed crystal growth, provides a more stable and concentrated heat source for crystal growth, and thereby reduces the probability of screw dislocation formation.

[0018] 3. This polycrystalline silicon carbide vapor growth device introduces a thermal buffer layer, and through its gradient material design, achieves a smooth transition in the heat transfer process, reduces the impact of sudden heat changes on seed crystal growth, and achieves a smooth transition of heat. The heat channels evenly arranged on the surface of the thermal buffer layer further enhance the uniform distribution of heat, reduce growth defects caused by uneven heat distribution, ensure the stability of the seed crystal growth environment, and help reduce screw dislocations caused by uneven heat distribution.

[0019] 4. In this polycrystalline silicon carbide vapor growth device, the ceramic coating on the inner wall surface of the crucible not only has good high temperature resistance, but also can effectively prevent the seepage of impurities and the penetration of gas, maintain the cleanliness of the inner surface and the purity of the seed crystal growth environment, thereby reducing the screw dislocation caused by impurity contamination.

[0020] 5. In this polycrystalline silicon carbide vapor growth device, the inner layer of the crucible is made of a ceramic material with low thermal conductivity, high temperature resistance and good affinity with silicon carbide, and the outer layer of the crucible is made of a high thermal conductivity material. This structure can effectively buffer the temperature gradient and reduce the influence of thermal stress on crystal growth. During the crystal growth process, the inner and outer layer materials work together, the inner layer provides a suitable thermal environment for crystal growth, and the outer layer dissipates excess heat in time to reduce screw dislocations caused by thermal stress. The gradient material can also control the diffusion of impurities to a certain extent. The inner layer material can block impurities that may exist in the outer layer of the crucible from penetrating into the growth area, thereby ensuring the purity of the growth environment, avoiding impurities from interfering with the crystal growth process, and reducing the frequency of crystal defects.

[0021] 6. This polycrystalline silicon carbide vapor growth device significantly improves the controllability and repeatability of silicon carbide crystal growth by precisely controlling key links such as heating, sublimation, transmission and heat conduction. Under the same growth conditions, it can more stably grow silicon carbide crystals of the same quality and reduce defects such as screw dislocations caused by process fluctuations.

[0022] 7. In this polycrystalline silicon carbide vapor growth device, the heat conduction mechanism and the heat buffer layer work together to optimize the heat transfer and distribution, promote the uniform deposition and sublimation crystallization of silicon carbide gaseous raw materials on the surface of the seed crystal, thereby accelerating the crystal growth rate and improving the uniformity and integrity of the crystal.

[0023] 8. A polycrystalline silicon carbide vapor growth device is provided with a metal shell installed on the outside of the crucible. The metal shell is provided with a sealing structure. At the same time, the gap between the inside of the metal shell and the crucible is filled with inert gas, which effectively prevents the outside air and its impurities, oxygen and other active components from invading the inside of the crucible. On the one hand, it avoids chemical reactions such as oxidation of the substances in the crucible, prevents the production of new substances due to chemical changes that change the thermal properties, maintains the uniformity of the internal thermal properties, and eliminates the hidden dangers of thermal stress fluctuations induced by chemical factors; on the other hand, the stable internal environment reduces the temperature unevenness caused by external interference during the crystal growth process, and reduces the probability of screw dislocations.

[0024] 9. In this polycrystalline silicon carbide vapor growth device, a fixing ring, a fixing cylinder, a limit block, a guide rod, a high-temperature resistant spring and an inner clamping block are used to fix the crucible. When the crucible undergoes thermal expansion and contraction, the fixing structure can always maintain a stable clamping force to ensure that the crucible is fixed in position without shaking or displacement, thereby avoiding internal temperature gradient disturbances caused by changes in the crucible position, reducing thermal stress concentration, and thus greatly reducing the probability of screw dislocation formation.

[0025] 10. In this polycrystalline silicon carbide vapor growth device, the cross-shaped heat pipes evenly absorb heat from the inside of the crucible, eliminate local overheating, maintain the overall temperature uniformity of the crucible, and reduce the source of thermal stress. The thermal insulation layer guides the heat to the heat sink fins to avoid disorderly heat conduction. The heat sink fins and air efficiently exchange heat, and the heat from the heat pipes is dissipated in time to ensure that the heat of the device is dissipated in a timely and efficient manner and maintain internal thermal balance. During the production process, the temperature inside the crucible is stabilized to avoid uncontrolled temperature fluctuations, protect the crystal from interference from uneven thermal stress, and thereby reduce the possibility of screw dislocations. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of the crucible of the present invention; Figure 2 It is a structural schematic diagram of the installation angle of the heat conducting mechanism of the present invention; Figure 3 For the present invention Figure 2 A schematic diagram of the structure from a side view; Figure 4 It is a cross-sectional schematic diagram of the heat conduction mechanism of the present invention; Figure 5 This is a schematic diagram of the structure of the thermal buffer layer of the present invention; Figure 6 For the present invention Figure 1 A partial enlarged view of area A in the middle.

[0027] Figure 7 It is a schematic structural diagram of a polycrystalline silicon carbide vapor phase growth device of the present invention; Figure 8It is a schematic diagram of the structure of the polycrystalline silicon carbide vapor phase growth device from a top view of the present invention; Fig. 9 It is a structural schematic diagram of the clamping structure of the present invention; Fig.10 It is a schematic structural diagram of a side view of a polycrystalline silicon carbide vapor phase growth device of the present invention.

[0028] In the figure: 1. crucible; 2. silicon carbide powder; 3. seed crystal cover; 4. seed crystal; 5. heat conduction mechanism; 6. thermal resistance block; 7. heat conduction channel; 8. heat conduction column; 9. thermal buffer layer; 10. gap; 11. heat channel; 12. coating; 13. second gap; 14. fixing ring; 15. metal shell; 16. metal cover; 17. fixing bolt; 18. third gap; 19. center hole; 20. fixing cylinder; 21. limit groove; 22. limit block; 23. guide rod; 24. high temperature resistant spring; 25. inner clamping block; 26. rough surface; 27. second rough surface; 28. heat pipe; 29. ​​thermal insulation layer; 30. heat sink fins. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field without making creative work based on the embodiments in the present invention are within the scope of protection of the present invention.

[0030] See also Figure 1-10 , a polycrystalline silicon carbide vapor phase growth device, comprising a crucible 1, the bottom of the crucible 1 is used to place silicon carbide powder 2, the upper end of the crucible 1 is equipped with a seed crystal cover 3 for installation, and the lower end of the seed crystal cover 3 is evenly equipped with multiple seed crystals 4, and also includes: a heat conduction mechanism 5, the heat conduction mechanism 5 includes a thermal resistor block 6, and the inner side of the thermal resistor block 6 is surrounded by multiple heat conduction channels 7 for transferring heat, and a heat conduction column 8 for heat conduction is fixedly installed at the center of the thermal resistor block 6. The crucible 1 is conical in shape, with a wider bottom and gradually narrowing upwards. The whole is composed of gradient materials, and its bottom is used to place silicon carbide powder 2 to provide a raw material basis for the growth of polycrystalline silicon carbide; the seed crystal cover 3 is installed at the upper end, which is an important container and reaction place of the whole device. The seed crystal cover 3 is installed at the upper end of the crucible 1 to protect the internal growth environment and fix the seed crystals. The heat conduction mechanism 5 provides a stable thermal environment for the growth process through the synergistic effect of the thermal resistor block 5, the heat conduction column 8 and the heat conduction channel 7.

[0031] Furthermore, the crucible 1 is in a conical shape, the bottom of the crucible 1 is relatively wide and gradually narrows upwards, the crucible 1 is made of a gradient material as a whole, the inner layer of the crucible 1 is made of a material with low thermal conductivity, high temperature resistance and good affinity with silicon carbide, and the outer layer is made of a high thermal conductivity material to assist in heat dissipation, and the conical shape allows the heat to diffuse naturally to the surroundings during the process of gradually conducting upwards inside the crucible 1. Since the crucible 1 gradually narrows upwards, the heat will converge toward the central area along the inner wall of the crucible 1 when it is transferred upwards, so that the heat forms a relatively uniform temperature distribution inside the crucible 1. This uniform The temperature distribution is conducive to the uniform growth of polycrystalline silicon carbide and avoids uneven crystal growth caused by local overheating or overcooling. The crucible 1 is composed of gradient materials as a whole, and the inner layer of the crucible 1 is made of materials with good affinity to silicon carbide. During the gas phase growth process, silicon carbide molecules are more likely to deposit and grow on the surface of the inner layer material with good affinity, which is conducive to the formation of high-quality polycrystalline silicon carbide and avoids heat transfer to the seed crystal area too quickly, thereby preventing the seed crystal from being subjected to thermal shock. The outer layer uses high thermal conductivity materials to assist in heat dissipation, which can effectively dissipate excess heat inside the crucible 1.

[0032] Furthermore, the heat-conducting channel 7 is connected to the inside of the thermal resistance block 6 by brazing, and multiple heat-conducting channels 7 are installed at an angle. The thermal resistance block 6 is arranged in a fitted state with the inner wall of the crucible 1. A second gap 13 is arranged at the lower end of the thermal resistance block 6, and the silicon carbide powder 2 is placed in the second gap 13. The heat-conducting channel 7 is fixed to the inside of the thermal resistance block 6 by brazing. Brazing is a process that can tightly connect two metal materials, which can reduce the thermal resistance at the connection. Brazing can reduce the thermal resistance at the connection, can achieve good heat conduction, and ensure the smooth transfer of heat between the interfaces of the two materials. At the same time, the brazing connection provides higher connection strength and stability, prevents the heat-conducting channel 7 from loosening or shifting during operation, and ensures the stability of the heat transfer path. The heat-conducting channel 7 is installed at an angle to better adapt to the direction of heat flow. The heat-conducting channel 7 is installed at an angle so that the heat can be naturally transferred along the direction of temperature increase, which is more consistent with the main direction of heat flow, reducing the resistance and directional mutation in the heat transfer process. The thermal resistance block 6 is fixed in a fit with the inner wall of the crucible 1 to prevent the relative displacement between the components from affecting heat conduction and crystal growth.

[0033] Furthermore, the heat conducting channels 7 are arrayed around the heat conducting column 8 as the center point and surround the inside of the thermal resistance block 6. There are eight heat conducting channels 7, and the angle between adjacent heat conducting channels 7 is 45°. The eight heat conducting channels 7 are arrayed around the heat conducting column 8 as the center, which can capture gases from different directions and ensure all-round gas collection of the surrounding thermal environment. In the polycrystalline silicon carbide vapor growth device, the uniform heat intake method can avoid local heat leakage, make the heat collection more comprehensive, and help to disperse thermal stress. The uniform angle design of 45° between adjacent heat conducting channels 7 ensures that heat can be evenly conducted to the heat conducting column 8.

[0034] Furthermore, the lower half of the heat-conducting column 8 is set in a spiral shape to increase the contact area between the heat-conducting column 8 and the surrounding thermal environment. The middle of the heat-conducting column 8 is set as a straight column. The middle straight column part smoothly transfers the heat collected by the lower half upward. The upper half of the heat-conducting column 8 is set in an inward spiral shape. The spiral of the upper part guides the heat to gather in the central area. The spiral shape significantly increases the contact area between the lower half of the heat-conducting column 8 and the surrounding thermal environment. More heat can be transferred from the surrounding environment to the heat-conducting column 8, effectively absorbing the heat from the bottom of the crucible 1. The straight column part can make the heat more stable during the upward transmission. According to the principle of heat conduction, thermal resistance is related to the length and complexity of the heat flow path. The straight column part is shorter and has a simple structure, which can reduce the resistance of heat transmission inside the heat-conducting column 8. The inward spiral shape of the upper part can guide the heat transferred from the lower part and the middle straight column part and gather it in the central area. In the vapor phase growth of polycrystalline silicon carbide, the seed crystal 4 is usually located near the center position. The inner spiral shape can make the heat act more concentratedly on the seed crystal 4, provide more sufficient heat for the seed crystal 4, meet the temperature requirements of crystal growth, and promote the growth of polycrystalline silicon carbide on the seed crystal 4. At the same time, the inward spiral structure can form a specific thermal field distribution in the upper part of the thermal column 8, so that the heat is more evenly distributed in the central area, avoiding local overheating or overcooling in the central area, thereby creating a more ideal thermal growth environment for the seed crystal 4 and reducing crystal defects caused by uneven thermal field.

[0035] Furthermore, a heat buffer layer 9 for heat buffering is fixedly installed on the upper end of the heat conducting mechanism 5 inside the crucible 1. The heat buffer layer 9 is made of a gradient material as a whole. The overall gradient process of the heat buffer layer 9 is exponentially decreasing from bottom to top. The overall material of the heat buffer layer 9 is adhered to the inner material of the crucible 1. Furthermore, a plurality of heat channels 11 for guiding are arranged on the surface of the heat buffer layer 9. The plurality of heat channels 11 are evenly arranged on the surface of the heat buffer layer 9 in a tiny shape. A gap 10 for buffering is arranged between the upper end of the heat conducting mechanism 5 and the heat buffer layer 9. The heat buffer layer 9 is located between the heat conducting mechanism 5 and the seed crystal 4, and can effectively buffer the heat transmitted from the heat conducting mechanism 5. When the heat is conducted from the heat conducting channel 7 and the heat conducting column 8 to the heat buffer layer 9, due to its gradient The characteristics of the variable material are that the thermal conductivity of the bottom material is relatively high, which can quickly absorb and disperse heat, avoid local concentration of heat, and prevent thermal shock from directly acting on the seed crystal 4. When the heat flow changes suddenly, the thermal buffer layer 9 can slow down the drastic change of the heat flow, making the temperature rise process around the seed crystal 4 more gentle. The gradient material structure of the thermal buffer layer 9 helps to maintain a stable thermal environment, and its thermal conductivity decreases exponentially from bottom to top, thereby forming a relatively stable temperature area around the seed crystal 4, reducing the change in crystal growth rate due to temperature fluctuations, affecting the quality and structure of the crystal, and then increasing the probability of screw dislocations. The material of the thermal buffer layer 9 adheres to the inner material of the crucible 1, so that in a high temperature environment, the thermal buffer layer 9 does not The heat channels 11 are arranged on the surface of the heat buffer layer 9, and the heat transfer mechanism 5 is arranged on the surface of the heat buffer layer 9. The heat channels 11 are arranged on the surface of the heat buffer layer 9, and the heat transfer mechanism 5 is arranged on the surface of the heat buffer layer 9. The heat channels 11 are arranged on the surface of the heat buffer layer 9, and the heat transfer mechanism 5 is arranged on the surface of the heat buffer layer 9. The heat channels 11 are arranged on the surface of the heat buffer layer 9, and the heat transfer mechanism 5 is arranged on the surface of the heat buffer layer 9. The heat channels 11 are arranged on the surface of the heat buffer layer 9, and the heat channels 11 are ... When the heat flux suddenly enters the heat buffer layer 9 from the heat conducting mechanism 5, the heat channel 11 can play a buffering role to reduce the impact of thermal shock on the heat buffer layer 9 and the seed crystal 4. The heat resistance block 6 is mainly used to limit the unexpected diffusion of heat, and its temperature distribution is quite different from that of the heat buffer layer. After the interval 10 is set, the heat flux will not be directly transferred from the heat resistance block 6 to the heat buffer layer 9, but will pass through the gas in the interval. The thermal conductivity of the gas is much lower than that of the solid material, which can play a buffering role to prevent the heat buffer layer 9 from being subjected to the thermal shock inside the heat resistance block 6. For example, in the initial stage of heating, the temperature of the heat resistance block 6 may rise rapidly. The interval 10 can prevent the overheated heat resistance block 6 from transferring heat to the heat buffer layer 9 too quickly, making the temperature rise process of the heat buffer layer 9 more gentle.At the same time, the gas layer in the interval 10 allows the heat flow to diffuse and adjust its direction to a certain extent before reaching the thermal buffer layer. The thermal resistance block 6 and the thermal buffer layer 9 are made of different materials. Under high temperature environment, these materials may react chemically. Setting the interval 10 can isolate the two materials and reduce the chance of their direct contact, thereby avoiding possible chemical reactions.

[0036] Furthermore, a coating 12 is provided on the inner wall surface of the crucible 1 to prevent the seepage of impurities in the crucible 1 itself and to keep the inner surface clean. The coating 12 is made of a ceramic coating, which can not only improve the smoothness of the inner surface, but also prevent the seepage of impurities in the crucible 1 material itself, thereby preventing impurities from interfering with the crystal growth process. The coating 12 has a good interaction with silicon carbide atoms, which can guide the orderly deposition of atoms and reduce screw dislocations caused by impurities or surface irregularities.

[0037] Furthermore, a metal shell 15 for protection is installed on the outside of the crucible 1, a groove is set at the upper end of the metal shell 15, a metal cover 16 is installed inside the groove, a fixing bolt 17 for fixing is movably installed at the side end of the metal shell 15 corresponding to the position of the metal cover 16, a sealing gasket for sealing is installed at the connection between the lower end of the metal cover 16 and the metal shell 15, a third gap 18 is set between the inside of the metal shell 15 and the crucible 1, and the inside of the third gap 18 is filled with inert gas, the groove at the upper end of the metal shell 15 is tightly matched with the metal cover 16 embedded therein, and the fixing bolt 17 at the side end The metal cover 16 is fixed. At the same time, the third gap 18 arranged between the inside of the metal shell 15 and the crucible 1 is filled with inert gas to form a sealing system. This sealing structure and the inert gas can effectively prevent external dust, water vapor and other impurities from entering the crucible 1. During the crystal growth process, the invasion of impurities can easily cause local thermal performance fluctuations, and then breed uneven thermal stress, which becomes the cause of screw dislocations. The perfect sealing and inert gas protection mechanism creates a stable and pure environment for crystal growth. The metal shell 15 provides all-round physical support for the crucible 1.

[0038] Furthermore, a fixing ring 14 for fixing is fixedly installed inside the metal shell 15, a center hole 19 is provided at the center of the fixing ring 14, and a fixing cylinder 20 for supporting is fixedly installed inside the fixing ring 14. A limiting groove 21 for sliding is arranged inside the fixed cylinder 20, a limiting block 22 is installed for sliding inside the limiting groove 21, a guide rod 23 for guiding is fixedly installed on the inner end of the limiting block 22, and the other end of the guide rod 23 is connected to the inner clamping block 25, a high temperature resistant spring 24 is installed around the surface of the guide rod 23, one end of the high temperature resistant spring 24 is fixedly installed on the limiting block 22, and the other end of the high temperature resistant spring 24 is fixedly connected to the inner wall of the fixed cylinder 20, the inner clamping block 25 fits the outer surface of the crucible 1, a rough surface 26 is arranged on the inner end surface of the inner clamping block 25, and a second rough surface 27 is arranged on the outer surface of the corresponding crucible 1, and the fixing ring 14 is precisely surrounded by the outer side of the crucible 1 through the center hole 19, providing a crucible 1 with The initial positioning and constraint ensure that the crucible 1 is in a stable central position in the metal shell 15. When the device is running in different stages of the heating and cooling cycle, the crucible 1 will change in size due to the thermal expansion and contraction effect. The limit block 22 can slide flexibly in the limit groove 21, and the position of the inner clamping block 25 can be adjusted in real time through the guide rod 23. This adaptive adjustment mechanism can always keep the inner clamping block 25 in close contact with the outer surface of the crucible 1, prevent the crucible 1 from having gaps or collisions with surrounding components due to size changes, avoid temperature field disturbances caused by loosening and shaking of the crucible 1, reduce thermal stress fluctuations, and thus reduce the probability of screw dislocations. In the heating and cooling cycles of the device, the thermal expansion and contraction of the crucible 1 can be adjusted. The crucible 1 can be larger in size, and the high temperature resistant spring 24 can buffer the impact caused by such dimensional changes, which ensures that the crucible 1 will not be squeezed and deformed due to excessive expansion, nor will it be separated from the fixed structure due to excessive contraction. The stable clamping state makes the heat conduction path around the crucible 1 stable, and the heat can be transferred and dissipated in an orderly manner, avoiding thermal stress abnormalities caused by structural instability. In order to reduce the possibility of screw dislocation, the presence of the rough surface 26 and the second rough surface 27 increases the friction between the inner clamping block 25 and the crucible 1. When the crucible has a large thermal expansion and contraction, the inner clamping block 25 can hold the crucible 1 more firmly by virtue of the strong friction between the rough surfaces, so that the crucible 1 always maintains a fixed position inside the metal shell 15, and will not The crucible 1 is not easily displaced or shaken, which effectively avoids the disturbance of the uniform temperature field inside due to the change of the position of the crucible 1, reduces the uneven distribution of thermal stress, and thus reduces the risk of screw dislocation. The close fit between the rough surfaces is conducive to the conduction of heat. The rough surface 26 and the second rough surface 27 have more contact points. These contact points are like tiny thermal bridges, which can allow heat to be more efficiently transferred from the crucible 1 to the inner clamping block 25, and then dissipated to the surroundings through structures such as the fixing ring 14. During the crystal growth process, the stable and efficient heat conduction path ensures that the heat of the crucible 1 will not accumulate, and the temperature distribution is more uniform, creating a stable thermal environment for crystal growth, and effectively suppressing screw dislocations caused by local overheating or local overcooling.

[0039] Furthermore, a plurality of heat pipes 28 for heat dissipation are fixedly installed on the surface of the crucible 1 corresponding to the lower end of the fixing ring 14. The heat pipes 28 are arranged in a square shape. A thermal insulation layer 29 is arranged at the connection between the outer end of the heat pipe 28 and the metal shell 15. A plurality of heat dissipation fins 30 for heat dissipation are arranged on the outer surface of the metal shell 15 corresponding to the position of the heat pipe 28. The heat pipe 28 penetrates the plurality of heat dissipation fins 30. Four heat pipes 28 are arranged. The four square heat pipes 28 arranged in a cross shape are closely attached to the surface of the crucible 1 to form a balanced heat absorption structure. The structure absorbs the heat generated by the crucible 1 from multiple directions simultaneously. Compared with a single heat pipe or a randomly distributed heat pipe, the structure has a wider coverage and more uniform heat absorption. At the same time, the contact area between the heat pipe 28 and the inside of the metal shell 15 is increased, thereby increasing the heat dissipation efficiency. The efficiency of heating absorption reduces the hidden danger of excessive local heat accumulation. The cross-shaped heat pipe layout can maintain the uniformity of the overall temperature of the crucible 1, reduce the thermal stress concentration caused by uneven temperature, and thus reduce the risk of screw dislocations. The thermal insulation layer 29 prevents unnecessary heat loss or accumulation on the metal shell 15, ensures the accuracy of the heat transfer path, effectively prevents local temperature anomalies caused by disordered heat conduction, further stabilizes the temperature field inside the metal shell 15, and reduces the inducing factors of screw dislocations. The heat dissipation fins 30 quickly dissipate the heat transferred by the heat pipes 28 through their own area, maintain a suitable temperature environment, so that the crystal growth interface is always stable, greatly reducing thermal stress mutations caused by temperature fluctuations, and reducing the occurrence of screw dislocations.

[0040] Instructions Working principle: The core component of the device is the crucible 1, which is made of a special gradient material. The bottom of the crucible is wide and gradually narrows upwards, which is not only conducive to the uniform heating of the raw materials, but also effectively prevents the accumulation of heat at the bottom of the crucible, thereby avoiding thermal stress caused by excessive temperature gradient. The inner layer of the crucible is made of a material with low thermal conductivity, high temperature resistance and good affinity with silicon carbide. This material can ensure that the silicon carbide powder will not react chemically with the inner wall of the crucible during the sublimation process, thereby ensuring the purity of the crystal. The outer layer of the crucible is made of a high thermal conductivity material to quickly transfer heat to the external environment, ensuring heating efficiency while reducing energy loss, helping to maintain the uniformity of temperature in the growth chamber, thereby reducing stress caused by temperature fluctuations, and further reducing the probability of screw dislocations. Inside the crucible 1, silicon carbide powder 2 is placed, which is the main raw material for growing silicon carbide crystals. When the crucible 1 is heated by an external heating source, the silicon carbide powder 2 will sublimate at high temperature to form gaseous silicon carbide. These gaseous silicon carbides will form a certain gas pressure and temperature gradient inside the crucible 1, providing necessary conditions for subsequent crystal growth. In order to ensure that the gaseous silicon carbide can be evenly and stably transmitted to the surface of the seed crystal 4, a heat conduction mechanism 5 is set inside the crucible 1; The heat conduction mechanism 5 includes a heat resistance block 6, a heat conduction channel 7 and a heat conduction column 8. The heat conduction mechanism ensures that heat can be evenly and efficiently transferred to the seed crystal cover 3 and the seed crystal 4. The main function of the heat resistance block 6 is to reduce the disordered heat transfer and ensure that the heat can be transferred along a predetermined path. The heat conduction channel 7 is centered on the heat conduction column 8 and surrounds the heat resistance block 6 in an array at a 45° angle. The heat conduction channel 7 improves the efficiency of heat transfer and ensures the stability of the growth environment of the seed crystal 4, which helps to reduce the screw dislocation caused by uneven temperature. The spiral shape of the upper and lower ends of the heat conduction column 8 optimizes the heat transfer path. The spiral shape of the lower half of the heat conduction column 8 collects heat from the gas below, the middle straight column part smoothly transports heat, and the upper half guides the heat to converge in the central area, providing a stable thermal environment for the growth of the seed crystal 4. The heat conduction mechanism 5 helps to reduce thermal stress during the growth of the seed crystal, thereby reducing the risk of screw dislocation. A heat buffer layer 9 is provided above the heat conducting mechanism 5 to further reduce the influence of sudden changes in heat on the growth of the seed crystal 4. The heat buffer layer 9 adopts a gradient material, and its thermal conductivity decreases exponentially from bottom to top, so that the heat can be gradually slowed down during the transfer process, thereby achieving a smooth transition of heat. At the same time, heat channels 11 are evenly provided on the surface of the heat buffer layer 9 to further guide the heat and stabilize the growth environment of the seed crystal 4, which is conducive to the uniform distribution of heat and can also reduce screw dislocations caused by uneven heat distribution; The seed crystal 4 is located below the seed crystal cover 3 and is the starting point of the growth of the silicon carbide crystal. The gaseous silicon carbide is deposited on the surface of the seed crystal 4 and undergoes sublimation crystallization to form polycrystalline silicon carbide crystals. The seed crystal cover 3 protects the seed crystal 4 from interference from the external environment and ensures that the gaseous silicon carbide can be uniformly deposited on the surface of the seed crystal 4, thereby reducing screw dislocations caused by uneven deposition. In addition, in order to prevent the impurities of the crucible 1 from seeping out, the inner wall surface of the crucible 1 is also coated with a ceramic coating 12, which not only has good high temperature resistance, but also can effectively prevent the seepage of impurities and the penetration of gas, keep the inner surface clean and the growth environment of the seed crystal 4 pure, thereby reducing screw dislocations caused by impurity contamination; The metal shell 15 on the outside of the crucible 1 provides protection for the crucible 1. The groove on the upper end of the metal shell 15 is used to accommodate the metal cover 16. The metal cover 16 is fixed to the metal shell 15 by fixing bolts 17 to form a closed space. The sealing gasket is installed at the connection between the metal cover 16 and the metal shell 15 to ensure the sealing of the internal space, so that the third gap 18 between the metal shell 15 and the crucible 1 can be kept full of inert gas. The sealed environment prevents the outside air from entering. The stable inert gas environment avoids the chemical reaction between the substance in the crucible 1 and the active ingredients such as oxygen in the outside air. By maintaining a pure internal environment, it is helpful to maintain uniform thermal performance and reduce thermal stress changes caused by chemical factors, thereby reducing the probability of screw dislocations. The fixing ring 14 surrounds the crucible 1 through the center hole 19, the fixing cylinder 20 provides internal support, the limit block 22 slides in the limit groove 21, the guide rod 23 connects the limit block 22 and the inner clamping block 25, and the high temperature resistant spring 24 provides an inward elastic force, so that the inner clamping block 25 is tightly fitted with the second rough surface 27 on the outer surface of the crucible 1 through the rough surface 26, so as to achieve stable fixation of the crucible 1. When the crucible 1 changes in size due to thermal expansion and contraction, the high temperature resistant spring 24 can adaptively adjust the position of the inner clamping block 25 to maintain a stable clamping force. The stable clamping structure ensures that the position of the crucible 1 is fixed during the heating and cooling process, and avoids the shaking or displacement of the crucible 1. If the position of the crucible 1 is unstable, it will lead to an uneven distribution of the internal temperature field and generate thermal stress. This stable fixing method helps to reduce the temperature gradient change caused by the change of the position of the crucible 1, thereby reducing the probability of screw dislocation. Four cross-shaped square heat pipes 28 are arranged on the surface of the crucible 1. They fit tightly to the crucible 1 and efficiently absorb the heat generated by the crucible 1. Due to the cross-shaped distribution, the heat generated by different areas of the crucible 1 can be evenly absorbed from multiple key directions, which greatly avoids the situation of local heat accumulation. The heat pipe 28 transfers the absorbed heat to the outside. At the connection with the metal shell 15, the thermal insulation layer 29 plays a key role. It reduces the unnecessary conduction of heat to the metal shell 15 and accurately guides the heat to flow mainly in the direction of the heat dissipation fins 30. The heat dissipation fins 30 are installed on the outer surface of the metal shell 15 according to the position of the heat pipe 28. The surface area of ​​the crucible 1 can fully exchange heat with the external air, and the heat transmitted from the heat pipe 28 can be quickly dissipated into the surrounding environment, so as to ensure the timeliness and efficiency of heat dissipation of the entire device, maintain the thermal balance inside the device, and the uniform temperature field can protect the crystal from the interference of uneven thermal stress during the growth process, which greatly reduces the root cause of screw dislocation. The powerful heat dissipation performance of the heat dissipation fins 30 further ensures that the temperature of the crucible 1 is always within a reasonable control range. Whether it is the heating, constant temperature or cooling stage of crystal growth, it can accurately maintain the appropriate temperature, reduce the thermal stress mutation caused by temperature fluctuation or loss of control, and help reduce the probability of screw dislocation in all directions.

[0041] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A polycrystalline silicon carbide vapor phase growth device, comprising a crucible (1), the bottom of the crucible (1) being used to place silicon carbide powder (2), the upper end of the crucible (1) being provided with a seed crystal cover (3) for installation, the lower end of the seed crystal cover (3) being provided with a plurality of seed crystals (4) evenly installed, characterized in that: Also includes: A heat conduction mechanism (5), the heat conduction mechanism (5) comprising a heat resistance block (6), a plurality of heat conduction channels (7) for transferring heat being installed around the outside of the heat resistance block (6), and a heat conduction column (8) for heat conduction being fixedly installed at the center of the heat resistance block (6).

2. The polycrystalline silicon carbide vapor phase growth device according to claim 1, characterized in that: The crucible (1) is conical in shape, with the bottom of the crucible (1) being wider and gradually narrowing upwards; the crucible (1) is made of a gradient material as a whole; the inner layer of the crucible (1) is made of a material with low thermal conductivity, high temperature resistance and good affinity with silicon carbide, and the outer layer is made of a material with high thermal conductivity to assist heat dissipation.

3. The polycrystalline silicon carbide vapor phase growth device according to claim 1, characterized in that: The heat conduction channel (7) is connected to the inside of the heat resistance block (6) by brazing, the multiple heat conduction channels (7) are installed in an inclined manner, the heat resistance block (6) is arranged in a close-fitting manner with the inner wall of the crucible (1), a second gap (13) is arranged at the lower end of the heat resistance block (6), and the silicon carbide powder (2) is placed inside the second gap (13).

4. The polycrystalline silicon carbide vapor phase growth device according to claim 3, characterized in that: The heat-conducting channels (7) are arranged in an array around the interior of the thermal resistance block (6) with the heat-conducting column (8) as the center point. Eight heat-conducting channels (7) are provided, and the angle between adjacent heat-conducting channels (7) is 45°.

5. The polycrystalline silicon carbide vapor phase growth device according to claim 1, characterized in that: The lower part of the heat-conducting column (8) is arranged in a spiral shape to increase the contact area between the heat-conducting column (8) and the surrounding thermal environment; the middle of the heat-conducting column (8) is arranged in a straight column, and the middle straight column part smoothly transports the heat collected by the lower part upward; the upper part of the heat-conducting column (8) is arranged in an inward spiral shape, and the spiral of the upper part guides the heat to gather in the central area.

6. The polycrystalline silicon carbide vapor phase growth device according to claim 1, characterized in that: A heat buffer layer (9) for heat buffering is fixedly installed at the upper end of the heat conducting mechanism (5) inside the crucible (1); the heat buffer layer (9) is made of a gradient material as a whole; the gradient process of the heat buffer layer (9) decreases exponentially from bottom to top; the whole material of the heat buffer layer (9) is adhered to the inner material of the crucible (1); a plurality of heat channels (11) for guiding are arranged on the surface of the heat buffer layer (9); the plurality of heat channels (11) are evenly arranged in a tiny shape on the surface of the heat buffer layer (9); and a gap (10) for buffering is arranged between the upper end of the heat conducting mechanism (5) and the heat buffer layer (9).

7. The polycrystalline silicon carbide vapor phase growth device according to claim 1, characterized in that: A coating (12) is provided on the inner wall surface of the crucible (1) to prevent impurities from seeping out of the crucible (1) itself and to keep the inner surface clean; the coating (12) is made of a ceramic coating.

8. The polycrystalline silicon carbide vapor phase growth device according to claim 1, characterized in that: A metal shell (15) for protection is installed on the outer side of the crucible (1), a groove is arranged at the upper end of the metal shell (15), a metal cover (16) is installed inside the groove, a fixing bolt (17) for fixing is movably installed at the side end of the metal shell (15) corresponding to the position of the metal cover (16), a sealing gasket for sealing is installed at the connection between the lower end of the metal cover (16) and the metal shell (15), a third gap (18) is arranged between the inside of the metal shell (15) and the crucible (1), and the inside of the third gap (18) is filled with an inert gas.

9. The polycrystalline silicon carbide vapor phase growth device according to claim 8, characterized in that: A fixing ring (14) for fixing is fixedly installed inside the metal shell (15), a center hole (19) is arranged at the center of the fixing ring (14), a fixing cylinder (20) for supporting is fixedly installed inside the fixing ring (14), a limiting groove (21) for sliding is arranged inside the fixing cylinder (20), a limiting block (22) is slidably installed inside the limiting groove (21), a guide rod (23) for guiding is fixedly installed on one inner end of the limiting block (22), and the other end of the guide rod (23) is fixedly mounted on the inner end of the limiting block (22). The end of the guide rod (23) is connected to the inner clamping block (25), a high temperature resistant spring (24) is installed around the surface of the guide rod (23), one end of the high temperature resistant spring (24) is fixedly installed to the limit block (22), and the other end of the high temperature resistant spring (24) is fixedly connected to the inner wall of the fixed cylinder (20), the inner clamping block (25) is in contact with the outer surface of the crucible (1), and a rough surface (26) is provided on the inner end surface of the inner clamping block (25), and a second rough surface (27) is provided on the outer surface of the corresponding crucible (1).

10. The polycrystalline silicon carbide vapor phase growth device according to claim 1, characterized in that: A plurality of heat pipes (28) for heat dissipation are fixedly mounted on the surface of the crucible (1) corresponding to the lower end of the fixing ring (14); the heat pipes (28) are arranged in a square shape; a heat insulating layer (29) is arranged at the connection between the outer end of the heat pipe (28) and the metal shell (15); a plurality of heat dissipation fins (30) for heat dissipation are arranged on the outer surface of the metal shell (15) corresponding to the position of the heat pipe (28); and the heat pipes (28) penetrate the plurality of heat dissipation fins (30).

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