Silicon carbide crystal growth method and silicon carbide crystal growth furnace

Abstract

The invention relates to the technical field of crystal growth, in particular to a silicon carbide crystal growth method and a silicon carbide crystal growth furnace. The silicon carbide crystal growth method comprises the following steps: laying a first silicon carbide raw material layer at the bottom of the reaction cavity; laying a second silicon carbide raw material layer on the first silicon carbide raw material layer; wherein the particle size of the second silicon carbide raw material layer is larger than that of the first silicon carbide raw material layer; the cover body fixed with the seed crystal is arranged on the crucible body in a covering manner; starting a heater to form a temperature gradient of which the temperature decreases from bottom to top in the reaction cavity, so that the first silicon carbide raw material layer sublimates preferentially, the second silicon carbide raw material layer sublimates in a delayed manner, and silicon carbide is formed to form a gas phase and rises; and completing crystal growth. And by arranging different silicon carbide raw materials, the technical effect of improving the growth quality of the silicon carbide crystals is achieved.

Description

A method for growing silicon carbide crystals and a silicon carbide crystal growth furnace Technical Field

[0001] This application relates to the field of crystal growth technology, and in particular to a silicon carbide crystal growth method and a silicon carbide crystal growth furnace. Background Technology

[0002] In the field of third-generation semiconductor materials, silicon carbide, with its excellent physical and electrical properties, has become a core material supporting the development of high-end industries such as new energy, 5G communication, and aerospace. As device manufacturing upgrades towards larger sizes and higher power, the market demand for 8-inch and larger silicon carbide single crystals continues to rise.

[0003] In existing technologies, the physical vapor transport method (PVT) is the mainstream technology for SiC single crystal growth. It involves heating the SiC raw material at the bottom and around the crucible to sublimate it, and then transporting the vapor phase to the top seed crystal surface for deposition and growth under the drive of the temperature gradient. During the physical vapor transport (PVT) growth of silicon carbide single crystals, the silicon carbide vapor transport rate is affected by a variety of factors. Whether the vapor phase is slow or fast, it will affect the growth quality of silicon carbide crystals, leading to a decrease in the quality of silicon carbide crystals.

[0004] Therefore, the technical problem with the existing technology is that the growth quality of silicon carbide crystals is relatively low. Summary of the Invention

[0005] This application provides a silicon carbide crystal growth method and a silicon carbide crystal growth furnace, which achieves the technical effect of improving the growth quality of silicon carbide crystals by arranging different silicon carbide raw materials.

[0006] On one hand, this application provides a silicon carbide crystal growth method, which adopts the following technical solution: A silicon carbide crystal growth method, applicable to a silicon carbide crystal growth furnace, the silicon carbide crystal growth furnace comprising: a furnace body; a heater, the heater being disposed inside the furnace body; and a crucible, the crucible being located inside the heater, the crucible comprising: a crucible body, the crucible body having a reaction chamber, the bottom of the reaction chamber being used to contain silicon carbide raw material; a cover, the cover being used to cover the crucible body, the cover being used to fix the seed crystal; the... The silicon carbide crystal growth method includes: laying a first silicon carbide raw material layer at the bottom of the reaction chamber; laying a second silicon carbide raw material layer on the first silicon carbide raw material layer; wherein the particle size of the second silicon carbide raw material layer is larger than the particle size of the first silicon carbide raw material layer; covering the crucible body with a cap fixed with a seed crystal; turning on the heater to form a temperature gradient that decreases from bottom to top in the reaction chamber, so that the first silicon carbide raw material layer sublimates preferentially and the second silicon carbide raw material layer sublimates with a delay, forming a silicon carbide gas phase that rises; and completing the crystal growth.

[0007] Preferably, the crucible further includes a filter screen; before laying the second silicon carbide raw material layer on the first silicon carbide raw material layer, the method further includes: laying a filter screen on the first silicon carbide raw material layer, wherein the pore size of the filter screen is smaller than the particle size of the first silicon carbide raw material layer.

[0008] Preferably, the crucible further includes: a flow guiding unit connected to the crucible, the flow guiding unit being arranged in a ring around the seed crystal, the flow guiding unit including a vertical part and a beveled part, the center of the vertical part forming a buffer zone with equal upper and lower diameters, the buffer zone being located below the seed crystal; the beveled part being connected to the lower part of the vertical part, the center of the beveled part forming a collection area that is narrower at the top and wider at the bottom, the collection area communicating with the buffer zone, and the collection area being located below the buffer zone; the silicon carbide crystal growth method further includes: accelerating and collecting the gas phase through the collection area, allowing the gas phase to enter the buffer zone, and depositing the gas phase on the seed crystal.

[0009] Preferably, the flow guiding unit is slidably connected to the crucible, and the crucible further includes: an adjustment unit disposed between the inner wall of the crucible and the flow guiding unit, the adjustment unit being used to control the vertical height of the flow guiding unit; the silicon carbide crystal growth method further includes: when the first silicon carbide raw material layer is almost completely sublimated to make the crystal thicker, the adjustment unit causes the flow guiding unit to descend to form a buffer zone that meets preset requirements.

[0010] Preferably, the crucible further includes a connector connected between the filter and the flow guiding unit; the silicon carbide crystal growth method further includes: when the first silicon carbide raw material layer is almost completely sublimated to thicken the crystal, the adjusting unit causes the flow guiding unit to descend to form a buffer zone that meets preset requirements; the filter descends with the flow guiding unit to make the second silicon carbide raw material layer reach the bottom of the reaction chamber, so that the second silicon carbide raw material layer is heated and sublimated to continue crystal growth.

[0011] Preferably, the connector is a tungsten wire rope.

[0012] Preferably, the inner wall of the crucible body is provided with a groove, and the flow guiding unit is provided with a slider. The slider slides and engages with the groove to allow the flow guiding unit to move relative to the crucible. The adjustment unit includes an adjustment block, which is disposed at the bottom of the groove. The slider abuts against the adjustment block. The adjustment block is regulated by temperature to form a first state and a second state: in the first state, the adjustment block is solid, causing the flow guiding unit to be located at a first height; in the second state, the adjustment block sublimates, causing the flow guiding unit to descend to a second height at the bottom of the groove. The silicon carbide crystal growth method further includes: when the first silicon carbide raw material layer has sublimated to make the crystal thicken, the heater heats and sublimates the adjustment block, causing the flow guiding unit to descend to the second height at the bottom of the groove. The filter screen descends with the flow guiding unit to make the second silicon carbide raw material layer reach the bottom of the reaction chamber, causing the second silicon carbide raw material layer to sublimate and continue crystal growth.

[0013] Preferably, the material of the adjustment block is silicon.

[0014] On the other hand, the silicon carbide crystal growth furnace provided in this application adopts the following technical solution: A silicon carbide crystal growth furnace includes: a furnace body; a heater, the heater being disposed inside the furnace body; and a crucible, the crucible being located inside the heater, the crucible including: a crucible body, the crucible body having a reaction chamber, the bottom of the reaction chamber being used to contain silicon carbide raw materials; and a cover, the cover being used to cover the crucible body, the cover being used to fix the seed crystal.

[0015] Preferably, the crucible further includes: a filter screen, which is disposed between the first silicon carbide raw material layer and the second silicon carbide raw material layer, and the pore size of the filter screen is smaller than the particle size of the first silicon carbide raw material layer; a flow guiding unit, which is slidably connected to the crucible and is arranged in a ring around the seed crystal, the flow guiding unit including a vertical part and a beveled part, the center of the vertical part forming a buffer zone with equal upper and lower diameters, the buffer zone being located below the seed crystal; the beveled part being connected to the lower part of the vertical part, the center of the beveled part forming a collection area that is narrower at the top and wider at the bottom, the collection area communicating with the buffer zone, and the collection area being located below the buffer zone; an adjustment unit, which is disposed between the inner wall of the crucible and the flow guiding unit, the adjustment unit being used to control the vertical height of the flow guiding unit; and a connector, the connector being connected between the filter screen and the flow guiding unit.

[0016] In summary, this application includes at least one of the following beneficial technical effects: It employs a two-layer gradient particle size raw material layer layout, adapted to a temperature field that decreases from bottom to top within the crucible, achieving sequential sublimation of the raw material from bottom to top. The small particles in the first silicon carbide raw material layer preferentially sublimate to provide the initial gas phase, while the larger particles in the second silicon carbide raw material layer delay sublimation. Simultaneously, the interparticle gaps in the second silicon carbide raw material layer act as a throttling buffer for the gas phase, effectively reducing the gas phase rise rate and preventing disordered atomic accumulation. Furthermore, by precisely controlling the temperature field through multiple independent heating units, the stability of the sublimation rate is further ensured, significantly reducing the risk of polycrystalline formation and improving crystal quality. Attached Figure Description

[0017] Figure 1 is a schematic diagram of the silicon carbide crystal growth furnace described in this application; Figure 2 is a schematic diagram of the filter screen of the silicon carbide crystal growth furnace described in this application; Figure 3 is a schematic diagram of the flow guiding unit of the silicon carbide crystal growth furnace described in this application; Figure 4 is a schematic diagram of the adjustment unit of the silicon carbide crystal growth furnace described in this application; Figure 5 is a schematic diagram of the operation of the flow guiding unit of the silicon carbide crystal growth furnace described in this application; Figure 6 is a schematic diagram of the state switching of the adjustment unit of the silicon carbide crystal growth furnace described in this application; Figure 7 is a schematic diagram of the connection between the flow guiding unit and the crucible body of the silicon carbide crystal growth furnace described in this application.

[0018] Explanation of reference numerals in the attached drawings: 100, furnace body; 200, heater; 300, crucible; 310, crucible body; 311, reaction chamber; 312, chute; 320, cover; 330, filter screen; 340, flow guiding unit; 341, vertical part; 3411, buffer zone; 342, inclined part; 3421, collection area; 343, slider; 350, adjusting unit; 351, adjusting block; 360, connector; 410, first silicon carbide raw material layer; 420, second silicon carbide raw material layer; 430, seed crystal. Detailed Implementation

[0019] The serial numbers assigned to components in this document, such as "first" and "second," are used solely to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages). It should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are used solely for the convenience of describing this application and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0020] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0021] This application provides a silicon carbide crystal growth method and a silicon carbide crystal growth furnace, which achieves the technical effect of improving the growth quality of silicon carbide crystals by arranging different silicon carbide raw materials.

[0022] To better understand the above technical solutions, a detailed description of the technical solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit the scope of this application.

[0023] The purpose of this application is to overcome the shortcomings of existing physical vapor transport silicon carbide growth technology, such as difficulty in controlling the sublimation rate, unstable vapor transport, easy collapse of the raw material layer, unreliable adjustment of the flow guiding unit 340, and poor adaptability to thick crystal growth. This application provides a silicon carbide crystal growth method and a silicon carbide crystal growth furnace. By adapting the gradient raw material layer to the temperature field to achieve orderly sublimation, combined with the filter 330 to prevent dust clogging, the flow guiding unit 340 to adjust for thick crystal growth, the adjustment unit 350 to precisely control the height, and the connecting parts 360 to ensure a smooth descent of the raw material layer, the application achieves the technical effects of controllable sublimation rate, stable vapor transport, and smooth descent of the raw material layer during thick crystal growth, significantly improving the quality of thick crystal growth and the stability of mass production.

[0024] A silicon carbide crystal growth method, as shown in Figure 1, is applicable to a silicon carbide crystal growth furnace. The silicon carbide crystal growth furnace includes a furnace body 100, a heater 200, and a crucible 300. The heater 200 is disposed inside the furnace body 100. The crucible 300 is located inside the heater 200 and includes a crucible body 310 and a cover 320. The crucible body 310 has a reaction chamber 311, the bottom of which is used to contain silicon carbide raw materials. The cover 320 is used to cover the crucible body 310 and to fix a seed crystal 430. The silicon carbide crystal growth method includes: A first silicon carbide raw material layer 410 is laid at the bottom of the reaction chamber 311; a second silicon carbide raw material layer 420 is laid on the first silicon carbide raw material layer 410; wherein the particle size of the second silicon carbide raw material layer 420 is larger than that of the first silicon carbide raw material layer 410; a cover 320 with seed crystals 430 fixed is placed on the crucible body 310; the heater 200 is turned on, so that a temperature gradient with decreasing temperature from bottom to top is formed in the reaction chamber 311, so that the first silicon carbide raw material layer 410 sublimates preferentially and the second silicon carbide raw material layer 420 sublimates with delay, forming silicon carbide gas phase and rising; crystal growth is completed.

[0025] Specifically, as shown in Figure 1, the silicon carbide crystal growth furnace includes a furnace body 100, a heater 200, and a crucible 300. These components work together to create a closed and controllable environment suitable for the growth of thick silicon carbide crystals. The furnace body 100 has a hollow structure and is made of a material with high temperature resistance and excellent thermal insulation properties.

[0026] Heater 200 is disposed inside furnace body 100 and arranged around crucible 300. Heater 200 is used to provide a uniform and controllable temperature field within crucible 300. Heater 200 includes multiple sets of independent heating units distributed vertically. Each set of independent heating units can have its heating power adjusted individually by an external control system, thereby precisely forming a temperature gradient that decreases from bottom to top within crucible 300, i.e., a temperature field that is higher at the bottom and lower at the top. This temperature field layout provides the basic conditions for the orderly sublimation of the gradient raw material layer. At the same time, the independent heating units located on the inner wall of crucible 300 corresponding to the area of ​​adjustment unit 350 can also be used to precisely adjust the temperature of adjustment unit 350, realizing the state switching of adjustment unit 350.

[0027] The crucible 300 is located inside the heater 200 and is the core reaction area for crystal growth. The crucible 300 includes a crucible body 310, a cover 320, a filter 330, a flow guiding unit 340, an adjustment unit 350, and a connector 360. The crucible body 310 has a top-opening structure, and its inner wall has one or more vertically oriented grooves 312. The length of the grooves 312 is adapted to the maximum descent stroke of the flow guiding unit 340. The inner wall of the grooves 312 is smoothed to reduce frictional resistance during the sliding of the slider 343. Notably, an expansion gap exists between the grooves 312 and the slider 343 to prevent them from becoming stuck due to thermal expansion. The crucible body 310 contains a reaction chamber 311. The bottom of the reaction chamber 311 is used to hold silicon carbide raw material. The size of the reaction chamber 311 is determined according to the size of the target crystal to ensure sufficient raw material loading to meet the requirements of thick crystal growth.

[0028] The cover 320 is used to cover the top opening of the crucible body 310, thereby sealing the reaction chamber 311. A seed crystal 430 fixing structure is located at the center of the cover 320. The seed crystal 430 is fixed below the cover 320 and is coaxially arranged with the crucible body 310, ensuring uniform gas phase supply to all areas of the seed crystal 430 surface. The cover 320 is made of a high-temperature resistant material with excellent thermal conductivity, which can conduct away the heat absorbed by the seed crystal 430, maintaining a stable surface temperature and ensuring the orderly deposition process.

[0029] The reaction chamber 311 is filled with a gradient distribution of silicon carbide raw material. The silicon carbide raw material adopts a two-layer gradient particle layout, including a first silicon carbide raw material layer 410 located below and a second silicon carbide raw material layer 420 located above. The particle size of the first silicon carbide raw material layer 410 is smaller than the particle size of the second silicon carbide raw material layer 420.

[0030] The first silicon carbide raw material layer 410 is laid at the bottom of the reaction chamber 311, directly contacting the bottom of the crucible body 310, and uses small-particle silicon carbide raw material. The second silicon carbide raw material layer 420 is laid on top of the first silicon carbide raw material layer 410, and uses large-particle silicon carbide raw material. Due to its larger particle size and relatively smaller specific surface area, the activation energy required for sublimation is higher. Within the sublimation temperature range of the first silicon carbide raw material layer 410, the sublimation rate of the second silicon carbide raw material layer 420 is significantly lower than that of the first silicon carbide raw material layer 410, achieving delayed sublimation. The gradient raw material layer layout can provide sufficient raw material loading. The delayed sublimation and smooth descent of the second silicon carbide raw material layer 420 enable long-term continuous growth, adapting to the needs of thick crystal growth. The parameters are highly controllable throughout the growth process. Stable mass production can be achieved through monitoring and fine-tuning, solving the problem of large quality fluctuations in thick crystal growth in existing technologies and reducing production costs.

[0031] The gradient raw material layer layout is adapted to the temperature field within the crucible 300, which decreases from bottom to top, enabling sequential sublimation of the raw materials from bottom to top while controlling the sublimation rate. On one hand, the lower first silicon carbide raw material layer 410 is located in a higher temperature region, preferentially reaching the sublimation temperature and initiating sublimation, providing the initial gas phase supply for crystal growth. The upper second silicon carbide raw material layer 420 is located in a lower temperature region, with a slow sublimation rate in the initial stage, avoiding the problem of excessively rapid sublimation caused by the simultaneous generation of a large amount of gas phase. On the other hand, the large particle stacking of the second silicon carbide raw material layer 420... The first silicon carbide raw material layer 410 has a uniform interstitial structure. The gas phase generated by the sublimation of the first silicon carbide raw material layer 410 must pass through these gaps to be transported upward. The interstitial structure acts as a throttling buffer for the gas phase, further reducing the rising rate of the gas phase and preventing the gas phase from rushing to the surface of the seed crystal 430 and causing disordered atomic accumulation. During the process of the first silicon carbide raw material layer 410 sublimating completely, the second silicon carbide raw material layer 420 descends accordingly. In the subsequent growth process, it gradually approaches the high-temperature region at the bottom of the crucible 300. After the temperature rises, it begins to sublimate stably, providing a continuous gas phase supply for thick crystal growth and achieving long-term continuous growth.

[0032] Furthermore, as shown in Figure 2, the crucible 300 also includes a filter screen 330; before laying the second silicon carbide raw material layer 420 on the first silicon carbide raw material layer 410, the method further includes: laying the filter screen 330 on the first silicon carbide raw material layer 410, wherein the pore size of the filter screen 330 is smaller than the particle size of the first silicon carbide raw material layer 410.

[0033] The crucible 300 also includes a filter screen 330, which is horizontally positioned between the first silicon carbide raw material layer 410 and the second silicon carbide raw material layer 420, serving as a structure for isolation and dust prevention. The filter screen 330 is made of a porous material that is resistant to high temperatures, corrosion, and has excellent chemical stability, preferably graphite-coated silicon carbide. This material can not only withstand the high-temperature environment during silicon carbide growth but also avoid chemical reactions with gaseous species, preventing contamination of the crystals.

[0034] The pore size of filter 330 is smaller than the particle size of the first silicon carbide raw material layer 410, ensuring that particles of the first silicon carbide raw material layer 410 cannot pass through filter 330, while allowing gaseous phase particles to pass through smoothly. This effectively intercepts dust particles that are carried upwards by the gas phase during the sublimation process of the first silicon carbide raw material layer 410. The first silicon carbide raw material layer 410 consists of small particles, and under the upward movement of the gas phase, some unsublimated fine particles will form dust. If this dust enters the gaps of the second silicon carbide raw material layer 420, it will gradually accumulate and cause gap blockage, hindering gas phase transmission. Filter 330 can effectively intercept dust, confining it to the area of ​​the first silicon carbide raw material layer 410, ensuring the unobstructed flow of the gaps in the second silicon carbide raw material layer 420, and ensuring that the gas phase can be stably transported upwards to the surface of the seed crystal 430.

[0035] Furthermore, as shown in Figure 3, the crucible 300 also includes a flow guiding unit 340, which is connected to the crucible 300. The flow guiding unit 340 is arranged in a ring around the seed crystal 430. The flow guiding unit 340 includes a vertical part 341 and a beveled part 342. A buffer zone 3411 with equal upper and lower diameters is formed at the center of the vertical part 341, and the buffer zone 3411 is located below the seed crystal 430. The beveled part 342 is connected to the lower part of the vertical part 341, and a collection area 3421 with a narrow upper portion and a wide lower portion is formed at the center of the beveled part 342. The collection area 3421 and the buffer zone 3411 are connected, and the collection area 3421 is located below the buffer zone 3411. The silicon carbide crystal growth method also includes: accelerating and collecting the gas phase through the collection area 3421, allowing the gas phase to enter the buffer zone 3411, and depositing the gas phase on the seed crystal 430.

[0036] Specifically, the flow guiding unit 340 is connected to the crucible 300, specifically through a sliding connection. The flow guiding unit 340 can move vertically along the inner wall of the crucible 300. It is arranged in a ring around the seed crystal 430, positioned above the second silicon carbide raw material layer 420 and directly below the seed crystal 430. The flow guiding unit 340 is the core component for gas phase collection and flow stabilization. It includes a vertical section 341 and an inclined section 342, which work together to achieve efficient gas phase collection and flow rate buffering.

[0037] The vertical section 341 is a cylindrical structure. A buffer zone 3411 with equal upper and lower diameters is formed at the center of the vertical section 341. The buffer zone 3411 is coaxially aligned with the seed crystal 430 and located directly below the seed crystal 430. The inner diameter of the buffer zone 3411 matches the diameter of the seed crystal 430, ensuring that the gas phase can be accurately guided to the surface of the seed crystal 430. The inclined section 342 is a trumpet-shaped structure, coaxially connected to the lower part of the vertical section 341. The trumpet opening expands from top to bottom, forming a collection area 3421 that is narrow at the top and wide at the bottom. The collection area 3421 is connected to the buffer zone 3411 and is located below the buffer zone 3411.

[0038] During the gas phase transport process, the gas phase rising from the gaps in the second silicon carbide raw material layer 420 first enters the collection area 3421 of the inclined section 342. The funnel-shaped collection area 3421 can converge and guide the dispersed gas phase, causing it to flow towards the center along the inner wall of the inclined section 342 and enter the buffer zone 3411 of the vertical section 341. The buffer zone 3411 has a cylindrical structure, which can effectively reduce the flow rate of the gas phase and prevent the high-speed gas phase from directly impacting the surface of the seed crystal 430. After being buffered by the buffer zone 3411, the gas phase flow rate is stable and can be evenly distributed on the surface of the seed crystal 430, providing a stable gas phase environment for atomically ordered deposition and significantly reducing the risk of polycrystalline formation.

[0039] The inclined portion 342 of the flow guiding unit 340, with a collection area 3421, can collect the gas phase to the maximum extent and avoid gas phase loss; the vertical portion 341, with a buffer zone 3411, effectively reduces the gas phase flow rate and prevents high-speed gas phase from impacting the surface of the seed crystal 430; at the same time, the adjustment unit 350 can precisely adjust the height of the flow guiding unit 340 according to the thickness change of the seed crystal 430, ensuring that the buffer zone 3411 always maintains sufficient buffer space, maintaining the stability of gas phase transmission no matter how the thickness of the seed crystal 430 increases, ensuring uniform gas phase supply on the surface of the seed crystal 430, and improving the consistency of crystal growth.

[0040] As shown in Figures 3 and 4, the flow guiding unit 340 is slidably connected to the crucible 300. The crucible 300 also includes an adjustment unit 350, which is disposed between the inner wall of the crucible 300 and the flow guiding unit 340. The adjustment unit 350 is used to control the vertical height of the flow guiding unit 340. The silicon carbide crystal growth method further includes: when the first silicon carbide raw material layer 410 is almost completely sublimated to make the crystal thicker, the adjustment unit 350 causes the flow guiding unit 340 to descend to form a buffer zone 3411 that meets the preset requirements.

[0041] An adjustment unit 350 is disposed between the inner wall of the crucible 300 and the flow guiding unit 340. The adjustment unit 350 is used to control the vertical height of the flow guiding unit 340 so that it can be adaptively adjusted according to the change in the thickness of the seed crystal 430 to meet the requirements of thick crystal growth. The adjustment unit 350 cooperates with the groove 312 on the inner wall of the crucible body 310 and the slider 343 of the flow guiding unit 340 to realize the height adjustment of the flow guiding unit 340.

[0042] As shown in Figure 3-6, the inner wall of the crucible body 310 is provided with a groove 312, and a slider 343 is provided on the flow guiding unit 340. The slider 343 slides and engages with the groove 312 to make the flow guiding unit 340 movable relative to the crucible 300. The adjustment unit 350 includes an adjustment block 351, which is disposed at the bottom of the groove 312. The slider 343 abuts against the adjustment block 351. The adjustment block 351 is adjusted by temperature to form a first state and a second state: in the first state, the adjustment block 351 is solid, so that the flow guiding unit 340 is located at a first high temperature. In the second state, the regulating block 351 sublimates, causing the flow guiding unit 340 to descend to the second height at the bottom of the chute 312; the silicon carbide crystal growth method further includes: when the first silicon carbide raw material layer 410 is almost completely sublimated to thicken the crystal, the heater 200 heats and sublimates the regulating block 351, causing the flow guiding unit 340 to descend to the second height at the bottom of the chute 312, and the filter screen 330 descends with the flow guiding unit 340 to make the second silicon carbide raw material layer 420 reach the bottom of the reaction chamber 311, so that the second silicon carbide raw material layer 420 is heated and sublimated to continue crystal growth.

[0043] Specifically, as shown in Figure 7, the inner wall of the crucible body 310 is provided with a groove 312, which extends vertically and has a T-shaped cross-section. This groove limits the slider 343, preventing it from disengaging. A slider 343 is provided on the flow guiding unit 340, and is fixedly connected to the outer wall of the flow guiding unit 340. The shape of the slider 343 matches the groove 312, fitting within it. The slider 343 slides and engages with the groove 312, allowing the flow guiding unit 340 to move relative to the crucible 300. The slider 343 is made of a high-temperature resistant and wear-resistant material, and its surface is lubricated to ensure smooth sliding along the groove 312 even at high temperatures. It is worth noting that an expansion gap exists between the groove 312 and the slider 343 to prevent either from becoming stuck due to thermal expansion.

[0044] The adjustment unit 350 includes an adjustment block 351, as shown in Figures 3-6. The adjustment block 351 is disposed at the bottom of the slide groove 312. In the initial state, the slider 343 abuts against the adjustment block 351, and the adjustment block 351 supports the slider 343, so that the flow guiding unit 340 is stably at the initial first height. The adjustment block 351 is adjusted by temperature to form a first state and a second state. In the first state, the adjustment block 351 is solid and can provide sufficient support force to keep the flow guiding unit 340 at the initial seed crystal thickness 430. In the first height, the buffer zone 3411 of the flow guiding unit 340 and the initial seed crystal 430 form a preset buffer distance to ensure the gas phase buffering effect. In the second state, the adjusting block 351 sublimates and loses its supporting role for the slider 343. The slider 343 slides down along the slide groove 312 under the gravity of the flow guiding unit 340 and the structure above, causing the flow guiding unit 340 to drop to the second height. The second height is adapted to the thickness of the thickened seed crystal 430 to ensure that the buffer zone 3411 always maintains sufficient buffer space.

[0045] The preferred material for the regulating block 351 is silicon. Silicon's sublimation temperature is compatible with the temperature distribution within the silicon carbide crystal growth furnace. During normal crystal growth, the temperature in the area where the regulating block 351 is located is controlled by an independent heating unit at the corresponding position, keeping it below the silicon sublimation temperature, thus keeping the regulating block 351 in a solid state. As shown in Figure 3-6, when the height of the flow guiding unit 340 needs to be adjusted, the heater 200 at the corresponding position is activated via an external control system, raising the temperature of that area to the silicon sublimation temperature, thereby releasing the support for the slider 343 and allowing the flow guiding unit 340 to descend. Using silicon as the material for the regulating block 351 not only ensures that the sublimation temperature is compatible with the furnace environment, but also, as silicon is a constituent element of silicon carbide, it will not contaminate the crystal, ensuring crystal purity. The height of the flow guiding unit 340 is adjusted by using a silicon-based regulating block 351 in conjunction with an independent heating unit. This eliminates the need for mechanical transmission components, avoids damaging the sealing performance of the crucible 300, ensures the stability of the vacuum and inert gas atmosphere inside the furnace, and improves crystal purity. The sublimation temperature of silicon is adapted to the furnace environment, and the adjustment process is precise and controllable. Furthermore, since silicon is a constituent element of silicon carbide, there is no risk of residual contamination, significantly improving the reliability and safety of the adjustment.

[0046] Furthermore, as shown in Figures 3-6, the crucible 300 also includes a connector 360, which is connected between the filter screen 330 and the flow guiding unit 340. The silicon carbide crystal growth method further includes: when the first silicon carbide raw material layer 410 is almost completely sublimated to make the crystal thicker, the adjustment unit 350 causes the flow guiding unit 340 to descend to form a buffer zone 3411 that meets the preset requirements; the filter screen 330 descends with the flow guiding unit 340 so that the second silicon carbide raw material layer 420 reaches the bottom of the reaction chamber 311, so that the second silicon carbide raw material layer 420 is heated and sublimated to continue crystal growth.

[0047] Specifically, as shown in Figure 3-6, the crucible 300 also includes a connector 360, which connects the filter screen 330 and the flow guiding unit 340 to achieve linkage between the filter screen 330 and the flow guiding unit 340. This allows the flow guiding unit 340 to descend synchronously and smoothly drive the filter screen 330 and the upper second silicon carbide raw material layer 420 downwards. The connector 360 uses a high-temperature resistant tungsten wire rope. Tungsten wire rope has excellent high-temperature resistance and can maintain structural stability in the high-temperature environment of silicon carbide growth without melting or other problems. The tungsten wire rope has high strength and can withstand the weight of the filter screen 330 and the second silicon carbide raw material layer 420, ensuring structural reliability during the linkage process. One end of the tungsten wire rope is fixed to the flow guiding unit 340. The filter screen 330 is uniformly distributed along the circumference of the flow guiding unit 340. In one embodiment, 3-4 tungsten wire ropes are provided to ensure that the filter screen 330 is subjected to uniform force. The other end is fixed to the edge of the filter screen 330, forming a firm connection with the filter screen 330. The rigid linkage between the filter screen 330 and the flow guiding unit 340 is achieved through the tungsten wire ropes. When the flow guiding unit 340 descends, it simultaneously drives the filter screen 330 and the second silicon carbide raw material layer 420 to descend smoothly, ensuring that the second silicon carbide raw material layer 420 is evenly accumulated during the descent and avoiding collapse. The filter screen 330 can effectively intercept the dust of the first silicon carbide raw material layer 410, prevent the gaps of the second silicon carbide raw material layer 420 from being blocked, ensure the smooth flow of the gas phase transmission channel, and provide a continuous and stable gas phase supply for thick crystal growth.

[0048] As shown in Figure 3-6, when the flow guiding unit 340 descends under the action of the adjusting unit 350, the filter screen 330 carries the second silicon carbide raw material layer 420. Due to gravity, the filter screen 330 descends synchronously with the flow guiding unit 340 through the traction of the tungsten wire rope. The second silicon carbide raw material layer 420 above the filter screen 330 also descends smoothly under the influence of the filter screen 330, gradually approaching the high-temperature region at the bottom of the crucible 300. This ensures that the second silicon carbide raw material layer 420 maintains a uniform stacking state during the descent process, avoiding collapse and ensuring the unobstructed flow between the particles of the second silicon carbide raw material layer 420. At the same time, the second silicon carbide raw material layer 420 can gradually enter the high-temperature region to achieve stable sublimation, providing a continuous and stable gas phase supply for thick crystal growth.

[0049] It should be noted that, based on experience or historical data (when the first silicon carbide raw material layer 410 is exhausted), as the seed crystal 430 grows thicker (the distance between the seed crystal 430 and the inclined surface 342 is shortened) and the second layer of silicon carbide raw material needs to descend to replenish the sublimation and replenish the gas phase, the flow guiding unit 340 needs to descend to maintain the buffer space 3411 of the vertical part 341, and avoid the gas phase flow rate being too fast, which would lead to polycrystalline formation; the descent process is achieved by controlling the temperature of the slider 343 through the temperature component, which is stable and precise.

[0050] This application also provides a silicon carbide crystal growth furnace, including: a furnace body 100, a heater 200, and a crucible 300; the heater 200 is disposed inside the furnace body 100; the crucible 300 is located inside the heater 200, and the crucible 300 includes a crucible body 310 and a cover 320. The crucible body 310 has a reaction chamber 311, and the bottom of the reaction chamber 311 is used to contain silicon carbide raw materials; the cover 320 is used to cover the crucible body 310 and to fix the seed crystal 430.

[0051] Furthermore, the crucible 300 also includes a filter screen 330, a flow guiding unit 340, an adjustment unit 350, and a connector 360; the filter screen 330 is arranged between the first silicon carbide raw material layer 410 and the second silicon carbide raw material layer 420, and the pore size of the filter screen 330 is smaller than the particle size of the first silicon carbide raw material layer 410; the flow guiding unit 340 is slidably connected to the crucible 300, and the flow guiding unit 340 is arranged in a ring around the seed crystal 430. The flow guiding unit 340 includes a vertical part 341 and a beveled part 342, and a buffer with equal diameters at the center of the vertical part 341 is formed. Zone 3411 and buffer zone 3411 are located below seed crystal 430; beveled section 342 is connected to the lower part of vertical section 341, and a collection zone 3421 with a narrow upper part and a wide lower part is formed in the center of beveled section 342. Collection zone 3421 and buffer zone 3411 are connected, and collection zone 3421 is located below buffer zone 3411; adjustment unit 350 is disposed between inner wall of crucible 300 and flow guiding unit 340, and adjustment unit 350 is used to control vertical height of flow guiding unit 340; connector 360 is connected between filter screen 330 and flow guiding unit 340.

[0052] Specifically, based on the structure of the silicon carbide crystal growth furnace described above, the silicon carbide crystal growth method of this application includes the following steps to ensure the orderliness and stability of thick crystal growth: Step 1: Furnace body 100 pretreatment and raw material laying First, the inside of the furnace body 100 is cleaned to remove residual impurities and contaminants, ensuring the cleanliness of the growth environment.

[0053] Next, the raw material laying operation is carried out: a first silicon carbide raw material layer 410 is laid at the bottom of the reaction chamber 311 of the crucible body 310. The first silicon carbide raw material layer 410 uses small-particle silicon carbide raw material. During the laying process, it is gently compacted by a vibrating fixture to make the first silicon carbide raw material layer 410 evenly piled and have a certain density to avoid voids; then, a filter screen 330 is laid horizontally above the first silicon carbide raw material layer 410 to ensure that the filter screen 330 completely covers the laying range of the first silicon carbide raw material layer 410. The edge of the filter screen 330 is attached to the inner wall of the crucible body 310 to prevent dust from leaking out from the edge gaps; after the filter screen 330 is laid, a second silicon carbide raw material layer 420 is laid above the filter screen 330. The second silicon carbide raw material layer 420 uses large-particle silicon carbide raw material. It is also compacted by a vibrating fixture to make the second silicon carbide raw material layer 420 form a uniform pile gap to ensure that the gas phase can pass through smoothly.

[0054] Step 2: Assembling the flow guiding unit 340 and the seed crystal 430. Fix the slider 343 to the flow guiding unit 340 to ensure a firm connection. Then, embed the slider 343 into the groove 312 on the inner wall of the crucible body 310, so that the bottom of the slider 343 abuts against the adjusting block 351 at the bottom of the groove 312. At this time, the flow guiding unit 340 is stably at the first height. This height is set according to the thickness of the initial seed crystal 430, so that the buffer zone 3411 of the vertical part 341 of the flow guiding unit 340 and the initial seed crystal 430 maintain a preset buffer distance to ensure that the gas phase can be fully buffered.

[0055] The seed crystal 430 is fixed by the seed crystal 430 fixing structure on the cover 320 to ensure that the seed crystal 430 is coaxial with the crucible body 310. Then, the cover 320 is placed on the top opening of the crucible body 310 to seal the reaction chamber 311 through the sealing structure. The sealing structure uses a high-temperature resistant sealing gasket to ensure the airtightness of the reaction chamber 311.

[0056] Step 3: Temperature field construction and the independent heating units of the first-stage crystal growth start-up heater 200 are adjusted by an external control system to create a temperature gradient that decreases from bottom to top within the crucible 300, i.e., the temperature is highest at the bottom of the crucible 300 and gradually decreases upwards; the first silicon carbide raw material layer 410 is located in the high-temperature region at the bottom of the crucible 300, and it first reaches the sublimation temperature and begins to sublimate, producing gaseous species containing silicon, carbon, and small silicon carbide molecules; the second silicon carbide raw material layer 420 is located in the upper low-temperature region and has a larger particle size, so the sublimation rate is slow at this time, mainly playing a throttling buffering role for the sublimation gas phase of the first silicon carbide raw material layer 410.

[0057] The gas phase generated by the sublimation of the first silicon carbide raw material layer 410 moves upward and first passes through the filter screen 330. The filter screen 330 intercepts the dust carried by the first silicon carbide raw material layer 410 in the gas phase, preventing the dust from entering the gaps of the second silicon carbide raw material layer 420. Subsequently, the gas phase enters the interparticle gaps of the second silicon carbide raw material layer 420. The gap structure further throttles and buffers the gas phase, reducing the gas phase rising rate. After being buffered, the gas phase continues to move upward and enters the collection area 3421 of the inclined section 342 of the guide unit 340. The funnel-shaped collection area 3421 gathers and guides the dispersed gas phase to the buffer zone 3411 of the vertical section 341. The buffer zone 3411 reduces the gas phase flow rate, allowing the gas phase to be smoothly transported to the surface of the seed crystal 430. Driven by the temperature gradient on the surface of the seed crystal 430, the atoms of the gas phase diffuse to the lattice sites and are deposited in an orderly manner, and the seed crystal 430 begins to grow.

[0058] During the first stage of crystal growth, the temperature, pressure and gas phase composition inside the furnace are monitored in real time by an external control system. The power of the heater 200 is finely adjusted according to the monitoring data to maintain a stable sublimation rate of the first silicon carbide raw material layer 410 and ensure uniform gas phase supply on the surface of the seed crystal 430. This stage continues until the first silicon carbide raw material layer 410 is completely sublimated and the seed crystal 430 has grown to a certain thickness.

[0059] Step 4: Adjustment of the flow guiding unit 340 and the second stage of crystal growth. When the first silicon carbide raw material layer 410 has sublimated to the point of exhaustion, the seed crystal 430 has thickened significantly, and the gap between the seed crystal 430 and the flow guiding unit 340 has narrowed. If the height of the flow guiding unit 340 is not adjusted, the flow rate of the gas phase entering the buffer zone 3411 will increase, affecting the buffering effect. At this time, the heater 200 corresponding to the position of the adjustment block 351 raises the temperature of this area to the sublimation temperature of silicon. The silicon material adjustment block 351 is heated and sublimated, releasing the support effect on the slider 343.

[0060] Under the gravity of the flow guiding unit 340, the filter screen 330 and the second silicon carbide raw material layer 420, the slider 343 slides smoothly down the groove 312 on the inner wall of the crucible body 310, driving the flow guiding unit 340 down to the second height. This height is adapted to the thickness of the thickened seed crystal 430, so that a sufficient buffer space is re-formed between the buffer zone 3411 and the seed crystal 430, ensuring that the gas phase can continue to be transported smoothly.

[0061] As the flow guiding unit 340 descends, the filter screen 330 descends synchronously with it through the linkage of the tungsten wire rope. The filter screen 330 drives the upper second silicon carbide raw material layer 420 to descend smoothly, gradually approaching the high-temperature region at the bottom of the crucible 300. As the second silicon carbide raw material layer 420 enters the high-temperature region, its temperature rises to the sublimation temperature and begins to sublimate stably. The generated gas phase is throttled by the interparticle gaps of the second silicon carbide raw material layer 420 itself and collected and buffered by the flow guiding unit 340 before being smoothly transported to the surface of the seed crystal 430 for continued deposition and growth.

[0062] Step 5: Crystal growth completed and cooling down. Continuously monitor the growth thickness of the seed crystal 430 until the entire growth process is completed.

[0063] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0064] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for growing silicon carbide crystals, characterized in that, A silicon carbide crystal growth furnace is applicable, the silicon carbide crystal growth furnace comprising: a furnace body (100); a heater (200) disposed inside the furnace body (100); and a crucible (300) located inside the heater (200), the crucible (300) comprising: a crucible body (310) having a reaction chamber (311) inside, the bottom of the reaction chamber (311) being used to contain silicon carbide raw materials; a cover (320) covering the crucible body (310) and fixing a seed crystal (430); the silicon carbide crystal growth method comprising: A first silicon carbide raw material layer (410) is laid at the bottom of the reaction chamber (311); a second silicon carbide raw material layer (420) is laid on the first silicon carbide raw material layer (410); wherein the particle size of the second silicon carbide raw material layer (420) is larger than that of the first silicon carbide raw material layer (410); a cover (320) with seed crystals (430) fixed is placed on the crucible body (310); the heater (200) is turned on, so that a temperature gradient with decreasing temperature from bottom to top is formed in the reaction chamber (311), so that the first silicon carbide raw material layer (410) sublimates preferentially and the second silicon carbide raw material layer (420) sublimates with delay, forming silicon carbide gas phase and rising; crystal growth is completed.

2. The silicon carbide crystal growth method according to claim 1, characterized in that, The crucible (300) further includes a filter screen (330); before laying the second silicon carbide raw material layer (420) on the first silicon carbide raw material layer (410), the method further includes laying a filter screen (330) on the first silicon carbide raw material layer (410), wherein the pore size of the filter screen (330) is smaller than the particle size of the first silicon carbide raw material layer (410).

3. The silicon carbide crystal growth method according to claim 2, characterized in that, The crucible (300) further includes a flow guiding unit (340), which is connected to the crucible (300). The flow guiding unit (340) is arranged in a ring around the seed crystal (430). The flow guiding unit (340) includes a vertical part (341) and a beveled part (342). A buffer zone (3411) with equal upper and lower diameters is formed at the center of the vertical part (341), and the buffer zone (3411) is located below the seed crystal (430). The beveled part (342) is connected to... Below the vertical portion (341), a collection area (3421) narrow at the top and wide at the bottom is formed in the center of the inclined portion (342). The collection area (3421) is connected to the buffer zone (3411), and the collection area (3421) is located below the buffer zone (3411). The silicon carbide crystal growth method further includes: accelerating and collecting the gas phase through the collection area (3421), allowing the gas phase to enter the buffer zone (3411), and depositing the gas phase on the seed crystal (430).

4. The silicon carbide crystal growth method according to claim 3, characterized in that, The flow guiding unit (340) is slidably connected to the crucible (300). The crucible (300) further includes an adjustment unit (350), which is disposed between the inner wall of the crucible (300) and the flow guiding unit (340). The adjustment unit (350) is used to control the vertical height of the flow guiding unit (340). The silicon carbide crystal growth method further includes: when the first silicon carbide raw material layer (410) is almost completely sublimated to make the crystal thicker, the adjustment unit (350) causes the flow guiding unit (340) to descend to form a buffer zone (3411) that meets the preset requirements.

5. The silicon carbide crystal growth method according to claim 4, characterized in that, The crucible (300) further includes a connector (360) connected between the filter (330) and the flow guiding unit (340); the silicon carbide crystal growth method further includes: when the first silicon carbide raw material layer (410) is almost completely sublimated to make the crystal thicker, the adjustment unit (350) causes the flow guiding unit (340) to descend to form a buffer zone (3411) that meets the preset requirements; the filter (330) descends with the flow guiding unit (340) to make the second silicon carbide raw material layer (420) reach the bottom of the reaction chamber (311), so that the second silicon carbide raw material layer (420) is heated and sublimated to continue crystal growth.

6. The silicon carbide crystal growth method according to claim 5, characterized in that, The connector (360) is a tungsten wire rope.

7. The silicon carbide crystal growth method according to claim 4, characterized in that, The inner wall of the crucible body (310) is provided with a groove (312), and a slider (343) is provided on the flow guiding unit (340). The slider (343) slides and engages with the groove (312) to make the flow guiding unit (340) movable relative to the crucible (300). The adjustment unit (350) includes an adjustment block (351), which is located at the bottom of the groove (312). The slider (343) abuts against the adjustment block (351). The adjustment block (351) is regulated by temperature to form a first state and a second state: in the first state, the adjustment block (351) is solid, so that the flow guiding unit (340) is located at a first high position. In the second state, the regulating block (351) sublimates, causing the flow guiding unit (340) to descend to the second height at the bottom of the chute (312); the silicon carbide crystal growth method further includes: when the first silicon carbide raw material layer (410) is almost completely sublimated to make the crystal thicker, the heater (200) heats and sublimates the regulating block (351), causing the flow guiding unit (340) to descend to the second height at the bottom of the chute (312), and the filter screen (330) descends with the flow guiding unit (340) to make the second silicon carbide raw material layer (420) reach the bottom of the reaction chamber (311), so that the second silicon carbide raw material layer (420) is heated and sublimated to continue crystal growth.

8. The silicon carbide crystal growth method according to claim 7, characterized in that, The material of the adjustment block (351) is silicon.

9. A silicon carbide crystal growth furnace, characterized in that, include: Furnace body (100); heater (200), the heater (200) being disposed inside the furnace body (100); And a crucible (300), the crucible (300) being located inside the heater (200), the crucible (300) comprising: a crucible body (310), the crucible body (310) having a reaction chamber (311) inside, the bottom of the reaction chamber (311) being used to contain silicon carbide raw material; and a cover (320), the cover (320) being used to cover the crucible body (310), the cover (320) being used to fix the seed crystal (430).

10. The silicon carbide crystal growth furnace according to claim 9, wherein the crucible (300) further comprises: A filter screen (330) is disposed between a first silicon carbide raw material layer (410) and a second silicon carbide raw material layer (420). The pore size of the filter screen (330) is smaller than the particle size of the first silicon carbide raw material layer (410). A flow guiding unit (340) is slidably connected to the crucible (300). The flow guiding unit (340) is arranged in a ring around the seed crystal (430). The flow guiding unit (340) includes a vertical part (341) and a beveled part (342). A buffer zone (3411) with equal upper and lower diameters is formed in the center of the vertical part (341). The buffer zone (3411) is located below the seed crystal (430). The beveled part... (342) Connected to the lower part of the vertical part (341), the center of the inclined part (342) forms a collection area (3421) that is narrow at the top and wide at the bottom, the collection area (3421) and the buffer zone (3411) are connected, and the collection area (3421) is located below the buffer zone (3411); adjustment unit (350), the adjustment unit (350) is disposed between the inner wall of the crucible (300) and the flow guiding unit (340), the adjustment unit (350) is used to control the vertical height of the flow guiding unit (340); and connector (360), the connector (360) is connected between the filter screen (330) and the flow guiding unit (340).

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