WO2018176302A1 - Method and apparatus for preparing sic raw material for growing sic crystal - Google Patents

Method and apparatus for preparing sic raw material for growing sic crystal Download PDF

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Publication number
WO2018176302A1
WO2018176302A1 PCT/CN2017/078726 CN2017078726W WO2018176302A1 WO 2018176302 A1 WO2018176302 A1 WO 2018176302A1 CN 2017078726 W CN2017078726 W CN 2017078726W WO 2018176302 A1 WO2018176302 A1 WO 2018176302A1
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WIPO (PCT)
Prior art keywords
graphite crucible
sic
heating device
raw material
temperature
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Application number
PCT/CN2017/078726
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French (fr)
Chinese (zh)
Inventor
彭同华
刘春俊
王波
张平
邹宇
赵宁
Original Assignee
新疆天科合达蓝光半导体有限公司
北京天科合达半导体股份有限公司
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Application filed by 新疆天科合达蓝光半导体有限公司, 北京天科合达半导体股份有限公司 filed Critical 新疆天科合达蓝光半导体有限公司
Priority to PCT/CN2017/078726 priority Critical patent/WO2018176302A1/en
Priority to JP2019527120A priority patent/JP6829767B2/en
Priority to CN201780054385.1A priority patent/CN109844185B/en
Publication of WO2018176302A1 publication Critical patent/WO2018176302A1/en

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    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B23/00—Single-crystal growth by condensing evaporated or sublimed materials
    • C30B23/02—Epitaxial-layer growth
    • C30B23/06—Heating of the deposition chamber, the substrate or the materials to be evaporated
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/36—Carbides

Definitions

  • the invention relates to a preparation method and a preparation device for a SiC raw material for growing SiC crystal, which can significantly reduce the impurity content in the SiC crystal, reduce the micro-wrapping in the SiC crystal, reduce the dislocation density of the SiC crystal, and increase the crystal growth rate. And yield, in the field of crystal growth.
  • a wide-bandgap semiconductor material typified by silicon carbide (SiC) or gallium nitride (GaN) is a third-generation semiconductor material after silicon (Si) or gallium arsenide (GaAs).
  • SiC has excellent properties such as high thermal conductivity, high breakdown field strength, high saturation electron drift rate and high bonding energy, and has huge advantages in high temperature, high frequency, high power and radiation resistant devices. Application prospects.
  • due to the close lattice constant and thermal expansion coefficient of SiC and GaN it has extremely broad application prospects in the field of optoelectronic devices.
  • the SiC crystal growth method is mainly the Physical Vapor Transport Method, and the growth chamber structure is shown in FIG.
  • the temperature in the crucible is raised to 2100-2400 °C, so that the SiC powder is sublimated, sublimation produces gas phase materials Si2C, SiC2 and Si, and the SiC seed crystal is placed on the upper part of the crucible which is relatively lower than the temperature of the SiC powder, and the sublimation is produced.
  • the gas phase material is transported from the surface of the SiC powder to the relatively low temperature SiC seed crystal under the action of a temperature gradient, and crystallizes on the SiC seed crystal to form a bulk SiC crystal.
  • the gas phase substances formed in the growth chamber from the above reaction formula are mainly Si, Si2C and SiC2.
  • the partial pressure of Si vapor in the three gas phase materials (Si, Si2C, and SiC2) is much higher than the partial pressure of C vapor in the temperature range of 2100 ° C to 2400 ° C required for crystal growth. Due to the high-temperature evaporation characteristics of the SiC powder itself, that is, the ratio of the gas phase partial pressure required by the system, the SiC powder is inevitably graphitized, that is, the graphite particles remain in the SiC powder.
  • the particle size of the SiC powder used is generally several micrometers to several millimeters, and the SiC powder particles and the particles are isolated from each other.
  • the SiC powder near the graphite crucible wall has the highest degree of graphitization due to the highest temperature, resulting in a large amount of graphite particles remaining. Since these graphite particles are graphitized from SiC powder, the particle size is small, the density is small, and the graphite particles are isolated from each other, these fine graphite particles are easily transported to the SiC by the vapor phase material formed by sublimation of the SiC powder.
  • the surface of the crystal is thus wrapped into the SiC crystal to form a wrap defect that affects the quality and yield of the SiC crystal.
  • the density of SiC powder is only about 60% of the density of SiC crystals, that is, about 1.9 g/cm 3 .
  • the SiC powder near the inner wall of the graphite crucible sublimes, and the generated gas phase material is transported not only from the crucible wall and the periphery of the SiC powder to the crystal growth surface, but also to the inside and the upper portion of the SiC powder.
  • the gas phase material transported into the SiC powder continues to be transported to the crystal growth surface through the gap between the powders, and on the other hand, the original SiC particles are nucleated inside and above the relatively low temperature powder.
  • the crystal growth continuously consumes the vapor phase material produced by the sublimation of the SiC powder, so that the particle size of the SiC powder at the crystal growth in the SiC powder gradually increases, the density gradually increases, and the voids gradually decrease.
  • the voids inside and above the SiC powder gradually disappear, and the density reaches a density close to that of the SiC crystal, that is, about 3.2 g/cm 3 . This will seriously deplete the gas phase material produced by the sublimation of the SiC powder, and reduce the growth rate and yield of the SiC crystal in the middle and late stages.
  • the present invention aims to provide a method for preparing a SiC raw material and a device for preparing a SiC raw material, which can significantly reduce the impurity content in the SiC crystal and reduce the SiC crystal in the SiC crystal.
  • Micro-wraps reduce the dislocation density of SiC crystals and increase the growth rate and yield of SiC crystals in the middle and late stages.
  • a method for preparing a SiC raw material for growing SiC crystals comprising: loading a SiC powder into a first graphite crucible, and mounting a second graphite on the first graphite crucible And placing the installed two graphite crucibles into a heating device, evacuating the heating device and raising the temperature inside the heating device to a preset temperature, wherein the first graphite crucible is located at the heating device a relatively high temperature region within the second graphite crucible located in a relatively low temperature region within the heating device, the SiC powder being sublimated and transported to the second graphite crucible located in a relatively low temperature region to be crystallized, thereby A crystalline SiC raw material is obtained.
  • the method further comprises: providing a spacer from the bottom in the second graphite crucible, the spacer being spaced apart from the sidewall of the second graphite crucible by a predetermined distance.
  • the spacer is located at a central location within the second graphite crucible.
  • the spacer comprises graphite.
  • the spacer is a solid or hollow structure.
  • the height of the spacer from the bottom of the second graphite crucible is set to be at least equal to or higher than the height of the SiC material desired to be crystallized.
  • inverting the second graphite crucible on the first graphite crucible comprises: mounting the second graphite crucible on the first graphite crucible by sealing, the sealing manner comprises: a threaded seal, a snap ring seal, At least one of a ferrule seal.
  • the vacuuming the heating device comprises: after pumping the heating device to make the internal pressure less than 10 Pa, charging the inert gas of the predetermined pressure for a first predetermined time; after the first predetermined time, pumping the heating device Until the internal pressure is less than 1 Pa; raising the temperature in the heating device to the first temperature, maintaining the first temperature and continuously pumping the heating device for a second predetermined time, wherein the first temperature is half of the preset temperature; After the second predetermined time, the heating device is charged with a predetermined pressure of inert gas and after being held for a third predetermined time, the heating device is evacuated to an internal pressure of less than 10-1 Pa.
  • raising the temperature inside the heating device to a preset temperature comprises: raising the temperature inside the heating device to a preset temperature by induction heating or resistance heating.
  • the method further comprises: setting a temperature gradient in the heating device to 5 ° C / cm to 100 ° C / cm, so that the sublimated SiC powder is transported to the second graphite crucible under the driving force of the temperature gradient And crystallize.
  • the temperature gradient ranges from 10 ° C/cm to 50 ° C/cm.
  • an apparatus for preparing a SiC raw material for growing SiC crystal comprising: a first graphite crucible; and a second graphite crucible having a separator disposed from a bottom portion in the second graphite crucible, The spacer is spaced apart from the sidewall of the second graphite crucible by a predetermined distance; and a heating device having a relatively high temperature region and a relatively low temperature region within the heating device, wherein when the SiC material is prepared, the second graphite crucible is mounted upside down A first graphite crucible having SiC powder, and the first graphite crucible is located in a relatively high temperature region within the heating device, and the second graphite crucible is located in a relatively low temperature region within the heating device.
  • the spacer is located at a central location within the second graphite crucible.
  • the spacer comprises graphite.
  • the spacer is a solid or hollow structure.
  • the height of the spacer from the bottom of the second graphite crucible is at least equal to or higher than the height of the SiC material desired to be crystallized.
  • the impurity content thereof is greatly reduced, so that the impurity content in the SiC raw material is greatly reduced compared to the SiC powder.
  • the SiC raw material prepared by the present invention is used for crystal growth, and the content of iron and aluminum impurities in the obtained SiC crystal is less than 0.1 ppm, respectively, and the deterioration of crystal quality caused by impurities in the SiC crystal is suppressed.
  • the SiC raw material is a SiC polycrystalline block obtained by sublimation of SiC powder at a high temperature, and the SiC polycrystalline block is densely crystallized and has a density of approximately 3.2 g/cm 3 .
  • the SiC polycrystalline block is densely crystallized, and the SiC grain boundaries interact with each other strongly.
  • the SiC raw material although the surface of the SiC polycrystalline block is graphitized as the growth process continues, there is a strong interaction between the graphite on the surface of the SiC polycrystalline block, which is not easily sublimated.
  • the vapor phase material is brought to the crystal growth interface, thereby avoiding the formation of microscopic graphite inclusions during the growth of the SiC crystal.
  • the finally formed SiC raw material has a hollow annular structure.
  • the SiC raw material is grown by using the SiC raw material having the structure, since the SiC raw material is a ring-shaped hollow structure, there is no gas phase substance transporting and consuming the sublimation of the SiC raw material in the central portion of the SiC raw material, and the gas phase substance can be directly It is transferred to the crystal growth surface, so that the utilization rate of the SiC raw material is remarkably improved.
  • the growth rate of the SiC crystal is kept substantially constant throughout the entire production process, thereby improving the yield.
  • 1 is a schematic view showing the structure of a growth chamber for growing SiC crystal by physical vapor phase transfer; 1. graphite cap; 2. first graphite crucible; 3. SiC powder; 4. binder; 5. SiC seed crystal; ;
  • Figure 2 is a flow chart showing a method of preparing a SiC raw material
  • FIG. 3 is a cross-sectional view of a portion of a SiC material preparation apparatus. 7. Second graphite crucible; 8. SiC raw material; 9. Isolation member; 10. Induction heating coil; 11. Insulation material; 12. Heating device.
  • an embodiment of a method of preparing a SiC raw material for growing SiC crystals is provided.
  • Figure 2 shows a flow chart of a method of preparing a SiC raw material. As shown in FIG. 2, the method includes the following steps:
  • step S101 the SiC powder is charged into the first graphite crucible, and the second graphite crucible is placed upside down on the first graphite crucible.
  • the above SiC powder has a certain impurity content, and the ash content of the first graphite crucible and the second graphite crucible is less than a predetermined value.
  • Step S103 placing the installed two graphite crucibles into a heating device, vacuuming the heating device and raising the temperature inside the heating device to a preset temperature, wherein the first graphite crucible is located in a relatively high temperature region in the heating device, and second The graphite crucible is located in a relatively low temperature region within the heating device, and the SiC powder is sublimed and transported to a second graphite crucible located in a relatively low temperature region to be crystallized, thereby obtaining a crystalline SiC raw material.
  • the heating device includes, but is not limited to, a heating furnace.
  • the temperature field in the heating device is controllable such that there is a relatively high temperature zone and a relatively low temperature zone in the heating device,
  • the heating device can be evacuated by various means, for example, by a mechanical pump, but the invention is not limited thereto.
  • the pumping time, the temperature in the heating device, the temperature holding time, and the like may be set to ensure that the pressure in the heating device reaches a desired vacuum requirement.
  • the first graphite crucible containing the SiC powder is usually located in a relatively high temperature region within the heating device, and the second graphite crucible opposed thereto is usually located in a relatively low temperature region within the heating device, thereby being in the first graphite crucible and the second graphite crucible A temperature difference is formed such that the SiC powder sublimated from the first graphite crucible crystallizes in the second graphite crucible.
  • the SiC raw material is prepared by high temperature sublimation of the SiC powder. Since the impurity content of the SiC powder sublimation crystallization is greatly reduced, the impurity content in the SiC raw material is greatly reduced compared with the SiC powder, which is remarkably improved. The quality of SiC crystal grown using SiC raw materials.
  • a method for preparing a SiC raw material for growing SiC crystals may further include: providing a spacer from a bottom portion in a second graphite crucible, the spacer being spaced apart from a sidewall of the second graphite crucible. distance.
  • the spacer is a member that blocks the SiC powder sublimated from the first graphite crucible to be crystallized in the middle of the second graphite crucible, so that the finally formed SiC raw material is a hollow structure.
  • the spacer may be of any shape as long as it can block the sublimation of the SiC powder from crystallizing in the middle of the second graphite crucible.
  • the SiC raw material is formed into a hollow structure, which improves the utilization of the SiC raw material, maintains the growth rate of the SiC crystal, and increases the yield of the SiC crystal in the process of growing the SiC crystal using the SiC raw material.
  • the rate has great advantages.
  • the spacer is located at a central location within the second graphite crucible.
  • the spacer comprises graphite.
  • the spacer is a solid or hollow structure.
  • the height of the spacer from the bottom of the second graphite crucible is set to be at least higher than the height of the SiC raw material desired to be crystallized.
  • the height of the spacer from the bottom of the second graphite crucible refers to the height of the spacer in the longitudinal direction when the bottom of the second graphite crucible is placed downward and the opening is placed upward.
  • a SiC material is formed around the spacer.
  • the height of the separator is at least equal to or higher than the height of the finally formed SiC raw material.
  • the outside of the opening of one of the two graphite crucibles may be in the form of a nut, and the inside of the opening of the other may be in the form of a bolt, and the two openings are screwed to seal the two graphite crucibles in a threaded manner.
  • the invention is not limited thereto, and the two graphite crucibles may be sealed by providing a snap ring, a ferrule, or the like.
  • evacuating the heating device comprises: after pumping the heating device to an internal pressure of less than 10 Pa, charging the inert gas at a predetermined pressure for a first predetermined time; After a predetermined time, the heating device is evacuated to an internal pressure of less than 1 Pa; the temperature in the heating device is raised to a first temperature, the first temperature is maintained, and the heating device is continuously pumped for a second predetermined time, wherein The temperature is half of the preset temperature; and after the second predetermined time, the heating device is charged with a predetermined pressure of inert gas and after being maintained for the third predetermined time, the heating device is evacuated to an internal pressure of less than 10-1 Pa.
  • the inert gas charged into the heating device may include: argon gas, helium gas.
  • the first predetermined time may be from 5 minutes to 180 minutes.
  • the first temperature may range from 1000 °C to 1250 °C.
  • the second predetermined time can be from 5 minutes to 300 minute.
  • the preset temperature can range from 2000 °C to 2500 °C.
  • the predetermined pressure may range from 1000 Pa to 90,000 Pa.
  • the third predetermined time may be from 5 minutes to 300 minutes.
  • raising the temperature in the heating device to the preset temperature comprises: raising the temperature in the heating device to a preset temperature by induction heating or resistance heating.
  • the preset temperature may range from 2000 ° C to 2500 ° C.
  • the method for preparing a SiC raw material for growing SiC crystals may further include: setting a temperature gradient in the heating device to 5 ° C / cm to 100 ° C / cm, so that the sublimated SiC powder It is transported into the second graphite crucible by the driving force of the temperature gradient to be crystallized.
  • the temperature gradient ranges from 10 ° C/cm to 50 ° C/cm.
  • Figure 3 shows a preparation apparatus for a SiC raw material for growing SiC crystals.
  • the SiC powder 3 was placed in the graphite crucible 2, and a separator 9 was placed at a position near the center of the bottom of the graphite crucible 7.
  • the total impurity content of the SiC powder 3 is less than 10 ppm, preferably less than 1 ppm; and the particle size of the SiC powder 3 is less than 10 mm, preferably less than 5 mm.
  • the ash content of the graphite crucible 2 and the graphite crucible 7 is less than 50 ppm, preferably less than 1 ppm.
  • the spacer 9 is a solid column body whose first end is connected to the bottom of the graphite crucible 7 and the second end extends toward the opening of the second crucible 7, for example, a cylinder, a square cylinder, a triangular cylinder, a polygonal cylinder, etc., but The invention is not limited to this.
  • the spacer 9 can also be a hollow cylindrical body.
  • the separator 9 may have any other shape such as a truncated cone shape or a conical shape as long as it can prevent the formation of the SiC raw material at a position near the center of the graphite crucible 7.
  • the first end of the spacer 9 may be physically or chemically connected to the bottom of the graphite crucible 7, or the spacer 9 may be integrally formed with the graphite crucible 7 to be fixed to the bottom of the graphite crucible 7.
  • the outer wall of the spacer 9 is spaced apart from the inner wall of the graphite crucible 7, and preferably, the spacer 9 is located at the center of the graphite crucible 7.
  • the height of the spacer 9 from the bottom of the graphite crucible 7 is at least higher than the height of the SiC raw material 8 desired to be crystallized.
  • the graphite crucible 7 was mounted upside down on the graphite crucible 2 such that the openings of the graphite crucible 7 and the graphite crucible 2 were opposed.
  • the graphite crucibles 2 and 7 can be sealed by means of a threaded seal, a snap ring seal, a ferrule seal or the like.
  • the oppositely disposed graphite crucible 2 and graphite crucible 7 are placed in a heating furnace, and the furnace is evacuated by a mechanical pump to bring the interior to a vacuum state, which means that the pressure in the heating furnace is less than 10-1 Pa.
  • the inert gas is filled with argon gas so that the internal pressure reaches 50,000 Pa and maintained for 15 minutes; after 15 minutes, the furnace is evacuated to an internal pressure of less than 1 Pa.
  • the temperature in the heating furnace was raised to 1000 ° C; the temperature was maintained at 1000 ° C and the furnace was continuously pumped for 60 minutes. After 60 minutes, the furnace was charged with 50,000 argon gas and heated for 60 minutes. The furnace is evacuated to an internal pressure of less than 10-1 Pa.
  • the furnace is heated to have an internal temperature of, for example, 2,200 °C.
  • the temperature in the relatively high temperature zone is in the range of 2000 to 2500 °C
  • the temperature in the relatively low temperature zone is in the range of 1900 to 2400 °C.
  • the graphite crucible 2 is placed in a relatively high temperature region, and the graphite crucible 7 is placed in a relatively low temperature region, and the SiC powder in the graphite crucible 2 is sublimated due to the action of high temperature, and transported to the presence under the driving force of the temperature gradient.
  • the graphite crucible 7 in the relatively low temperature region is crystallized to obtain a crystalline SiC raw material.
  • the impurity content of the SiC powder is greatly reduced during the sublimation crystallization process, the impurity content in the SiC raw material is greatly reduced compared with the SiC powder, and further, the SiC raw material thus obtained is used for growth. In the case of SiC crystals, the quality of SiC crystals is remarkably improved.
  • the SiC raw material is a SiC polycrystalline block obtained by sublimation of SiC powder at a high temperature
  • the SiC polycrystalline block is densely crystallized and has a density of approximately 3.2 g/cm 3 .
  • the SiC polycrystalline block is densely crystallized, and the SiC grain boundaries interact with each other strongly.
  • the SiC raw material although the surface of the SiC polycrystalline block is graphitized as the growth process continues, there is a strong interaction between the graphite on the surface of the SiC polycrystalline block, which is not easily sublimated.
  • the vapor phase material is brought to the crystal growth interface, thereby avoiding the formation of microscopic graphite inclusions during the growth of the SiC crystal.
  • the finally formed SiC raw material has a hollow structure.
  • the SiC raw material is grown by using the SiC raw material having the structure, since the SiC raw material has a hollow structure, there is no gas phase substance transporting and consuming the sublimation of the SiC raw material in the central portion of the SiC raw material, and the gas phase substance can be directly transported. To the crystal growth surface, the utilization rate of the SiC raw material is remarkably improved.
  • the growth rate of the SiC crystal is kept substantially constant throughout the entire production process, thereby improving the yield.
  • an apparatus for preparing a SiC raw material for growing SiC crystals is provided.
  • the preparation device comprises:
  • a second graphite crucible 7, in the second graphite crucible 7 is provided with a spacer 9 from the bottom, the spacer 9 is spaced apart from the sidewall of the second graphite crucible 7 by a predetermined distance;
  • the spacer 9 is a solid column body whose first end is connected to the bottom of the graphite crucible 7 and the second end extends toward the opening of the second crucible 7, for example, a cylinder, a square cylinder, a triangular cylinder, a polygonal cylinder, etc.
  • the invention is not limited thereto.
  • the spacer 9 can also be a hollow cylindrical body.
  • the separator 9 may have any other shape such as a truncated cone shape or a conical shape as long as it can prevent the formation of the SiC raw material at a position near the center of the graphite crucible 7.
  • the first end of the spacer 9 may be physically or chemically connected to the bottom of the graphite crucible 7, or the spacer 9 may be integrally formed with the graphite crucible 7 to be fixed to the bottom of the graphite crucible 7.
  • the outer wall of the spacer 9 is spaced apart from the inner wall of the graphite crucible 7, and preferably, the spacer 9 is located at the center of the graphite crucible 7.
  • the height of the spacer 9 from the bottom of the graphite crucible 7 is at least higher than the height of the SiC raw material desired to be crystallized.
  • the heating device 12 has a relatively high temperature zone and a relatively low temperature zone in the heating device 12, wherein when the SiC raw material 8 is prepared, the second graphite crucible 7 is mounted upside down on the first graphite crucible 2 containing the SiC powder 3, and The first graphite crucible 2 is located in a relatively high temperature region within the heating device 12, and the second graphite crucible 7 is located in a relatively low temperature region.
  • the heating device 12 includes, but is not limited to, a heating furnace.
  • the temperature field within the heating device 12 is controllable such that there is a relatively high temperature zone and a relatively low temperature zone in the heating device 12,
  • the graphite crucible 7 When preparing the SiC raw material, the graphite crucible 7 was mounted upside down on the graphite crucible 2 such that the openings of the graphite crucible 7 and the graphite crucible 2 were opposed.
  • the graphite crucibles 2 and 7 can be sealed by means of a threaded seal, a snap ring seal, a ferrule seal or the like.
  • the oppositely disposed graphite crucible 2 and graphite crucible 7 are placed in a heating furnace, and the furnace is evacuated by a mechanical pump to bring the interior to a vacuum state, which means that the pressure in the heating furnace is less than 10-1 Pa.
  • the inert gas is filled with argon gas so that the internal pressure reaches 50,000 Pa and maintained for 15 minutes; after 15 minutes, the furnace is evacuated to an internal pressure of less than 1 Pa.
  • the temperature in the heating furnace was raised to 1000 ° C; the temperature was maintained at 1000 ° C and the furnace was continuously pumped for 60 minutes. After 60 minutes, the furnace was charged with 50,000 argon gas and heated for 60 minutes. The furnace is evacuated to an internal pressure of less than 10-1 Pa.
  • the furnace is heated to have an internal temperature of, for example, 2,200 °C.
  • the temperature in the relatively high temperature zone is in the range of 2000 to 2500 °C
  • the temperature in the relatively low temperature zone is in the range of 1900 to 2400 °C.
  • the graphite crucible 2 is placed in a relatively high temperature region, and the graphite crucible 7 is placed in a relatively low temperature region, and the SiC powder in the graphite crucible 2 is sublimated due to the action of high temperature, and transported to the presence under the driving force of the temperature gradient.
  • the graphite crucible 7 in the relatively low temperature region is crystallized to obtain a crystalline SiC raw material.
  • the finally formed SiC raw material has a hollow structure.
  • the SiC raw material is grown by using the SiC raw material having the structure, since the SiC raw material has a hollow structure, there is no gas phase substance transporting and consuming the sublimation of the SiC raw material in the central portion of the SiC raw material, and the gas phase substance can be directly transported. To the crystal growth surface, the utilization rate of the SiC raw material is remarkably improved. Moreover, since there is no transmission of the gas phase substance which blocks and consumes the sublimation of the SiC raw material at the central portion of the SiC raw material, the growth rate of the SiC crystal is kept substantially constant throughout the growth thereof, thereby improving the yield.

Abstract

Provided are a method and apparatus for preparing a SiC raw material for growing a SiC crystal. The method comprises: loading SiC powder into a first graphite crucible, and installing, in an inverted manner, a second graphite crucible on the first graphite crucible; and putting the two graphite crucibles, which have been installed, in a heating apparatus, evacuating the heating apparatus and raising the temperature to a pre-set temperature, wherein the first graphite crucible is located in a relatively high temperature region, the second graphite crucible is located in a relatively low temperature region, and the SiC powder is sublimated and transported to the second graphite crucible, and is crystallized to obtain a crystalline SiC raw material to be used for growing a SiC crystal. The apparatus comprises a first graphite crucible, a second graphite crucible and a heating apparatus; furthermore, a separator is arranged, in an upward manner, at the bottom of the second graphite crucible, wherein the separator is spaced apart from the side wall of the second graphite crucible by a predetermined distance. The method and the apparatus can reduce the amount of impurities in a SiC crystal prepared from this raw material, reduce microscopic inclusions, reduce dislocation density, and provide the growth rate and yield of the SiC crystal in the middle and later stages.

Description

用于生长SiC晶体的SiC原料的制备方法和制备装置Preparation method and preparation device of SiC raw material for growing SiC crystal 技术领域Technical field
本发明涉及用于生长SiC晶体的SiC原料的制备方法和制备装置，该方法可以显著降低SiC晶体中的杂质含量，减少SiC晶体中的微观包裹物，降低SiC晶***错密度，提高晶体生长速率和产率，涉及晶体生长领域。The invention relates to a preparation method and a preparation device for a SiC raw material for growing SiC crystal, which can significantly reduce the impurity content in the SiC crystal, reduce the micro-wrapping in the SiC crystal, reduce the dislocation density of the SiC crystal, and increase the crystal growth rate. And yield, in the field of crystal growth.
背景技术Background technique
以碳化硅(SiC)、氮化镓(GaN)为代表的宽禁带半导体材料，是继硅(Si)、砷化镓(GaAs)之后的第三代半导体材料。与Si和GaAs传统半导体材料相比，SiC具有高热导率、高击穿场强、高饱和电子漂移速率和高键合能等优异性能，在高温、高频、高功率及抗辐射器件方面拥有巨大的应用前景。此外，由于SiC与GaN相近的晶格常数和热膨胀系数，使其在光电器件领域也具有极其广阔的应用前景。A wide-bandgap semiconductor material typified by silicon carbide (SiC) or gallium nitride (GaN) is a third-generation semiconductor material after silicon (Si) or gallium arsenide (GaAs). Compared with traditional semiconductor materials such as Si and GaAs, SiC has excellent properties such as high thermal conductivity, high breakdown field strength, high saturation electron drift rate and high bonding energy, and has huge advantages in high temperature, high frequency, high power and radiation resistant devices. Application prospects. In addition, due to the close lattice constant and thermal expansion coefficient of SiC and GaN, it has extremely broad application prospects in the field of optoelectronic devices.
SiC晶体生长方法主要为物理气相传输法(Physical Vapor Transport Method)，其生长室结构如图1所示。将坩埚内的温度升至2100～2400℃，使得SiC粉料升华，升华产生气相物质Si2C、SiC2和Si，将SiC籽晶置于比SiC粉料温度相对稍低的坩埚上部，升华所产生的气相物质在温度梯度的作用下从SiC粉料的表面输运到温度相对稍低的SiC籽晶处,并在SiC籽晶上结晶形成块状SiC晶体。The SiC crystal growth method is mainly the Physical Vapor Transport Method, and the growth chamber structure is shown in FIG. The temperature in the crucible is raised to 2100-2400 °C, so that the SiC powder is sublimated, sublimation produces gas phase materials Si2C, SiC2 and Si, and the SiC seed crystal is placed on the upper part of the crucible which is relatively lower than the temperature of the SiC powder, and the sublimation is produced. The gas phase material is transported from the surface of the SiC powder to the relatively low temperature SiC seed crystal under the action of a temperature gradient, and crystallizes on the SiC seed crystal to form a bulk SiC crystal.
目前，这种方法生长SiC晶体仍然存在一些技术问题。首先，由于SiC粉料中存在一定量的杂质，并且这些在SiC粉料内部的杂质不能用传统酸洗的方式将其去除，导致采用SiC粉料生长的SiC晶体中杂质含量较高，从而严重影响SiC晶体质量，生长的SiC晶体不能满足高压、大功率器件对SiC单晶衬底质量要求。At present, there are still some technical problems in the growth of SiC crystals by this method. First, due to the presence of a certain amount of impurities in the SiC powder, and the impurities inside the SiC powder cannot be removed by conventional pickling, the SiC crystal grown by the SiC powder has a high impurity content, which is serious. Affecting the quality of SiC crystals, the growth of SiC crystals cannot meet the quality requirements of high-voltage, high-power devices for SiC single crystal substrates.
其次，在物理气相传输法生长SiC晶体的过程中，SiC粉料在高温下蒸发所发生的基本反应包括：Secondly, in the process of growing SiC crystal by physical vapor transport, the basic reactions of evaporation of SiC powder at high temperature include:
SiC(s)→Si(g)+C(s)SiC(s)→Si(g)+C(s)
2SiC(s)→Si(g)+SiC2(g) 2SiC(s)→Si(g)+SiC2(g)
2SiC(s)→Si2C(g)+C(s)，式中s和g分别表示固相和气相。2SiC(s)→Si2C(g)+C(s), where s and g represent the solid phase and the gas phase, respectively.
由上述反应式可见生长室内形成的气相物质主要为Si、Si2C和SiC2。在晶体生长所需要的2100℃～2400℃温度范围内，三种气相物质(Si、Si2C和SiC2)中Si蒸气的分压比C蒸气的分压高出很多。由于SiC粉料自身高温蒸发特性，即体系所要求的气相分压比例，SiC粉料必然会发生石墨化，即在SiC粉料中剩余石墨颗粒。在物理气相传输法生长SiC晶体过程中，所用SiC粉料粒径一般为几微米到几毫米，并且SiC粉料颗粒与颗粒间是彼此孤立的。随着SiC晶体逐渐长厚，靠近石墨坩埚壁处的SiC粉料由于温度最高，发生石墨化程度最严重，导致剩下大量的石墨颗粒。由于这些石墨颗粒由SiC粉料石墨化而来，颗粒粒径小、密度小，并且这些石墨颗粒间彼此孤立，因此这些细小石墨颗粒极易被SiC粉料升华形成的气相物质输运带到SiC晶体表面，从而被包裹到SiC晶体中，形成包裹物缺陷，影响SiC晶体的质量和产率。The gas phase substances formed in the growth chamber from the above reaction formula are mainly Si, Si2C and SiC2. The partial pressure of Si vapor in the three gas phase materials (Si, Si2C, and SiC2) is much higher than the partial pressure of C vapor in the temperature range of 2100 ° C to 2400 ° C required for crystal growth. Due to the high-temperature evaporation characteristics of the SiC powder itself, that is, the ratio of the gas phase partial pressure required by the system, the SiC powder is inevitably graphitized, that is, the graphite particles remain in the SiC powder. In the process of growing SiC crystal by physical vapor transport, the particle size of the SiC powder used is generally several micrometers to several millimeters, and the SiC powder particles and the particles are isolated from each other. As the SiC crystal grows thicker, the SiC powder near the graphite crucible wall has the highest degree of graphitization due to the highest temperature, resulting in a large amount of graphite particles remaining. Since these graphite particles are graphitized from SiC powder, the particle size is small, the density is small, and the graphite particles are isolated from each other, these fine graphite particles are easily transported to the SiC by the vapor phase material formed by sublimation of the SiC powder. The surface of the crystal is thus wrapped into the SiC crystal to form a wrap defect that affects the quality and yield of the SiC crystal.
再次，在物理气相传输法生长SiC晶体过程中，由于温场设置的因素，SiC粉料内部存在轴向和径向温度梯度，并且SiC粉料之间存在很大的空隙。据统计，SiC粉料的密度只有SiC晶体密度的60％左右，即约1.9克/立方厘米。在SiC晶体生长初期，靠近石墨坩埚内壁的SiC粉料升华，产生的气相物质不仅从坩埚壁与SiC粉料四周之间传输至晶体生长面，同时也向SiC粉料内部和上部传输。传输到SiC粉料中的气相物质一方面通过粉料之间的空隙继续传输到晶体生长面，另一方面还会在温度相对较低的粉料内部和上部以原有的SiC颗粒为晶核结晶生长，不断消耗SiC粉料升华产生的气相物质，使得SiC粉料中结晶生长处的SiC粉料的粒径逐渐增大，密度逐渐增加，空隙逐渐减少。随着晶体生长的持续，SiC粉料内部和上部的空隙逐渐消失，密度达到接近SiC晶体的密度，即约3.2克/立方厘米。如此将严重消耗SiC粉料升华产生的气相物质，降低了中后期SiC晶体生长速率和产率。Thirdly, in the process of growing SiC crystal by physical vapor transport method, due to the temperature field setting factor, there are axial and radial temperature gradients inside the SiC powder, and there is a large gap between the SiC powder. According to statistics, the density of SiC powder is only about 60% of the density of SiC crystals, that is, about 1.9 g/cm 3 . At the initial stage of SiC crystal growth, the SiC powder near the inner wall of the graphite crucible sublimes, and the generated gas phase material is transported not only from the crucible wall and the periphery of the SiC powder to the crystal growth surface, but also to the inside and the upper portion of the SiC powder. The gas phase material transported into the SiC powder continues to be transported to the crystal growth surface through the gap between the powders, and on the other hand, the original SiC particles are nucleated inside and above the relatively low temperature powder. The crystal growth, continuously consumes the vapor phase material produced by the sublimation of the SiC powder, so that the particle size of the SiC powder at the crystal growth in the SiC powder gradually increases, the density gradually increases, and the voids gradually decrease. As the crystal growth continues, the voids inside and above the SiC powder gradually disappear, and the density reaches a density close to that of the SiC crystal, that is, about 3.2 g/cm 3 . This will seriously deplete the gas phase material produced by the sublimation of the SiC powder, and reduce the growth rate and yield of the SiC crystal in the middle and late stages.
针对上述技术问题，目前还未提出有效的解决方案。In response to the above technical problems, no effective solution has been proposed yet.
发明内容Summary of the invention
针对目前物理气相传输法生长SiC晶体存在的技术问题，本发明的目的在于提供一种SiC原料的制备方法和SiC原料的制备装置，其可以显著降低SiC晶体中的杂质含量，减少SiC晶体中的微观包裹物，降低SiC晶***错密度，提高中后期SiC晶体生长速率和产率。 The present invention aims to provide a method for preparing a SiC raw material and a device for preparing a SiC raw material, which can significantly reduce the impurity content in the SiC crystal and reduce the SiC crystal in the SiC crystal. Micro-wraps reduce the dislocation density of SiC crystals and increase the growth rate and yield of SiC crystals in the middle and late stages.
根据本发明的一个方面，提供了一种用于生长SiC晶体的SiC原料制备方法，包括：将SiC粉料装入到第一石墨坩埚中，在所述第一石墨坩埚上倒置安装第二石墨坩埚；以及将安装好的两石墨坩埚放入加热装置中，将所述加热装置抽真空并将所述加热装置内温度升至预设温度，其中，所述第一石墨坩埚位于所述加热装置内的相对高温区，所述第二石墨坩埚位于所述加热装置内的相对低温区，所述SiC粉料升华并被输运至位于相对低温区的所述第二石墨坩埚中而结晶，从而获得结晶的SiC原料。According to an aspect of the present invention, a method for preparing a SiC raw material for growing SiC crystals, comprising: loading a SiC powder into a first graphite crucible, and mounting a second graphite on the first graphite crucible And placing the installed two graphite crucibles into a heating device, evacuating the heating device and raising the temperature inside the heating device to a preset temperature, wherein the first graphite crucible is located at the heating device a relatively high temperature region within the second graphite crucible located in a relatively low temperature region within the heating device, the SiC powder being sublimated and transported to the second graphite crucible located in a relatively low temperature region to be crystallized, thereby A crystalline SiC raw material is obtained.
可选地，该方法还包括：在第二石墨坩埚内自底部向上设置隔离件，隔离件与第二石墨坩埚的侧壁隔开预定距离。Optionally, the method further comprises: providing a spacer from the bottom in the second graphite crucible, the spacer being spaced apart from the sidewall of the second graphite crucible by a predetermined distance.
可选地，隔离件位于第二石墨坩埚内的中心位置。Optionally, the spacer is located at a central location within the second graphite crucible.
可选地，隔离件包括石墨。Optionally, the spacer comprises graphite.
可选地，隔离件为实心或空心结构。Optionally, the spacer is a solid or hollow structure.
可选地，将隔离件自第二石墨坩埚的底部向上的高度设置为至少等于或高于期望结晶的SiC原料的高度。Optionally, the height of the spacer from the bottom of the second graphite crucible is set to be at least equal to or higher than the height of the SiC material desired to be crystallized.
可选地，在第一石墨坩埚上倒置安装第二石墨坩埚包括：通过密封的方式将第二石墨坩埚倒置安装在第一石墨坩埚上，密封的方式包括：螺纹式密封、卡环式密封、卡套式密封中的至少一种。Optionally, inverting the second graphite crucible on the first graphite crucible comprises: mounting the second graphite crucible on the first graphite crucible by sealing, the sealing manner comprises: a threaded seal, a snap ring seal, At least one of a ferrule seal.
可选地，将加热装置抽真空包括：对加热装置抽气使其内部压力小于10Pa后，充入预定压力的惰性气体并保持第一预定时间；在第一预定时间后，对加热装置抽气至其内部压力小于1Pa；将加热装置内的温度升至第一温度，维持第一温度并持续对加热装置抽气达第二预定时间，其中，第一温度为预设温度的一半；以及在第二预定时间后，向加热装置内充入预定压力的惰性气体并在保持第三预定时间后，对加热装置抽气至其内部压力小于10-1Pa。Optionally, the vacuuming the heating device comprises: after pumping the heating device to make the internal pressure less than 10 Pa, charging the inert gas of the predetermined pressure for a first predetermined time; after the first predetermined time, pumping the heating device Until the internal pressure is less than 1 Pa; raising the temperature in the heating device to the first temperature, maintaining the first temperature and continuously pumping the heating device for a second predetermined time, wherein the first temperature is half of the preset temperature; After the second predetermined time, the heating device is charged with a predetermined pressure of inert gas and after being held for a third predetermined time, the heating device is evacuated to an internal pressure of less than 10-1 Pa.
可选地，将加热装置内温度升至预设温度包括：通过感应加热或电阻加热将加热装置内温度升至预设温度。 Optionally, raising the temperature inside the heating device to a preset temperature comprises: raising the temperature inside the heating device to a preset temperature by induction heating or resistance heating.
可选地，方法还包括：将加热装置内的温度梯度设定为5℃/cm～100℃/cm，使得升华的SiC粉料在温度梯度的驱动力作用下输运至第二石墨坩埚中而结晶。Optionally, the method further comprises: setting a temperature gradient in the heating device to 5 ° C / cm to 100 ° C / cm, so that the sublimated SiC powder is transported to the second graphite crucible under the driving force of the temperature gradient And crystallize.
可选地，温度梯度的范围为10℃/cm～50℃/cm。Alternatively, the temperature gradient ranges from 10 ° C/cm to 50 ° C/cm.
根据本发明的另一方面，提供了一种用于生长SiC晶体的SiC原料的制备装置，包括：第一石墨坩埚；第二石墨坩埚，在第二石墨坩埚内自底部向上设置有隔离件，隔离件与第二石墨坩埚的侧壁隔开预定距离；以及加热装置，在加热装置内具有相对高温区和相对低温区，其中，当制备所述SiC原料时，第二石墨坩埚倒置安装在装有SiC粉料的第一石墨坩埚上，且第一石墨坩埚位于加热装置内的相对高温区，第二石墨坩埚位于加热装置内的相对低温区。According to another aspect of the present invention, there is provided an apparatus for preparing a SiC raw material for growing SiC crystal, comprising: a first graphite crucible; and a second graphite crucible having a separator disposed from a bottom portion in the second graphite crucible, The spacer is spaced apart from the sidewall of the second graphite crucible by a predetermined distance; and a heating device having a relatively high temperature region and a relatively low temperature region within the heating device, wherein when the SiC material is prepared, the second graphite crucible is mounted upside down A first graphite crucible having SiC powder, and the first graphite crucible is located in a relatively high temperature region within the heating device, and the second graphite crucible is located in a relatively low temperature region within the heating device.
可选地，隔离件位于第二石墨坩埚内的中心位置。Optionally, the spacer is located at a central location within the second graphite crucible.
可选地，隔离件包括石墨。Optionally, the spacer comprises graphite.
可选地，隔离件为实心或空心结构。Optionally, the spacer is a solid or hollow structure.
可选地，隔离件自第二石墨坩埚的底部向上的高度至少等于或高于期望结晶的SiC原料的高度。Optionally, the height of the spacer from the bottom of the second graphite crucible is at least equal to or higher than the height of the SiC material desired to be crystallized.
本发明的显著效果主要有以下三点：The significant effects of the present invention are mainly as follows:
1.在本发明中，在SiC粉料升华结晶过程中，其中的杂质含量得到大幅降低，使得SiC原料中的杂质含量相比SiC粉料大幅度降低。采用本发明制备的SiC原料进行晶体生长，获得的SiC晶体中的铁、铝杂质含量分别小于0.1ppm，抑制了SiC晶体中由杂质导致的晶体质量下降。1. In the present invention, in the SiC powder sublimation crystallization process, the impurity content thereof is greatly reduced, so that the impurity content in the SiC raw material is greatly reduced compared to the SiC powder. The SiC raw material prepared by the present invention is used for crystal growth, and the content of iron and aluminum impurities in the obtained SiC crystal is less than 0.1 ppm, respectively, and the deterioration of crystal quality caused by impurities in the SiC crystal is suppressed.
2.在本发明中，SiC原料是由SiC粉料高温升华制备得到的SiC多晶料块，该SiC多晶料块结晶致密，密度接近3.2克/立方厘米。相比于传统物理气相传输法生长SiC晶体所采用的SiC粉料，SiC多晶料块结晶致密，SiC晶界间彼此相互作用力强。采用该SiC原料生长SiC晶体过程中，随着生长过程的持续，尽管SiC多晶料块表面也会石墨化，但是SiC多晶料块表面的石墨间存在强相互作用，不易被升华所产生的气相物质带至晶体生长界面，从而避免了在SiC晶体生长过程中产生微观石墨包裹物。 2. In the present invention, the SiC raw material is a SiC polycrystalline block obtained by sublimation of SiC powder at a high temperature, and the SiC polycrystalline block is densely crystallized and has a density of approximately 3.2 g/cm 3 . Compared with the SiC powder used in the growth of SiC crystal by the conventional physical vapor phase transmission method, the SiC polycrystalline block is densely crystallized, and the SiC grain boundaries interact with each other strongly. During the growth of SiC crystals using the SiC raw material, although the surface of the SiC polycrystalline block is graphitized as the growth process continues, there is a strong interaction between the graphite on the surface of the SiC polycrystalline block, which is not easily sublimated. The vapor phase material is brought to the crystal growth interface, thereby avoiding the formation of microscopic graphite inclusions during the growth of the SiC crystal.
3.在本发明中，由于在SiC原料结晶的坩埚中设置了阻隔件，使得最终形成的SiC原料呈中空的环形结构。当采用具有该结构的SiC原料来生长SiC晶体时，由于SiC原料的是环形中空结构，所以，在SiC原料的中央部位不存在阻挡和消耗SiC原料升华所得的气相物质的传输，气相物质可以直接传输至晶体生长面，从而使得SiC原料的利用率显著提高。而且，由于在SiC原料的中央部位不存在阻挡和消耗SiC原料升华所得的气相物质的传输，所以，SiC晶体的生长速率在其整个生产过程中基本保持恒定，从而提高了产率。3. In the present invention, since the barrier member is provided in the ruthenium in which the SiC raw material is crystallized, the finally formed SiC raw material has a hollow annular structure. When the SiC raw material is grown by using the SiC raw material having the structure, since the SiC raw material is a ring-shaped hollow structure, there is no gas phase substance transporting and consuming the sublimation of the SiC raw material in the central portion of the SiC raw material, and the gas phase substance can be directly It is transferred to the crystal growth surface, so that the utilization rate of the SiC raw material is remarkably improved. Moreover, since there is no transmission of the gas phase substance which blocks and consumes the sublimation of the SiC raw material in the central portion of the SiC raw material, the growth rate of the SiC crystal is kept substantially constant throughout the entire production process, thereby improving the yield.
附图说明DRAWINGS
图1为物理气相传输法生长SiC晶体的生长室结构示意图；1.石墨盖；2.第一石墨坩埚；3.SiC粉料；4.粘合剂；5.SiC籽晶；6.SiC晶体；1 is a schematic view showing the structure of a growth chamber for growing SiC crystal by physical vapor phase transfer; 1. graphite cap; 2. first graphite crucible; 3. SiC powder; 4. binder; 5. SiC seed crystal; ;
图2示出了SiC原料的制备方法的流程图；Figure 2 is a flow chart showing a method of preparing a SiC raw material;
图3是SiC原料制备装置的一部分的截面图。7.第二石墨坩埚；8.SiC原料；9.隔离件；10.感应加热线圈；11.保温材料；12.加热装置。3 is a cross-sectional view of a portion of a SiC material preparation apparatus. 7. Second graphite crucible; 8. SiC raw material; 9. Isolation member; 10. Induction heating coil; 11. Insulation material; 12. Heating device.
具体实施方式detailed description
下面通过实施方式进一步描述本发明，但实际可实现的工艺不限于这些具体实施方式。The invention is further described below by way of embodiments, but the actual achievable processes are not limited to these specific embodiments.
实施例1Example 1
根据本发明实施例，提供了一种用于生长SiC晶体的SiC原料制备方法的实施例。According to an embodiment of the present invention, an embodiment of a method of preparing a SiC raw material for growing SiC crystals is provided.
图2示出了SiC原料的制备方法的流程图。如图2所示，该方法包括以下步骤：Figure 2 shows a flow chart of a method of preparing a SiC raw material. As shown in FIG. 2, the method includes the following steps:
步骤S101，将SiC粉料装入到第一石墨坩埚中，在第一石墨坩埚上倒置安装第二石墨坩埚。In step S101, the SiC powder is charged into the first graphite crucible, and the second graphite crucible is placed upside down on the first graphite crucible.
通常，上述SiC粉料具有一定的杂质含量，第一石墨坩埚和第二石墨坩埚的灰份小于预定的值。 Generally, the above SiC powder has a certain impurity content, and the ash content of the first graphite crucible and the second graphite crucible is less than a predetermined value.
步骤S103，将安装好的两石墨坩埚放入加热装置中，将加热装置抽真空并将加热装置内温度升至预设温度，其中，第一石墨坩埚位于加热装置内的相对高温区，第二石墨坩埚位于加热装置内的相对低温区，SiC粉料升华并被输运至位于相对低温区的第二石墨坩埚中而结晶，从而获得结晶的SiC原料。Step S103, placing the installed two graphite crucibles into a heating device, vacuuming the heating device and raising the temperature inside the heating device to a preset temperature, wherein the first graphite crucible is located in a relatively high temperature region in the heating device, and second The graphite crucible is located in a relatively low temperature region within the heating device, and the SiC powder is sublimed and transported to a second graphite crucible located in a relatively low temperature region to be crystallized, thereby obtaining a crystalline SiC raw material.
具体地，加热装置包括但不限于加热炉。加热装置内的温场是可控的，使得在加热装置中存在相对高温区和相对低温区，Specifically, the heating device includes, but is not limited to, a heating furnace. The temperature field in the heating device is controllable such that there is a relatively high temperature zone and a relatively low temperature zone in the heating device,
可以通过各种方式将加热装置抽真空，例如，通过机械泵，但本发明并不限于此。The heating device can be evacuated by various means, for example, by a mechanical pump, but the invention is not limited thereto.
并且，在对加热装置抽真空的过程中，可以对抽气时间，加热装置内的温度，温度保持时间等进行设置，以确保加热装置内的压力达到期望的真空要求。Further, in the process of evacuating the heating device, the pumping time, the temperature in the heating device, the temperature holding time, and the like may be set to ensure that the pressure in the heating device reaches a desired vacuum requirement.
装有SiC粉料的第一石墨坩埚通常位于加热装置内的相对高温区，与其对置的第二石墨坩埚通常位于加热装置内的相对低温区，从而在第一石墨坩埚和第二石墨坩埚之间形成温度差，使得从第一石墨坩埚内升华的SiC粉料在第二石墨坩埚中结晶。The first graphite crucible containing the SiC powder is usually located in a relatively high temperature region within the heating device, and the second graphite crucible opposed thereto is usually located in a relatively low temperature region within the heating device, thereby being in the first graphite crucible and the second graphite crucible A temperature difference is formed such that the SiC powder sublimated from the first graphite crucible crystallizes in the second graphite crucible.
根据上述实施例，SiC原料由SiC粉料高温升华制备得到，由于SiC粉料升华结晶过程中，杂质含量得到大幅降低，使得SiC原料中的杂质含量相比SiC粉料大幅度降低，这显著提高了采用SiC原料生长的SiC晶体的质量。According to the above embodiment, the SiC raw material is prepared by high temperature sublimation of the SiC powder. Since the impurity content of the SiC powder sublimation crystallization is greatly reduced, the impurity content in the SiC raw material is greatly reduced compared with the SiC powder, which is remarkably improved. The quality of SiC crystal grown using SiC raw materials.
可选地，根据本发明实施例，用于生长SiC晶体的SiC原料制备方法还可以包括：在第二石墨坩埚内自底部向上设置隔离件，隔离件与第二石墨坩埚的侧壁隔开预定距离。Optionally, according to an embodiment of the present invention, a method for preparing a SiC raw material for growing SiC crystals may further include: providing a spacer from a bottom portion in a second graphite crucible, the spacer being spaced apart from a sidewall of the second graphite crucible. distance.
具体地，隔离件为阻挡从第一石墨坩埚中升华的SiC粉料结晶在第二石墨坩埚的中部位置，从而使得最终形成的SiC原料为中空结构的部件。Specifically, the spacer is a member that blocks the SiC powder sublimated from the first graphite crucible to be crystallized in the middle of the second graphite crucible, so that the finally formed SiC raw material is a hollow structure.
隔离件可以为任意形状，只要其能够阻挡升华的SiC粉料结晶在第二石墨坩埚的中部位置即可。The spacer may be of any shape as long as it can block the sublimation of the SiC powder from crystallizing in the middle of the second graphite crucible.
通过在第二石墨坩埚中设置隔离件，SiC原料被形成为中空结构，这对使用SiC原料来生长SiC晶体的过程中提高SiC原料的利用率，保持SiC晶体的生长速率以及提高SiC晶体的产率具有极大的优势。 By providing a spacer in the second graphite crucible, the SiC raw material is formed into a hollow structure, which improves the utilization of the SiC raw material, maintains the growth rate of the SiC crystal, and increases the yield of the SiC crystal in the process of growing the SiC crystal using the SiC raw material. The rate has great advantages.
可选地，根据本发明实施例，隔离件位于第二石墨坩埚内的中心位置。Optionally, in accordance with an embodiment of the invention, the spacer is located at a central location within the second graphite crucible.
可选地，根据本发明实施例，隔离件包括石墨。Optionally, in accordance with an embodiment of the invention, the spacer comprises graphite.
可选地，根据本发明实施例，隔离件为实心或空心结构。Optionally, according to an embodiment of the invention, the spacer is a solid or hollow structure.
可选地，根据本发明实施例，将隔离件自第二石墨坩埚的底部向上的高度设置为至少高于期望结晶的SiC原料的高度。Alternatively, according to an embodiment of the invention, the height of the spacer from the bottom of the second graphite crucible is set to be at least higher than the height of the SiC raw material desired to be crystallized.
这里需要说明的是，隔离件自第二石墨坩埚的底部向上的高度指的是将第二石墨坩埚的底部朝下、开口向上放置时，隔离件在纵向上的高度。It should be noted here that the height of the spacer from the bottom of the second graphite crucible refers to the height of the spacer in the longitudinal direction when the bottom of the second graphite crucible is placed downward and the opening is placed upward.
SiC原料环绕隔离件周围形成。为了使得最终形成的SiC原料为中空结构，隔离件的高度至少等于或高于最终形成的SiC原料的高度。A SiC material is formed around the spacer. In order to make the finally formed SiC raw material a hollow structure, the height of the separator is at least equal to or higher than the height of the finally formed SiC raw material.
可选地，根据本发明实施例，在步骤S101，在第一石墨坩埚上倒置安装第二石墨坩埚包括：通过密封的方式将第二石墨坩埚倒置安装在第一石墨坩埚上，密封的方式包括：螺纹式密封、卡环式密封、卡套式密封中的至少一种。Optionally, in accordance with an embodiment of the present invention, in step S101, mounting the second graphite crucible on the first graphite crucible comprises: mounting the second graphite crucible on the first graphite crucible by sealing, the manner of sealing comprises : at least one of a threaded seal, a snap ring seal, and a ferrule seal.
为防止对置的两石墨坩埚中升华的SiC粉料溢出石墨坩埚，需要将两石墨坩埚的接合部位进行密封。例如，可以将两石墨坩埚中的一个的开口部的外部做成螺母的形式，而另一个的开口部的内部做成螺栓的形式，将两个开口部拧紧而以螺纹式将两石墨坩埚密封。但并发明并不限于此，也可以通过设置卡环、卡套等对两石墨坩埚进行密封。In order to prevent the sublimated SiC powder in the opposite two graphite crucibles from overflowing the graphite crucible, it is necessary to seal the joint portions of the two graphite crucibles. For example, the outside of the opening of one of the two graphite crucibles may be in the form of a nut, and the inside of the opening of the other may be in the form of a bolt, and the two openings are screwed to seal the two graphite crucibles in a threaded manner. . However, the invention is not limited thereto, and the two graphite crucibles may be sealed by providing a snap ring, a ferrule, or the like.
可选地，根据本发明实施例，在步骤S103，将加热装置抽真空包括：对加热装置抽气使其内部压力小于10Pa后，充入预定压力的惰性气体并保持第一预定时间；在第一预定时间后，对加热装置抽气至其内部压力小于1Pa；将加热装置内的温度升至第一温度，维持第一温度并持续对加热装置抽气达第二预定时间，其中，第一温度为预设温度的一半；以及在第二预定时间后，向加热装置内充入预定压力的惰性气体并在保持第三预定时间后，对加热装置抽气至其内部压力小于10-1Pa。Optionally, in accordance with an embodiment of the present invention, in step S103, evacuating the heating device comprises: after pumping the heating device to an internal pressure of less than 10 Pa, charging the inert gas at a predetermined pressure for a first predetermined time; After a predetermined time, the heating device is evacuated to an internal pressure of less than 1 Pa; the temperature in the heating device is raised to a first temperature, the first temperature is maintained, and the heating device is continuously pumped for a second predetermined time, wherein The temperature is half of the preset temperature; and after the second predetermined time, the heating device is charged with a predetermined pressure of inert gas and after being maintained for the third predetermined time, the heating device is evacuated to an internal pressure of less than 10-1 Pa.
具体地，充入加热装置中的惰性气体可以包括：氩气、氦气。第一预定时间可以为5分钟至180分钟。第一温度的范围可以为1000℃～1250℃。第二预定时间可以为5分钟至300 分钟。预设温度的范围可以为2000℃～2500℃。预定压力的范围可以为1000Pa～90000Pa。第三预定时间可以为5分钟至300分钟。Specifically, the inert gas charged into the heating device may include: argon gas, helium gas. The first predetermined time may be from 5 minutes to 180 minutes. The first temperature may range from 1000 °C to 1250 °C. The second predetermined time can be from 5 minutes to 300 minute. The preset temperature can range from 2000 °C to 2500 °C. The predetermined pressure may range from 1000 Pa to 90,000 Pa. The third predetermined time may be from 5 minutes to 300 minutes.
可选地，根据本发明实施例，将加热装置内温度升至预设温度包括：通过感应加热或电阻加热将加热装置内温度升至预设温度。Optionally, according to an embodiment of the invention, raising the temperature in the heating device to the preset temperature comprises: raising the temperature in the heating device to a preset temperature by induction heating or resistance heating.
其中，预设温度的范围可以为2000℃～2500℃。The preset temperature may range from 2000 ° C to 2500 ° C.
可选地，根据本发明实施例，用于生长SiC晶体的SiC原料制备方法还可以包括：将加热装置内的温度梯度设定为5℃/cm～100℃/cm，使得升华的SiC粉料在温度梯度的驱动力作用下输运至第二石墨坩埚中而结晶。Optionally, according to an embodiment of the present invention, the method for preparing a SiC raw material for growing SiC crystals may further include: setting a temperature gradient in the heating device to 5 ° C / cm to 100 ° C / cm, so that the sublimated SiC powder It is transported into the second graphite crucible by the driving force of the temperature gradient to be crystallized.
通过在加热装置内设定5℃/cm～100℃/cm的温度梯度，能够在第二石墨坩埚中获得结晶较致密、质量较均匀的SiC原料。By setting a temperature gradient of 5 ° C / cm to 100 ° C / cm in the heating device, a SiC raw material having a relatively dense crystal and a relatively uniform quality can be obtained in the second graphite crucible.
可选地，根据本发明的实施例，温度梯度的范围为10℃/cm～50℃/cm。Alternatively, according to an embodiment of the invention, the temperature gradient ranges from 10 ° C/cm to 50 ° C/cm.
下面结合图2和图3，对发明一种优选的用于生长SiC晶体的SiC原料的制备方法进行详细说明。图3示出了用于生长SiC晶体的SiC原料的制备装置。A preferred method for preparing a SiC raw material for growing SiC crystals will be described in detail below with reference to FIGS. 2 and 3. Figure 3 shows a preparation apparatus for a SiC raw material for growing SiC crystals.
准备两个石墨坩埚2、7。Prepare two graphite crucibles 2, 7.
将SiC粉料3装入到石墨坩埚2中，在石墨坩埚7的底部靠近中央的位置设置隔离件9。The SiC powder 3 was placed in the graphite crucible 2, and a separator 9 was placed at a position near the center of the bottom of the graphite crucible 7.
其中，SiC粉料3的总杂质含量小于10ppm，优选地小于1ppm；SiC粉料3的粒径小于10mm，优选地小于5mm。Wherein, the total impurity content of the SiC powder 3 is less than 10 ppm, preferably less than 1 ppm; and the particle size of the SiC powder 3 is less than 10 mm, preferably less than 5 mm.
石墨坩埚2和石墨坩埚7的灰份小于50ppm，优选地小于1ppm。The ash content of the graphite crucible 2 and the graphite crucible 7 is less than 50 ppm, preferably less than 1 ppm.
隔离件9为第一端连接至石墨坩埚7的底部而第二端朝向第二坩埚7的开口延伸的实心柱状体，例如，圆柱体，方柱形、三角柱形、多角柱形等，但本发明不并限于此。The spacer 9 is a solid column body whose first end is connected to the bottom of the graphite crucible 7 and the second end extends toward the opening of the second crucible 7, for example, a cylinder, a square cylinder, a triangular cylinder, a polygonal cylinder, etc., but The invention is not limited to this.
例如，隔离件9也可以为空心柱状体。除了柱状体之外，隔离件9还可以为圆台形、圆锥形等其他任意形状，只要其能够防止在石墨坩埚7的靠近中央的位置形成SiC原料即可。 For example, the spacer 9 can also be a hollow cylindrical body. In addition to the columnar body, the separator 9 may have any other shape such as a truncated cone shape or a conical shape as long as it can prevent the formation of the SiC raw material at a position near the center of the graphite crucible 7.
隔离件9的第一端可以以物理或化学的方式连接至石墨坩埚7的底部，或者隔离件9与石墨坩埚7一体形成而固定在石墨坩埚7内的底部。The first end of the spacer 9 may be physically or chemically connected to the bottom of the graphite crucible 7, or the spacer 9 may be integrally formed with the graphite crucible 7 to be fixed to the bottom of the graphite crucible 7.
隔离件9的外壁与石墨坩埚7的内壁隔开一定的间隔，优选地，隔离件9位于石墨坩埚7的中心位置。The outer wall of the spacer 9 is spaced apart from the inner wall of the graphite crucible 7, and preferably, the spacer 9 is located at the center of the graphite crucible 7.
隔离件9自石墨坩埚7的底部向上的高度至少高于期望结晶的SiC原料8的高度。The height of the spacer 9 from the bottom of the graphite crucible 7 is at least higher than the height of the SiC raw material 8 desired to be crystallized.
将石墨坩埚7倒置安装在石墨坩埚2上，使得石墨坩埚7和石墨坩埚2的开口对置。可以通过螺纹式密封、卡环式密封、卡套式密封等方式，将石墨坩埚2和7密封。The graphite crucible 7 was mounted upside down on the graphite crucible 2 such that the openings of the graphite crucible 7 and the graphite crucible 2 were opposed. The graphite crucibles 2 and 7 can be sealed by means of a threaded seal, a snap ring seal, a ferrule seal or the like.
将对置设置的石墨坩埚2和石墨坩埚7放入加热炉中，通过机械泵将加热炉抽气使内部达到真空状态，该真空状态是指加热炉内压力小于10-1Pa。The oppositely disposed graphite crucible 2 and graphite crucible 7 are placed in a heating furnace, and the furnace is evacuated by a mechanical pump to bring the interior to a vacuum state, which means that the pressure in the heating furnace is less than 10-1 Pa.
具体地，对加热炉抽气使其内部压力小于10Pa后，充入惰性气体氩气使得其内部压力达到50000Pa，并保持15分钟；在15分钟后，对加热炉抽气至其内部压力小于1Pa；将加热炉内的温度升至1000℃；维持1000℃并持续对加热炉抽气60分钟，在60分钟后，向加热炉内充入50000Pa的氩气，并在保持60分钟后，对加热炉抽气至其内部压力小于10-1Pa。Specifically, after the furnace is evacuated to have an internal pressure of less than 10 Pa, the inert gas is filled with argon gas so that the internal pressure reaches 50,000 Pa and maintained for 15 minutes; after 15 minutes, the furnace is evacuated to an internal pressure of less than 1 Pa. The temperature in the heating furnace was raised to 1000 ° C; the temperature was maintained at 1000 ° C and the furnace was continuously pumped for 60 minutes. After 60 minutes, the furnace was charged with 50,000 argon gas and heated for 60 minutes. The furnace is evacuated to an internal pressure of less than 10-1 Pa.
对加热炉进行加热，使其内部温度达到例如，2200℃。The furnace is heated to have an internal temperature of, for example, 2,200 °C.
在加热炉内，通过设置温场，存在相对高温区和相对低温区，通常，相对高温区的温度在2000～2500℃的范围内，相对低温区的温度在1900～2400℃的范围内。In the heating furnace, by setting the temperature field, there are relatively high temperature zones and relatively low temperature zones. Generally, the temperature in the relatively high temperature zone is in the range of 2000 to 2500 °C, and the temperature in the relatively low temperature zone is in the range of 1900 to 2400 °C.
将石墨坩埚2置于相对高温区中，而将石墨坩埚7置于相对低温区中，石墨坩埚2中的SiC粉料由于高温的作用而升华，在温度梯度的驱动力作用下输运至处于相对低温区的石墨坩埚7内结晶，从而获得结晶的SiC原料。The graphite crucible 2 is placed in a relatively high temperature region, and the graphite crucible 7 is placed in a relatively low temperature region, and the SiC powder in the graphite crucible 2 is sublimated due to the action of high temperature, and transported to the presence under the driving force of the temperature gradient. The graphite crucible 7 in the relatively low temperature region is crystallized to obtain a crystalline SiC raw material.
根据本发明实施例，由于SiC粉料升华结晶过程中，杂质含量得到大幅降低，使得SiC原料中的杂质含量相比SiC粉料大幅度降低，进而，在采用由此制得的SiC原料来生长SiC晶体时，SiC晶体的质量显著提高。 According to the embodiment of the present invention, since the impurity content of the SiC powder is greatly reduced during the sublimation crystallization process, the impurity content in the SiC raw material is greatly reduced compared with the SiC powder, and further, the SiC raw material thus obtained is used for growth. In the case of SiC crystals, the quality of SiC crystals is remarkably improved.
另外，根据本发明实施例，SiC原料是由SiC粉料高温升华制备得到的SiC多晶料块，该SiC多晶料块结晶致密，密度接近3.2克/立方厘米。相比于传统物理气相传输法生长SiC晶体所采用的SiC粉料，SiC多晶料块结晶致密，SiC晶界间彼此相互作用力强。采用该SiC原料生长SiC晶体过程中，随着生长过程的持续，尽管SiC多晶料块表面也会石墨化，但是SiC多晶料块表面的石墨间存在强相互作用，不易被升华所产生的气相物质带至晶体生长界面，从而避免了在SiC晶体生长过程中产生微观石墨包裹物。In addition, according to an embodiment of the invention, the SiC raw material is a SiC polycrystalline block obtained by sublimation of SiC powder at a high temperature, and the SiC polycrystalline block is densely crystallized and has a density of approximately 3.2 g/cm 3 . Compared with the SiC powder used in the growth of SiC crystal by the conventional physical vapor phase transmission method, the SiC polycrystalline block is densely crystallized, and the SiC grain boundaries interact with each other strongly. During the growth of SiC crystals using the SiC raw material, although the surface of the SiC polycrystalline block is graphitized as the growth process continues, there is a strong interaction between the graphite on the surface of the SiC polycrystalline block, which is not easily sublimated. The vapor phase material is brought to the crystal growth interface, thereby avoiding the formation of microscopic graphite inclusions during the growth of the SiC crystal.
再次，根据本发明实施例，由于在SiC粉料结晶的坩埚中设置了阻隔件，使得最终形成的SiC原料呈中空的结构。当采用具有该结构的SiC原料来生长SiC晶体时，由于SiC原料的是中空结构，所以，在SiC原料的中央部位不存在阻挡和消耗SiC原料升华所得的气相物质的传输，气相物质可以直接传输至晶体生长面，从而使得SiC原料的利用率显著提高。而且，由于在SiC原料的中央部位不存在阻挡和消耗SiC原料升华所得的气相物质的传输，所以，SiC晶体的生长速率在其整个生产过程中基本保持恒定，从而提高了产率。Further, according to the embodiment of the present invention, since the barrier member is provided in the ruthenium of the SiC powder crystal, the finally formed SiC raw material has a hollow structure. When the SiC raw material is grown by using the SiC raw material having the structure, since the SiC raw material has a hollow structure, there is no gas phase substance transporting and consuming the sublimation of the SiC raw material in the central portion of the SiC raw material, and the gas phase substance can be directly transported. To the crystal growth surface, the utilization rate of the SiC raw material is remarkably improved. Moreover, since there is no transmission of the gas phase substance which blocks and consumes the sublimation of the SiC raw material in the central portion of the SiC raw material, the growth rate of the SiC crystal is kept substantially constant throughout the entire production process, thereby improving the yield.
实施例2Example 2
根据本发明的实施例，提供了一种用于生长SiC晶体的SiC原料的制备装置。According to an embodiment of the present invention, an apparatus for preparing a SiC raw material for growing SiC crystals is provided.
图3是SiC原料的制备装置的一部分的截面图。如图3所示，该制备装置包括：3 is a cross-sectional view of a portion of an apparatus for preparing a SiC raw material. As shown in FIG. 3, the preparation device comprises:
第一石墨坩埚2； First graphite crucible 2;
第二石墨坩埚7，在第二石墨坩埚7内自底部向上设置有隔离件9，隔离件9与所述第二石墨坩埚7的侧壁隔开预定距离；a second graphite crucible 7, in the second graphite crucible 7 is provided with a spacer 9 from the bottom, the spacer 9 is spaced apart from the sidewall of the second graphite crucible 7 by a predetermined distance;
具体地，隔离件9为第一端连接至石墨坩埚7的底部而第二端朝向第二坩埚7的开口延伸的实心柱状体，例如，圆柱体，方柱形、三角柱形、多角柱形等，但本发明不并限于此。Specifically, the spacer 9 is a solid column body whose first end is connected to the bottom of the graphite crucible 7 and the second end extends toward the opening of the second crucible 7, for example, a cylinder, a square cylinder, a triangular cylinder, a polygonal cylinder, etc. However, the invention is not limited thereto.
例如，隔离件9也可以为空心柱状体。除了柱状体之外，隔离件9还可以为圆台形、圆锥形等其他任意形状，只要其能够防止在石墨坩埚7的靠近中央的位置形成SiC原料即可。For example, the spacer 9 can also be a hollow cylindrical body. In addition to the columnar body, the separator 9 may have any other shape such as a truncated cone shape or a conical shape as long as it can prevent the formation of the SiC raw material at a position near the center of the graphite crucible 7.
隔离件9的第一端可以以物理或化学的方式连接至石墨坩埚7的底部，或者隔离件9与石墨坩埚7一体形成而固定在石墨坩埚7内的底部。 The first end of the spacer 9 may be physically or chemically connected to the bottom of the graphite crucible 7, or the spacer 9 may be integrally formed with the graphite crucible 7 to be fixed to the bottom of the graphite crucible 7.
隔离件9的外壁与石墨坩埚7的内壁隔开一定的间隔，优选地，隔离件9位于石墨坩埚7的中心位置。The outer wall of the spacer 9 is spaced apart from the inner wall of the graphite crucible 7, and preferably, the spacer 9 is located at the center of the graphite crucible 7.
隔离件9自石墨坩埚7的底部向上的高度至少高于期望结晶的SiC原料的高度。The height of the spacer 9 from the bottom of the graphite crucible 7 is at least higher than the height of the SiC raw material desired to be crystallized.
加热装置12，在加热装置12内具有相对高温区和相对低温区，其中，当制备SiC原料8时，第二石墨坩埚7倒置安装在装有SiC粉料3的第一石墨坩埚2上，且第一石墨坩埚2位于加热装置12内的相对高温区，第二石墨坩埚7位于相对低温区。The heating device 12 has a relatively high temperature zone and a relatively low temperature zone in the heating device 12, wherein when the SiC raw material 8 is prepared, the second graphite crucible 7 is mounted upside down on the first graphite crucible 2 containing the SiC powder 3, and The first graphite crucible 2 is located in a relatively high temperature region within the heating device 12, and the second graphite crucible 7 is located in a relatively low temperature region.
具体地，加热装置12包括但不限于加热炉。加热装置12内的温场是可控的，使得在加热装置12中存在相对高温区和相对低温区，Specifically, the heating device 12 includes, but is not limited to, a heating furnace. The temperature field within the heating device 12 is controllable such that there is a relatively high temperature zone and a relatively low temperature zone in the heating device 12,
当制备SiC原料时，将石墨坩埚7倒置安装在石墨坩埚2上，使得石墨坩埚7和石墨坩埚2的开口对置。可以通过螺纹式密封、卡环式密封、卡套式密封等方式，将石墨坩埚2和7密封。When preparing the SiC raw material, the graphite crucible 7 was mounted upside down on the graphite crucible 2 such that the openings of the graphite crucible 7 and the graphite crucible 2 were opposed. The graphite crucibles 2 and 7 can be sealed by means of a threaded seal, a snap ring seal, a ferrule seal or the like.
将对置设置的石墨坩埚2和石墨坩埚7放入加热炉中，通过机械泵将加热炉抽气使内部达到真空状态，该真空状态是指加热炉内压力小于10-1Pa。The oppositely disposed graphite crucible 2 and graphite crucible 7 are placed in a heating furnace, and the furnace is evacuated by a mechanical pump to bring the interior to a vacuum state, which means that the pressure in the heating furnace is less than 10-1 Pa.
具体地，对加热炉抽气使其内部压力小于10Pa后，充入惰性气体氩气使得其内部压力达到50000Pa，并保持15分钟；在15分钟后，对加热炉抽气至其内部压力小于1Pa；将加热炉内的温度升至1000℃；维持1000℃并持续对加热炉抽气60分钟，在60分钟后，向加热炉内充入50000Pa的氩气，并在保持60分钟后，对加热炉抽气至其内部压力小于10-1Pa。Specifically, after the furnace is evacuated to have an internal pressure of less than 10 Pa, the inert gas is filled with argon gas so that the internal pressure reaches 50,000 Pa and maintained for 15 minutes; after 15 minutes, the furnace is evacuated to an internal pressure of less than 1 Pa. The temperature in the heating furnace was raised to 1000 ° C; the temperature was maintained at 1000 ° C and the furnace was continuously pumped for 60 minutes. After 60 minutes, the furnace was charged with 50,000 argon gas and heated for 60 minutes. The furnace is evacuated to an internal pressure of less than 10-1 Pa.
对加热炉进行加热，使其内部温度达到例如，2200℃。The furnace is heated to have an internal temperature of, for example, 2,200 °C.
在加热炉内，通过设置温场，存在相对高温区和相对低温区，通常，相对高温区的温度在2000～2500℃的范围内，相对低温区的温度在1900～2400℃的范围内。In the heating furnace, by setting the temperature field, there are relatively high temperature zones and relatively low temperature zones. Generally, the temperature in the relatively high temperature zone is in the range of 2000 to 2500 °C, and the temperature in the relatively low temperature zone is in the range of 1900 to 2400 °C.
将石墨坩埚2置于相对高温区中，而将石墨坩埚7置于相对低温区中，石墨坩埚2中的SiC粉料由于高温的作用而升华，在温度梯度的驱动力作用下输运至处于相对低温区的石墨坩埚7内结晶，从而获得结晶的SiC原料。 The graphite crucible 2 is placed in a relatively high temperature region, and the graphite crucible 7 is placed in a relatively low temperature region, and the SiC powder in the graphite crucible 2 is sublimated due to the action of high temperature, and transported to the presence under the driving force of the temperature gradient. The graphite crucible 7 in the relatively low temperature region is crystallized to obtain a crystalline SiC raw material.
由于在SiC粉料结晶的坩埚中设置了阻隔件，使得最终形成的SiC原料呈中空的结构。当采用具有该结构的SiC原料来生长SiC晶体时，由于SiC原料是中空的结构，所以，在SiC原料的中央部位不存在阻挡和消耗SiC原料升华所得的气相物质的传输，气相物质可以直接传输至晶体生长面，从而使得SiC原料的利用率显著提高。而且，由于在SiC原料的中央部位不存在阻挡和消耗SiC原料升华所得的气相物质的传输，所以，SiC晶体的生长速率在其整个生长过程中基本保持恒定，从而提高了产率。Since the barrier member is provided in the ruthenium in which the SiC powder is crystallized, the finally formed SiC raw material has a hollow structure. When the SiC raw material is grown by using the SiC raw material having the structure, since the SiC raw material has a hollow structure, there is no gas phase substance transporting and consuming the sublimation of the SiC raw material in the central portion of the SiC raw material, and the gas phase substance can be directly transported. To the crystal growth surface, the utilization rate of the SiC raw material is remarkably improved. Moreover, since there is no transmission of the gas phase substance which blocks and consumes the sublimation of the SiC raw material at the central portion of the SiC raw material, the growth rate of the SiC crystal is kept substantially constant throughout the growth thereof, thereby improving the yield.
应该指出，上述的具体实施方式仅是本发明的优选实施方式。对于本领域的技术人员而言，在不偏离权利要求的宗旨和范围时，可以有多种形式和细节的变化，而这些变化也是为本发明的保护范围。 It should be noted that the specific embodiments described above are merely preferred embodiments of the invention. Various changes in form and detail may be made by those skilled in the art without departing from the spirit and scope of the invention.

Claims (16)

  1. 一种用于生长SiC晶体的SiC原料的制备方法，其特征在于，包括如下步骤：A method for preparing a SiC raw material for growing SiC crystals, comprising the steps of:
    将SiC粉料装入到第一石墨坩埚中，在所述第一石墨坩埚上倒置安装第二石墨坩埚；以及Loading the SiC powder into the first graphite crucible, and mounting the second graphite crucible upside down on the first graphite crucible;
    将安装好的两石墨坩埚放入加热装置中，将所述加热装置抽真空并将所述加热装置内温度升至预设温度，其中，所述第一石墨坩埚位于所述加热装置内的相对高温区，所述第二石墨坩埚位于所述加热装置内的相对低温区，所述SiC粉料升华并被输运至位于相对低温区的所述第二石墨坩埚中而结晶，从而获得结晶的SiC原料。Putting two installed graphite crucibles into a heating device, vacuuming the heating device and raising the temperature inside the heating device to a preset temperature, wherein the first graphite crucible is located in the heating device In the high temperature region, the second graphite crucible is located in a relatively low temperature region in the heating device, and the SiC powder is sublimated and transported to the second graphite crucible located in a relatively low temperature region to be crystallized, thereby obtaining crystallized SiC raw material.
  2. 如权利要求1所述的制备方法，其特征在于，所述方法还包括：The method according to claim 1, wherein the method further comprises:
    在所述第二石墨坩埚内自底部向上设置隔离件，所述隔离件与所述第二石墨坩埚的侧壁隔开预定距离。A spacer is disposed in the second graphite crucible from the bottom, the spacer being spaced apart from a sidewall of the second graphite crucible by a predetermined distance.
  3. 如权利要求2所述的制备方法，其特征在于，所述隔离件位于所述第二石墨坩埚内的中心位置。The method according to claim 2, wherein the spacer is located at a center position in the second graphite crucible.
  4. 如权利要求2所述的制备方法，其特征在于，所述隔离件包括石墨。The method according to claim 2, wherein the spacer comprises graphite.
  5. 如权利要求2至3中任一项所述的制备方法，其特征在于，所述隔离件为实心或空心结构。The preparation method according to any one of claims 2 to 3, wherein the spacer is a solid or hollow structure.
  6. 如权利要求2至3中任一项所述的制备方法，其特征在于，将所述隔离件自所述第二石墨坩埚的底部向上的高度设置为至少等于或高于期望结晶的SiC原料的高度。The preparation method according to any one of claims 2 to 3, wherein a height of the separator from a bottom of the second graphite crucible is set to be at least equal to or higher than a SiC raw material desired to be crystallized. height.
  7. 如权利要求1所述的制备方法，其特征在于，在所述第一石墨坩埚上倒置安装第二石墨坩埚包括：The method according to claim 1, wherein the inverting the second graphite crucible on the first graphite crucible comprises:
    通过密封的方式将所述第二石墨坩埚倒置安装在所述第一石墨坩埚上，所述密封的方式包括：螺纹式密封、卡环式密封、卡套式密封中的至少一种。 The second graphite crucible is mounted on the first graphite crucible by inversion, and the sealing manner includes at least one of a threaded seal, a snap ring seal, and a ferrule seal.
  8. 如权利要求1所述的制备方法，其特征在于，将所述加热装置抽真空包括：The method according to claim 1, wherein the vacuuming the heating device comprises:
    对所述加热装置抽气使其内部压力小于10Pa后，充入预定压力的惰性气体并保持第一预定时间；After the heating device is evacuated to have an internal pressure of less than 10 Pa, the inert gas of a predetermined pressure is charged and maintained for a first predetermined time;
    在所述第一预定时间后，对所述加热装置抽气至其内部压力小于1Pa；After the first predetermined time, pumping the heating device to an internal pressure of less than 1 Pa;
    将所述加热装置内的温度升至第一温度，维持所述第一温度并持续对所述加热装置抽气达第二预定时间，其中，所述第一温度为所述预设温度的一半；以及Raising the temperature in the heating device to a first temperature, maintaining the first temperature and continuously pumping the heating device for a second predetermined time, wherein the first temperature is half of the preset temperature ;as well as
    在所述第二预定时间后，向所述加热装置内充入所述预定压力的惰性气体并在保持第三预定时间后，对所述加热装置抽气至其内部压力小于10-1Pa。After the second predetermined time, the heating device is charged with the predetermined pressure of inert gas and after being held for a third predetermined time, the heating device is evacuated to an internal pressure of less than 10-1 Pa.
  9. 如权利要求1所述的制备方法，其特征在于，将所述加热装置内温度升至预设温度包括：通过感应加热或电阻加热将所述加热装置内温度升至预设温度。The preparation method according to claim 1, wherein raising the temperature inside the heating device to a preset temperature comprises: raising the temperature inside the heating device to a preset temperature by induction heating or resistance heating.
  10. 如权利要求1所述的制备方法，其特征在于，所述方法还包括：将所述加热装置内的温度梯度设定为5℃/cm～100℃/cm，使得升华的所述SiC粉料在所述温度梯度的驱动力作用下输运至所述第二石墨坩埚中而结晶。The preparation method according to claim 1, wherein the method further comprises: setting a temperature gradient in the heating device to 5 ° C / cm to 100 ° C / cm, so that the sublimated SiC powder It is transported into the second graphite crucible by the driving force of the temperature gradient to be crystallized.
  11. 如权利要求10所述的制备方法，其特征在于，所述温度梯度的范围为10℃/cm～50℃/cm。The method according to claim 10, wherein the temperature gradient ranges from 10 ° C / cm to 50 ° C / cm.
  12. 一种用于生长SiC晶体的SiC原料的制备装置，其特征在于，包括：A device for preparing a SiC raw material for growing SiC crystal, comprising:
    第一石墨坩埚；First graphite crucible;
    第二石墨坩埚，在所述第二石墨坩埚内自底部向上设置有隔离件，所述隔离件与所述第二石墨坩埚的侧壁隔开预定距离；以及a second graphite crucible in which a spacer is disposed from the bottom in the second graphite crucible, the spacer being spaced apart from a sidewall of the second graphite crucible by a predetermined distance;
    加热装置，在所述加热装置内具有相对高温区和相对低温区，a heating device having a relatively high temperature zone and a relatively low temperature zone within the heating device
    其中，当制备所述SiC原料时，所述第二石墨坩埚倒置安装在装有SiC粉料的所述第一石墨坩埚上，且所述第一石墨坩埚位于所述加热装置内的所述相对高温区，所述第二石墨坩埚位于所述加热装置内的所述相对低温区。 Wherein, when preparing the SiC raw material, the second graphite crucible is mounted upside down on the first graphite crucible containing SiC powder, and the relative relationship of the first graphite crucible in the heating device In the high temperature zone, the second graphite crucible is located in the relatively low temperature zone within the heating device.
  13. 根据权利要求12所述的制备装置，其特征在于，所述隔离件位于所述第二石墨坩埚内的中心位置。The preparation apparatus according to claim 12, wherein the spacer is located at a center position in the second graphite crucible.
  14. 根据权利要求12所述的制备装置，其特征在于，所述隔离件包括石墨。The preparation apparatus according to claim 12, wherein the spacer comprises graphite.
  15. 根据权利要求12所述的制备装置，其特征在于，所述隔离件为实心或空心结构。The preparation apparatus according to claim 12, wherein the spacer is a solid or hollow structure.
  16. 根据权利要求12所述的制备装置，其特征在于，所述隔离件自所述第二石墨坩埚的底部向上的高度至少等于或高于期望结晶的SiC原料的高度。 The preparation apparatus according to claim 12, wherein the height of the spacer from the bottom of the second graphite crucible is at least equal to or higher than the height of the SiC raw material desired to be crystallized.
PCT/CN2017/078726 2017-03-30 2017-03-30 Method and apparatus for preparing sic raw material for growing sic crystal WO2018176302A1 (en)

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