WO2020087722A1 - 一种碳化硅单晶的制备方法及其生长装置 - Google Patents

一种碳化硅单晶的制备方法及其生长装置 Download PDF

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Publication number
WO2020087722A1
WO2020087722A1 PCT/CN2018/123716 CN2018123716W WO2020087722A1 WO 2020087722 A1 WO2020087722 A1 WO 2020087722A1 CN 2018123716 W CN2018123716 W CN 2018123716W WO 2020087722 A1 WO2020087722 A1 WO 2020087722A1
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Prior art keywords
single crystal
transmission shaft
silicon carbide
carbide single
raw material
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PCT/CN2018/123716
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English (en)
French (fr)
Inventor
刘鹏飞
刘家朋
李加林
李长进
孙元行
李宏刚
高超
Original Assignee
山东天岳先进材料科技有限公司
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Priority claimed from CN201811303465.9A external-priority patent/CN109234799B/zh
Priority claimed from CN201821809551.2U external-priority patent/CN209144311U/zh
Priority claimed from CN201811303461.0A external-priority patent/CN109355706B/zh
Application filed by 山东天岳先进材料科技有限公司 filed Critical 山东天岳先进材料科技有限公司
Publication of WO2020087722A1 publication Critical patent/WO2020087722A1/zh

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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
    • 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 present application belongs to the field of crystal growth, and specifically relates to a method for preparing a silicon carbide single crystal and a growth device thereof.
  • the most widely used SiC single crystal growth method is the PVT technology, which uses a graphite crucible as a reaction vessel, SiC wafer as a seed crystal, SiC powder as a growth material in the graphite crucible, and the seed crystal is fixed on the top of the graphite crucible.
  • the growth raw material is decomposed into the gas phase component Si m C n and then transported to the seed crystal under the driving of the axial temperature gradient in the graphite crucible to grow SiC crystals.
  • the temperature field in the crucible is The crystal growth rate plays a decisive role.
  • the devices disclosed in the prior art for growing silicon carbide single crystals cannot change the radial distribution of the Si m C n gas phase component on the surface of the seed crystal, nor can they control the crystallization speed of the SiC single crystal, which ultimately affects the crystal surface morphology And block defects. There is also no good solution in the prior art to increase the growth rate of crystals while reducing carbon inclusions.
  • this application proposes a method for preparing a silicon carbide single crystal and a growth device thereof.
  • a silicon carbide single crystal growth device including: a raw material portion, a receiving portion, and a gas phase circulation area;
  • the raw material part is used for placing raw materials and providing a place where raw materials are sublimated by heat;
  • the receiving part is used for receiving products obtained after the sublimation of raw materials
  • the raw material After heating and sublimating, the raw material passes through the gas-phase circulation area and reaches the receiving part;
  • a condensed carbon adsorption part is provided in the gas phase circulation area, and the condensed carbon adsorption part is used to adsorb the condensed carbon formed in the gas phase circulation area;
  • It also includes a control unit for adjusting the pressure distribution in the gas-phase circulation area.
  • the raw material part, the gas phase circulation area and the receiving part may be different parts of the whole, for example, the silicon carbide single crystal growth device is a crucible, the part containing the raw material at the bottom of the crucible is the raw material part, and the cavity in the upper crucible of the raw material is the gas phase circulation area ;
  • the raw material part and the gas-phase circulation area may also be separately provided components.
  • the raw materials are placed in the raw material section and heated under the effect of a protective gas atmosphere to sublimate the raw materials, and then pass through the low-pressure area and the high-pressure area in turn, and finally The receiving part forms a crystal.
  • control part may divide the gas-phase circulation area into an adjacent low-pressure area and a high-pressure area according to pressure distribution, the low-pressure area is adjacent to the raw material portion, and the high-pressure area is adjacent to the receiving portion.
  • the low-pressure zone and the high-pressure zone in the gas-phase circulation area can be realized by means commonly used by those skilled in the art, for example, a rotatable fan is provided in the gas-phase circulation area, or an air inlet and an air outlet are provided in the gas-phase circulation area.
  • the lower part of the circulation area is the low-pressure zone, and the upper part is the effect of the high-pressure zone.
  • the setting of the high-pressure zone and the low-pressure zone in the gas-phase circulation area is on the one hand to increase the driving force of the gas-phase component from the raw material to the surface of the seed crystal.
  • the low-pressure zone makes the raw material rise to the gas-phase component faster, and the high-pressure zone makes the gas-phase component faster Condensation into SiC crystals can accelerate the growth of crystals; on the other hand, the gas phase circulation area is divided into a high pressure area and a low pressure area.
  • the vapor partial pressure of the silicon component in the gas phase component is higher than that of the carbon component.
  • the carbon in the component will condense faster than silicon.
  • the condensed carbon particles are adsorbed on the crucible wall with the rotating gas flow before reaching the crystal growth surface, reducing the carbon inclusions in the crystal The number of crystals is higher.
  • a plurality of heat conductors are provided in the raw material part.
  • the heat conductor is heat-resistant and heat-resistant material, such as quartz and graphite.
  • quartz and graphite When the SiC single crystal is grown by PVT method, the highest temperature intermediate material area first decomposes and sublimates to generate various forms of Si m C n gas phase components; meanwhile, the particles migrate, bond and sinter, and finally, the raw material center is colder The area recrystallizes into SiC grains that have not been carbonized, wasting raw materials.
  • the heat conductor is a graphite rod, one end of the graphite rod is connected to the bottom end of the raw material part, and the other end is located in the raw material part and / or the gas phase circulation area.
  • the graphite rod and the raw material part may be integral or separate.
  • a condensed carbon adsorbing portion is provided in the gas phase circulation area, and the condensed carbon adsorption portion is used to adsorb the condensed carbon formed in the gas phase circulation area.
  • the condensed carbon adsorption part may be the crucible wall, or it may be a separately provided condensed carbon adsorption part; if the gas-phase circulation area and the raw material part are separate parts, the condensed carbon adsorption part is provided at In the gas-phase circulation area.
  • a condensed carbon adsorption part is provided in the gas-phase circulation area, which can reduce the number of carbon inclusions in the crystal and obtain a higher quality crystal.
  • the condensed carbon adsorption part is provided in the high-pressure area and / or the low-pressure area adjacent to the high-pressure area. After the gas phase reaches the high-pressure zone from the low-pressure zone, the carbon in the components will condense faster than silicon.
  • the raw material part is a graphite crucible
  • the graphite crucible includes a graphite crucible chamber and a graphite crucible cover
  • the gas-phase circulation area is provided in the chamber above the graphite crucible and / or the space above the graphite crucible.
  • the raw material part and the gas phase circulation area can be in a space, for example, in a graphite crucible, the part where the raw material is placed at the bottom of the crucible is the raw material part, and the upper gas phase circulation area is divided into the gas phase circulation area; There is a space above the graphite crucible that can be used as the gas phase circulation area.
  • the receiving part is a graphite crucible cover, and the graphite crucible cover is hermetically connected to the graphite crucible.
  • a seed crystal is provided inside the graphite crucible cover.
  • the control part includes providing a fan in the gas-phase circulation area, the fan being provided between the high-pressure area and the low-pressure area, the fan being used to form the high-pressure area and the low-pressure area in the gas-phase circulation area.
  • the fan is used to form the high-pressure area and the low-pressure area in the gas-phase circulation area.
  • the rotation of the fan in the gas-phase circulation area can make the thermal field distribution of the gas-phase circulation area uniform, and the components in the radial direction of the seed surface The concentration is the same, so that the gas phase components are evenly distributed on the surface of the seed crystal.
  • the raw material of silicon carbide is sublimated into the gas phase component of Si m C n , and the meteorological component is guided by the rotating fan blades, forming a specific clockwise / counterclockwise flow direction in the crucible.
  • the fan rotates at a certain speed, so that the atmosphere can flow stably in the crucible, to suppress irregular convection in the crucible, change the radial non-uniformity of the temperature, and reduce the temperature fluctuation amplitude of the growth surface.
  • the transmission shaft further includes a transmission shaft, one end of the transmission shaft is connected to the fan, the other end of the transmission shaft extends out of the single crystal growth device, and the transmission shaft drives the fan to rotate.
  • the drive shaft must be a high temperature resistant drive shaft, such as a graphite drive shaft.
  • the transmission shaft can be installed through the thermal conductor or not, and the main function of the transmission shaft is to protect the transmission shaft and increase the service life of the transmission shaft.
  • the sweeping area of the fan is 60-85% of the cross-sectional area of the gas-phase circulation area. This ensures that the fan rotates freely in the gas-phase circulation area.
  • the silicon carbide single crystal growth device includes a device shell layer;
  • the transmission shaft includes a first transmission shaft and a second transmission shaft, the first transmission shaft is located above the second transmission shaft, and one end of the second transmission shaft is connected to the first transmission shaft , The other end of the second transmission shaft passes through the bottom end of the device casing layer and is connected to the motor; a sealing device is provided between the device casing layer and the second transmission shaft, and the end of the first transmission shaft away from the second transmission shaft is connected to the fan;
  • One drive shaft is graphite tantalum plated drive shaft, the second drive shaft is stainless steel drive shaft;
  • the fan is graphite tantalum plated fan.
  • a PVT method silicon carbide single crystal growth device including a graphite crucible, a sealed crucible cover is provided on the graphite crucible, and a solid connection with the inner wall of the bottom of the graphite crucible is provided in the graphite crucible
  • the vertically arranged first graphite rod is provided with a raw material part in the graphite crucible.
  • the first graphite rod extends beyond the raw material part and is provided with a gas phase circulation area above the raw material part.
  • a transmission shaft passes through the first graphite rod
  • a fan is arranged on the transmission shaft, and the fan is arranged in the gas-phase circulation area.
  • the raw material part, the gas phase circulation area and the receiving part may be different parts of the whole, for example, the silicon carbide single crystal growth device is a crucible, the part containing the raw material at the bottom of the crucible is the raw material part, and the cavity in the upper crucible of the raw material is the gas phase circulation area ;
  • the raw material part and the gas-phase circulation area may also be separately provided components.
  • the low-pressure zone and the high-pressure zone in the gas-phase circulation area can be realized by means commonly used by those skilled in the art, for example, a rotatable fan is provided in the gas-phase circulation area, or an air inlet and an air outlet are provided in the gas-phase circulation area.
  • the lower part of the circulation area is the low-pressure zone, and the upper part is the effect of the high-pressure zone.
  • the setting of the high-pressure zone and the low-pressure zone in the gas-phase circulation area is on the one hand to increase the driving force of the gas-phase component from the raw material to the surface of the seed crystal.
  • the low-pressure zone makes the raw material rise to the gas-phase component faster, and the high-pressure zone makes the gas-phase component faster Condensation into SiC crystals can accelerate the growth of crystals; on the other hand, the gas phase circulation area is divided into a high pressure area and a low pressure area.
  • the vapor partial pressure of the silicon component in the gas phase component is higher than that of the carbon component.
  • the carbon in the component will condense faster than silicon.
  • the condensed carbon particles are adsorbed on the crucible wall with the rotating gas flow before reaching the crystal growth surface, reducing the carbon inclusions in the crystal The number of crystals is higher.
  • silicon carbide single crystal growth device proposed in this application to prepare silicon carbide single crystals
  • the raw materials are placed in the raw material section and heated under the effect of a protective gas atmosphere to sublimate the raw materials, pass through the gas phase zone, and finally in the receiving section Crystals are formed.
  • a plurality of heat conductors are provided in the raw material part.
  • the heat conductor is heat-resistant and heat-resistant material, such as quartz and graphite.
  • quartz and graphite When the SiC single crystal is grown by PVT method, the highest temperature intermediate material area first decomposes and sublimates to generate various forms of Si m C n gas phase components; meanwhile, the particles migrate, bond and sinter, and finally, the raw material center is colder The area recrystallizes into SiC grains that have not been carbonized, wasting raw materials.
  • the "center" of the "cold area of raw material” above is a radial description.
  • the magnetic field cuts the crucible wall to generate heat, and the heat is transferred from the crucible wall to the raw material, so the area closer to the crucible wall is hotter and the area farther away from the crucible wall The colder.
  • This is mainly because the axial distribution temperature gap is large, the substance in the middle is heated by the coil, and the emitted environment is poor, resulting in the highest temperature, while the bottom is poorly heated, but the heat dissipation effect Good factors lead to its recrystallization and waste of raw materials.
  • the provision of a number of heat conductors in the raw material section avoids the occurrence of colder areas in the center of the raw material and improves the raw material utilization rate.
  • a condensed carbon adsorbing portion is provided in the gas phase circulation area, and the condensed carbon adsorption portion is used to adsorb the condensed carbon formed in the gas phase circulation area.
  • the condensed carbon adsorption part may be the crucible wall, or it may be a separately provided condensed carbon adsorption part; if the gas-phase circulation area and the raw material part are separate parts, the condensed carbon adsorption part is provided at In the gas-phase circulation area.
  • a condensed carbon adsorption part is provided in the gas-phase circulation area, which can reduce the number of carbon inclusions in the crystal and obtain a higher quality crystal.
  • the condensed carbon adsorption part is provided between the fan and the crucible cover. After the gas phase reaches the high-pressure zone from the low-pressure zone, the carbon in the components will condense faster than silicon.
  • the heat conductor is a second graphite rod, one end of the second graphite rod is connected to the bottom end of the raw material part, and the other end is located in the raw material part and / or the gas phase circulation area.
  • the second graphite rod and the crucible may be integral or separate.
  • the raw material part is a graphite crucible
  • the gas-phase circulation area is provided in a chamber above the graphite crucible and / or a space above the graphite crucible.
  • the raw material part and the gas phase circulation area can be in a space, for example, in a graphite crucible, the part where the raw material is placed at the bottom of the crucible is the raw material part, and the upper gas phase circulation area is divided into the gas phase circulation area; it can also be separate, such as There is a space above the graphite crucible that can be used as the gas phase circulation area.
  • the receiving part is a graphite crucible cover, and the graphite crucible cover is hermetically connected to the graphite crucible.
  • a seed crystal is provided inside the graphite crucible cover.
  • a fan is provided in the gas phase circulation area, the fan is provided between the high pressure area and the low pressure area, and the fan is used to form the high pressure area and the low pressure area in the gas phase circulation area.
  • the fan is used to form the high-pressure area and the low-pressure area in the gas-phase circulation area.
  • the rotation of the fan in the gas-phase circulation area can make the thermal field distribution of the gas-phase circulation area uniform, and the components in the radial direction of the seed surface The concentration is the same, so that the gas phase components are evenly distributed on the surface of the seed crystal.
  • the raw material of silicon carbide is sublimated into the gas phase component of Si m C n , and the meteorological component is guided by the rotating fan blades, forming a specific clockwise / counterclockwise flow direction in the crucible.
  • the fan rotates at a certain speed, so that the atmosphere can flow stably in the crucible, to suppress irregular convection in the crucible, change the radial non-uniformity of the temperature, and reduce the temperature fluctuation amplitude of the growth surface.
  • the transmission shaft further includes a transmission shaft, one end of the transmission shaft is connected to the fan, the other end of the transmission shaft extends out of the single crystal growth device, and the transmission shaft drives the fan to rotate.
  • the drive shaft must be a high temperature resistant drive shaft, such as a graphite drive shaft.
  • the transmission shaft can be installed through the thermal conductor or not, and the main function of the transmission shaft is to protect the transmission shaft and increase the service life of the transmission shaft.
  • the sweeping area of the fan is 60-85% of the cross-sectional area of the gas-phase circulation area. This ensures that the fan rotates freely in the gas-phase circulation area.
  • the fan is a graphite tantalum-plated fan.
  • the silicon carbide single crystal growth device includes a device shell layer, the device shell layer is disposed on the periphery of the graphite crucible and crucible cover, the transmission shaft includes a first transmission shaft and a second transmission shaft, the first transmission shaft is located Above the transmission shaft, one end of the second transmission shaft is connected to the first transmission shaft, and the other end of the second transmission shaft passes through the bottom end of the device housing layer and is connected to the motor.
  • the second transmission shaft is sealed with the device casing, and the end of the first transmission shaft away from the second transmission shaft is connected to the fan.
  • a sealing device is provided between the outer shell of the device and the second transmission shaft.
  • the first transmission shaft is a graphite tantalum-plated transmission shaft
  • the second transmission shaft is a stainless steel transmission shaft.
  • a method for improving the growth quality of a silicon carbide single crystal of the PVT method includes heating and sublimating a long crystal raw material to obtain a gaseous raw material, and the gaseous raw material passes through a gas phase circulation area to form crystals in a receiving portion
  • the pressure distribution of the gas-phase circulation area is adjusted so that the gas-phase circulation area forms a low-pressure area and a high-pressure area, and the gaseous raw material passes through the low-pressure area and the high-pressure area in sequence to reach the receiving portion to form crystals.
  • the silicon carbide single crystal growth occurs in the silicon carbide single crystal growth device.
  • the single crystal growth device includes a raw material part, the long crystal raw material is placed in the raw material part, and the raw material is sublimated by heating under the action of a protective gas atmosphere;
  • the silicon carbide single crystal growth device also includes a control unit that controls the pressure distribution of the gas phase circulation area.
  • the control portion divides the gas phase circulation area into a low-pressure area and a high-pressure area, and the sublimation raw materials pass through the low-pressure area and the high-pressure area in sequence, and finally in the receiving section Crystals are formed.
  • the raw material part, the gas phase circulation area and the receiving part may be different parts of the whole, for example, the silicon carbide single crystal growth device is a crucible, the part containing the raw material at the bottom of the crucible is the raw material part, and the cavity in the upper crucible of the raw material is the gas phase circulation area ;
  • the raw material part and the gas-phase circulation area may also be separately provided components.
  • the low-pressure zone and the high-pressure zone in the gas-phase circulation area can be realized by means commonly used by those skilled in the art, for example, a rotatable fan is provided in the gas-phase circulation area, or an air inlet and an air outlet are provided in the gas-phase circulation area.
  • the lower part of the circulation area is the low-pressure zone, and the upper part is the effect of the high-pressure zone.
  • the setting of the high-pressure zone and low-pressure zone in the gas-phase circulation area is on the one hand to increase the driving force of the gas-phase components from the raw material to the surface of the seed crystal. Condensation into SiC crystals can accelerate the growth of crystals; on the other hand, the gas phase circulation area is divided into a high pressure area and a low pressure area.
  • the vapor partial pressure of the silicon component in the gas phase component is higher than that of the carbon component.
  • the carbon in the component will condense faster than silicon.
  • the condensed carbon particles are adsorbed on the crucible wall with the rotating gas flow before reaching the crystal growth surface, reducing the carbon inclusions in the crystal The number of crystals is higher.
  • the raw materials are placed in the raw material section and heated under the effect of a protective gas atmosphere to sublimate the raw materials, and then pass through the low pressure area and the high pressure area in turn. Finally, crystals are formed in the receiving part.
  • the shielding gas is one or a mixture of two or more of helium, neon or argon, and a number of heat conductors are provided in the raw material part.
  • the heat conductor is heat-resistant and heat-resistant material, such as quartz and graphite.
  • the highest temperature intermediate material area first decomposes and sublimates to generate various forms of Si m C n gas phase components; meanwhile, the particles migrate, bond and sinter, and finally, the raw material center is colder
  • the area recrystallizes into SiC grains that have not been carbonized, wasting raw materials. This is mainly because the axial distribution temperature gap is large, the substance in the middle is heated by the coil, and the emitted environment is poor, resulting in the highest temperature, while the bottom is poorly heated, but the heat dissipation effect Good factors lead to its recrystallization and waste of raw materials.
  • the provision of a number of heat conductors in the raw material section avoids the occurrence of colder areas in the center of the raw material and improves the raw material utilization rate.
  • the heat conductor is a graphite rod, one end of the graphite rod is connected to the bottom end of the raw material part, and the other end is located in the raw material part and / or the gas phase circulation area.
  • the graphite rod and the raw material part may be integral or separate.
  • a condensed carbon adsorbing portion is provided in the gas phase circulation area, and the condensed carbon adsorption portion is used to adsorb the condensed carbon formed in the gas phase circulation area.
  • the condensed carbon adsorption part may be the crucible wall, or it may be a separately provided condensed carbon adsorption part; if the gas phase circulation area and the raw material part are separate components, the condensed carbon adsorption part is provided at In the gas-phase circulation area.
  • a condensed carbon adsorption part is provided in the gas-phase circulation area, which can reduce the number of carbon inclusions in the crystal and obtain a higher quality crystal.
  • the condensed carbon adsorption part is provided adjacent to the high-pressure region and / or the low-pressure region. After the gas phase reaches the high-pressure zone from the low-pressure zone, the carbon in the components will condense faster than silicon.
  • the raw material part is a graphite crucible
  • the gas-phase circulation area is provided in a chamber above the graphite crucible and / or a space above the graphite crucible.
  • the raw material part and the gas phase circulation area can be in a space, for example, in a graphite crucible, the part where the raw material is placed at the bottom of the crucible is the raw material part, and the upper gas phase circulation area is divided into the gas phase circulation area; it can also be separate, such as There is a space above the graphite crucible that can be used as the gas phase circulation area.
  • the receiving part is a graphite crucible cover, and the graphite crucible cover is hermetically connected to the graphite crucible.
  • a seed crystal is provided inside the graphite crucible cover.
  • a fan is provided in the gas phase circulation area, the fan is provided between the high pressure area and the low pressure area, and the fan is used to form the high pressure area and the low pressure area in the gas phase circulation area.
  • the fan is used to form the high-pressure area and the low-pressure area in the gas-phase circulation area.
  • the rotation of the fan in the gas-phase circulation area can make the thermal field distribution of the gas-phase circulation area uniform, and the components in the radial direction of the seed crystal surface. The concentration is the same, so that the gas phase components are evenly distributed on the surface of the seed crystal.
  • the raw material of silicon carbide is sublimated into the gas phase component of Si m C n , and the meteorological component is guided by the rotating fan blades, forming a specific clockwise / counterclockwise flow direction in the crucible.
  • the fan rotates at a certain speed, so that the atmosphere can flow stably in the crucible, to suppress irregular convection in the crucible, change the radial non-uniformity of the temperature, and reduce the temperature fluctuation amplitude of the growth surface.
  • the transmission shaft further includes a transmission shaft, one end of the transmission shaft is connected to the fan, the other end of the transmission shaft extends out of the single crystal growth device, and the transmission shaft drives the fan to rotate.
  • the drive shaft must be a high temperature resistant drive shaft, such as a graphite drive shaft.
  • the transmission shaft can be installed through the thermal conductor or not.
  • the main function of the transmission shaft is to protect the transmission shaft and increase the service life of the transmission shaft.
  • the sweeping area of the fan is 60-85% of the cross-sectional area of the gas-phase circulation area. This ensures that the fan rotates freely in the gas-phase circulation area.
  • the silicon carbide single crystal growth device includes a device shell layer;
  • the transmission shaft includes a first transmission shaft and a second transmission shaft, the first transmission shaft is located above the second transmission shaft, and one end of the second transmission shaft is connected to the first transmission shaft , The other end of the second transmission shaft passes through the bottom end of the device casing and is connected to the motor;
  • a sealing device is provided between the device casing and the second transmission shaft;
  • the first transmission shaft is a graphite tantalum-plated transmission shaft, and the second transmission shaft is Stainless steel drive shaft;
  • fan is graphite tantalum-plated fan.
  • the silicon carbide single crystal is ⁇ -silicon carbide single crystal
  • the growth method of the ⁇ -silicon carbide single crystal includes the following steps:
  • Assembly stage fix the single crystal growth device on the heat source, and place the insulation blanket on the bottom of the single crystal growth device; put silicon carbide powder and seed crystal in the single crystal growth device; bare in the single crystal growth device Thermal insulation felt is placed on the outer surface;
  • Heating and heating stage vacuum is applied in the single crystal growth device, and then the protective gas is introduced, and the absolute pressure in the single crystal growth device is maintained at 0.8 * 10 5 ⁇ 1.2 * 10 5 Pa; then the temperature in the single crystal growth device is increased by heating Reach 1800-2000K; then turn on the fan and adjust the speed to 6-60r / min;
  • Crystal growth stage During the crystal growth process, the pressure in the single crystal growth device is controlled at 500-5000Pa, and the temperature is controlled at 2200-2800K; then the fan speed is adjusted to 10-100r / min, and the pressure difference between the upper and lower pressure of the fan is 5 ⁇ 500Pa;
  • cooling stage turn off the heating device, fill the furnace cavity with protective gas, the pressure in the single crystal growth device is controlled at 1 * 10 4 -4 * 10 4 Pa, and the temperature is controlled at 1800-2000K; when the temperature is lower than 1800- At 2000K, stop the fan rotation;
  • the Si m C n reaching the upper seed crystal is very uniform in terms of composition and temperature distribution; a high-quality SiC crystal with a uniform surface and no polymorphs is obtained.
  • This application increases the driving force of the gas phase components from the raw material to the surface of the seed crystal, and the formation of the high-pressure region and the low-pressure region can accelerate the growth of the crystal.
  • This application reduces the number of carbon inclusions in the crystal, resulting in a higher quality crystal.
  • This application has the characteristics of simple operation, strong security, strong practicability, and suitable for promotion and use.
  • FIG. 1 is a schematic diagram of a silicon carbide single crystal growth device
  • FIG. 2 is a schematic diagram of another silicon carbide single crystal growth device
  • FIG. 3 is a schematic diagram of another silicon carbide single crystal growth device
  • FIG. 4 is a schematic diagram of another silicon carbide single crystal growth device.
  • first and second are used for description purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated.
  • the features defined as “first” and “second” may explicitly or implicitly include one or more of the features.
  • the meaning of “plurality” is two or more, unless otherwise specifically limited.
  • the terms “installation”, “connected”, “connected”, “fixed” and other terms should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection , Or integrated; it can be mechanical connection, electrical connection, or communication; it can be directly connected or indirectly connected through an intermediary, it can be the connection between two components or the interaction between two components .
  • installation can be a fixed connection or a detachable connection , Or integrated; it can be mechanical connection, electrical connection, or communication; it can be directly connected or indirectly connected through an intermediary, it can be the connection between two components or the interaction between two components .
  • the first feature is “on” or “under” the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly through an intermediary contact.
  • the description referring to the terms “one embodiment”, “some embodiments”, “examples”, “specific examples”, or “some examples” means specific features described in conjunction with the embodiment or examples , Structure, material or characteristic is included in at least one embodiment or example of the present application.
  • the schematic representation of the above terms does not necessarily refer to the same embodiment or example.
  • the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
  • Example 1 Silicon carbide single crystal growth device:
  • the present application provides a silicon carbide single crystal growth device, including: a raw material part 1, which is used to place raw materials, and provides a place where raw materials are sublimated by heating; and also includes a gas-phase circulation area 2, where gas-phase circulation The area 2 is divided into an adjacent low-pressure area 21 and a high-pressure area 22, and the low-pressure area 21 is adjacent to the raw material portion 1; it also includes a receiving portion 3, which is adjacent to the high-pressure area 22, and the receiving portion 3 is used to receive After the raw materials are sublimated, the products obtained through the low-pressure zone 21 and the high-pressure zone 22 are sequentially obtained.
  • the arrangement of the low-pressure area 21 and the high-pressure area 22 adopts a method that can be realized by those skilled in the art, and the arrangement of the low-pressure area 21 and the high-pressure area 22 does not change the growth environment such as the temperature required for the growth of the silicon carbide single crystal, nor does it affect the carbonization Sealability of silicon single crystal growth devices.
  • the present application provides another silicon carbide single crystal growth device, including: a raw material part 1, which is used to place raw materials, and provides a place where raw materials are sublimated by heating; and also includes a gas phase circulation area 2, a gas phase
  • the circulation area 2 is divided into an adjacent low-pressure area 21 and a high-pressure area 22 under the action of the control portion.
  • the low-pressure area 21 is adjacent to the raw material portion 1; it also includes a receiving portion 3, which is adjacent to the high-pressure area 22
  • the receiving part 3 is used to receive the products obtained through the low-pressure area 21 and the high-pressure area 22 in turn after the raw materials are sublimated.
  • the formation of the high-pressure region 22 and the low-pressure region 21 is provided by a control unit, the control unit includes an air inlet 31 provided in the high-pressure region 22, and an air outlet 32 provided in the low-pressure region 21, the gas is not Gases that affect the original single crystal growth environment, such as inert gas argon, etc., and by controlling the ventilation rate and other conditions to ensure that the original ambient temperature is not changed after the gas is introduced, so that a low-pressure area 21 and a high-pressure area are formed in the gas-phase circulation area 2 22, and can form a gas cycle, which can also achieve the purpose of uniform gas temperature near the seed crystal.
  • the control unit includes an air inlet 31 provided in the high-pressure region 22, and an air outlet 32 provided in the low-pressure region 21, the gas is not Gases that affect the original single crystal growth environment, such as inert gas argon, etc., and by controlling the ventilation rate and other conditions to ensure that the original ambient temperature is not changed after the gas is introduced, so that a low-pressure area 21 and
  • the silicon carbide single crystal growth device in the embodiment is used for preparing the silicon carbide single crystal by the PVT method.
  • the raw material part 1 is a graphite crucible, the part where the raw material is placed at the bottom of the crucible is the raw material part 1, the gas-phase circulation area 2 is provided in the upper chamber of the graphite crucible and / or the space above the graphite crucible, and the receiving part 3 is a graphite crucible cover, which The seed crystal is placed inside the crucible cover, and the graphite crucible cover is hermetically connected to the graphite crucible.
  • a plurality of heat conductors 5, such as graphite rods, are provided in the raw material part 1.
  • the one end of the heat conductive body 5 is connected to the bottom end of the raw material part 1, and the other end is located in the raw material part 1 and / or the gas-phase circulation region 2.
  • the present application provides yet another silicon carbide single crystal growth device, including: a raw material part 1, which is used to place raw materials and provide a place where raw materials are sublimated by heating; and further includes a gas phase circulation area 2, a gas phase
  • the circulation area 2 is divided into an adjacent low-pressure area 21 and a high-pressure area 22, and the low-pressure area 21 is adjacent to the raw material portion 1; it also includes a receiving portion 3, which is adjacent to the high-pressure area 22, and the receiving portion 3 is used to After the raw materials are sublimated, the products obtained through the low-pressure zone 21 and the high-pressure zone 22 are sequentially received.
  • the raw material portion 1 is a graphite crucible, and the gas-phase circulation area 2 is provided in the space above the graphite crucible.
  • the gas-phase circulation area 2 and the raw material portion 1 are not in the same device, it is also a means that can be realized by those skilled in the art to ensure that the entire silicon carbide cannot be affected The tightness of the single crystal growth device.
  • a plurality of heat conductors 5 are provided in the raw material portion 1, the heat conductor 5 is a graphite rod, one end of the graphite rod is connected to the bottom end of the raw material portion 1, and the other end is located in the raw material portion 1.
  • a condensed carbon adsorption unit 4 is provided in the gas-phase circulation region 2, and the condensed carbon adsorption unit 4 is used to adsorb condensed carbon formed in the gas-phase circulation region.
  • the condensed carbon adsorption part 4 is provided in the high-pressure region 22 and / or the low-pressure region 21 adjacent to the high-pressure region 22. After the gas phase reaches the high-pressure region 22 from the low-pressure region 21, the carbon in the components will condense faster than silicon.
  • a fan 6 is provided in the gas-phase circulation area 2.
  • the fan 6 is provided between the high-pressure area 22 and the low-pressure area 21.
  • the fan 6 is used to form the high-pressure area 22 and the low-pressure area 21 in the gas-phase circulation area 2.
  • the transmission shaft 7 is also included. One end of the transmission shaft 7 is connected to the fan 6, and the other end of the transmission shaft 7 extends out of the single crystal growth device.
  • the setting of the fan and the transmission shaft is a means that can be realized by those skilled in the art, in which the fan and the transmission shaft are both high-temperature resistant materials to ensure that they can work under high temperature.
  • the sweeping area of the fan 6 is 60-85% of the cross-sectional area of the gas-phase circulation area 2, so as to ensure that the fan 6 can rotate in the gas-phase circulation area 2.
  • the silicon carbide single crystal growth device includes a device shell layer 9, and the transmission shaft 7 includes a first transmission shaft 71 and a second transmission shaft 72.
  • the first transmission shaft 71 is located above the second transmission shaft 72, and the second One end of the transmission shaft 72 is connected to the first transmission shaft 71, the other end of the second transmission shaft 72 passes through the bottom end of the device casing layer 9 and is connected to the motor 8, and a sealing device 73 is provided between the device casing layer 9 and the second transmission shaft 72 .
  • the first transmission shaft 71 is a graphite tantalum-plated transmission shaft
  • the second transmission shaft 72 is a stainless steel transmission shaft
  • the fan is a graphite tantalum-plated fan.
  • Part of the first drive shaft 71 and the fan are in the graphite crucible 1, and the temperature is higher during the growth of silicon carbide single crystal, and the silicon vapor generated therein will corrode the graphite material, so the first drive shaft 71 and the fan are graphite coated Tantalum material not only resists high temperature, but also prevents it from being eroded.
  • the starter motor 8 drives the second transmission shaft 72, thereby driving the first transmission shaft 71, and then the fan in the graphite crucible 1 to rotate.
  • the device casing 9 protects the transmission shaft 7
  • the aspect provides a closed protective space, so that the silicon carbide single crystal is more free from interference from the external environment when growing, the growth environment is more stable, and a higher quality silicon carbide single crystal is obtained.
  • Assembly stage fix the single crystal growth device on the heat source, and place the insulation blanket on the bottom of the single crystal growth device; put silicon carbide powder and seed crystal in the single crystal growth device; bare in the single crystal growth device Thermal insulation felt is placed on the outer surface;
  • Heating and heating stage vacuum is applied in the single crystal growth device, and then the protective gas is introduced, and the absolute pressure in the single crystal growth device is maintained at 0.8 * 10 5 ⁇ 1.2 * 10 5 Pa; then the temperature in the single crystal growth device is increased by heating Reach 1800-2000K; then turn on the fan and adjust the speed to 6-60r / min;
  • Crystal growth stage During the crystal growth process, the pressure in the single crystal growth device is controlled at 500-5000Pa, and the temperature is controlled at 2200-2800K; then the fan speed is adjusted to 10-100r / min, and the pressure difference between the upper and lower pressure of the fan is 5 ⁇ 500Pa;
  • cooling stage turn off the heating device, fill the furnace cavity with protective gas, the pressure in the single crystal growth device is controlled at 1 * 10 4 -4 * 10 4 Pa, and the temperature is controlled at 1800-2000K; when the temperature is lower than 1800- At 2000K, stop the fan rotation;
  • the single crystal in this embodiment may be a silicon carbide single crystal.
  • the test method for the concentration of inclusions is: select 10 grown crystals, observe the other inclusions under the microscope after slicing the crystal, and extract the 5th and 10th pieces of each crystal uniformly, under 50 times magnification, statistics Concentration of inclusions.
  • the difference in thickness is: the average value of the difference between the maximum thickness and the minimum thickness of 10 crystals grown at the edges.
  • the number of microtubes is: select the number of large clusters of microtubes in 10 crystals grown.
  • the gas-phase circulation area is set to a high-pressure area and a low-pressure area.
  • the carbon coating concentration is significantly reduced, and the crystal thickness difference is also significantly reduced
  • the number of microtubes also decreased significantly, indicating that the gas-phase circulation area is divided into a high-pressure area and a low-pressure area.
  • the vapor partial pressure of the silicon component in the gas phase component is higher than that of the carbon component.
  • the rotating fan makes the heat field distribution in the gas-phase circulation area uniform, and the seed crystal
  • the concentration of each component in the radial direction of the surface is the same, so that the gas phase components are evenly distributed on the surface of the seed crystal, so the obtained crystal has a low carbon coating concentration, a small crystal thickness difference and a small number of microtubes.
  • the setting of the condensed carbon adsorption part in the single crystal growth device compared to the absence of this setting, because the condensed carbon adsorption part can adsorb carbon components, it will reduce the carbon inclusion to a certain extent
  • the concentration, the difference in crystal thickness and the number of microtubes will also be reduced, and the quality of the obtained crystal is better.
  • the provision of a thermal conductor, a condensed carbon adsorption part, and a high-pressure zone and a low-pressure zone in the gas phase circulation area in the single crystal growth device will reduce the carbon packing concentration, the single crystal thickness difference, and the number of microtubes, and increase the silicon carbide single The quality of the crystal.

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Abstract

本申请涉及一种碳化硅单晶生长装置，包括：原料部、接收部和气相流通区域；所述原料部用于放置原料，并提供原料受热升华的场所；所述接收部用于接收原料升华后得到的产品；所述原料受热升华后经过气相流通区域到达接收部；在气相流通区域设有凝结碳吸附部，所述凝结碳吸附部用于吸附在气相流通区域形成的凝结碳；还包括控制部，所述控制部用于调节气相流通区域的压力分布。本申请使到达上部籽晶附近的SimCn不管是在组分还是温度分布上都非常均匀；得到表面均匀且无小片多型的高质量SiC晶体；本申请增加组分从原料到籽晶表面的的驱动力。

Description

一种碳化硅单晶的制备方法及其生长装置 技术领域
本申请属于晶体生长领域，具体涉及一种碳化硅单晶的制备方法及其生长装置。
背景技术
目前SiC单晶生长方法应用最广泛的是PVT技术，其采用石墨坩埚作为反应容器，采用SiC晶片作为籽晶，在石墨坩埚内装有SiC粉末作为生长原料，籽晶被固定在石墨坩埚顶部。通过控制坩埚内的生长温度、压力，生长原料分解成气相组分Si mC n后在石墨坩埚内部轴向温度梯度的驱动下输运到籽晶处结晶生长SiC晶体，坩埚内的温度场对晶体的生长速率起决定性作用。
现有技术中利用PVT法生长碳化硅单晶容易产生区域性小片多型等晶体缺陷，这是由于原料填装不均匀和石墨件组装不居中等方面导致原料分布不均匀，或者因为坩埚内径向传热不均匀导致热场分布不均匀，都使得气相组分分布不均匀，籽晶表面径向各方向各组分浓度不同，最终造成晶体表面不均匀或者小片多型的产生。由于在SiC单晶生长中会产生碳组分，晶体生长中碳包裹物的数量会影响晶体的质量。在产业化生产时，SiC单晶的生长速率对于产品的效益是很重要的因素，如何提高SiC单晶的生长速率，现有技术中没有得到很好的解决思路。
现有技术中公开的用于生长碳化硅单晶的装置均不能改变Si mC n气相组分在籽晶表面的径向分布，也不能控制SiC单晶的结晶速度，最终影响晶体表面形貌和区块状缺陷。现有技术中也没有很好的解决提高晶 体生长速度同时可以降低碳包裹物的技术。
发明内容
为了解决上述问题，本申请提出了一种碳化硅单晶的制备方法及其生长装置。
根据本申请的一个方面，提出了一种碳化硅单晶生长装置，包括：原料部、接收部和气相流通区域；
所述原料部用于放置原料，并提供原料受热升华的场所；
所述接收部用于接收原料升华后得到的产品；
所述原料受热升华后经过气相流通区域到达接收部；
在气相流通区域设有凝结碳吸附部，所述凝结碳吸附部用于吸附在气相流通区域形成的凝结碳；
还包括控制部，所述控制部用于调节气相流通区域的压力分布。
其中，原料部和气相流通区域以及接收部可以是一个整体中的不同部分，例如碳化硅单晶生长装置为坩埚，坩埚底部装原料的部分为原料部，原料上部坩埚内空腔为气相流通区域；原料部和气相流通区域也可以是单独分开设置的部件。
利用本申请提出的一种碳化硅单晶生长装置制备碳化硅单晶时，将原料置于原料部，并在保护气气氛的作用下加热使得原料升华，依次通过低压区和高压区，最后在接收部形成晶体。
优选地，所述控制部可将气相流通区域根据压力分布的不同分为相邻设置的低压区和高压区，所述低压区与原料部相邻设置，高压区与接收部相邻设置。气相流通区域中低压区和高压区的实现可以采用本领域 技术人员常用的手段，例如在气相流通区域中设置可旋转的风扇，或者在气相流通区域中设置进气口和出气口，达到在气相流通区域中下部为低压区，上部为高压区的效果。气相流通区域中高压区和低压区的设置一方面是为了增加气相组分从原料到籽晶表面的的驱动力，低压区使原料更快升华为气相组分，高压区使气相组分更快凝华为SiC晶体，能够加速晶体的生长；另一方面，气相流通区域被分为高压区与低压区，气相组分中硅组分的蒸汽分压高于碳组分的蒸汽分压，气相由低压区到达高压区后，组分中的碳会比硅更快的凝结，凝结的碳颗粒在未到达晶体生长表面时就随着旋转气流被吸附在坩埚壁上，降低了晶体中碳包裹物的数量，得到更高质量的晶体。
优选地，在原料部设有若干导热体。设置的导热体为耐高温导热材料，如石英、石墨等。PVT法生长SiC单晶时，温度最高的中间料区首先发生分解升华，生成各种形式的Si mC n气相组分；同时，颗粒发生迁移、粘结和烧结，最终在，原料中心较冷区域重新结晶成未能炭化的SiC晶粒，浪费了原料。这主要是因为轴向分布温度差距较大，处在中间的物质由于受到线圈加热的强度较大，且发散出去的环境较差，从而导致其温度最高，而底部由于受热较差，但散热效果较好的因素，导致其重结晶，浪费了原料。通过在原料部设有若干导热体，使得避免在原料中心出现较冷区域，使得原料利用率得到提高。
优选地，导热体为石墨棒，石墨棒一端连接在原料部底端，另一端位于原料部和/或气相流通区域中。石墨棒与原料部可以是整体，也可以是分体。
优选地，在气相流通区域设有凝结碳吸附部，所述凝结碳吸附部用于吸附在气相流通区域形成的凝结碳。若碳化硅单晶生长装置为坩埚，那么凝结碳吸附部可以为坩埚壁，也可以是单独设置的凝结碳吸附部；若气相流通区域和原料部是单独的部件，则凝结碳吸附部设置在气相流通区域中。在气相流通区域设有凝结碳吸附部，可以降低晶体中碳包裹物的数量，得到更高质量的晶体。
凝结碳吸附部设在高压区和/或低压区与高压区相邻处。气相由低压区到达高压区后，组分中的碳会比硅更快的凝结。
优选地，原料部为石墨坩埚，石墨坩埚包括石墨坩埚腔室和石墨坩埚盖，气相流通区域设在石墨坩埚上部的腔室和/或石墨坩埚上方空间内。原料部和气相流通区域可以在一个空间内，例如在一个石墨坩埚中，坩埚内底部放置原料的部分为原料部，上方的气相流通区域分为气相流通区域；也可以为分体的，例如在石墨坩埚上方有一个空间可以作为气相流通区域。
优选地，接收部为石墨坩埚盖，所述石墨坩埚盖与石墨坩埚密封相连。在石墨坩埚盖内侧设置籽晶作为气相的接收部。
优选地，控制部包括在气相流通区域中设置风扇，所述风扇设在高压区和低压区之间，所述风扇用于形成气相流通区域中的高压区和低压区。风扇一方面用于形成气相流通区域中的高压区和低压区，另一方面通过风扇在气相流通区域中的旋转，可以使气相流通区域热场分布均匀，籽晶表面径向各方向各组分浓度相同，使气相组分在籽晶表面分布均匀。在长晶过程中，碳化硅原料升华为Si mC n气相组分，气象组分被旋转的扇 叶引导，在坩埚内形成顺/逆时针的特定气流方向。风扇在碳化硅单晶生长时以一定速度旋转，使气氛能够在坩埚内稳定流动，以抑制坩埚内不规则的对流，改变了温度的径向不均匀性，降低了生长表面的温度波动振幅。
优选地，还包括传动轴，传动轴一端与风扇相连接，传动轴另一端伸出单晶生长装置，传动轴带动风扇做旋转运动。传动轴必须为耐高温传动轴，如石墨传动轴等。传动轴可以穿过导热体设置，也可以不穿过导热体，穿过导热体设置的主要作用是为了可以保护传动轴，增加传动轴的使用寿命。所述风扇的扫风面积为气相流通区域横截面积的60—85％。这样可以保证风扇在气相流通区域中自由旋转。
优选地，碳化硅单晶生长装置包括一装置外壳层；传动轴包括第一传动轴和第二传动轴，第一传动轴位于第二传动轴上方，第二传动轴一端与第一传动轴相连，第二传动轴另一端穿过装置外壳层底端并与电机相连；装置外壳层与第二传动轴之间设置有密封装置，第一传动轴远离第二传动轴的一端与风扇相连；第一传动轴为石墨镀钽传动轴，第二传动轴为不锈钢传动轴；风扇为石墨镀钽风扇。
根据本申请的另一方面，提供一种PVT法碳化硅单晶生长装置，包括一石墨坩埚，在石墨坩埚上设有一密封相连的坩埚盖，在石墨坩埚内设有一与石墨坩埚底部内壁固连的垂直布置的第一石墨棒，在石墨坩埚内设有原料部，所述第一石墨棒伸出原料部设置，在原料部的上方设有气相流通区域，一传动轴穿出第一石墨棒设置，并在传动轴上设有一风扇，所述风扇设在气相流通区域内。
其中，原料部和气相流通区域以及接收部可以是一个整体中的不同部分，例如碳化硅单晶生长装置为坩埚，坩埚底部装原料的部分为原料部，原料上部坩埚内空腔为气相流通区域；原料部和气相流通区域也可以是单独分开设置的部件。气相流通区域中低压区和高压区的实现可以采用本领域技术人员常用的手段，例如在气相流通区域中设置可旋转的风扇，或者在气相流通区域中设置进气口和出气口，达到在气相流通区域中下部为低压区，上部为高压区的效果。气相流通区域中高压区和低压区的设置一方面是为了增加气相组分从原料到籽晶表面的的驱动力，低压区使原料更快升华为气相组分，高压区使气相组分更快凝华为SiC晶体，能够加速晶体的生长；另一方面，气相流通区域被分为高压区与低压区，气相组分中硅组分的蒸汽分压高于碳组分的蒸汽分压，气相由低压区到达高压区后，组分中的碳会比硅更快的凝结，凝结的碳颗粒在未到达晶体生长表面时就随着旋转气流被吸附在坩埚壁上，降低了晶体中碳包裹物的数量，得到更高质量的晶体。
利用本申请提出的一种PVT法碳化硅单晶生长装置制备碳化硅单晶时，将原料置于原料部，并在保护气气氛的作用下加热使得原料升华，通过气相区，最后在接收部形成晶体。
优选地，在原料部设有若干导热体。设置的导热体为耐高温导热材料，如石英、石墨等。PVT法生长SiC单晶时，温度最高的中间料区首先发生分解升华，生成各种形式的Si mC n气相组分；同时，颗粒发生迁移、粘结和烧结，最终在，原料中心较冷区域重新结晶成未能炭化的SiC晶粒，浪费了原料。上述“原料中心较冷区域”的“中心”为径向描述，磁场 切割坩埚壁使其发热，热量从坩埚壁传热至原料，所以越靠近坩埚壁的区域越热，越远离坩埚壁的区域越冷。这主要是因为轴向分布温度差距较大，处在中间的物质由于受到线圈加热的强度较大，且发散出去的环境较差，从而导致其温度最高，而底部由于受热较差，但散热效果较好的因素，导致其重结晶，浪费了原料。通过在原料部设有若干导热体，使得避免在原料中心出现较冷区域，使得原料利用率得到提高。
优选地，在气相流通区域设有凝结碳吸附部，所述凝结碳吸附部用于吸附在气相流通区域形成的凝结碳。若碳化硅单晶生长装置为坩埚，那么凝结碳吸附部可以为坩埚壁，也可以是单独设置的凝结碳吸附部；若气相流通区域和原料部是单独的部件，则凝结碳吸附部设置在气相流通区域中。在气相流通区域设有凝结碳吸附部，可以降低晶体中碳包裹物的数量，得到更高质量的晶体。
优选地，凝结碳吸附部设在风扇与坩埚盖之间。气相由低压区到达高压区后，组分中的碳会比硅更快的凝结。
优选地，所述导热体为第二石墨棒，第二石墨棒一端连接在原料部底端，另一端位于原料部和/或气相流通区域中。第二石墨棒与坩埚可以是整体，也可以是分体。
优选地，所述原料部为石墨坩埚，所述气相流通区域设在石墨坩埚上部的腔室和/或石墨坩埚上方空间内。原料部和气相流通区域可以在一个空间内，例如在一个石墨坩埚中，坩埚内底部放置原料的部分为原料部，上方的气相流通区域分为气相流通区域；也可以为分体的，例如在石墨坩埚上方有一个空间可以作为气相流通区域。
优选地，接收部为石墨坩埚盖，所述石墨坩埚盖与石墨坩埚密封相连。在石墨坩埚盖内侧设置籽晶作为气相的接收部。
优选地，在气相流通区域中设置风扇，所述风扇设在高压区和低压区之间，所述风扇用于形成气相流通区域中的高压区和低压区。风扇一方面用于形成气相流通区域中的高压区和低压区，另一方面通过风扇在气相流通区域中的旋转，可以使气相流通区域热场分布均匀，籽晶表面径向各方向各组分浓度相同，使气相组分在籽晶表面分布均匀。在长晶过程中，碳化硅原料升华为Si mC n气相组分，气象组分被旋转的扇叶引导，在坩埚内形成顺/逆时针的特定气流方向。风扇在碳化硅单晶生长时以一定速度旋转，使气氛能够在坩埚内稳定流动，以抑制坩埚内不规则的对流，改变了温度的径向不均匀性，降低了生长表面的温度波动振幅。
优选地，还包括传动轴，传动轴一端与风扇相连接，传动轴另一端伸出单晶生长装置，传动轴带动风扇做旋转运动。传动轴必须为耐高温传动轴，如石墨传动轴等。传动轴可以穿过导热体设置，也可以不穿过导热体，穿过导热体设置的主要作用是为了可以保护传动轴，增加传动轴的使用寿命。所述风扇的扫风面积为气相流通区域横截面积的60—85％。这样可以保证风扇在气相流通区域中自由旋转。
优选地，风扇为石墨镀钽风扇。
优选地，碳化硅单晶生长装置包括一装置外壳层，所述装置外壳层设在石墨坩埚和坩埚盖的外围，传动轴包括第一传动轴和第二传动轴，第一传动轴位于第二传动轴上方，第二传动轴一端与第一传动轴相连，第二传动轴另一端穿过装置外壳层底端并与电机相连。
第二传动轴与装置外壳层密封设置，第一传动轴远离第二传动轴的一端与风扇相连。装置外壳层与第二传动轴之间设置有密封装置。
优选地，第一传动轴为石墨镀钽传动轴，第二传动轴为不锈钢传动轴。
根据本申请的又一方面，提供了一种提高PVT法碳化硅单晶生长质量的方法，所述方法包括将长晶原料加热升华得到气态原料、气态原料经过气相流通区域在接收部形成晶体的步骤，调节所述气相流通区域的压力分布，以使得气相流通区域形成低压区和高压区，所述气态原料依次通过低压区和高压区，到达接收部形成晶体。
优选地，碳化硅单晶生长发生于碳化硅单晶生长装置中，单晶生长装置包括原料部，将长晶原料置于原料部内，并在保护气气氛的作用下加热使得原料升华；
碳化硅单晶生长装置还包括控制部，利用控制部控制气相流通区域的压力分布，控制部将气相流通区域分为低压区和高压区，升华原料依次通过低压区和高压区，最后在接收部形成晶体。
其中，原料部和气相流通区域以及接收部可以是一个整体中的不同部分，例如碳化硅单晶生长装置为坩埚，坩埚底部装原料的部分为原料部，原料上部坩埚内空腔为气相流通区域；原料部和气相流通区域也可以是单独分开设置的部件。气相流通区域中低压区和高压区的实现可以采用本领域技术人员常用的手段，例如在气相流通区域中设置可旋转的风扇，或者在气相流通区域中设置进气口和出气口，达到在气相流通区域中下部为低压区，上部为高压区的效果。气相流通区域中高压区和低压区的设置一方面是为了增加气相组分从原料到籽晶表面的的驱动力，低压区使原料更快升华为气相组分，高压区使气相组分更快凝华为SiC晶 体，能够加速晶体的生长；另一方面，气相流通区域被分为高压区与低压区，气相组分中硅组分的蒸汽分压高于碳组分的蒸汽分压，气相由低压区到达高压区后，组分中的碳会比硅更快的凝结，凝结的碳颗粒在未到达晶体生长表面时就随着旋转气流被吸附在坩埚壁上，降低了晶体中碳包裹物的数量，得到更高质量的晶体。
利用本申请提出的一种PVT法碳化硅单晶生长装置制备碳化硅单晶时，将原料置于原料部，并在保护气气氛的作用下加热使得原料升华，依次通过低压区和高压区，最后在接收部形成晶体。
优选地，保护气为氦气、氖气或氩气的其中一种或两种以上任意比例的混合物，在原料部设有若干导热体。
设置的导热体为耐高温导热材料，如石英、石墨等。PVT法生长SiC单晶时，温度最高的中间料区首先发生分解升华，生成各种形式的Si mC n气相组分；同时，颗粒发生迁移、粘结和烧结，最终在，原料中心较冷区域重新结晶成未能炭化的SiC晶粒，浪费了原料。这主要是因为轴向分布温度差距较大，处在中间的物质由于受到线圈加热的强度较大，且发散出去的环境较差，从而导致其温度最高，而底部由于受热较差，但散热效果较好的因素，导致其重结晶，浪费了原料。通过在原料部设有若干导热体，使得避免在原料中心出现较冷区域，使得原料利用率得到提高。
优选地，导热体为石墨棒，石墨棒一端连接在原料部底端，另一端位于原料部和/或气相流通区域中。石墨棒与原料部可以是整体，也可以是分体。
优选地，在气相流通区域设有凝结碳吸附部，所述凝结碳吸附部用于吸附在气相流通区域形成的凝结碳。若碳化硅单晶生长装置为坩埚，那么凝结碳吸附部可以为坩埚壁，也可以是单独设置的凝结碳吸附部； 若气相流通区域和原料部是单独的部件，则凝结碳吸附部设置在气相流通区域中。在气相流通区域设有凝结碳吸附部，可以降低晶体中碳包裹物的数量，得到更高质量的晶体。
优选地，凝结碳吸附部设在高压区和/或低压区与高压区相邻处。气相由低压区到达高压区后，组分中的碳会比硅更快的凝结。
优选地，所述原料部为石墨坩埚，所述气相流通区域设在石墨坩埚上部的腔室和/或石墨坩埚上方空间内。原料部和气相流通区域可以在一个空间内，例如在一个石墨坩埚中，坩埚内底部放置原料的部分为原料部，上方的气相流通区域分为气相流通区域；也可以为分体的，例如在石墨坩埚上方有一个空间可以作为气相流通区域。
优选地，接收部为石墨坩埚盖，所述石墨坩埚盖与石墨坩埚密封相连。在石墨坩埚盖内侧设置籽晶作为气相的接收部。
优选地，在气相流通区域中设置风扇，所述风扇设在高压区和低压区之间，所述风扇用于形成气相流通区域中的高压区和低压区。风扇一方面用于形成气相流通区域中的高压区和低压区，另一方面通过风扇在气相流通区域中的旋转，可以使气相流通区域热场分布均匀，籽晶表面径向各方向各组分浓度相同，使气相组分在籽晶表面分布均匀。在长晶过程中，碳化硅原料升华为Si mC n气相组分，气象组分被旋转的扇叶引导，在坩埚内形成顺/逆时针的特定气流方向。风扇在碳化硅单晶生长时以一定速度旋转，使气氛能够在坩埚内稳定流动，以抑制坩埚内不规则的对流，改变了温度的径向不均匀性，降低了生长表面的温度波动振幅。
优选地，还包括传动轴，传动轴一端与风扇相连接，传动轴另一端伸出单晶生长装置，传动轴带动风扇做旋转运动。传动轴必须为耐高温传动轴，如石墨传动轴等。传动轴可以穿过导热体设置，也可以不穿过导热体，穿过导热体设置的主要作用是为了可以保护传动轴，增加传动 轴的使用寿命。所述风扇的扫风面积为气相流通区域横截面积的60—85％。这样可以保证风扇在气相流通区域中自由旋转。
优选地，碳化硅单晶生长装置包括一装置外壳层；传动轴包括第一传动轴和第二传动轴，第一传动轴位于第二传动轴上方，第二传动轴一端与第一传动轴相连，第二传动轴另一端穿过装置外壳层底端并与电机相连；装置外壳层与第二传动轴之间设置有密封装置；第一传动轴为石墨镀钽传动轴，第二传动轴为不锈钢传动轴；风扇为石墨镀钽风扇。
优选地，碳化硅单晶为β‐碳化硅单晶，所述β‐碳化硅单晶的生长方法包括如下步骤：
S1、组装阶段：将单晶生长装置固定在热源上，并在单晶生长装置底部垫放保温毡；在单晶生长装置中放入碳化硅粉料和籽晶；在单晶生长装置的裸露外表面放置保温毡；
S2、加热升温阶段：单晶生长装置内抽真空，然后通入保护气，单晶生长装置内绝对压力维持在0.8*10 5‐1.2*10 5Pa；然后升温加热使单晶生长装置内温度达到1800‐2000K；然后打开风扇，调整转速为6‐60r/min；
S3、长晶阶段：长晶过程中，单晶生长装置内压力控制在500‐5000Pa，温度控制在2200‐2800K；然后调整风扇转速控制在10‐100r/min，风扇上下压力的压差为5‐500Pa；
S4、降温阶段：关闭加热装置，向炉腔内充入保护气，单晶生长装置内压力控制在1*10 4‐4*10 4Pa，温度控制在1800‐2000K；当温度低于1800‐2000K时，停止风扇旋转；
S5、开炉阶段：当温度降至室温，打开炉腔，打开单晶生长装置，取出碳化硅单晶。
本申请能够带来如下有益效果：
1.本申请使到达上部籽晶附近的Si mC n不管是在组分还是温度分布上都非常均匀；得到表面均匀且无小片多型的高质量SiC晶体。
2.本申请增加气相组分从原料到籽晶表面的的驱动力，高压区和低压区的形成能够加速晶体的生长。
3.本申请降低了晶体中碳包裹物的数量，得到更高质量的晶体。
4.本申请具有使用便利、结构简单、可靠，经济性强的特点；
5.本申请具有操作简单、安全性强、实用性强、适合推广使用的特点。
附图说明
此处所说明的附图用来提供对本申请的进一步理解，构成本申请的一部分，本申请的示意性实施例及其说明用于解释本申请，并不构成对本申请的不当限定。在附图中：
图1为一种碳化硅单晶生长装置示意图；
图2为另一种碳化硅单晶生长装置示意图；
图3为又一种碳化硅单晶生长装置示意图；
图4为再一种碳化硅单晶生长装置示意图。
具体实施方式
为能清楚说明本方案的技术特点，下面通过具体实施方式，并结合其附图，对本申请进行详细阐述。
如图中所示，为了更清楚的阐释本申请的整体构思，下面结合说明书附图以示例的方式进行详细说明。
另外，在本申请的描述中，需要理解的是，术语“中心”、“上”、“下”、“前”、“后”、“左”、“右”、“竖直”、“水平”、“顶”、“底”、“内”、“外”、“轴向”、“径向”、“周向”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本申请和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请的限制。
本说明书中的各个实施例均采用递进的方式描述，各个实施例之间相同相似的部分互相参见即可，每个实施例重点说明的都是与其他实施例的不同之处。
此外，术语“第一”、“第二”仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”的特征可以明示或者隐含地包括一个或者更多个该特征。在本申请的描述中，“多个”的含义是两个或两个以上，除非另有明确具体的限定。
在本申请中，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”、“固定”等术语应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或成一体；可以是机械连接，也可以是电连接，还可以是通信；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通或两个元件的相互作用关系。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本申请中的具体含义。
在本申请中，除非另有明确的规定和限定，第一特征在第二特征“上”或“下”可以是第一和第二特征直接接触，或第一和第二特征通过中间媒介 间接接触。在本说明书的描述中，参考术语“一个实施例”、“一些实施例”、“示例”、“具体示例”、或“一些示例”等的描述意指结合该实施例或示例描述的具体特征、结构、材料或者特点包含于本申请的至少一个实施例或示例中。在本说明书中，对上述术语的示意性表述不必须针对的是相同的实施例或示例。而且，描述的具体特征、结构、材料或者特点可以在任一个或多个实施例或示例中以合适的方式结合。
实施例1：碳化硅单晶生长装置：
如图1所示，本申请提供了一种碳化硅单晶生长装置，包括：原料部1，原料部1用于放置原料，并提供原料受热升华的场所；还包括气相流通区域2，气相流通区域2分为相邻设置的低压区21和高压区22，低压区21与原料部1相邻设置；还包括接收部3，接收部3与高压区22相邻设置，接收部3用于接收原料升华后依次通过低压区21、高压区22得到的产品。低压区21和高压区22的设置采用本领域技术人员可以实现的方式，而且低压区21和高压区22的设置并不改变碳化硅单晶生长时所需温度等生长环境，也不会影响碳化硅单晶生长装置的密封性等。
如图2所示，本申请提供了另一种碳化硅单晶生长装置，包括：原料部1，原料部1用于放置原料，并提供原料受热升华的场所；还包括气相流通区域2，气相流通区域2在控制部的作用下分为相邻设置的低压区21和高压区22，低压区21与原料部1相邻设置；还包括接收部3，接收部3与高压区22相邻设置，接收部3用于接收原料升华后依次通过低压区21、高压区22得到的产品。其中，高压区22和低压区21的形成是通过设置控制部，所述控制部包括设在高压区22中设置进气口31，在低压 区21中设置出气口32，通入的气体为不影响原本单晶生长环境的气体如惰性气体氩气等，以及通过控制通气速率等条件保证通入气体后不改变原本的环境温度，这样就在气相流通区域2中形成了低压区21和高压区22，而且可以形成气体循环，同样可以达到籽晶附近的气相温度均匀的目的。
实施例中的碳化硅单晶生长装置用于PVT法制备碳化硅单晶。
原料部1为石墨坩埚，坩埚内底部放置原料的部分为原料部1，气相流通区域2设在石墨坩埚上部的腔室和/或石墨坩埚上方空间内，接收部3为石墨坩埚盖，在石墨坩埚盖内侧放置籽晶，石墨坩埚盖与石墨坩埚密封相连。
在原料部1中设有若干导热体5，如石墨棒，导热体5一端连接在原料部1底端，另一端位于原料部1和/或气相流通区域2中。
如图3所示，本申请提供了又一种碳化硅单晶生长装置，包括：原料部1，原料部1用于放置原料，并提供原料受热升华的场所；还包括气相流通区域2，气相流通区域2分为相邻设置的低压区21和高压区22，低压区21与原料部1相邻设置；还包括接收部3，接收部3与高压区22相邻设置，接收部3用于接收原料升华后依次通过低压区21、高压区22得到的产品。
原料部1为石墨坩埚，气相流通区域2设在石墨坩埚上方空间内，虽然气相流通区域2与原料部1不在一个装置中，但是也是本领域技术人员可以实现的手段，保证不能影响整个碳化硅单晶生长装置的密封性等。在原料部1设有若干导热体5，导热体5为石墨棒，石墨棒一端连接 在原料部1底端，另一端位于原料部1中。
在气相流通区域2设有凝结碳吸附部4，凝结碳吸附部4用于吸附在气相流通区域形成的凝结碳。凝结碳吸附部4设在高压区22和/或低压区21与高压区22相邻处，气相由低压区21到达高压区22后，组分中的碳会比硅更快的凝结。
在气相流通区域2中设置风扇6，风扇6设在高压区22和低压区21之间，风扇6用于形成气相流通区域2中的高压区22和低压区21。还包括传动轴7，传动轴7一端与风扇6相连接，传动轴7另一端伸出单晶生长装置。风扇和传动轴的设置为本领域技术人员可以实现的手段，其中风扇和传动轴均为耐高温材料，保证可以在高温下工作。风扇6的扫风面积为气相流通区域2横截面积的60—85％，这样可以保证风扇6在气相流通区域2中可以旋转。
如图4所示，碳化硅单晶生长装置包括一装置外壳层9，传动轴7包括第一传动轴71和第二传动轴72，第一传动轴71位于第二传动轴72上方，第二传动轴72一端与第一传动轴71相连，第二传动轴72另一端穿过装置外壳层9底端并与电机8相连，装置外壳层9与第二传动轴72之间设置有密封装置73。其中，第一传动轴71为石墨镀钽传动轴，第二传动轴72为不锈钢传动轴，风扇为石墨镀钽风扇。部分第一传动轴71和风扇由于处于石墨坩埚1中，在碳化硅单晶生长中温度较高，且其中产生的硅蒸汽会对石墨材料产生侵蚀，所以第一传动轴71和风扇为石墨镀钽材料，既耐高温，又能防止其被侵蚀。
本申请工作时，启动电机8带动第二传动轴72，从而带动第一传动 轴71，进而带动石墨坩埚1中的风扇转动，装置外壳层9一方面起到保护传动轴7的作用，另一方面提供了一个密闭的保护空间，使碳化硅单晶在生长时，更加不受外界环境干扰，生长环境更稳定，得到质量更高的碳化硅单晶。
实施例2：碳化硅单晶的合成方法：
S1、组装阶段：将单晶生长装置固定在热源上，并在单晶生长装置底部垫放保温毡；在单晶生长装置中放入碳化硅粉料和籽晶；在单晶生长装置的裸露外表面放置保温毡；
S2、加热升温阶段：单晶生长装置内抽真空，然后通入保护气，单晶生长装置内绝对压力维持在0.8*10 5‐1.2*10 5Pa；然后升温加热使单晶生长装置内温度达到1800‐2000K；然后打开风扇，调整转速为6‐60r/min；
S3、长晶阶段：长晶过程中，单晶生长装置内压力控制在500‐5000Pa，温度控制在2200‐2800K；然后调整风扇转速控制在10‐100r/min，风扇上下压力的压差为5‐500Pa；
S4、降温阶段：关闭加热装置，向炉腔内充入保护气，单晶生长装置内压力控制在1*10 4‐4*10 4Pa，温度控制在1800‐2000K；当温度低于1800‐2000K时，停止风扇旋转；
S5、开炉阶段：当温度降至室温，打开炉腔，打开单晶生长装置，取出碳化硅单晶。
本实施方式中的单晶可以为碳化硅单晶。
具体的实施条件如下：
Figure PCTCN2018123716-appb-000001
实施例3：表征
对包裹体浓度的测试方法为：选取生长出的晶体10块，晶体切片后在显微镜下观察其他包裹体情况，每块晶体统一抽取第5片和第10片，在50倍放大倍数下，统计的包裹体浓度。
厚度差为：选取生长出的晶体10块，其边缘的最大厚度与最小厚度之差的平均值。
微管数目为：选取生长出的晶体10块中出现大簇微管的数目。
Figure PCTCN2018123716-appb-000002
根据对比例与样品2以及样品8的表征结果可以看出，气相流通区域设置为高压区和低压区与没有设置高、低压区相比，碳包裹浓度明显 降低，晶体厚度差也明显变小，微管数目也明显降低，说明将气相流通区域被分为高压区与低压区，气相组分中硅组分的蒸汽分压高于碳组分的蒸汽分压，气相由低压区到达高压区后，组分中的碳会比硅更快的凝结，凝结的碳颗粒在未到达晶体生长表面时就随着旋转气流被吸附在坩埚壁上，降低了晶体中碳包裹物的数量，得到更高质量的晶体。根据样品2和样品8的表征结果可以看出，气相流通区域设置风扇与设置为进出气口相比较，气相流通区域通过风扇形成高低压区，转动的风扇使得气相流通区域热场分布均匀，籽晶表面径向各方向各组分浓度相同，使气相组分在籽晶表面分布均匀，所以得到的晶体碳包裹浓度较低，晶体厚度差和微管数目较小。根据样品2和样品6的表征结果可以看出，在单晶生长装置中设置凝结碳吸附部与无此设置相比，由于凝结碳吸附部可以吸附碳组分，就会一定程度降低碳包裹物浓度，晶体厚度差和微管数目也会有所降低，得到的晶体质量较好。根据样品2和样品10的表征结果可以看出，在单晶生长装置中设置导热体，就会改善单晶生长装置中的热场分布，那么得到的晶体碳包裹数就会有所降低，单晶的厚度差和微管数目也会有所降低，得到的单晶质量较好。根据样品12和样品13的表征结果可以看出，该生长条件下得到的是α‐碳化硅单晶，也证明了本申请可以适用的范围较广。
综上所述，在单晶生长装置中设置导热体、凝结碳吸附部以及在气相流通区域设置高压区、低压区，都会降低碳包裹浓度、单晶厚度差以及微管数目，提高碳化硅单晶的质量。
本说明书中的各个实施例均采用递进的方式描述，各个实施例之间 相同相似的部分互相参见即可，每个实施例重点说明的都是与其他实施例的不同之处。尤其，对于系统实施例而言，由于其基本相似于方法实施例，所以描述的比较简单，相关之处参见方法实施例的部分说明即可。
以上所述仅为本申请的实施例而已，并不用于限制本申请。对于本领域技术人员来说，本申请可以有各种更改和变化。凡在本申请的精神和原理之内所作的任何修改、等同替换、改进等，均应包含在本申请的权利要求范围之内。

Claims (25)

  1. 一种碳化硅单晶生长装置，其特征在于，包括：原料部、接收部和气相流通区域；
    所述原料部用于放置原料，并提供原料受热升华的场所；
    所述接收部用于接收原料升华后得到的产品；
    所述原料受热升华后经过气相流通区域到达接收部；
    在气相流通区域设有凝结碳吸附部，所述凝结碳吸附部用于吸附在气相流通区域形成的凝结碳；
    还包括控制部，所述控制部用于调节气相流通区域的压力分布。
  2. 根据权利要求1所述的一种碳化硅单晶生长装置，其特征在于：所述控制部可将气相流通区域根据压力分布的不同分为相邻设置的低压区和高压区，所述低压区与原料部相邻设置，高压区与接收部相邻设置。
  3. 根据权利要求1所述的一种碳化硅单晶生长装置，其特征在于：在原料部设有若干导热体。
  4. 根据权利要求2所述的一种碳化硅单晶生长装置，其特征在于：在气相流通区域设有凝结碳吸附部，所述凝结碳吸附部用于吸附在气相流通区域形成的凝结碳；所述凝结碳吸附部设在高压区和/或低压区与高压区相邻处。
  5. 根据权利要求1所述的一种碳化硅单晶生长装置，其特征在于：所述原料部为石墨坩埚，所述石墨坩埚包括石墨坩埚腔室和石墨坩埚盖，所述气相流通区域设在石墨坩埚上部的腔室和/或石墨坩埚上方空间内。
  6. 根据权利要求5所述的一种碳化硅单晶生长装置，其特征在于：所述接收部为石墨坩埚盖，所述石墨坩埚盖与石墨坩埚密封相连。
  7. 根据权利要求3所述的一种碳化硅单晶生长装置，其特征在于：所述导热体为石墨棒，石墨棒一端连接在原料部底端，另一端位于原料部和/或气相流通区域中。
  8. 根据权利要求2所述的一种碳化硅单晶生长装置，其特征在于：所述控制部包括在气相流通区域中设置风扇，所述风扇设在高压区和低压区之间，所述风扇用于形成气相流通区域中的高压区和低压区。
  9. 根据权利要求8所述的一种碳化硅单晶生长装置，其特征在于：还包括传动轴，传动轴一端与风扇相连接，传动轴另一端伸出单晶生长装置，所述风扇的扫风面积为气相流通区域横截面积的60—85％。
  10. 根据权利要求9所述的一种碳化硅单晶生长装置，其特征在于：所述碳化硅单晶生长装置包括一装置外壳层；所述传动轴包括第一传动轴和第二传动轴，所述第一传动轴位于第二传动轴上方，所述第二传动轴一端与第一传动轴相连，所述第二传动轴另一端穿过装置外壳层底端并与电机相连；所述装置外壳层与第二传动轴之间设置有密封装置，第一传动轴远离第二传动轴的一端与风扇相连；所述第一传动轴为石墨镀钽传动轴，所述第二传动轴为不锈钢传动轴；所述风扇为石墨镀钽风扇。
  11. 根据权利要求1‐10任一项所述的一种碳化硅单晶生长装置，其特征在于：该生长装置用于PVT法制备碳化硅单晶。
  12. 根据权利要求11所述的一种碳化硅单晶生长装置，其特征在于：该生长装置包括：一石墨坩埚，在石墨坩埚上设有一密封相连的坩埚盖， 在石墨坩埚内设有一与石墨坩埚底部内壁固连的垂直布置的第一石墨棒，在石墨坩埚内设有原料部，所述第一石墨棒伸出原料部设置，在原料部的上方设有气相流通区域，一传动轴穿出第一石墨棒设置，并在传动轴上设有一风扇，所述风扇设在气相流通区域内。
  13. 根据权利要求12所述的一种碳化硅单晶生长装置，其特征在于：在气相流通区域设有凝结碳吸附部，所述凝结碳吸附部用于吸附在气相流通区域形成的凝结碳；所述凝结碳吸附部设在风扇与坩埚盖之间。
  14. 根据权利要求12所述的一种碳化硅单晶生长装置，其特征在于：在原料部设有若干导热体；所述导热体为第二石墨棒，第二石墨棒一端连接在原料部底端，另一端位于原料部和/或气相流通区域中。
  15. 根据权利要求12所述的一种碳化硅单晶生长装置，其特征在于：还包括一装置外壳层，所述装置外壳层设在石墨坩埚和坩埚盖的外围，所述传动轴包括第一传动轴和第二传动轴，所述第一传动轴位于第二传动轴上方，所述第二传动轴一端与第一传动轴相连，所述第二传动轴另一端穿过装置外壳层底端并与电机相连，第二传动轴与装置外壳层密封设置，第一传动轴远离第二传动轴的一端与风扇相连。
  16. 一种提高PVT法碳化硅单晶生长质量的方法，所述方法包括将长晶原料加热升华得到气态原料、气态原料经过气体流通区域在接收部形成晶体的步骤，其特征在于：调节所述气体流通区域的压力分布，以使得气体流通区域形成低压区和高压区，所述气态原料依次通过低压区和高压区，到达接收部形成晶体。
  17. 根据权利要求16所述的一种提高PVT法碳化硅单晶生长质量的方法，其特征在于：碳化硅单晶生长发生于碳化硅单晶生长装置中，所 述单晶生长装置包括原料部，将所述长晶原料置于原料部内，并在保护气气氛的作用下加热使得原料升华；
    所述碳化硅单晶生长装置还包括控制部，利用控制部控制气体流通区域的压力分布，所述控制部将气体流通区域分为低压区和高压区，升华原料依次通过低压区和高压区，最后在接收部形成晶体。
  18. 根据权利要求17所述的一种提高PVT法碳化硅单晶生长质量的方法，其特征在于：保护气为氦气、氖气或氩气的其中一种或两种以上任意比例的混合物；在原料部设有若干导热体。
  19. 根据权利要求18所述的一种提高PVT法碳化硅单晶生长质量的方法，其特征在于：所述导热体为石墨棒，石墨棒一端连接在原料部底端，另一端位于原料部和/或气体流通区域中。
  20. 根据权利要求16所述的一种提高PVT法碳化硅单晶生长质量的方法，其特征在于：在气体流通区域设有凝结碳吸附部，所述凝结碳吸附部用于吸附在气体流通区域形成的凝结碳；优选的，所述凝结碳吸附部设在高压区和/或低压区与高压区相邻处。
  21. 根据权利要求17所述的一种提高PVT法碳化硅单晶生长质量的方法，其特征在于：所述原料部为石墨坩埚，所述气体流通区域设在石墨坩埚上部的腔室和/或石墨坩埚上方空间内，优选的，所述接收部为石墨坩埚盖，所述石墨坩埚盖与石墨坩埚密封相连。
  22. 根据权利要求17所述的一种提高PVT法碳化硅单晶生长质量的方法，其特征在于：在气体流通区域中设置风扇，所述风扇设在高压区和低压区之间，所述风扇用于形成气体流通区域中的高压区和低压区。
  23. 根据权利要求22所述的一种提高PVT法碳化硅单晶生长质量的方法，其特征在于：还包括传动轴，传动轴一端与风扇相连接，传动轴另一端伸出碳化硅单晶生长装置，所述风扇的扫风面积为气体流通区域 横截面积的60—85％。
  24. 根据权利要求23所述的一种提高PVT法碳化硅单晶生长质量的方法，其特征在于：所述碳化硅单晶生长装置包括一装置外壳层；所述传动轴包括第一传动轴和第二传动轴，所述第一传动轴位于第二传动轴上方，所述第二传动轴一端与第一传动轴相连，所述第二传动轴另一端穿过装置外壳层底端并与电机相连；所述装置外壳层与第二传动轴之间设置有密封装置；所述第一传动轴为石墨镀钽传动轴，所述第二传动轴为不锈钢传动轴；所述风扇为石墨镀钽风扇。
  25. 根据权利要求22所述的一种提高PVT法碳化硅单晶生长质量的方法，其特征在于：所述碳化硅单晶为β‐碳化硅单晶，所述β‐碳化硅单晶的生长方法包括如下步骤：
    S1、组装阶段：将碳化硅单晶生长装置固定在热源上，并在碳化硅单晶生长装置底部垫放保温毡；在碳化硅单晶生长装置中放入碳化硅粉料和籽晶；在碳化硅单晶生长装置的裸露外表面放置保温毡；
    S2、加热升温阶段：碳化硅单晶生长装置内抽真空，然后通入保护气，碳化硅单晶生长装置内绝对压力维持在0.8*10 5‐1.2*10 5Pa；然后升温加热使单晶生长装置内温度达到1800‐2000K；然后打开风扇，调整转速为6‐60r/min；
    S3、长晶阶段：长晶过程中，碳化硅单晶生长装置内绝对压力控制在500‐5000Pa，温度控制在2200‐2800K；然后调整风扇转速控制在10‐100r/min，风扇上下压力的压差为5‐500Pa；
    S4、降温阶段：关闭加热装置，向炉腔内充入保护气，碳化硅单晶生长装置内绝对压力控制在1*10 4‐4*10 4Pa，温度控制在1800‐2000K；当温度低于1800‐2000K时，停止风扇旋转；
    S5、开炉阶段：当温度降至室温，打开炉腔，打开碳化硅单晶生长装置，取出碳化硅单晶。
PCT/CN2018/123716 2018-11-02 2018-12-26 一种碳化硅单晶的制备方法及其生长装置 WO2020087722A1 (zh)

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