CN113005512A - Silicon carbide single crystal ingot growth equipment and method - Google Patents
Silicon carbide single crystal ingot growth equipment and method Download PDFInfo
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- CN113005512A CN113005512A CN202110416789.9A CN202110416789A CN113005512A CN 113005512 A CN113005512 A CN 113005512A CN 202110416789 A CN202110416789 A CN 202110416789A CN 113005512 A CN113005512 A CN 113005512A
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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
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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
- C30B23/002—Controlling or regulating
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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
- 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
Abstract
The invention relates to a silicon carbide single crystal ingot growth device and a method, wherein the device comprises a feeding device, a preheating treatment device, a sublimation separation device and an ingot growth device; the feeding device, the preheating treatment device and the sublimation separation device are sequentially communicated in the vertical direction, and the sublimation separation device and the crystal ingot growth device are communicated in the horizontal direction. The invention can realize uninterrupted feeding in the growing process of the crystal ingot and provide sufficient source material preparation for preparing large-size crystal ingots. The particle powder source material is movably heated, so that the graphite ceramic of the source material can be avoided, the exhaustion of a growth source is avoided, and the preparation of a large-size crystal ingot is facilitated. In addition, the system recovers silicon carbide fixed substances and gas phase substances in the ingot growing process, the silicon carbide fixed substances and the gas phase substances can be recycled through simple treatment, the production source material cost is low, in addition, the invention has no complicated mechanical design and low equipment cost, is particularly suitable for large-size ingot growing, and has higher product competitiveness.
Description
Technical Field
The invention relates to the technical field of preparation of silicon carbide single crystal ingots, in particular to silicon carbide single crystal ingot growth equipment and a silicon carbide single crystal ingot growth method.
Background
At present, the main mass production technology of silicon carbide (SiC) single crystal ingots is a seeded sublimation method, which is also called as a physical vapor transport growth method (PVT). The sublimation method of seed crystal is to heat the solid silicon carbide source material in vacuum environment to produce sublimed gas phase material of Si and Si2C、SC2. A single crystal ingot is grown by transporting a gas phase substance to a seed crystal position for solidification by a transport gas, as shown in fig. 1. In order to break through the limitation existing in PVT growth of silicon carbide, a high-temperature chemical vapor deposition method is developed to grow a silicon carbide single crystal ingot. Silicon carbide ingot growth is carried out in a graphite crucible of vertical construction in which the precursor gas is transported upward and deposited after passing through a heated zone to the top seed crystal. The precursor gas adopts SiH diluted by carrier gas4And hydrocarbons such as alkanes and alkenes, as shown in FIG. 2. Growing ingots from eutectic melts is a standard technique for preparing semiconductor ingots; a graphite crucible is filled with a silicon-based melt and a seed crystal is placed in contact with the surface of the melt at a temperature slightly below the temperature of the melt to provide a driving force for growth. Aiming at the proposal of inhibiting the silicon atoms from evaporating from the melt in advance, a high-pressure growth method is respectively provided to increase the evaporation temperature of the silicon; there are also solution growth methods that incorporate a solvent for the added metal to increase the solubility of carbon in silicon and allow the ingot to be grown at relatively low temperatures, as shown in fig. 3.
The growth temperature of the source material in PVT is 2300-2400 ℃, and the temperature can not inhibit the preferential evaporation of silicon in the silicon carbide source material, so that the graphite ceramization of the silicon carbide source material is caused in the sublimation growth process, the growth source material can enter an exhausted state, and the crystal ingot growth size is limited. The high-temperature chemical vapor deposition method can continuously supply precursor gas in principle, source material exhaustion cannot occur, the typical growth temperature is very high, seed crystals and graphite walls are easy to corrode or react with the seed crystals, helium is used as carrier gas and can be heated immediately, cold spraying to the surfaces of the seed crystals is not easy to cause, and in addition, the helium and the high-purity precursor gas are high in cost, so that the product does not have competitiveness and is not suitable for large-scale mass production. The growth by the solution method is still in an experimental stage at present, the variables in a high-pressure solution growth or solution growth system of a metal solvent are difficult to master, and high-quality large-size crystal ingots grown by the system are not seen.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide silicon carbide single crystal ingot growth equipment and a method, which can not cause the problems of exhaustion of growth source materials and the like caused by graphite ceramization of silicon carbide source materials, can be suitable for preparing large-size silicon carbide single crystal ingots, and has low equipment cost.
In order to achieve the purpose, the invention adopts the technical scheme that:
a silicon carbide single crystal ingot growth device comprises a feeding device, a preheating treatment device, a sublimation separation device and an ingot growth device; the feeding device, the preheating treatment device and the sublimation separation device are sequentially communicated in the vertical direction, and the sublimation separation device and the crystal ingot growth device are communicated in the horizontal direction;
the feeding device comprises a material groove for storing source materials, a sealing cover for sealing an inlet of the material groove, a discharge pipe arranged at an outlet at the bottom of the material groove, and a first air pipe for communicating the material groove with an external vacuum pump air system; a discharge valve and a vacuum switch valve are sequentially arranged on the discharge pipe from top to bottom;
the preheating device comprises a heating channel, a feeding valve arranged on the heating channel and a second air pipe which is communicated with the heating channel and is arranged at the lower end of the feeding valve; the second gas pipe is used for introducing carrier gas;
the sublimation separation device comprises a cavity, wherein a laser module for heating and sublimating the source material discharged from the heating channel, a graphite crucible for promoting and maintaining the sublimation of the source material, a recovery tank for recovering the solid source material, a plurality of third gas pipes for introducing carrier gas and a first heating mechanism for heating the graphite crucible and the third gas pipes are arranged in the cavity;
the ingot production device comprises a graphite cavity, a second heating mechanism for heating the graphite cavity and a seed crystal puller arranged in the graphite cavity; one end of the graphite cavity is communicated with the graphite crucible, and the other end of the graphite cavity is communicated with an external vacuum pump gas system.
Preferably, the feeding valve comprises a shell, a central column and a rotating shaft, a cylindrical cavity is arranged in the shell, and a through hole is formed in the shell; the central column is tightly matched with the inner cavity and rotates in the inner cavity, and the through hole is blocked by the central column; the cylindrical surface of the central column is provided with a plurality of grooves in the vertical direction, and the grooves can be opposite to the through holes when the central column is rotated; the rotating shaft is connected with the central column and extends to the outside of the shell.
Preferably, the preheating device further comprises a heating tank and a spiral heater, the feeding valve is arranged between the heating tank and the spiral heater, and the heating tank, the feeding valve and the spiral heater are matched to form the heating channel;
the heating groove is in a bucket shape, and a plurality of radiating fins are arranged in the heating groove; the heating groove is made of solid conductive materials, and the upper end and the lower end of the heating groove are respectively connected with two poles of a first alternating current power supply to form a first heating body;
the spiral heater comprises a circular tube and a spiral body arranged in the circular tube, the spiral body is made of a solid conductive material, and the upper end and the lower end of the spiral body are respectively connected with two poles of a second alternating current power supply to form a second heating body.
Preferably, the device also comprises two groups of electromagnet mechanisms, wherein each electromagnet mechanism comprises a magnetic core and a coil wound on the periphery of the magnetic core, and two ends of the coil are respectively connected with two poles of a direct-current power supply; and the two groups of electromagnet mechanisms respectively generate electromagnetic induction with the preheating filling groove and the spiral body, so that the preheating filling groove and the spiral body vibrate.
Preferably, the heating channel extends into the cavity, a reflecting plate matched with the laser module is arranged at the outlet of the heating channel, and an included angle of 45 degrees is formed between the reflecting plate and the horizontal plane.
Preferably, the bottom of the graphite crucible is provided with a slope, the slope is arranged below the heating channel, and an included angle of 30-60 degrees is formed between the slope and the horizontal plane; and a discharge port communicated with the recovery tank is arranged at the slope bottom of the slope.
Preferably, the number of the third air pipes is two, and the two third air pipes are aligned up and down and are respectively arranged at the top of the slope and the middle position of the slope; the third gas pipe is a graphite pipe which is integrally formed with the graphite crucible.
Preferably, the graphite cavity comprises a small graphite cavity and a large graphite cavity which are integrally formed, the graphite crucible is provided with an air hole, and the small graphite cavity is communicated with the air hole; the pipe diameter of the small graphite cavity is equal to the pore diameter of the air hole, and the pipe diameter of the large graphite cavity is more than one time larger than that of the small graphite cavity; the seed crystal support is arranged in the large graphite cavity.
Preferably, the first heating mechanism and the second heating mechanism each comprise a radio frequency coil and a radio frequency power supply.
Preferably, the graphite crucible heating device further comprises an insulating layer used for wrapping the heating channel, the graphite crucible, the third air pipe and the graphite cavity.
The invention also discloses a silicon carbide single crystal ingot growth method which is realized by adopting any one of the silicon carbide single crystal ingot growth devices, and the method comprises the following steps:
step one, feeding: closing the discharge valve and the vacuum switch valve, putting gravel or powder source materials into the feed chute, sealing tightly, and respectively vacuumizing the upper and lower closed spaces isolated by the vacuum switch valve through an external vacuum pump gas system until the production requirements are met;
step two, introducing carrier gas: the second air pipe and the third air pipe respectively preheat carrier gas;
step three, preheating: the heating channel forms two temperature fields by taking the feeding valve as a boundary, the temperature of the temperature field at the upper end is 500-800 ℃, and the temperature of the temperature field at the lower end is 1600-1800 ℃; the source material stays in the upper temperature field for heating, the source material moves in the lower temperature field for heating, and the source material can be heated to 1600-1800 ℃ when being discharged out of the heating channel through the two temperature fields;
step four, sublimation separation: a temperature field with the temperature of 2300-2600 ℃ is formed in the graphite crucible; irradiating the source material discharged from the heating channel by laser beams to ensure that part of the source material absorbs a large amount of light energy and is sublimated into a gas phase substance, and the part of the source material which is not sublimated falls into the graphite crucible to be continuously heated, so that part of the source material is sublimated into the gas phase substance, and finally the source material which is not sublimated falls into the recovery tank; the sublimated gas phase substance is carried into the ingot growing device by the carrier gas;
step five, ingot growing: forming a temperature field with gradually decreased temperature in the graphite cavity, wherein the gradually decreased direction is from the graphite crucible to the graphite cavity, and the temperature of the seed crystal placing position is lower than that of the graphite crucible by 100-200 ℃; solidifying the gas-phase substance on the seed crystal to form a silicon carbide single crystal ingot; and the unused carrier gas and gas phase substance flow to the vacuum pump gas system for recycling.
Preferably, the source material fed into the feed chute has a particle radius of not more than 0.5 mm.
Preferably, the carrier gas is an inert gas.
After the scheme is adopted, the feeding device can be isolated into an independent vacuum feeding space through the vacuum switch valve, so that uninterrupted feeding in the ingot growing process is realized, and sufficient source material preparation is provided for preparing large-size ingots. The particle powder source material is movably heated in advance in the preheating treatment device, so that the graphite ceramic of the source material can be avoided, the exhaustion of a growth source is avoided, and the preparation of a large-size crystal ingot is facilitated; meanwhile, the preheating treatment device preheats the source materials, so that the heating time of the source materials in the sublimation stage can be shortened, and the growth process is accelerated. The preheating device, the sublimation separation device and the crystal ingot growing device are respectively provided with an independent heating mechanism, which becomes a production parameter for directly controlling variables, reduces the coupling among different stage temperatures, improves the fineness and the accuracy of the temperature control of the whole system, and effectively reduces the thermal budget of the system. The carrier gas is heated before being mixed with the gas-phase substance, so that the cold spraying effect of the carrier gas can be reduced; meanwhile, the system recovers silicon carbide fixed substances and gas-phase substances in the ingot growing process, the silicon carbide fixed substances and the gas-phase substances can be recycled through simple treatment, the production source material cost is low, in addition, the invention has no complicated mechanical design and low equipment cost, is particularly suitable for large-size ingot growing, and has higher product competitiveness.
Drawings
FIG. 1 is a schematic diagram of a PVT process;
FIG. 2 is a schematic view of a high temperature chemical vapor deposition process;
FIG. 3 is a schematic view of a solution growth process;
FIG. 4 is a schematic view of the apparatus of the present invention;
FIG. 5 is a schematic view of a charging device according to the present invention;
FIG. 6 is a schematic view of a preheating apparatus according to the present invention;
FIG. 7 is a schematic view of a feed valve in the preheating apparatus according to the present invention;
FIG. 8 is a schematic view of a sublimation separation apparatus of the invention;
fig. 9 is a schematic view of an ingot growing apparatus of the present invention.
Description of reference numerals:
the device comprises a feeding device 10, a trough 11, a sealing cover 12, a discharge pipe 13, a first air pipe 14, a discharge valve 15 and a vacuum switch valve 16;
the preheating device 20, the heating tank 21, the heat radiating fins 211, the charging valve 22, the shell 221, the central column 222, the rotating shaft 223, the through hole 224, the groove 225, the circular tube 231, the spiral body 232, the second air tube 24 and the electromagnet mechanism 25;
a sublimation separation apparatus 30, a cavity 31, a laser module 32, a reflection plate 33, a graphite crucible 34, a slope 341, a recovery tank 35, a third gas pipe (graphite pipe) 36, and a first heating mechanism 37;
a seed crystal 50;
and an insulating layer 60.
Detailed Description
As shown in FIGS. 4 to 9, the present invention discloses a silicon carbide single crystal ingot growing apparatus comprising a charging device 10, a preheating treatment device 20, a sublimation separation device 30, and an ingot growing device 40. The charging device 10, the preheating device 20 and the sublimation and separation device 30 are sequentially communicated in the vertical direction, and the sublimation and separation device 30 and the ingot growing device 40 are communicated in the horizontal direction.
The feeding device 10 comprises a trough 11 for storing source materials, a cover 12 for sealing an inlet of the trough 11, a discharge pipe 13 arranged at an outlet at the bottom of the trough 11, and a first air pipe 14 for communicating the trough 11 with an external vacuum pump air system. Discharge valve 15 and vacuum switch valve 16 have set gradually on discharging pipe 13 top-down, and the latus rectum of vacuum switch valve 16 is greater than the latus rectum of discharge valve 15 for the source material can not drop on vacuum switch valve 16, avoids the problem of source material clearance difficulty, simultaneously with the isolated effect in vacuum of guaranteeing vacuum switch valve 16.
The preheating device 20 includes a heating channel, a feeding valve 22 disposed on the heating channel, and a second gas pipe 24 communicated with the heating channel and disposed at a lower end of the feeding valve 22. The second gas pipe 24 is used for introducing a carrier gas. Specifically, the heating channel is bounded by a feeding valve 22, the upper end of the heating channel is a heating groove 21, the lower end of the heating channel is a spiral heater, the feeding valve 22 is arranged between the heating groove 21 and the spiral heater, and the heating groove 21, the feeding valve 22 and the spiral heater are matched to form the heating channel.
The heating tank 21 is in a bucket shape, a plurality of radiating fins 211 are arranged in the heating tank 21, the heating tank 21 and the radiating fins 211 are both made of solid conducting materials, and the upper end and the lower end of the heating tank 21 are respectively connected with two poles of a first alternating current power supply to form a first heating body. The spiral heater comprises a circular tube 231 and a spiral body 232 arranged in the circular tube 231, wherein the spiral body 232 is made of a solid conductive material, and the upper end and the lower end of the spiral body 232 are respectively connected with two poles of a second alternating current power supply to form a second heating body. The second air pipe 24 communicates with the upper end of the circular pipe 231.
The charging valve 22 includes a housing 221, a center post 222, and a rotating shaft 223, wherein a cylindrical cavity is provided inside the housing 221, and a through hole 224 penetrating the housing 221 upward and downward is provided on the housing 221. The center post 222 is tightly fitted into the inner cavity and freely rotates in the inner cavity, and the center post 222 blocks the through hole 224. The center post 222 has a groove 225 formed in a vertical direction, and the groove 225 can face the through hole 224 when the center post 222 is rotated. The rotating shaft 223 is connected to the center post 222 and the rotating shaft 223 extends to the outside of the housing 221. The bottom opening of the heating tank 21 faces the through hole 224 at the upper end of the casing 221, and the top opening of the circular tube 231 faces the through hole 224 at the lower end of the casing 221.
In addition, the preheating device 20 further includes two sets of electromagnet mechanisms 25, each electromagnet mechanism 25 includes a magnetic core and a coil wound around the periphery thereof, and two ends of the coil are respectively connected to two poles of a dc power supply. The two groups of electromagnet mechanisms 25 respectively generate electromagnetic induction with alternating current passing through the preheating filler groove 11 and the spiral body 232, so that the preheating filler groove 11 and the spiral body 232 vibrate. Through producing the vibration for the source material can supply kinetic energy at the removal in-process, and then overcomes the kinetic energy loss that causes like frictional force etc. and guarantees that the source material can continuously remove.
The sublimation separation apparatus 30 includes a cavity 31, and a laser module 32 for heating and sublimating the source material discharged from the heating passage, a graphite crucible 34 for promoting and maintaining sublimation of the source material, a recovery tank 35 for recovering the solid source material, two sets of third gas pipes 36 for introducing carrier gas, and a first heating mechanism 37 for heating the graphite crucible 34 and the third gas pipes 36 are provided in the cavity 31. The heating channel stretches into the cavity 31, the reflecting plate 33 matched with the laser module 32 is arranged at the outlet of the spiral heater, an included angle of 45 degrees is formed between the reflecting plate 33 and the horizontal plane, the pulse laser beam is emitted from the laser module 32 and is absorbed by the source material falling from the spiral heater, so that the source material is sublimated, the laser energy which is not absorbed by the source material is reflected by the reflecting plate 33 and enters the spiral heater, and the preheating effect of the source material is further enhanced.
A slope 341 is arranged at the bottom of the graphite crucible 34, the slope 341 forms an included angle of 30-60 degrees with the horizontal plane, and the slope 341 is arranged below the heating channel. The two third air pipes 36 are aligned up and down and are respectively arranged at the top of the slope 341 and the middle position of the slope 341; preferably, the third gas pipe 36 is a graphite pipe integrally formed with the graphite crucible 34. The graphite crucible 34 is provided with an air hole communicating with the ingot producing apparatus at a position opposite to the side where the third gas pipe 36 is provided. The slope bottom position of slope 341 is equipped with the bin outlet with accumulator 35 intercommunication. The solid raw material which has absorbed the laser energy and has not sublimated falls onto the slope 341, and is continuously heated by the graphite crucible 34 to be sublimated in the process of moving down on the slope 341, and finally the solid raw material which has not sublimated falls into the recovery tank 35.
The ingot producing apparatus includes a graphite chamber, a second heating mechanism 42 for heating the graphite chamber, and a seed crystal puller 43 disposed inside the graphite chamber. Specifically, the graphite chamber includes a small graphite chamber 411 and a large graphite chamber 412 which are integrally formed, and the small graphite chamber 411 is communicated with the air hole. The pipe diameter of the small graphite cavity 411 is equal to the aperture of the air hole, and the pipe diameter of the large graphite cavity 412 is more than one time larger than that of the small graphite cavity 411. Seed crystal 50 torr is placed within large graphite chamber 412. The gap between the seed crystal 50 torr and the large graphite chamber 412 forms an exhaust port that is connected to an external vacuum pump gas system.
The first heating mechanism 37 and the second heating mechanism 42 each include a radio frequency coil and a radio frequency power supply. In addition, an insulating layer 60 is provided for covering the heating channel, the graphite crucible 34, the third gas pipe 36 and the graphite cavity.
The invention also discloses a silicon carbide single crystal ingot growth method which is realized by adopting the silicon carbide single crystal ingot growth device, and the method comprises the following steps:
step one, feeding: the discharge valve 15 and the vacuum switch valve 16 are closed, and a gravel or powder source material with a particle radius of not more than 0.5mm is adopted. The source material is put into the feed chute 11 and then tightly sealed, and the upper and lower closed spaces isolated by the vacuum switch valve 16 are respectively vacuumized by an external vacuum pump gas system until the production requirements are met. After the source material enters the next stage from the feeding device 10, the vacuum switch valve 16 is closed again, the feeding device 10 can be isolated, the feeding step can be repeated under the condition of not influencing the work of the next stage, the source material is supplemented, the source material can be continuously supplied to the production without interruption, and the problem of source material exhaustion can not occur.
Step two, introducing carrier gas: the second gas pipe 24 and the third gas pipe 36 respectively preheat the carrier gas.
Step three, preheating: the heating channel forms two temperature fields with the feeding valve 22 as a boundary, the temperature field at the upper end is the heating groove 21 with the temperature of 500-. The source material is first heated in the heating tank 21, and then fed into the screw heater in a fixed amount controlled by the rotational frequency of the feed valve 22. The source material is moved and heated in the spiral heater and is heated by two temperature fields, so that the source material can be heated to 1600-1800 ℃ when being discharged out of the heating channel. When the source material is in the spiral heater, the vibration frequency of the spiral body 232 is controlled by controlling the current passing through the electromagnet mechanism 25, so that the moving speed of the source material is controlled. In addition, the vibration also increases the rolling of the granular source material in the screw 232, so that the source material is heated more uniformly.
Step four, sublimation separation: a temperature field with the temperature of 2300-2600 ℃ is formed in the graphite crucible 34. The source material which is discharged from the heating channel through laser beam irradiation and falls on the reflecting plate 33 is firstly made to absorb a large amount of light energy to sublimate into gas phase substance, and the non-sublimated part of the source material falls into the graphite crucible 34 to continue heating, so that a part of the source material is sublimated into gas phase substance, and finally the non-sublimated source material falls into the recovery tank 35. The sublimated vapor phase material is mixed with a carrier gas and flowed into ingot growing apparatus 40.
Step five, ingot growing: a temperature field with gradually decreasing temperature is formed in the graphite cavity, the gradually decreasing direction is from the graphite crucible 34 to the graphite cavity, and the temperature of the position where the seed crystal 50 is placed is 100-200 ℃ lower than that of the graphite crucible 34. The gas phase substances are solidified on the seed crystal 50 into a silicon carbide single crystal ingot, and the carrier gas and the gas phase substances which are not utilized flow to the vacuum pump gas system for recycling.
In the above steps, the carrier gas is one or two inert gases, preferably argon, which has relatively low cost, and the argon can meet the use requirement because the carrier gas has long heating time. Alternatively, the carrier gas may be other inert gas other than argon, or a mixed gas of argon and other inert gas; the carrier gas may be mainly the above-mentioned gas, mixed with a small amount of auxiliary gas and/or organic metal gas, wherein the auxiliary gas may be one or two or all of nitrogen, hydrogen and hydrogen chloride.
The key point of the invention is that the feeding device 10 can be isolated into an independent vacuum feeding space through the vacuum switch valve 16, thereby realizing uninterrupted feeding in the ingot growing process and providing sufficient source material preparation for preparing large-size ingots. The particle powder source material is firstly heated in a moving way in the preheating device 20 and is also in a moving heating state in the sublimation separation device 30, so that the graphite ceramic of the source material can be avoided, the exhaustion of a growth source is avoided, and the preparation of a large-size crystal ingot is facilitated; meanwhile, the preheating device 20 preheats the source material, so that the heating time of the source material in the sublimation stage can be shortened, and the growth process is accelerated. The preheating device 20, the sublimation separation device 30 and the ingot growing device 40 are respectively provided with an independent heating mechanism, which becomes a production parameter for directly controlling variables, reduces the coupling among different stages of temperature, improves the fineness and the accuracy of the temperature control of the whole system, and effectively reduces the thermal budget of the system. The carrier gas is heated before being mixed with the gas-phase substance, so that the cold spraying effect of the carrier gas can be reduced; meanwhile, the system recovers silicon carbide fixed substances and gas-phase substances in the ingot growing process, the silicon carbide fixed substances and the gas-phase substances can be recycled through simple treatment, the production source material cost is low, in addition, the invention has no complicated mechanical design and low equipment cost, is particularly suitable for large-size ingot growing, and has higher product competitiveness.
The above description is only exemplary of the present invention and is not intended to limit the technical scope of the present invention, so that any minor modifications, equivalent changes and modifications made to the above exemplary embodiments according to the technical spirit of the present invention are within the technical scope of the present invention.
Claims (13)
1. A silicon carbide single crystal ingot growth apparatus characterized by: comprises a feeding device, a preheating treatment device, a sublimation separation device and a crystal ingot growing device; the feeding device, the preheating treatment device and the sublimation separation device are sequentially communicated in the vertical direction, and the sublimation separation device and the crystal ingot growth device are communicated in the horizontal direction;
the feeding device comprises a material groove for storing source materials, a sealing cover for sealing an inlet of the material groove, a discharge pipe arranged at an outlet at the bottom of the material groove, and a first air pipe for communicating the material groove with an external vacuum pump air system; a discharge valve and a vacuum switch valve are sequentially arranged on the discharge pipe from top to bottom;
the preheating device comprises a heating channel, a feeding valve arranged on the heating channel and a second air pipe which is communicated with the heating channel and is arranged at the lower end of the feeding valve; the second gas pipe is used for introducing carrier gas;
the sublimation separation device comprises a cavity, wherein a laser module for heating and sublimating the source material discharged from the heating channel, a graphite crucible for promoting and maintaining the sublimation of the source material, a recovery tank for recovering the solid source material, a plurality of third gas pipes for introducing carrier gas and a first heating mechanism for heating the graphite crucible and the third gas pipes are arranged in the cavity;
the ingot production device comprises a graphite cavity, a second heating mechanism for heating the graphite cavity and a seed crystal puller arranged in the graphite cavity; one end of the graphite cavity is communicated with the graphite crucible, and the other end of the graphite cavity is communicated with an external vacuum pump gas system.
2. An apparatus for growing a silicon carbide single crystal ingot according to claim 1, wherein: the feeding valve comprises a shell, a central column and a rotating shaft, wherein a cylindrical cavity is arranged in the shell, and a through hole is formed in the shell; the central column is tightly matched with the inner cavity and rotates in the inner cavity, and the through hole is blocked by the central column; the cylindrical surface of the central column is provided with a plurality of grooves in the vertical direction, and the grooves can be opposite to the through holes when the central column is rotated; the rotating shaft is connected with the central column and extends to the outside of the shell.
3. An apparatus for growing a silicon carbide single crystal ingot according to claim 1 or 2, wherein: the preheating device also comprises a heating groove and a spiral heater, the feeding valve is arranged between the heating groove and the spiral heater, and the heating groove, the feeding valve and the spiral heater are matched to form the heating channel;
the heating groove is in a bucket shape, and a plurality of radiating fins are arranged in the heating groove; the heating groove is made of solid conductive materials, and the upper end and the lower end of the heating groove are respectively connected with two poles of a first alternating current power supply to form a first heating body;
the spiral heater comprises a circular tube and a spiral body arranged in the circular tube, the spiral body is made of a solid conductive material, and the upper end and the lower end of the spiral body are respectively connected with two poles of a second alternating current power supply to form a second heating body.
4. An apparatus for growing a silicon carbide single crystal ingot according to claim 3, wherein: the electromagnetic mechanism comprises a magnetic core and a coil wound on the periphery of the magnetic core, and two ends of the coil are respectively connected with two poles of a direct-current power supply; and the two groups of electromagnet mechanisms respectively generate electromagnetic induction with the preheating filling groove and the spiral body, so that the preheating filling groove and the spiral body vibrate.
5. An apparatus for growing a silicon carbide single crystal ingot according to claim 1, wherein: the heating channel stretches into the cavity, a reflecting plate matched with the laser module is arranged at the outlet of the heating channel, and a 45-degree included angle is formed between the reflecting plate and the horizontal plane.
6. An apparatus for growing a silicon carbide single crystal ingot according to claim 1, wherein: the bottom of the graphite crucible is provided with a slope, the slope is arranged below the heating channel, and an included angle of 30-60 degrees is formed between the slope and the horizontal plane; and a discharge port communicated with the recovery tank is arranged at the slope bottom of the slope.
7. An apparatus for growing a silicon carbide single crystal ingot according to claim 6, wherein: the two third air pipes are aligned up and down and are respectively arranged at the top of the slope and the middle position of the slope; the third gas pipe is a graphite pipe which is integrally formed with the graphite crucible.
8. An apparatus for growing a silicon carbide single crystal ingot according to claim 1, wherein: the graphite cavity comprises a small graphite cavity and a large graphite cavity which are integrally formed, the graphite crucible is provided with an air hole, and the small graphite cavity is communicated with the air hole; the pipe diameter of the small graphite cavity is equal to the pore diameter of the air hole, and the pipe diameter of the large graphite cavity is more than one time larger than that of the small graphite cavity; the seed crystal support is arranged in the large graphite cavity.
9. An apparatus for growing a silicon carbide single crystal ingot according to claim 1, wherein: the first heating mechanism and the second heating mechanism both comprise a radio frequency coil and a radio frequency power supply.
10. An apparatus for growing a silicon carbide single crystal ingot according to claim 1, wherein: the graphite crucible heating device further comprises a heat insulation layer used for wrapping the heating channel, the graphite crucible, the third air pipe and the graphite cavity.
11. A silicon carbide single crystal ingot growth method, which is carried out using the silicon carbide single crystal ingot growth apparatus according to any one of claims 1 to 10, the method comprising:
step one, feeding: closing the discharge valve and the vacuum switch valve, putting gravel or powder source materials into the feed chute, sealing tightly, and respectively vacuumizing the upper and lower closed spaces isolated by the vacuum switch valve through an external vacuum pump gas system until the production requirements are met;
step two, introducing carrier gas: the second air pipe and the third air pipe respectively preheat carrier gas;
step three, preheating: the heating channel forms two temperature fields by taking the feeding valve as a boundary, the temperature of the temperature field at the upper end is 500-800 ℃, and the temperature of the temperature field at the lower end is 1600-1800 ℃; the source material stays in the upper temperature field for heating, the source material moves in the lower temperature field for heating, and the source material can be heated to 1600-1800 ℃ when being discharged out of the heating channel through the two temperature fields;
step four, sublimation separation: a temperature field with the temperature of 2300-2600 ℃ is formed in the graphite crucible; irradiating the source material discharged from the heating channel by laser beams to ensure that part of the source material absorbs a large amount of light energy and is sublimated into a gas phase substance, and the part of the source material which is not sublimated falls into the graphite crucible to be continuously heated, so that part of the source material is sublimated into the gas phase substance, and finally the source material which is not sublimated falls into the recovery tank; the sublimated gas phase substance is carried into the ingot growing device by the carrier gas;
step five, ingot growing: forming a temperature field with gradually decreased temperature in the graphite cavity, wherein the gradually decreased direction is from the graphite crucible to the graphite cavity, and the temperature of the seed crystal placing position is lower than that of the graphite crucible by 100-200 ℃; solidifying the gas-phase substance on the seed crystal to form a silicon carbide single crystal ingot; and the unused carrier gas and gas phase substance flow to the vacuum pump gas system for recycling.
12. A silicon carbide single crystal ingot growing method according to claim 11, wherein: the particle radius of the source material put into the feed chute is not more than 0.5 mm.
13. A silicon carbide single crystal ingot growing method according to claim 11, wherein: the carrier gas is an inert gas.
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| CN117779179A (en) * | 2024-02-23 | 2024-03-29 | 苏州优晶半导体科技股份有限公司 | Single crystal growth device and single crystal growth method |
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