CN116536766A

CN116536766A - Growth method and apparatus for preparing high quality silicon carbide crystal

Info

Publication number: CN116536766A
Application number: CN202310474685.2A
Authority: CN
Inventors: 许成凯
Original assignee: Jiangsu Jixin Semiconductor Silicon Research Institute Co Ltd
Current assignee: Jiangsu Jixin Advanced Materials Co ltd
Priority date: 2023-04-27
Filing date: 2023-04-27
Publication date: 2023-08-04

Abstract

The invention discloses a growth method and equipment for preparing high-quality silicon carbide crystals, wherein the method adopts two crystal growth stages, the first crystal growth stage adopts a pulling method to grow crystal on silicon carbide seed crystal, the silicon carbide seed crystal is immersed in silicon carbide melt, and micropipe defect dislocation in the seed crystal is eliminated; and in the second stage, a vapor phase method is adopted to carry out crystal growth on the silicon carbide seed crystal after the micropipe defect is eliminated. The device adopts an inner crucible and an outer crucible, the inner crucible is arranged in a melting chamber, a first crystal growth stage is carried out on silicon carbide melt in the inner crucible by seed crystals, micropipe defects and dislocation of the silicon carbide seed crystals are repaired, after the repair, a rotary lifting shaft drives the seed crystals to rise, in the rising process, a cover body and a guide device are slowly closed through a transmission device until the seed crystals rise to a preset position, the cover body and the guide device are completely closed, a second crystal growth stage is started, and defect-free crystal growth in the subsequent crystal growth process can be inherited because the first crystal growth stage has repaired the seed crystal defects, so that the quality of crystals is improved.

Description

Growth method and apparatus for preparing high quality silicon carbide crystal

Technical Field

The invention relates to the technical field of semiconductors, in particular to a method and equipment for preparing high-quality silicon carbide crystals.

Background

In the related art, the PVT method is one of the most commonly used methods for growing silicon carbide crystals, and in the process of growing silicon carbide crystals by using the PVT method, microscopic defects such as dislocation and micropipe easily occur in the crystals, and the defects such as dislocation and micropipe can inherit in the process of growing the crystals, so that the quality of the crystals is directly reduced.

Disclosure of Invention

The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, the invention aims to provide a growth method for preparing high-quality silicon carbide crystals, which can reduce defects such as dislocation and micropipe in the crystals and improve the quality of the crystals.

The invention also provides growth equipment based on the growth method for preparing the high-quality silicon carbide crystal.

A growth method for producing a high quality silicon carbide crystal according to the first aspect of the present invention comprises

1) A first crystal growth stage, wherein the first crystal growth stage adopts a pulling method to grow crystal of the silicon carbide seed crystal, the silicon carbide seed crystal is soaked in the silicon carbide melt, and micropipe defects in the seed crystal are eliminated;

2) And a second crystal growth stage, wherein the second stage adopts a gas phase method to carry out crystal growth on the silicon carbide seed crystal obtained in the step 1).

The scheme adopts two crystal growing stages, wherein the silicon carbide seed crystal is soaked in the silicon carbide melt in the first crystal growing stage, and the silicon carbide seed crystal is subjected to crystal growth by adopting a pulling method; eliminating micropipe defects and dislocation in seed crystal; and in the second stage, the silicon carbide seed crystal after the micropipe defect is eliminated is subjected to crystal growth by adopting a gas phase method. By the method, inherited dislocation in the seed crystal is effectively reduced, and the crystal quality is improved.

The growing equipment for preparing high-quality silicon carbide crystals according to the second aspect of the invention comprises an outer crucible, a melting chamber, an inner crucible, a flow guiding device, a rotary lifting shaft, a seed crystal support and a transmission device; the top of the outer crucible is sealed with a crucible cover, and the outer crucible defines a first space; the melting chamber is arranged on the bottom wall of the inner part of the outer crucible, and the upper part of the melting chamber is provided with an opening; the cover body is arranged at the top of the melting chamber; the inner crucible is installed in the melting chamber; the flow guiding device is connected to the inner wall of the outer crucible; the top end of the rotary lifting shaft is positioned outside the outer crucible and connected with an external rotary lifting device, the bottom end of the rotary lifting shaft is positioned inside the outer crucible, and the rotary lifting shaft and the inner crucible are coaxially arranged; the seed crystal support is arranged at the bottom of the rotary lifting shaft, and seed crystals are arranged on the lower surface of the seed crystal support; the transmission device is connected with the rotary lifting shaft through a connecting part, the transmission device controls the cover body to be closed along with the rising of the rotary lifting shaft, the transmission device controls the flow guiding device to be closed along with the rising of the rotary lifting shaft, and the first space is divided into a growth space and a raw material space after the flow guiding device is closed.

In the scheme, the double-crucible design is adopted, the inner crucible is used for loading the Si-C source, the outer crucible is used for loading the silicon carbide powder, and before crystal growth, the silicon carbide seed crystal is firstly placed in the inner crucible, and the initial state of the double-crucible type silicon carbide powder crystal growth device is as follows: fixing the inner crucible at a preset position in a melting chamber, opening a flow guiding device, enabling a rotating lifting shaft to pass through the flow guiding device, and placing silicon carbide seed crystals in the inner crucible; firstly, in the first crystal growth stage, dislocation and micropipe defects on the seed crystal are repaired by utilizing molten Si-C melt, after the repair is completed, the seed crystal is gradually lifted up by using a rotary lifting shaft, in the seed crystal lifting process, a transmission device drives a cover body and a flow guiding device to be slowly closed along with the lifting of the rotary lifting shaft, when the silicon carbide seed crystal is lifted to a preset position along with the rotary lifting shaft, the cover body and the flow guiding device are completely closed, at the moment, the crystal enters the second crystal growth stage, and the defects of micropipes, dislocation and the like of the silicon carbide seed crystal are repaired, so that the defects of micropipes, dislocation and the like can not occur in the subsequent crystal growth process, and the quality of the silicon carbide crystal is effectively improved.

In addition, as the guiding device is closed and the only power source for the inner crucible to descend is the ascending of the rotary ascending and descending shaft, the condition that excessive disturbance in the growth space is avoided is effectively ensured, and the quality of the silicon carbide crystal is further ensured.

In some embodiments, the flow guiding device comprises an annular flow guiding table and a flow guiding plate, wherein the annular flow guiding table is connected to the inner wall of the outer crucible, a flow guiding hole is defined in the middle of the annular flow guiding table, and the seed crystal holder can pass through the flow guiding hole along with the lifting of the rotary lifting shaft; the guide plate is connected to the annular guide table through a first rotating shaft, and the first rotating shaft can drive the guide plate to rotate under the action of the transmission device and form shielding on the guide hole so as to close the guide device.

In some embodiments, the baffle of the invention is composed of 4 porous plates with 1/4 circle, each porous plate is connected to the annular baffle table through a first rotating shaft, the first rotating shaft is connected with the rotating lifting shaft through the transmission device, when the rotating lifting shaft is lifted to a preset position, the transmission rotating shaft drives the porous plates to rotate and close into the baffle through the first rotating shaft, and the baffle hole is blocked to close the baffle device. According to the embodiment, the transmission device is controlled to act through the rotary lifting shaft, and the transmission device drives the first rotating shaft to rotate, so that the porous plate is rotated to be closed into the guide plate to close the guide device, the control mode cannot cause any interference on silicon carbide gas, therefore, the influence on the quality of silicon carbide crystals is avoided, after the guide holes are blocked by the porous plate, the silicon carbide gas enters into a growth space after passing through the porous plate, and the growth quality of the crystals is improved.

In some embodiments, the cover body is a double door structure consisting of two cover plates, and each door plate is connected with the side wall of the melting chamber through a hinge; the inner crucible is fixed on the bottom wall of the melting chamber through the telescopic support frame, and the inner crucible descends into the melting chamber along with the ascending of the rotary lifting shaft under the pulling of the transmission device; in the embodiment, when the rotary lifting shaft ascends, the transmission device is driven to act, the transmission device drives the inner crucible to descend, and when the inner crucible descends, the cover body is automatically closed under the action of the hinge and self gravity, so that the inner crucible is controlled to descend into the melting chamber in a purely mechanical mode, and meanwhile, the cover body is automatically closed, so that the influence on the quality of crystals is avoided.

In some embodiments, the transmission device comprises a first traction wire and a second traction wire, one end of each first traction wire is connected to the connecting part, the other end sequentially passes through the crucible cover and the side wall and the bottom wall of the outer crucible to be fixed at the bottom of the inner crucible, and the first traction wire pulls the inner crucible to descend along with the rising of the rotary lifting shaft; one end of each second traction wire is connected with the connecting part, and the other end of each second traction wire sequentially penetrates through the crucible cover, the side wall of the outer crucible and the side wall of the annular diversion table to be wound on the lower part of the first rotating shaft in the same direction; the second traction wire drives the porous plate to rotate and close to form the guide plate through the first rotating shaft along with the rising of the rotating lifting shaft; the number of the first traction wires and the second traction wires is four, and the first traction wires and the second traction wires are uniformly distributed at intervals in the circumferential direction. In the embodiment, the perforated plate is controlled to be closed through the traction wire so as to close the flow guiding device, and the inner crucible is controlled to be lowered into the melting chamber through the traction wire so as to close the cover body, so that the control mode is simple and convenient, and the cost is low.

In some embodiments, the present transmission further comprises a traction wire drive channel consisting essentially of a first traction wire drive channel, a second traction wire drive channel, and a third traction wire drive channel; the first traction wire transmission channel is defined in the crucible cover, the second traction wire transmission channel is defined in the inner part of the outer crucible wall, and the third traction wire transmission channel is defined in the inner part of the side wall of the annular diversion table; one end of the first traction wire transmission channel is communicated with the shaft hole of the rotary lifting shaft, the other end of the first traction wire transmission channel is communicated with one end of the second traction wire transmission channel, the other end of the second traction wire transmission channel is communicated with the bottom of the melting chamber, one end of the third traction wire transmission channel is communicated with the shaft hole of the first rotating shaft, and the other end of the third traction wire transmission channel is communicated with the second traction wire transmission channel; the four traction wire transmission channels are uniformly distributed at intervals in the circumferential direction, and each shaft hole of the first rotating shaft corresponds to one traction wire transmission channel; one end of the first traction wire is connected to the bottom of the inner crucible, and the other end of the first traction wire sequentially passes through the second traction wire transmission channel and the first traction wire transmission channel to be connected with the connecting part; one end of the second traction wire is wound on the first rotating shaft, and the other end sequentially penetrates through the third traction wire transmission channel, the second traction wire transmission channel and the first traction wire transmission channel to be connected with the connecting part. The traction wire transmission channel is offered to this embodiment, and first traction wire and second traction wire one end link to each other with adapting unit, and first traction wire and second traction wire other end pass traction wire transmission channel respectively and link to each other with first pivot and interior crucible bottom, because traction wire transmission channel has defined an accommodation space for hold the traction wire, consequently, reduced the traction wire in the motion in-process with the frictional force of outer crucible wall and crucible cover wall, prolonged the life of traction wire on the one hand, on the other hand make the transmission more smooth and easy.

In some embodiments, the connecting component is a connecting ring or a bearing, the side wall of the rotating lifting shaft is provided with an annular groove, the connecting ring or the bearing is sleeved on the rotating lifting shaft and is arranged in the annular groove, and the outer diameter of the connecting ring or the bearing is not larger than the outer diameter of the rotating lifting shaft; when the connecting part is a connecting ring, the connecting ring is in clearance fit with the rotary lifting shaft, the contact surfaces of the connecting ring and the rotary lifting shaft are polished surfaces, and the transmission device is fixedly connected with the connecting ring; when the connecting part is a bearing, the inner ring of the bearing is in interference fit with the rotary lifting shaft, and the transmission device is fixedly connected with the outer ring of the bearing.

In some embodiments, the inner crucible is fixedly arranged at the upper part of the inner side of the melting chamber, the cover body consists of 4 1/4 round cover plates, each cover plate is connected to the top of the side wall of the melting chamber through a second rotating shaft, and the second rotating shaft controls the cover body to be opened or closed along with the descending or ascending of the rotating lifting shaft under the action of the transmission device. In this embodiment, the crucible is fixed in position, and the cover plate is opened or closed by rotating.

In some embodiments, the connecting part is a rack, the rack is arranged on the outer wall of the rotary lifting shaft, the transmission device comprises a traction shaft and a gear, the traction shaft comprises a first traction shaft, a second traction shaft, a third traction shaft, a fourth traction shaft and a fifth traction shaft, one end of the first traction shaft is meshed with the rack through the gear, the other end of the first traction shaft is connected with one end of the third traction shaft through the second traction shaft, the other end of the third traction shaft is connected with the first rotating shaft, one end of the third traction shaft is connected with one end of the fifth traction shaft through the fourth traction shaft, and the other end of the fifth traction shaft is connected with the second rotating shaft; the first traction shaft is connected with the second traction shaft, the second traction shaft is connected with the third traction shaft, the third traction shaft is connected with the first rotating shaft, the third traction shaft is connected with the fourth traction shaft, the fourth traction shaft is connected with the fifth traction shaft, and the fifth traction shaft is connected with the second rotating shaft through bevel gear pairs; the traction shafts are four in number and are distributed at equal intervals in the circumferential direction. According to the embodiment, along with the rising of the rotary lifting shaft, the seed crystal rises along with the rising and passes through the diversion holes, meanwhile, under the meshing transmission of the gear and the rack and the bevel gear pair between the traction shafts, the porous plate and the cover plate are driven to rotate slowly and inwards, when the rotary lifting shaft rises to a preset position, the porous plate and the cover plate are completely closed or opened, namely the annular diversion table and the cover body are closed, the annular diversion table and the cover body are controlled to be closed or opened only through the rising of the rotary lifting shaft, and the influence on the growth quality of crystals is avoided.

In some embodiments, the invention further comprises a traction shaft drive channel, the traction shaft being mounted within the traction shaft drive channel by a retaining ring, the traction shaft being in clearance fit with the retaining ring; the traction shaft transmission channel comprises a first traction shaft transmission channel, a second traction shaft transmission channel and a third traction shaft transmission channel, the first traction shaft transmission channel is limited in the crucible cover, the second traction shaft transmission channel is limited in the side wall of the outer crucible, the third traction shaft transmission channel is limited in the side wall of the annular diversion table, one end of the first traction shaft transmission channel is communicated with the shaft hole of the rotary lifting shaft, the other end of the first traction shaft transmission channel is communicated with one end of the second traction shaft transmission channel, one end of the third traction shaft transmission channel is communicated with the shaft hole of the first rotating shaft, and the other end of the third traction shaft transmission channel is communicated with the second traction shaft transmission channel; the number of the traction shaft transmission channels is the same as that of the first rotating shafts, and each shaft hole of the first rotating shaft corresponds to one traction shaft transmission channel; the first traction shaft and the second traction shaft are respectively arranged in the first traction shaft transmission channel and the second traction shaft transmission channel, the third traction shaft and the fourth traction shaft are arranged in the second traction shaft transmission channel up and down, and each first rotating shaft corresponds to one traction shaft transmission channel; the traction shaft transmission channels are arranged in four in total and are uniformly distributed at intervals in the circumferential direction. The traction shaft channel can accommodate the traction shaft, friction between the traction shaft and the crucible cover, the outer crucible wall and the side wall of the annular flow guide table during rotation is reduced, and the service life of the traction shaft is prolonged.

Compared with the prior art, the invention has the following advantages:

1) The silicon material and the carbon powder are mainly carried in the inner crucible, and in the second crystal growth stage, the silicon material and the carbon powder continuously react to generate SiC, and the SiC is heated and decomposed to generate Si ₂ C、SiC ₂ Si gas, the silicon carbide gas after the gas rises mixes with the silicon carbide gas after the silicon carbide powder sublimates around, has increased the silicon vapor content in the gas after mixing, and excessive silicon vapor content can react with the carbon particle in the air to reduce the carbon content in the gas, and then reduced impurity such as carbon parcel, promoted crystal quality, the effect of homogenization air current can be played to the mixed gas through closed perforated plate, has further improved the growth quality of crystal.

2) In the heating process, the crucible is mainly used for heating, and then heat is conducted into the silicon carbide powder, so that the temperature of the silicon carbide powder at the position close to the crucible is higher than that at the position far away from the crucible.

3) In the crystal growth process, besides the uniform heat required by the silicon carbide powder, the temperature at the crystal is more uniform, and the uneven temperature distribution can increase the crystal stress, so that the stress is a main source of microscopic defects such as MP, BPD, TED and the like. The invention increases the intermediate heat due to the existence of the inner crucible, and the seed crystal can receive the heat conduction of the outer crucible and the heat radiation of the lower inner crucible, so that the radial temperature gradient is more uniform, the stress is reduced, and the growth quality of crystals is improved.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

FIG. 1 is a schematic diagram of a structure of an apparatus for producing high quality silicon carbide crystal growth according to one embodiment of the present invention;

FIG. 2 is a schematic diagram of a structure of an apparatus for producing high quality silicon carbide crystal growth according to one embodiment of the present invention;

FIG. 3 is a schematic diagram of a multi-well plate spin-closure process for a high quality silicon carbide crystal growth apparatus according to one embodiment of the present invention; wherein, the diagram (a) is a fully open state of the deflector, the diagrams (b) and (c) are semi-closed states of the deflector, and the diagram (d) is a fully closed state of the deflector;

FIG. 4 is a schematic view showing a process in which an inner crucible of an apparatus for producing high-quality silicon carbide crystal growth is lowered to a melting chamber and a lid is closed, according to an embodiment of the present invention; wherein, the diagram (a) is the fully opened state of the cover body, the diagram (b) is the semi-closed state of the cover body, and the diagram (c) is the fully closed state of the cover body;

FIG. 5 is a schematic diagram of a structure of an apparatus for producing high quality silicon carbide crystal growth according to one embodiment of the present invention;

FIG. 6 is a schematic view showing the structure of a lifting rotating shaft of an apparatus for producing high-quality silicon carbide crystal according to one embodiment of the present invention;

FIG. 7 is an enlarged schematic view of a structure in which a first pulling shaft and a second pulling shaft of an apparatus for producing high-quality silicon carbide crystal growth according to an embodiment of the present invention are coupled together by a bevel gear pair;

reference numerals:

100: a silicon carbide crystal growth apparatus;

10: thermal insulation cotton;

20: a crucible cover;

30: an outer crucible; 31: silicon carbide powder;

40: a flow guiding device; 41: an annular diversion table; 42: a deflector; 421: a porous plate; 43: a first rotating shaft; 44: a deflector aperture;

50: a retractable support;

60: a melting chamber; 61: a cover body; 611: a cover plate; 62: an inner crucible;

70: a seed crystal support; 71: seed crystal;

80: rotating the lifting shaft; 81: a connecting ring;

91: a first traction wire drive channel; 92: a second traction wire drive channel; 921: a first traction wire; 93: a third traction wire drive channel; 931: a second traction wire; 94: a fixing ring; 95: a rack; 961: a first traction shaft drive channel; 962: a second traction shaft drive channel; 963: a third traction shaft drive channel; 971: a first traction shaft; 972: a second traction shaft; 973: a third traction shaft; 974: a fourth traction shaft; 975: a fifth traction shaft; 98: bevel gear pair.

Detailed Description

Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.

The following disclosure provides many different embodiments, or examples, for implementing different structures of the invention. In order to simplify the present disclosure, components and arrangements of specific examples are described below. They are, of course, merely examples and are not intended to limit the invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art will recognize the applicability of other processes and/or the use of other materials.

Example 1

According to the growth method for preparing the high-quality silicon carbide crystal, the two-stage crystal growth is adopted, and the specific method is as follows:

1) A first crystal growth stage: the silicon carbide seed crystal 71 is immersed in a high-temperature silicon carbide melt, and the silicon carbide seed crystal 71 is subjected to crystal growth by adopting a pulling method, atoms in the melt can bridge microscopic defects and dislocations in the silicon carbide seed crystal 71, so that screw dislocations (Threading Screw Dislocation, TSD) or edge dislocations (Threading Edge Dislocat ion, TED) in the crystal are converted into Stacking Faults (SF) in the growth process, the propagation direction is changed, and finally the screw dislocations are discharged out of the crystal, thereby realizing the reduction of dislocation density in the grown crystal, and further obtaining the high-quality SiC crystal (silicon carbide crystal) without micropipes and with low dislocation density. The second growth stage is performed after the microscopic defects of the seed crystal 71 are eliminated.

2) A second crystal growth stage: the silicon carbide seed crystal 71 obtained in the step 1) after the micropipe defect and dislocation are eliminated is subjected to crystal growth by adopting a gas phase method, and the inherited dislocation in the seed crystal 71 can be reduced by adopting the method, so that the crystal quality is improved.

Example 2

1-4, a silicon carbide crystal growing apparatus 100 based on the above-described growing method is described, comprising an outer crucible 30, a melting chamber 60, a cover 60, an inner crucible 62, a deflector 40, a rotation elevating shaft 80, a seed crystal support 70 and a transmission device, wherein the outer crucible 30 comprises a heat insulation cotton 10 outside for maintaining the temperature inside the outer crucible 30, a crucible cover 20 is sealed at the top of the outer crucible 30, and the outer crucible 30 defines a first space; the melting chamber 60 is arranged on the bottom wall of the inner side of the outer crucible 30, an opening is formed in the upper part of the melting chamber 60, and the melting chamber 60 is of a cylindrical structure and is made of graphite; the cover 60 is installed on top of the melting chamber 60 for shielding the upper opening of the melting chamber 60; the inner crucible 62 is arranged at the inner side of the melting chamber 60, the inner crucible 62 is mainly used for containing silicon materials and carbon powder, the flow guiding device 40 is connected to the inner wall of the outer crucible 30 and plays a role in guiding silicon carbide gas, the top end of the rotary lifting shaft 80 is positioned at the outer part of the outer crucible 30 and connected with an external rotary lifting device, the bottom end of the rotary lifting shaft 80 is positioned inside the outer crucible 30, and the rotary lifting shaft 80 and the inner crucible 62 are coaxially arranged; the seed crystal support 70 is arranged at the bottom of the rotary lifting shaft 80, and the seed crystal 71 is arranged on the lower surface of the seed crystal support; the transmission device is connected with the rotary lifting shaft 80 through the connecting component, the transmission device controls the cover body 60 and the flow guiding device 40 to be slowly closed along with the rising of the rotary lifting shaft 80, the first space is separated into a growth space and a raw material space after the flow guiding device 40 is closed, the growth space is positioned at the upper part of the first space and used for growing silicon carbide crystals, and the raw material space is positioned at the lower part of the first space and used for containing silicon carbide powder.

Specifically, referring to fig. 1, in this embodiment, an outer crucible 30, a melting chamber 60 and an inner crucible 62 are coaxially disposed in sequence from outside to inside, a deflector 40 is connected to the inner wall of the outer crucible 30, and the deflector 40 and a cover 60 have two states: the initial states of the deflector 40 and the cover 60 are opened and closed, the rotation lifting shaft 80 penetrates through the deflector 40 to place the seed crystal 71 inside the inner crucible 62, si powder and C powder are placed in the inner crucible 62, and silicon carbide powder 31 is placed in the raw material space.

The apparatus is started, and the first crystal growth stage is performed, the temperature is raised to 1500-1700 ℃, silicon carbide crystals are grown in the inner crucible 62, and dislocation and micropipe on the seed crystal 71 are repaired by the molten si—c melt. When silicon carbide crystal grows in the inner crucible 62, a pulling method is adopted, the inner crucible 62 grows in the first crystal growth stage 10h, in 10h, the rotation lifting shaft 80 drives the seed crystal 71 to lift upwards at a speed of 0.05mm/h, namely, the rotation lifting shaft 80 drives the seed crystal 71 to lift upwards and rotate simultaneously, due to the existence of the connecting component, when the rotation lifting shaft 80 rotates, the connecting component cannot rotate along with the seed crystal, so that the transmission device cannot be driven to act, and further the cover body 60 and the flow guiding device 40 cannot be driven to move, but when the rotation lifting shaft 80 moves axially, the transmission device can be driven to act, and then the cover body 60 and the flow guiding device 40 are driven to be closed by the transmission device. When the repair is completed, the rotation lifting shaft 80 drives the seed crystal holder 70 to lift up rapidly, and the temperature continues to rise. Along with the rising of the seed crystal 71 (the rotation lifting shaft 80), the transmission device drives the flow guiding device 40 to be slowly closed, and simultaneously drives the cover body 60 to be slowly closed, and referring to fig. 2, when the seed crystal 71 (the rotation lifting shaft 80) rises to a preset position, the flow guiding device 40 and the cover body 60 are completely closed, at this time, the silicon carbide crystal enters a second crystal growth stage, when the temperature in the outer crucible 30 reaches a certain temperature, the silicon carbide powder sublimates into silicon carbide gas, rises upwards, enters a growth space through the flow guiding device 40, and is deposited on the silicon carbide crystal. In the silicon carbide crystal of the embodiment, the crystal is grown by a pulling method by firstly lowering the rotary lifting shaft 80 into the inner crucible 62, so that the defects of micropipes and dislocation are eliminated, and then the crystal is grown by a gas phase method by lifting the rotary lifting shaft 80 to a preset position, so that the quality of the silicon carbide crystal is improved.

In addition, during the heating process, both the inner crucible 62 and the outer crucible 30 generate heat, so that the heating of the silicon carbide powder 31 is more uniform, and meanwhile, the radial temperature gradient of the crystal is more uniform, which is beneficial to the improvement of the growth quality of the silicon carbide crystal. Meanwhile, the silicon material and the carbon powder are mainly carried in the inner crucible 62, and in the second crystal growth stage, namely the stage of adopting a gas phase method to grow crystals, the silicon material and the carbon powder continuously react to generate SiC, and the SiC is heated and decomposed to generate Si ₂ C、SiC ₂ Si gas, the silicon vapor content in the mixed gas is increased by mixing the gas after rising with the silicon carbide gas after sublimating the surrounding silicon carbide powder 31, and the excessive silicon vapor content can react with carbon particles in the air, so that the carbon content in the gas is reduced, further impurities such as carbon wrapping and the like are reduced, the crystal quality is improved, the mixed gas plays a role in homogenizing the air flow through the closed porous plate 421, and the growth quality of the crystal is further improved.

In some embodiments, the deflector 40 includes an annular deflector 41 and a deflector 42, the annular deflector 41 is connected to the inner wall of the outer crucible 30, a deflector hole 44 is defined in the middle of the annular deflector 41, and the seed holder 70 can pass through the deflector hole 44 along with the lifting of the rotating lifting shaft 80; the deflector 42 is connected to the annular deflector 41 through a first rotating shaft 43, the first rotating shaft 43 is connected to a connecting component of the rotating lifting shaft 80 through a transmission device, and along with the lifting of the rotating lifting shaft 80, the first rotating shaft 43 can drive the deflector 42 to rotate to form a shield for the deflector hole 44 under the transmission action of the transmission device so as to close the deflector 40.

Specifically, in this embodiment, the rotating and lifting device rises to drive the transmission device to act, the transmission device drives the first rotating shaft 43 to rotate to drive the deflector 42 to rotate, so as to form a shielding for the deflector 44, when the deflector 42 does not form a shielding for the deflector 44, the deflector 40 is in an open state, and when the deflector 42 forms a shielding for the deflector 44, the deflector 40 is in a closed state.

Referring to fig. 2, in some embodiments, the baffle 42 of the present invention is composed of 4 perforated plates 421 of 1/4 circle, each perforated plate 421 is connected to the upper surface of the annular baffle 41 through a first rotating shaft 43, the first rotating shaft 43 is connected to a rotating lifting shaft 80 through a transmission device, when the rotating lifting shaft 80 rises to a preset position, the transmission device drives the perforated plate 421 to rotate and close into the baffle 42 through the first rotating shaft 43, and the baffle hole 44 is blocked to close the baffle 40; the inner diameter of the outer crucible 30 is 2.1-2.2 times of the radius of the baffle plate 42, so that the descending or ascending of the seed crystal 71 is not blocked when the porous plate 421 is opened, and the rotation of the porous plate 421 is conveniently closed. Specifically, the silicon carbide gas enters the growth space through the baffle plate 42, and the baffle plate 42 is formed by the porous plate 421, so that the silicon carbide gas homogenizing device has the function of homogenizing the gas and is beneficial to improving the crystal quality.

Referring to FIG. 4, in some embodiments, the cover 60 of the present invention is a double door structure comprising two cover plates 611, each cover plate 611 being connected to the side wall of the melting chamber 60 by a hinge; the inner crucible 62 is fixed to the bottom wall of the melting chamber 60 by the telescopic support frame 50, and the inner crucible 62 is driven by the transmission device to descend into the melting chamber 60 along with the ascending of the rotary lifting shaft 80.

Specifically, when the rotary lifting shaft 80 is at the initial position, the inner crucible 62 is supported at the upper portion of the inner side of the melting chamber 60, that is, at the initial position of the inner crucible 62 by the telescopic supporting frame, and when the inner crucible 62 is at the initial position, the two door panels of the cover 60 are opened to both sides by the force of the lifting of the inner crucible 62 and are abutted against the side walls of the inner crucible 62, and at this time, the cover 60 is in the opened state. When the rotating lifting shaft 80 ascends, the downward force applied by the transmission device to the inner crucible 62 is larger than the supporting force of the telescopic supporting frame 50, the inner crucible 62 moves downwards under the acting force of the transmission device, when the rotating lifting shaft 80 ascends to the preset position, the inner crucible 62 descends to the preset position in the melting chamber 60, at the moment, the two door plates lose the blocking of the side wall of the inner crucible 62, and cover the top of the melting chamber 60 under the action of gravity and the hinge, so that the melting chamber 60 is shielded, a part of gas in the melting chamber 60 is prevented from entering into the growth space, and the influence on the quality of crystals is avoided.

Referring to fig. 1 and 2, in some embodiments, the transmission device of the present invention includes first traction wires 921 and second traction wires 931, one end of each first traction wire 921 is connected to the connection member, the other end sequentially passes through the crucible cover 20 and the side wall and bottom wall of the outer crucible 30 to be fixed to the bottom of the inner crucible 62, the first traction wires 921 pull the inner crucible 62 to descend as the rotation elevating shaft 80 ascends, and each first traction wire 921 is uniformly arranged in the circumferential direction. Specifically, since the length of each first traction wire 921 is fixed, when the rotation elevating shaft 80 is elevated, one end of the first traction wire 921 is pulled to be elevated, and the other end of the first traction wire 921 is pulled to be lowered, and when the rotation elevating shaft 80 is elevated to a predetermined position, the inner crucible 62 is completely lowered to the inside of the melting chamber 60 while the cover 60 is closed.

One end of each second traction wire 931 is connected with the connecting component, and the other end sequentially passes through the crucible cover 20, the side wall of the outer crucible 30 and the side wall of the annular diversion table 41 to be wound on the lower part of the first rotating shaft 43; the second traction wire 931 drives the porous plate 421 to rotate and close into the guide plate 42 through the first rotating shaft 43 along with the rising of the rotating lifting shaft 80; the number of the second traction wires 931 of the present embodiment is four, and the second traction wires 931 are uniformly arranged in the circumferential direction as the number of the first rotation shafts 43. Specifically, in this embodiment, the length of the second traction wire 931 is also fixed, one end of the second traction wire 931 is wound around the first rotation shaft 43, and the other end of the second traction wire 931 is connected to the connection member of the rotation lifting shaft 80, when the rotation lifting shaft 80 is lifted, the second traction wire 931 drives the porous plate 421 to rotate inwards and slowly close through the first rotation shaft 43, and when the rotation lifting shaft 80 is lifted to a preset position, the porous plate 421 is completely closed to form the deflector 42, so as to shield the deflector hole 44.

The only power source for controlling the actions of the inner crucible 62, the cover 60 and the porous plate 421 in this embodiment is the lifting of the rotary lifting shaft 80, and the traction line is pulled to lift by the lifting of the rotary lifting shaft 80, so that the purposes of the inner crucible 62 descending, the cover 60 closing and the porous plate 421 rotating closing are achieved, the crystal growth environment in the outer crucible 30 is not disturbed, the crystal growth quality is not affected, and the improvement of the crystal quality is facilitated.

Further, referring to fig. 1 and 2, in some embodiments, the present transmission further includes a traction wire drive channel consisting essentially of a first traction wire drive channel 91, a second traction wire drive channel 92, and a third traction wire drive channel 93; a first pull wire drive channel 91 is defined within the crucible cover 20, a second pull wire drive channel 92 is defined within the wall of the outer crucible 30, and a third pull wire drive channel 93 is defined within the sidewall of the annular baffle table 41 in the radial direction; wherein, one end of the first traction wire transmission channel 91 is communicated with the shaft hole of the rotary lifting shaft 80, the other end is communicated with one end of the second traction wire transmission channel 92, the other end of the second traction wire transmission channel 92 is communicated with the bottom of the melting chamber 60, one end of the third traction wire transmission channel 93 is communicated with the shaft hole of the first rotating shaft 43, and the other end is communicated with the second traction wire transmission channel 92; one end of the first pulling wire 921 is connected to the connecting member, and the other end is connected to the bottom of the inner crucible 62 through the first transmission passage 91 and the second transmission passage 92 in this order. One end of the second traction wire 931 is connected to the connection member, and the other end thereof is wound around the first rotation shaft 43 through the first transmission channel 91, the second transmission channel 92 and the third transmission channel 93 in this order. The number of the traction wire transmission channels is the same as that of the first rotating shafts 43, the traction wire transmission channels are uniformly distributed in the outer crucible 30 wall and the crucible cover 20 in the circumferential direction, the vertical section of each traction wire channel is E-shaped, the shaft hole of each first rotating shaft 43 is correspondingly connected with one traction wire transmission channel, and the shaft hole of each first rotating shaft 43 is communicated with a third traction wire transmission channel 93 of the transmission channel.

Specifically, the first traction wire transmission channel 91 is opened along the side wall and the top wall of the crucible cover 20, the second traction wire transmission channel 92 is opened along the side wall and the bottom wall of the outer crucible 30, the third traction wire transmission channel 93 is opened along the side wall of the annular flow guiding table 41 below the porous plate 421, the first traction wire transmission channel 91 is communicated with the second traction wire transmission channel 92, the third traction wire transmission channel 93 is communicated with the second traction wire transmission channel 92, wherein the first traction wire transmission channel 91 is communicated with the shaft hole of the rotary lifting shaft 80, and the second traction wire transmission channel 92 is communicated with the bottom of the melting chamber 60. The traction wire transmission channels are uniformly distributed on the wall of the outer crucible 30 and inside the crucible cover 20 in the circumferential direction. In this embodiment, the wall of the outer crucible 30 and the inside of the crucible cover 20 are provided with the traction wire transmission channel, and the traction wire passes through the traction wire transmission channel and is connected with the bottom of the inner crucible 62 and the first rotating shaft 43, so that the friction force in the traction wire transmission process is effectively reduced, the service life of the traction wire is prolonged, and meanwhile, the transmission is smoother. Further, in order to make the transmission smoother, pulleys can also be installed at the corners of the traction wire transmission channel, and traction wires in the traction wire transmission channel are tensioned on the pulleys at the corners.

In some embodiments, the connecting component of the present invention is a connecting ring 81 or a bearing (not shown); the side wall of the rotary lifting shaft 80 is provided with an annular groove, a connecting ring 81 or a bearing is sleeved on the rotary lifting shaft 80 and is positioned in the annular groove, and the outer diameter of the connecting ring 81 or the bearing is not larger than the outer diameter of the rotary lifting shaft 80; when the connecting component is a connecting ring 81, the connecting ring 81 is in clearance fit with the rotary lifting shaft 80, the contact surfaces of the connecting ring 81 and the rotary lifting shaft 80 are polished surfaces, and the transmission device is fixedly connected with the connecting ring 81; when the connecting component is a bearing, the inner ring of the bearing is in interference fit with the rotary lifting shaft 80, and the transmission device is fixedly connected with the outer ring of the bearing. Because the connecting ring 81 and the rotating and lifting shaft 80 are in clearance fit, and the contact surfaces of the connecting ring 81 and the rotating and lifting shaft 80 are polished surfaces, when the rotating and lifting shaft 80 rotates, the connecting ring 81 cannot rotate along with the rotating and lifting shaft 80, and the traction wire cannot rotate along with the rotating and lifting shaft 80.

Based on the above embodiment, the growth method for preparing high-quality silicon carbide crystal of the present invention comprises the following steps

1) And (2) charging: si powder and C powder are put into the inner crucible 62 according to a preset proportion, and if the preset proportion is: the molar ratio is Si: c=1:1.5, under which the grown crystal is flatter, pure SiC powder is put in the outer crucible 30, and the seed crystal 71 is bonded on the seed crystal holder 70;

2) Adjusting the device to an initial state:

the diversion device 40 and the cover 60 are both in an open state, namely the porous plate 421 is positioned on the annular diversion platform 41 outside the diversion hole 44;

the inner crucible 62 is higher than the melting chamber 60 under the supporting action of the telescopic supporting frame 50, and at this time, two door plates of the cover body 60 respectively lean against the side wall of the inner crucible 62;

the rotation of the lifting shaft 80 drives the seed crystal 71 to descend into the inner crucible 62.

3) Starting the equipment to start crystal growth, wherein the equipment comprises the following two stages:

3.1 First crystal growth stage): at the beginning of the first crystal growth stage, the temperature is raised to 1500-1700 c, preferably 1550 c, at which time the interior of the inner crucible 62 is in a molten state and the silicon carbide seed crystal 71 is grown by the Czochralski method for 10 hours. Within 10 hours, the rotation of the lifting shaft 80 proceeds at a speed of 0.05mm/h to pull the seed crystal 71 upward. During the process of pulling up the seed crystal 71 (during the growth process of the first crystal growth stage), the inner crucible 62 is pulled down to the inside of the melting chamber 60 by the first pulling wire 921, the two door panels of the cover 60 move down with each other under the action of gravity, and simultaneously, the first rotating shaft 43 is pulled and rotated by the second pulling wire 931 to drive the porous plate 421 to rotate inwards; when the seed crystal 71 is raised to the top end of the outer crucible 30 (the preset position of the seed crystal 71), the inner crucible 62 is completely lowered into the melting chamber 60, at this time, the cover 60 is completely closed, and the porous plate 421 is closed, so that the growth in the first crystal growth stage is completed, the repaired silicon carbide crystal is obtained, and the growth in the second crystal growth stage is started;

3.2 The second crystal growth stage is carried out for 100h, the crystal growth temperature is controlled at 2200-2300 ℃, the preferable temperature is 2240 ℃, the crystal growth pressure is controlled at 6mbar, meanwhile, silicon carbide powder in the outer crucible 30 sublimates into silicon carbide gas, the silicon carbide gas rises upwards, enters into a growth space through the flow guiding device 40, and the silicon carbide crystal obtained in the step 3.1 is subjected to crystal growth by adopting a gas phase method.

4) And (5) after the crystal growth is finished, obtaining the high-quality silicon carbide crystal.

Example 3

This embodiment is substantially the same as embodiment 2, except that the structure and driving manner of the connecting member, the transmission device, the inner crucible 62 and the cover 60 are different, and the specific differences are as follows:

referring to fig. 5, 6 and 7, in some embodiments, the inner crucible 62 of the present invention is fixedly installed at the upper portion of the inner side of the melting chamber 60, the cover 61 is composed of 4 1/4 round cover plates, each cover plate 61 is connected to the top of the sidewall of the melting chamber 60 through a second rotation shaft, and the second rotation shaft drives the cover 611 to rotate inwards along with the rising of the rotation lifting shaft 80 under the action of a transmission device, thereby controlling the cover 61 to be closed.

In some embodiments, the connecting component is a rack 82, the rack 82 is arranged on the outer wall of the rotary lifting shaft 80, the transmission device comprises a traction shaft and a gear, the traction shaft comprises a first traction shaft 971, a second traction shaft 972, a third traction shaft 973, a fourth traction shaft 974 and a fifth traction shaft 975, one end of the first traction shaft 971 is meshed with the rack through the gear, the other end of the first traction shaft 971 is connected with one end of the third traction shaft 973 through the second traction shaft, the other end of the third traction shaft 973 is connected with the first rotating shaft, one end of the third traction shaft 973 is connected with one end of the fifth traction shaft 975 through the fourth traction shaft 974, and the other end of the fifth traction shaft 975 is connected with the second rotating shaft; the first traction shaft 971 is connected with the second traction shaft 972, the second traction shaft 972 is connected with the third traction shaft 973, the third traction shaft 973 is connected with the first rotating shaft 43, the third traction shaft 973 is connected with the fourth traction shaft 974, the fourth traction shaft 974 is connected with the fifth traction shaft 975, and the fifth traction shaft 975 is connected with the second rotating shaft through a bevel gear pair 98; the traction shafts are arranged in total in 4 and evenly spaced in the circumferential direction.

Further, in order to avoid friction resistance between the traction shaft and the crucible cover 20, the side wall of the outer crucible 30 and the side wall of the annular flow guiding table 41, and prolong the service life of the traction shaft, the invention further comprises a traction shaft transmission channel, wherein the traction shaft is arranged in the traction shaft transmission channel through a fixed ring 94, and the traction shaft is in clearance fit with the fixed ring 94; the traction shaft transmission channel comprises a first traction shaft transmission channel 961, a second traction shaft transmission channel 962 and a third traction shaft transmission channel 963, wherein the first traction shaft transmission channel 961 is defined in the crucible cover 20, the second traction shaft transmission channel 962 is defined in the side wall of the outer crucible 30, the third traction shaft transmission channel 963 is defined in the side wall of the annular diversion table 41, one end of the first traction shaft transmission channel 961 is communicated with the shaft hole of the rotary lifting shaft 80, the other end is communicated with one end of the second traction shaft transmission channel 962, one end of the third traction shaft transmission channel 963 is communicated with the shaft hole of the first rotary shaft, and the other end is communicated with the second traction shaft transmission channel 962; the number of the traction shaft transmission channels is the same as that of the first rotating shafts 43, and the shaft hole of each first rotating shaft 43 corresponds to one traction shaft transmission channel; the first traction shaft 971 and the second traction shaft 972 are respectively arranged in a second traction shaft transmission channel 962 of the first traction shaft transmission channel, the third traction shaft 973 and the fourth traction shaft 974 are arranged in the second traction shaft transmission channel 962 up and down, and each first rotating shaft 43 corresponds to one traction shaft transmission channel; the traction shaft transmission channels are four in number and are distributed at equal intervals in the circumferential direction.

Specifically, the number of the traction shaft transmission channels is the same as the number of the first rotating shafts 43, the traction shaft transmission channels are uniformly distributed in the outer crucible 30 wall and the crucible cover 20 in the circumferential direction, each first rotating shaft 43 corresponds to one traction shaft transmission channel, and the third traction shaft transmission channel 963 of each traction shaft transmission channel is communicated with the shaft hole of the nearest first rotating shaft 43. The traction shafts are arranged in the traction shaft transmission channel through the fixing rings 94, both ends of each traction shaft and the lower part of the first rotating shaft 43 are arranged into a zigzag structure, the traction shafts and the first rotating shaft 43 and the second rotating shaft are connected together through bevel gear pairs 98 in a meshed mode, and the first traction shaft 971 is meshed with the rack 95 through gears. When the rotary lifting shaft 80 ascends, the rack 95 on the surface drives the gear to rotate, the gear drives the first traction shaft 971 to rotate, the first traction shaft 971 drives the second traction shaft 972 to rotate, the second traction shaft 972 drives the third traction shaft 973 and the fourth traction shaft 974 to rotate, the third traction shaft 973 drives the first rotating shaft 43 to rotate, the first rotating shaft 43 drives the porous plate 421 to rotate inwards, and meanwhile, the fourth traction shaft 974 drives the fifth traction shaft 975 to rotate, and the fifth traction shaft 975 drives the cover plate 611 to rotate inwards through the second rotating shaft. When the rotation lifting shaft 80 lifts up to a preset position with the seed crystal 71, the perforated plate 421 is completely closed to form the deflector 42 to close the deflector 40, and at the same time, the cover plate 611 is closed to shield the melting chamber 60, at this time, the first crystal growth stage ends and the second crystal growth stage is entered. In this embodiment, the bevel gear pair 98 is meshed to drive the traction shaft to rotate, so that the first rotating shaft 43 and the second rotating shaft are driven to rotate to drive the porous plate 421 and the cover plate 611 to rotate inwards to be closed, the driving mode is simple and convenient, no impurity is generated and enters the growth space, and therefore, the quality of crystals is not affected.

Based on the apparatus of this embodiment, the silicon carbide crystal growth method of this embodiment is as follows:

1) And (2) charging: si powder and C powder are put into the inner crucible 62 according to a preset proportion, and if the preset proportion is: the molar ratio is Si:C=1:1.2-1:1.5, and the preferable molar ratio is Si:C=1:1.3, under the ratio, the grown crystal is smoother, pure SiC powder is put in the outer crucible 30, and the seed crystal 71 is adhered on the seed crystal support 70;

2) Adjusting the device to an initial state:

the diversion device 40 and the cover 60 are both in an open state, namely the porous plate 421 is positioned on the annular diversion platform 41 outside the diversion hole 44; the rotation of the lifting shaft 80 drives the seed crystal 71 to descend into the inner crucible 62.

3.1 First crystal growth stage): when the crystal growth starts, the temperature is raised to 1500-1700 ℃, preferably 1600 ℃, at this moment, the interior of the inner crucible 62 is in a molten state, the silicon carbide seed crystal 71 is grown for 8-10h by adopting a pulling method, preferably the time of the first step Duan Changjing is 10h, in 8-10h, the rotation lifting shaft 80 drives the seed crystal 71 to lift upwards at the speed of 0.04-0.06mm/h, preferably the crystal growth speed is 0.04.5mm/h, during the process of lifting the seed crystal 71 upwards (during the growth process of the first crystal growth stage), the gear rotates along with the rising of the rack 95 on the outer surface of the rotation lifting shaft, the gear drives the first traction shaft 971 to rotate, under the action of the bevel gear pair 98, the second traction shaft 972, the third traction shaft 973, the fourth traction shaft 974 and the fifth traction shaft 975 rotate along with the first rotation shaft 43, the porous plate 421 is driven to rotate inwards slowly and are closed, simultaneously the fifth traction shaft 975 is driven to rotate slowly and inwards through the second rotation to be closed, and when the top end of the seed crystal 71 rises to the preset position of the outer crucible 71 (during the growth process of the first crystal growth stage), the crystal growth stage 60 is completely finished, and the crystal growth stage 60 is completely finished after the crystal growth is completed, and the crystal growth stage is completed;

3.2 The second crystal growth stage has a crystal growth time of 90-110h, preferably 95h, a crystal growth temperature of 2200-2300 ℃, preferably 2250 ℃, and a crystal growth pressure of 3-6mbar, preferably 5mbar, and at the same time, silicon carbide powder in the outer crucible 30 sublimates into silicon carbide gas, rises upward, enters into a growth space through the porous plate 421, and the silicon carbide crystal obtained in step 3.1 is grown by a gas phase method.

Other configurations of growth methods and apparatus for producing high quality silicon carbide crystals, such as inner crucible 62, outer crucible 30, telescoping support 50, and rotating lift shaft 80, and the like, and operation thereof, in accordance with embodiments of the present invention are known to those of ordinary skill in the art and will not be described in detail herein.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; the device can be mechanically connected, electrically connected and communicated; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: many changes, modifications, substitutions and variations may be made to the embodiments without departing from the spirit and principles of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A growth method for preparing high-quality silicon carbide crystal is characterized by comprising the following steps

1) A first crystal growth stage: soaking silicon carbide seed crystals in the silicon carbide melt, and growing the silicon carbide seed crystals by adopting a pulling method;

2) A second crystal growth stage: and (3) growing the silicon carbide seed crystal obtained in the step (1) by adopting a gas phase method.

2. A growth apparatus for producing high quality silicon carbide crystals, comprising

The top of the outer crucible is sealed with a crucible cover, and the outer crucible defines a first space;

the melting chamber is arranged on the bottom wall of the inner side of the outer crucible, and an opening is formed in the upper part of the melting chamber;

the cover body is arranged at the top of the melting chamber;

an inner crucible mounted within the melting chamber;

the flow guiding device is connected to the inner wall of the outer crucible;

the top end of the rotary lifting shaft is positioned outside the outer crucible and connected with an external rotary lifting device, the bottom end of the rotary lifting shaft is positioned inside the outer crucible, and the rotary lifting shaft and the inner crucible are coaxially arranged;

the seed crystal support is arranged at the bottom of the rotary lifting shaft, and seed crystals are arranged on the lower surface of the seed crystal support;

the transmission device is connected with the rotary lifting shaft through a connecting part, the transmission device controls the cover body to be closed along with the rising of the rotary lifting shaft, the transmission device controls the flow guiding device to be closed along with the rising of the rotary lifting shaft, and the first space is divided into a growth space and a raw material space after the flow guiding device is closed.

3. A growth apparatus for producing high quality etanerceptor crystals as defined in claim 2, wherein said flow directing means comprises

The annular flow guide table is connected to the inner wall of the outer crucible, a flow guide hole is defined in the middle of the annular flow guide table, and the seed crystal support can pass through the flow guide hole along with the lifting of the rotary lifting shaft;

the guide plate is connected to the annular guide table through a first rotating shaft, the first rotating shaft is connected with the connecting part of the rotary lifting shaft through the transmission device, and along with the rising of the rotary lifting shaft, the first rotating shaft can drive the guide plate to rotate under the action of the transmission device to form shielding on the guide hole so as to close the guide device.

4. A growth apparatus for producing high quality silicon carbide crystals according to claim 3 wherein the baffle plate is composed of 4 perforated plates of 1/4 circle, each of the perforated plates being connected to the annular baffle plate via a first shaft connected to the rotary lifting shaft via the transmission means, and when the rotary lifting shaft is lifted to a predetermined position, the transmission means drives the perforated plates to rotate and close into the baffle plate via the first shaft to form a shield for the baffle holes to close the guide means.

5. The growth apparatus for producing high quality silicon carbide crystals as defined in claim 4, wherein said cover has a double door structure comprising two cover plates, each door plate being connected to said melting chamber side wall by a hinge; the inner crucible is fixed on the bottom wall inside the melting chamber through the telescopic support frame, and the inner crucible is driven by the transmission device to descend into the melting chamber along with the ascending of the rotary lifting shaft.

6. A growth apparatus for producing high quality silicon carbide crystals as claimed in claim 5 wherein said actuator comprises

One end of each first traction wire is connected to the connecting part, the other end of each first traction wire sequentially penetrates through the crucible cover and the side wall and the bottom wall of the outer crucible to be fixed at the bottom of the inner crucible, and the first traction wires pull the inner crucible to descend along with the ascending of the rotary lifting shaft;

one end of each second traction wire is connected with the connecting part, and the other end of each second traction wire sequentially penetrates through the crucible cover, the outer crucible side wall and the annular flow guide table side wall to be wound on the lower part of the first rotating shaft in the same direction; the second traction wire drives the porous plate to rotate and close to form the guide plate through the first rotating shaft along with the rising of the rotating lifting shaft;

The number of the first traction wires and the second traction wires is four, and the first traction wires and the second traction wires are uniformly distributed at intervals in the circumferential direction.

7. The growth apparatus for producing high quality silicon carbide crystals as claimed in claim 6, further comprising a pull wire drive channel consisting essentially of a first pull wire drive channel, a second pull wire drive channel, and a third pull wire drive channel; the first traction wire transmission channel is defined in the crucible cover, the second traction wire transmission channel is defined in the inner part of the outer crucible wall, and the third traction wire transmission channel is defined in the inner part of the side wall of the annular diversion table; one end of the first traction wire transmission channel is communicated with the shaft hole of the rotary lifting shaft, the other end of the first traction wire transmission channel is communicated with one end of the second traction wire transmission channel, the other end of the second traction wire transmission channel is communicated with the bottom of the melting chamber, one end of the third traction wire transmission channel is communicated with the shaft hole of the first rotating shaft, and the other end of the third traction wire transmission channel is communicated with the second traction wire transmission channel; the four traction wire transmission channels are uniformly distributed at intervals in the circumferential direction, and each shaft hole of the first rotating shaft corresponds to one traction wire transmission channel;

One end of the first traction wire is connected to the bottom of the inner crucible, and the other end of the first traction wire sequentially passes through the second traction wire transmission channel and the first traction wire transmission channel to be connected with the connecting part; one end of the second traction wire is wound on the first rotating shaft, and the other end sequentially penetrates through the third traction wire transmission channel, the second traction wire transmission channel and the first traction wire transmission channel to be connected with the connecting part.

8. The growth apparatus for producing high quality silicon carbide crystals as claimed in claim 6 or 7, wherein the connecting member is a connecting ring or a bearing, an annular groove is provided on a side wall of the rotating and elevating shaft, the connecting ring or the bearing is sleeved on the rotating and elevating shaft and placed in the annular groove, and an outer diameter of the connecting ring or the bearing is not larger than an outer diameter of the rotating and elevating shaft;

when the connecting part is a connecting ring, the connecting ring is in clearance fit with the rotary lifting shaft, the contact surfaces of the connecting ring and the rotary lifting shaft are polished surfaces, and the transmission device is fixedly connected with the connecting ring;

when the connecting part is a bearing, the inner ring of the bearing is in interference fit with the rotary lifting shaft, and the transmission device is fixedly connected with the outer ring of the bearing.

9. The growing apparatus for producing high-quality silicon carbide crystals according to claim 2, wherein the inner crucible is fixedly installed at the upper part of the inner side of the melting chamber, the cover body is composed of 4 1/4 round cover plates, each cover plate is connected to the top of the side wall of the melting chamber through a second rotating shaft, and the second rotating shaft drives the cover plate to rotate inwards along with the rising of the rotating lifting shaft under the action of the transmission device, so that the cover body is controlled to be closed.

10. The growth apparatus for producing high-quality silicon carbide crystals as claimed in claim 9, wherein the connecting portion is a rack, the rack is provided on an outer wall of the rotating lift shaft, the transmission device includes a traction shaft and a gear, the traction shaft includes a first traction shaft, a second traction shaft, a third traction shaft, a fourth traction shaft, and a fifth traction shaft, one end of the first traction shaft is engaged with the rack through the gear, the other end of the first traction shaft is connected to one end of the third traction shaft through the second traction shaft, the other end of the third traction shaft is connected to the first rotation shaft, one end of the third traction shaft is connected to one end of the fifth traction shaft through the fourth traction shaft, and the other end of the fifth traction shaft is connected to the second rotation shaft; the first traction shaft is connected with the second traction shaft, the second traction shaft is connected with the third traction shaft, the third traction shaft is connected with the first rotating shaft, the third traction shaft is connected with the fourth traction shaft, the fourth traction shaft is connected with the fifth traction shaft, and the fifth traction shaft is connected with the second rotating shaft through bevel gear pairs;

The traction shafts are arranged in total in 4 and evenly spaced in the circumferential direction.

11. A growth apparatus for producing high quality silicon carbide crystals as claimed in claim 10 further comprising a drive shaft passage, said drive shaft being mounted within said drive shaft passage by a retaining ring, said drive shaft being in clearance fit with said retaining ring; the traction shaft transmission channel comprises a first traction shaft transmission channel, a second traction shaft transmission channel and a third traction shaft transmission channel, the first traction shaft transmission channel is limited in the crucible cover, the second traction shaft transmission channel is limited in the side wall of the outer crucible, the third traction shaft transmission channel is limited in the side wall of the annular diversion table, one end of the first traction shaft transmission channel is communicated with the shaft hole of the rotary lifting shaft, the other end of the first traction shaft transmission channel is communicated with one end of the second traction shaft transmission channel, one end of the third traction shaft transmission channel is communicated with the shaft hole of the first rotating shaft, and the other end of the third traction shaft transmission channel is communicated with the second traction shaft transmission channel; the number of the traction shaft transmission channels is the same as that of the first rotating shafts, and each shaft hole of the first rotating shaft corresponds to one traction shaft transmission channel; the first traction shaft and the second traction shaft are respectively arranged in the first traction shaft transmission channel and the second traction shaft transmission channel, the third traction shaft and the fourth traction shaft are arranged in the second traction shaft transmission channel up and down, and each first rotating shaft corresponds to one traction shaft transmission channel;

The traction shaft transmission channels are arranged in four in total and are uniformly distributed at intervals in the circumferential direction.