CN113622016B - Silicon carbide crystal growth apparatus and crystal growth method - Google Patents

Silicon carbide crystal growth apparatus and crystal growth method Download PDF

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Publication number
CN113622016B
CN113622016B CN202110940779.5A CN202110940779A CN113622016B CN 113622016 B CN113622016 B CN 113622016B CN 202110940779 A CN202110940779 A CN 202110940779A CN 113622016 B CN113622016 B CN 113622016B
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crucible
silicon carbide
crucible body
mesh
cover
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CN113622016A (en
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王睿仑
张洁
廖弘基
杨树
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Hunan Sanan Semiconductor Co Ltd
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Fujian Norstel Material Technologies Co ltd
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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
    • C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
    • C30B11/002—Crucibles or containers for supporting the melt
    • 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

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  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)

Abstract

The invention relates to the technical field of crystal growth, in particular to a silicon carbide crystal growth device and a crystal growth method. The silicon carbide crystal growing device comprises a crucible and a net-shaped piece; the mesh piece is arranged in a crucible body of the crucible, and the periphery of the mesh piece is abutted against the inner wall of the crucible body; the reticular piece is concave towards the bottom of the crucible body; the crucible bottom is configured to be used for containing raw material powder, the net-shaped piece is configured to be attached to cover the raw material powder, and the surface of the raw material powder facing the top surface of the crucible body is provided with a concave shape matched with the net-shaped piece. The thermal field can be effectively utilized through the change of the concave-convex degree of the charge level, so that the internal stress of the crystal is reduced, the nitrogen doping is more uniform, the SF is solved from two aspects, and the density of the BPD is reduced as far as possible.

Description

Silicon carbide crystal growth apparatus and crystal growth method
Technical Field
The invention relates to the technical field of crystal growth, in particular to a silicon carbide crystal growth device and a crystal growth method.
Background
In the growth process of the silicon carbide crystal in the prior art, as the thickness of the produced crystal increases, the distance from the flat material surface to the crystal surface changes, and the thermal field is not adapted any more.
The proportion of carbon will be higher due to the large consumption of silicon in the middle and later stages of growth, where the inappropriate formulation of the thermal field carbonizes the charge level, inducing the occurrence of carbon pack and the generation of Stacking Faults (SF). Meanwhile, the convexity generated on the surface of the crystal is not matched with the flat material surface, so that the axial stress is generated in the later period of the crystal growing by using the flat material surface, and more Base Plane Dislocations (BPD) exist. These problems make it impossible to circumvent the three defects of carbon pack, SF and BPD using a flat-plane grown silicon carbide crystal.
Disclosure of Invention
The object of the present invention includes, for example, providing a silicon carbide crystal growth apparatus and a crystal growth method which can effectively utilize a thermal field by changing the degree of unevenness of a charge level, make stress in a crystal decreased and nitrogen doping more uniform, solve the occurrence of SF in two respects and reduce the density of BPD as much as possible.
Embodiments of the invention may be implemented as follows:
in a first aspect, the present invention provides an apparatus for growing a silicon carbide crystal, comprising:
a crucible and a mesh;
the mesh piece is arranged in a crucible body of the crucible, the periphery of the mesh piece is abutted against the inner wall of the crucible body, and the mesh piece is concave towards the bottom of the crucible body;
the crucible bottom is configured to contain raw material powder, the net-shaped piece is configured to be attached to and cover the raw material powder, and the surface of the raw material powder facing the top surface of the crucible body is provided with a concave shape matched with the net-shaped piece.
Because the easy carbonization in growth later stage raw materials surface and by the powder area to the crystal surface formation carbon parcel after gaseous transportation after will carbonizing, this scheme uses the network as bottom powder charge level setting device. By covering the net member, when the convective growth atmosphere in the crucible passes through the net from the outside, the upper and lower disturbed air flows are formed inside the net so that the convective atmosphere cannot be blown to the surface of the raw material. Furthermore, the surface of the raw material fixed by the net is concave, so that the surface of the raw material is shaped into a concave surface, the distance difference of the atmosphere from the raw material to the surface of the crystal is reduced in the growth process, the temperature of the surface of the crystal is averaged, and therefore the slightly convex SiC crystal is easier to obtain. The net-like member is used, and the atmosphere for growth can be smoothly diffused to the crystal surface. Meanwhile, due to the existence of the net-shaped piece, turbulent flow fluid cannot be formed in ascending atmosphere effectively, and slow formation of a 4H-SiC crystal facet growth step is facilitated.
In conclusion, the silicon carbide crystal growing device has the characteristics of simple structure, convenience in arrangement and better growth quality of the silicon carbide crystal.
In an alternative embodiment, the mesh is a metal mesh sheet; and/or the presence of a gas in the gas,
the mesh is multi-layered.
In an alternative embodiment, the mesh is a tantalum mesh.
In an optional embodiment, the system further comprises a carrier;
the periphery of the carrying platform is abutted against the inner wall of the crucible body;
the center of the carrying platform is provided with a through drainage channel facing the crucible cover; and the opening of the drainage channel is gradually reduced from the direction far away from the crucible cover to the direction close to the crucible cover.
In an alternative embodiment, the longitudinal cross-section of the drainage channel is trapezoidal.
In an alternative embodiment, a metal screen is also included;
the metal screen is arranged on the top of the carrying platform close to the crucible cover so as to cover the opening of the drainage channel.
In an alternative embodiment, the drainage channel is provided with a sinking platform near the opening of the crucible cover;
the metal screen is arranged on the sinking platform to cover the opening of the drainage channel.
In an alternative embodiment, a pod is also included;
the flow guide cover is provided with a flow guide channel which penetrates through the crucible body along the height direction;
the bottom of the flow guide cover abuts against the periphery of the opening of the flow guide channel, and the top of the flow guide cover abuts against the periphery of the seed crystal on the crucible cover;
and the flow guide channel is opposite to the flow guide channel.
In an alternative embodiment, graphite paper is also included;
the periphery of the graphite paper is abutted against the inner wall of the crucible body; and the graphite paper is arranged on one side of the reticular part close to the bottom of the crucible body.
In an alternative embodiment, a polycrystalline silicon carbide ingot material is also included;
the polycrystalline silicon carbide ingot material is filled between the mesh and the graphite paper.
In an alternative embodiment, a porous graphite layer is also included;
the porous graphite layer is arranged on one side of the mesh piece, which is far away from the bottom of the crucible body.
In a second aspect, the present invention provides an apparatus for growing a silicon carbide crystal, comprising:
the crucible comprises a crucible body, and the crucible body is used for containing raw material powder;
the crucible comprises a crucible body, a mesh part and a raw material powder, wherein the mesh part is arranged in the crucible body, has a concave shape facing the bottom of the crucible body, is configured to be abutted against the inner wall of the crucible body and fix the raw material powder, and has a concave shape facing the top surface of the crucible body and matched with the mesh part.
In an alternative embodiment, the mesh is a metal mesh sheet; and/or the presence of a gas in the gas,
the mesh is multi-layered.
In an alternative embodiment, the mesh is a tantalum mesh.
In an alternative embodiment, graphite paper is also included;
the graphite paper is arranged in the crucible body, and the periphery of the graphite paper is abutted against the inner wall of the crucible body; and the graphite paper is arranged on one side of the reticular part close to the bottom of the crucible body.
In an alternative embodiment, a polycrystalline silicon carbide ingot material is also included;
the polycrystalline silicon carbide crystal ingot material is arranged in the crucible body and filled between the net-shaped piece and the graphite paper.
In an alternative embodiment, a porous graphite layer is also included;
the porous graphite layer is arranged in the crucible body, and the mesh piece is far away from one side of the bottom of the crucible body.
In a third aspect, the invention provides a crystal growth method, which comprises providing a crucible, wherein the crucible comprises a crucible body and a crucible cover, the crucible cover is provided with a seed crystal clamping part, and a seed crystal is combined on the seed crystal clamping part;
filling a preset amount of powder into the crucible body, and compacting the powder to enable the surface of the powder facing the top surface of the crucible body to be concave facing the bottom of the crucible body;
covering the powder with a mesh part, wherein the mesh part is provided with a concave shape matched with the surface of the powder facing the top surface of the crucible body, and the periphery of the mesh part is abutted against the inner wall of the crucible body;
closing the crucible cover to the crucible body;
and (3) loading the crucible into a crystal growth furnace for growth.
The beneficial effects of the embodiment of the invention include, for example:
the silicon carbide crystal growing device comprises a crucible and a net-shaped piece. Because the mesh is sunken towards the bottom of the crucible body, and the mesh is used for tiling and compacting on the powder in the crucible body. Therefore, the surface of the raw material can be shaped into a concave surface, the distance difference of the atmosphere from the raw material to the surface of the crystal is reduced in the growth process, the temperature of the surface of the crystal is averaged, and therefore the slightly convex SiC crystal is easier to obtain. Meanwhile, the net-shaped piece can enable the growing atmosphere to smoothly diffuse to the surface of the crystal. And because of the existence of the net-shaped piece, turbulent flow fluid can not be formed in the ascending atmosphere effectively, and the slow formation of the facet growth step of the 4H-SiC crystal is facilitated. The silicon carbide crystal growing device has the advantages of simple structure, convenience in arrangement and better quality of the obtained silicon carbide crystal.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a schematic structural view of a silicon carbide crystal growing apparatus according to an embodiment of the present invention.
Icon: 10-a silicon carbide crystal growing apparatus; 100-crucible; 110-a crucible body; 120-crucible cover; 200-a mesh; 300-a stage; 310-a drainage channel; 320-sinking a platform; 400-metal screen mesh; 500-a pod; 510-a flow guide channel; 600-graphite paper; 700-polycrystalline silicon carbide ingot material; 800-porous graphite layer; 21-seed crystal; 22-powder lot.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
In the description of the present invention, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. indicate an orientation or a positional relationship based on that shown in the drawings or that the product of the present invention is used as it is, this is only for convenience of description and simplification of the description, and it does not indicate or imply that the device or the element referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present invention.
Furthermore, the appearances of the terms "first," "second," and the like, if any, are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.
It should be noted that the features of the embodiments of the present invention may be combined with each other without conflict.
The silicon carbide single crystal material is an ideal substrate material for preparing high-temperature, high-frequency, high-power and radiation-resistant devices, and can be used for exposing the corner in the fields of hybrid electric vehicles, high-voltage power transmission, LED illumination, aerospace and the like, and the growing of high-quality SiC crystals is the basis for realizing the excellent performance of the SiC-based devices.
SiC crystals do not occur in nature and can only be obtained by synthetic methods. Of these, the physical vapor transport method is the most well developed and is adopted by most research institutes and companies worldwide.
Physical vapor deposition (PVT) uses medium frequency induction heating and a high density graphite crucible as a heating element. The SiC powder is placed at the bottom of the graphite crucible, the SiC seed crystal is positioned at the top of the graphite crucible, and 4H-SiC is grown by generally adopting a C surface as a growth surface for crystal growth.
The temperature of the SiC raw material area is higher by adjusting the heat insulation layer outside the crucible, and the temperature of the seed crystal covered on the top crucible is lower. Then directly subliming the silicon carbide powder into Si and Si at a temperature above 2100 ℃ and under a low-pressure environment2C、SiC2The gas is mixed, and the mixture is transported from the high-temperature area to the seed crystal of the lower-temperature area along the temperature gradient to deposit and crystallize into the silicon carbide single crystal.
Before the SiC crystal grows, all the raw materials are spread on the bottom of a graphite crucible. During initial growth, the seed crystal is a plane, the distances from the flat material surface to the crystal are equal, and the formed temperature gradient has high adaptation degree. Meanwhile, in the initial stage of crystal growth, the vapor pressure is low and the raw material is not carbonized due to the temperature rise stage, so that the quality of the crystal obtained in the initial stage is high. In the process of crystal growth, the thickness of the crystal is increased, and simultaneously, the center of the crystal is raised due to the higher temperature of the center of the thermal field. This change causes the temperature gradient from the charge level to the crystal surface to decrease, while the crystal surface forms a convex isotherm.
The distance from the flat level to the crystal surface changes, and the thermal field is no longer adapted. The proportion of carbon will be higher due to the large consumption of silicon in the middle and later stages of growth, where the inappropriate formulation of the thermal field carbonizes the charge level, inducing the occurrence of carbon pack and the generation of Stacking Faults (SF). Meanwhile, the convexity generated on the surface of the crystal is not matched with the flat material surface, so that the axial stress is generated in the later period of the crystal growing by using the flat material surface, and more Base Plane Dislocations (BPD) exist. These problems make it impossible to circumvent the three defects of carbon pack, SF and BPD using a flat-plane grown silicon carbide crystal.
SF and BPD in SiC substrates tend to have a significant impact on homoepitaxy. After the substrate is epitaxial, the SF area is magnified and 99% of the BPD is converted to TED. The amplified SF and unconverted BPD can severely affect the performance of SiC devices. It was observed that the presence of SF and BPD correlates with the internal stress of the crystal. Furthermore, the SF is relatively complex in its cause, and the concentration of scratches and nitrogen doping also induces SF generation.
In order to solve the above technical problems, the following embodiments provide a silicon carbide crystal growth apparatus, which can effectively utilize a thermal field by changing the degree of surface roughness, so as to reduce the stress in the crystal and make the nitrogen doping more uniform, thereby solving the problem of SF in two aspects and reducing the density of BPD as much as possible.
Referring to FIG. 1, the present embodiment provides a silicon carbide crystal growth apparatus 10 including a crucible 100 and a web 200.
The mesh 200 is arranged in the crucible 100 body of the crucible 100, the periphery of the mesh 200 is abutted against the inner wall of the crucible 100 body, and the mesh 200 is concave towards the bottom of the crucible 100 body;
the bottom of the crucible 100 is configured to contain the raw material powder 22, the mesh member 200 is configured to be attached to cover the raw material powder 22, and the surface of the raw material powder 22 facing the top surface of the crucible 100 has a concave shape matching with the mesh member 200. Because the easy carbonization of growth later stage raw materials surface and by the gas transportation with powder 22 after the carbonization to the crystal surface formation carbon parcel, this patent uses netted piece 200 as bottom powder 22 charge level setting device. By covering the mesh member 200, when the convective growth atmosphere in the crucible 100 passes through the mesh from the outside, the turbulent air flows are formed at the upper and lower sides of the mesh so that the convective atmosphere cannot be swept to the surface of the raw material.
It should be noted that the mesh member 200 is a metal mesh sheet; and/or the mesh 200 is multi-layered. In this embodiment, the mesh member 200 is a single-layer metal mesh sheet. It is understood that in other embodiments of the present invention, the net member 200 may be a multi-layer structure, which is merely an example and is not limited thereto.
Optionally, the mesh member 200 is made of a metal material such as tungsten, molybdenum, tantalum, niobium, and the like. Specifically, in the present embodiment, the mesh 200 is a tantalum mesh.
The metal of tungsten, molybdenum, tantalum, niobium, etc. is selected because during the heating process, the metal filter net and the current-suppressing net of tungsten, molybdenum, tantalum, niobium, etc. will gradually adsorb the surrounding carbon atoms, and react and convert into the high temperature resistant material of tungsten carbide, molybdenum carbide, tantalum carbide, niobium carbide, etc., which will cause the partial pressure of the C atoms in the growth atmosphere to be slightly reduced, slightly lower than the saturation partial pressure in the atmosphere, which will cause the carbon particles of several microns to tens of microns to be difficult to survive in the silicon-rich atmosphere, and the main reaction is Si2C + C ═ 2SiC and Si + C ═ SiC; and because the material such as tungsten, molybdenum, tantalum, niobium is a heating element in the eddy current heating, the mesh blockage caused by the recrystallization of the atmosphere on the surface can be avoided. As the growth proceeds, the convexity of the crystal is increased continuously, and the change of the thermal field in the growth chamber is started gradually. The concave-convex structure of the charge level mainly depends on external fixation to lead the charge level to tend to the desired concave-convex structure.
Further, in the present embodiment, the tantalum mesh is processed into a concave structure, and the number of processed tantalum meshes cannot exceed 50 meshes in order to ensure that the powder 22 does not pass through the tantalum mesh.
The tantalum mesh having a concave shape is used, and the surface of the powder 22 is shaped into a concave shape by the tantalum mesh when the powder 22 is charged. The surface of the raw material fixed by the tantalum net is concave. The concavity of the surface of the raw material can be achieved by adjusting the concavity of the tantalum mesh. By shaping the surface of the raw material into a concave surface, the distance difference of the atmosphere from the raw material to the surface of the crystal is reduced in the growth process, and the temperature of the surface of the crystal is averaged, so that the slightly convex SiC crystal is more easily obtained. And the tantalum net is used, so that the growing atmosphere can be smoothly diffused to the surface of the crystal. Meanwhile, due to the existence of the tantalum net, turbulent flow fluid cannot be formed in the rising atmosphere effectively, and slow formation of a 4H-SiC crystal facet growth step is facilitated.
Further, as can be seen, the mesh member 200 is movably disposed within the crucible body 110 to compress the frit 22 within the crucible body 110.
As can also be seen from fig. 1, in the present embodiment of the invention, silicon carbide crystal growing apparatus 10 further comprises a stage 300; the periphery of the carrier 300 abuts against the inner wall of the crucible body 110;
the center of the carrier 300 has a flow guide channel 310 that penetrates toward the crucible cover 120; and the opening of the drainage channel 310 gradually decreases from a direction away from the crucible cover 120 to a direction close to the crucible cover 120.
The stage 300 is capable of guiding the growth atmosphere to the growth surface of the seed crystal 21 on the crucible cover 120 to the maximum extent, thereby improving the quality and growth efficiency of the silicon carbide crystal.
In this embodiment of the invention, the longitudinal cross-section of the drainage channel 310 is trapezoidal. Alternatively, the carrier 300 has flat lower and upper surfaces, both of which are perpendicular to the inner wall of the crucible body 110. The lower and upper surfaces are connected by a flat wall that forms a drainage channel 310.
Further, in the present embodiment, the silicon carbide crystal growing apparatus 10 further includes a metal screen 400; a metal screen 400 is provided on the top of the carrier 300 near the crucible cover 120 to cover the opening of the drain channel 310. The metal screen 400 is used to filter out fine carbon particles to ensure high quality of the silicon carbide growth atmosphere and improve the quality of the silicon carbide crystal.
In the present embodiment of the invention, the drainage channel 310 is provided with a sinking platform 320 near the opening of the crucible cover 120; the metal screen 400 is disposed on the sink table 320 to cover the opening of the drainage channel 310.
Alternatively, the height of the sinking platform 320 is the same as the height of the metal screen 400, so that the upper surface of the metal screen 400 and the upper surface of the carrier 300 are flush with each other. Specifically, in the present embodiment, the metal screen 400 is circular, the sinking platform 320 is circular and stepped, and the diameter of the metal screen 400 is the same as the outer diameter of the sinking platform 320.
Due to the arrangement mode, the metal screen 400 is embedded on the sinking platform 320, so that the metal screen 400 can filter carbon particles in the production atmosphere, the stable connection between the metal screen 400 and the carrying platform 300 can be guaranteed, the volumes of the carrying platform 300 and the metal screen 400 can be reduced, and the space utilization rate of equipment is improved.
In the present embodiment of the invention, silicon carbide crystal growing apparatus 10 further comprises a draft shield 500; the guide shell 500 has a guide passage 510 penetrating in the height direction of the crucible body 110; the bottom of the flow guide cover 500 is propped against the periphery of the opening of the flow guide channel 310, and the top of the flow guide cover 500 is propped against the periphery of the seed crystal 21 on the crucible cover 120; and the guide channel 510 is aligned with the guide channel 310.
Optionally, the pod 500 is cylindrical and the flow channel 510 is also cylindrical. And the opening of the flow guide channel 510 and the opening of the flow guide channel 310 are both circular and have the same diameter. Further, as can be seen from fig. 1, the end of the air guide channel 510 of the air guide sleeve 500 abuts against the metal screen 400, so that the metal screen 400 is clamped between the carrier 300 and the air guide sleeve 500, and thus the stability of the arrangement of the metal screen 400 is ensured.
As can also be seen in the figure, the upper end of the flow guide channel 510 of the flow guide 500 faces the seed crystal 21 on the crucible cover 120, i.e., the upper end of the flow guide channel 510 is arranged around the seed crystal 21. Both the carrier 300 and the pod 500 are intended to maximize the introduction of the growth atmosphere to the growth surface of the seed crystal 21.
Further, as can be seen in FIG. 1, silicon carbide crystal growing apparatus 10 further comprises graphite paper 600; the periphery of the graphite paper 600 abuts against the inner wall of the crucible body 110; and the graphite paper 600 is disposed at one side of the mesh member 200 near the bottom of the crucible body 110. The graphite paper 600 herein mainly functions as:
during the growth process, the raw material near the side wall of the crucible 100 is firstly sublimated and is firstly graphitized, the graphitization is very serious to the middle and later stages of the growth, carbon particles can be avoided to the maximum extent by shielding with the graphite paper 600, and the growth atmosphere is mainly conveyed through a gas passage of the middle needle-shaped recrystallization.
In the present embodiment of the invention, the graphite paper 600 is arranged in parallel with the mesh member 200. I.e., the graphite paper 600 is recessed toward the bottom wall of the crucible body 110.
In this embodiment of the invention, silicon carbide crystal growing apparatus 10 further comprises a polycrystalline silicon carbide ingot material 700; polycrystalline silicon carbide ingot material 700 is filled between the mesh 200 and the graphite paper 600. Polycrystalline SiC ingot layer action: the grain size of the polycrystal is large, the carbonized grains are not easy to blow up, and the bottom carbon grains are easy to be wrapped by recrystallization on the surface of the sublimation method raw material after rising along with the growth atmosphere.
Further, in the present embodiment, silicon carbide crystal growth apparatus 10 further includes porous graphite layer 800; the porous graphite layer 800 is disposed on a side of the mesh member 200 away from the bottom of the crucible body 110. Specifically, the porous graphite layer 800 is arranged in the crucible body 110 in a flat manner, and the porous graphite layer 800 is perpendicular to the inner wall of the crucible body 110.
The porous graphite has the following functions: the convection effect of the growth atmosphere is inhibited by using the aerodynamic principle, and the carbon particles on the surface of the raw material are prevented from being blown up. In the system, the two-way insurance ensures that the carbon particles in the powder 22 are not blown up to the crystal forming carbon coating defect.
When in use, 1kg-3kg of SiC raw material purchased from the market is firstly filled at the bottom of the crucible 100;
pressing the surface of the raw material into a concave shape by a special tool, and placing a layer of concave tantalum net with the outer diameter of 130mm-200mm on the surface of the raw material to fix the material surface, wherein the thickness of the concave tantalum net is 0.3mm-1.2 mm; then compacting and fixing the raw materials, and sintering the raw materials;
a fixing area is arranged at the position 30mm-70mm high at the bottom of the crucible 100 and is used for fixing the tantalum mesh on the surface of the raw material;
arranging a trapezoidal carrier 300 at a position 130mm-150mm higher in the crucible 100, wherein the upper width of the carrier 300 is 40-80mm, the lower width of the carrier 300 is 10-40mm, a circular pit with the width of 2-5mm and the depth of 1-3mm is arranged in the middle of the top of the carrier 300 and used for placing a metal screen 400, the diameter of the circular metal screen 400 is 100-140mm, and a flow guide cover 500 is arranged at the top of the screen and used for guiding the growth atmosphere to the growth surface of the seed crystal 21;
the draft shield 500 is 20mm-50mm high and 1-3mm thick, and finally the crucible cover 120 adhered with the seed crystal 21 is placed on the top of the crucible 100.
In a second aspect, the present invention provides a crystal growth method, which comprises providing a crucible 100, wherein the crucible 100 comprises a crucible body 110 and a crucible cover 120, the crucible cover 120 is provided with a seed crystal clamping part, and a seed crystal is combined on the seed crystal clamping part;
filling a preset amount of powder 22 in the crucible body 110, and compacting the powder 22 to ensure that the surface of the powder 22 facing the top surface of the crucible body 110 is concave facing the bottom of the crucible body 110;
covering the mesh member 200 on the powder 22 and having a concave shape adapted to the surface of the powder facing the top surface of the crucible body 110, wherein the periphery of the mesh member 200 abuts against the inner wall of the crucible body 110;
closing the crucible cover 120 to the crucible body 110;
the crucible 100 is loaded into a crystal growth furnace for growth.
Further, sealing the crucible cover 120 bonded with the seed crystal 21 and the crucible 100 with the thermal field placed inside, wrapping the graphite soft felt heat preservation layer with the thickness of 5-10 mm of 1-4 layers around the growth crucible 100, wrapping the top and the bottom of the growth crucible 100, then placing the growth crucible 100 into a crystal growth furnace, firstly vacuumizing to the pressure of 5x10-2Below mbar, argon is filled to control the pressure to be 1-50 mbar, the water-cooled induction coil is electrified to heat the graphite crucible 100 by the electromagnetic induction principle, and when the heating temperature reaches more than 2100 ℃, the silicon carbide powder begins to sublimate to become Si and Si2C、SiC2And the gas is subjected to deposition crystallization along the temperature gradient from the high-temperature region to the seed crystal 21 in the lower-temperature region to form the silicon carbide single crystal, and the growth of the silicon carbide single crystal is completed after the deposition crystallization time of 5-10 days.
The thermal field structure of the design is adopted to grow 4-inch N-doped 4H-SiC crystals, the crystals are cut, ground and polished to obtain wafers, BPD density is calculated after the wafers are etched, and the density is lower than 500 pieces/cm2While the substrate is free of SF anomalies. The thermal field structure is used for crystal growth, so that the problems of internal stress and SF in the SiC crystal can be fundamentally solved.
In summary, embodiments of the present invention provide an apparatus 10 for growing a silicon carbide crystal and a method for growing a crystal, which have at least the following advantages:
according to the silicon carbide crystal growth device 10, the thermal field can be effectively utilized through the change of the concave-convex degree of the material surface, so that the internal stress of the crystal is reduced, the nitrogen doping is more uniform, the SF is solved from two aspects, and the density of the BPD is reduced as far as possible. Such a silicon carbide crystal growth apparatus 10 has the advantages of simple structure, convenient installation, and better quality of the obtained silicon carbide crystal.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (17)

1. An apparatus for growing a silicon carbide crystal, comprising:
a crucible (100) and a mesh (200);
the mesh piece (200) is arranged in a crucible body (110) of the crucible (100), the periphery of the mesh piece (200) is abutted against the inner wall of the crucible body (110), and the mesh piece (200) is concave towards the bottom of the crucible body (110);
the bottom of the crucible (100) is configured to contain raw material powder (22), the mesh (200) is configured to be attached to cover the raw material powder (22), and the surface of the raw material powder (22) facing the top surface of the crucible body (110) is provided with a concave shape matched with the mesh (200).
2. A silicon carbide crystal growth apparatus according to claim 1 wherein:
the net-shaped piece (200) is a metal grid sheet; and/or the mesh (200) is multi-layered.
3. A silicon carbide crystal growing apparatus according to claim 2 wherein:
the mesh (200) is a tantalum mesh.
4. A silicon carbide crystal growth apparatus according to claim 1 wherein:
further comprising a carrier (300);
the periphery of the carrying platform (300) is abutted against the inner wall of the crucible body (110);
the center of the carrier (300) is provided with a drainage channel (310) which is penetrated towards the crucible cover (120) of the crucible body (110); and the opening of the drainage channel (310) is gradually reduced from the direction far away from the crucible cover (120) to the direction close to the crucible cover (120).
5. A silicon carbide crystal growth apparatus according to claim 4 wherein:
further comprising a metal screen (400);
the metal screen (400) is arranged on the top of the carrier (300) close to the crucible cover (120) to cover the opening of the drainage channel (310).
6. A silicon carbide crystal growth apparatus according to claim 5 wherein:
a sinking platform (320) is arranged at the position, close to the opening of the crucible cover (120), of the drainage channel (310);
the metal screen (400) is disposed on the sinking platform (320) to cover an opening of the drainage channel (310).
7. The silicon carbide crystal growing apparatus of claim 6, wherein:
further comprising a pod (500);
the flow guide cover (500) is provided with a flow guide channel (510) which penetrates along the height direction of the crucible body (110);
the bottom of the flow guide cover (500) is abutted against the periphery of the opening of the flow guide channel (310), and the top of the flow guide cover (500) is abutted against the periphery of the seed crystal (21) on the crucible cover (120);
and the flow guide channel (510) is opposite to the flow guide channel (310).
8. A silicon carbide crystal growth apparatus according to claim 1 wherein:
also includes graphite paper (600);
the periphery of the graphite paper (600) is abutted against the inner wall of the crucible body (110); and the graphite paper (600) is arranged at one side of the reticular part (200) close to the bottom of the crucible body (110).
9. A silicon carbide crystal growing apparatus according to claim 8 wherein:
also includes a polycrystalline silicon carbide ingot material (700);
the polycrystalline silicon carbide ingot material (700) is filled between the mesh (200) and the graphite paper (600).
10. A silicon carbide crystal growth apparatus according to claim 1 wherein:
further comprising a porous graphite layer (800);
the porous graphite layer (800) is arranged on one side of the mesh part (200) far away from the bottom of the crucible body (110).
11. An apparatus for growing a silicon carbide crystal, comprising:
the crucible (100), the crucible (100) comprises a crucible body (110), and the crucible body (110) is used for containing raw material powder (22);
netted piece (200), netted piece (200) are used for setting up in the crucible body (110), have and be the concavity towards crucible body (110) bottom, be configured as with the inner wall of crucible body (110) supports and holds and fixes raw materials powder (22), the surface of raw materials powder (22) towards crucible body (110) top surface have with the concavity of netted piece (200) looks adaptation.
12. A silicon carbide crystal growing apparatus according to claim 11 wherein:
the net-shaped piece (200) is a metal grid sheet; and/or the presence of a gas in the gas,
the mesh (200) is multi-layered.
13. A silicon carbide crystal growing apparatus according to claim 12 wherein:
the mesh (200) is a tantalum mesh.
14. A silicon carbide crystal growing apparatus according to claim 11 wherein:
also includes graphite paper (600);
the graphite paper (600) is arranged in the crucible body (110), and the periphery of the graphite paper (600) is abutted against the inner wall of the crucible body (110); and the graphite paper (600) is arranged at one side of the reticular part (200) close to the bottom of the crucible body (110).
15. A silicon carbide crystal growing apparatus according to claim 14 wherein:
also includes a polycrystalline silicon carbide ingot material (700);
the polycrystalline silicon carbide ingot material (700) is for being disposed in the crucible body (110), and the polycrystalline silicon carbide ingot material (700) is filled between the mesh member (200) and the graphite paper (600).
16. A silicon carbide crystal growing apparatus according to claim 11 wherein:
further comprising a porous graphite layer (800);
the porous graphite layer (800) is arranged in the crucible body (110), and the mesh piece (200) is far away from one side of the bottom of the crucible body (110).
17. A crystal growth method, characterized by:
providing a crucible (100), wherein the crucible (100) comprises a crucible body (110) and a crucible cover (120), the crucible cover (120) is provided with a seed crystal clamping part, and a seed crystal is combined on the seed crystal clamping part;
filling a preset amount of powder (22) in the crucible body (110), and compacting the powder (22) to ensure that the surface of the powder (22) facing the top surface of the crucible body (110) is concave facing the bottom of the crucible body (110);
covering the powder material (22) with a mesh-shaped piece (200) and having a concave shape matched with the surface of the powder material (22) facing the top surface of the crucible body (110), wherein the periphery of the mesh-shaped piece (200) is abutted against the inner wall of the crucible body (110);
-closing the crucible cover (120) to the crucible body (110);
and (3) loading the crucible (100) into a crystal growth furnace for growth.
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