CN116163010A - Device for growing silicon carbide single crystal - Google Patents
Device for growing silicon carbide single crystal Download PDFInfo
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- CN116163010A CN116163010A CN202111405002.5A CN202111405002A CN116163010A CN 116163010 A CN116163010 A CN 116163010A CN 202111405002 A CN202111405002 A CN 202111405002A CN 116163010 A CN116163010 A CN 116163010A
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- 239000013078 crystal Substances 0.000 title claims abstract description 138
- 229910010271 silicon carbide Inorganic materials 0.000 title claims abstract description 92
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 title claims abstract description 90
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 178
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 166
- 239000010439 graphite Substances 0.000 claims abstract description 166
- 230000002093 peripheral effect Effects 0.000 claims abstract description 5
- 239000002994 raw material Substances 0.000 claims description 28
- 230000001154 acute effect Effects 0.000 claims description 3
- 238000000034 method Methods 0.000 description 7
- 239000007789 gas Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 239000012071 phase Substances 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 230000006698 induction Effects 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000012808 vapor phase Substances 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000004888 barrier function Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000006854 communication Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 239000007792 gaseous phase Substances 0.000 description 1
- 238000005087 graphitization Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 230000002269 spontaneous effect Effects 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B23/00—Single-crystal growth by condensing evaporated or sublimed materials
- C30B23/02—Epitaxial-layer growth
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B23/00—Single-crystal growth by condensing evaporated or sublimed materials
- C30B23/002—Controlling or regulating
-
- 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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- Chemical & Material Sciences (AREA)
- 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 provides a device for silicon carbide single crystal growth, which comprises a graphite crucible main body, a graphite crucible cover and a seed crystal, wherein the seed crystal is fixed on the inner side of the graphite crucible cover; wherein the apparatus further comprises a graphite ring located between the graphite crucible body and graphite crucible cover; the graphite ring is comprised of an expanded diameter section proximate to the graphite crucible cover and a constant diameter section distal from the graphite crucible cover, wherein the expanded diameter section has an inclined face inclined relative to the seed crystal and the inclined face extends toward the seed crystal in at least alignment with a peripheral edge of the seed crystal. Devices incorporating the graphite rings of the present invention can grow SiC single crystals of large sizes, such as 8 inches or more.
Description
Technical Field
The invention belongs to the field of crystal growth. In particular, the invention relates to an apparatus for silicon carbide crystal growth.
Background
Silicon carbide (SiC) has wide band gap, high thermal conductivity, high electron mobility, high breakdown field strength, good thermal stability and good chemical stability, is an ideal material for preparing high-temperature, high-frequency, high-power and radio-frequency devices, and has wide application prospect in the fields of new energy electric automobiles, rail transit, high-voltage power transmission and transformation, communication base stations and the like.
The large-size SiC single crystal, high raw material utilization rate and high growth rate can obviously reduce the cost of SiC devices.
Physical Vapor Transport (PVT) is the main method for growing large-size SiC single crystals, 6 inch SiC single crystals have been grown at present, and industrialization has been achieved. However, there is currently no commercialized 8 inch SiC single crystal and 8 inch SiC single crystal growth technology.
Aiming at the problem of large-size SiC single crystal growth, CN 113151895A realizes the growth of large-diameter silicon carbide single crystals by adopting a conical crucible cover structure and a double heating device. However, the silicon carbide single crystal grown by the method cannot realize the growth of a large-diameter silicon carbide constant diameter region, and it is difficult to realize the processing of a single crystal wafer. In addition, this patent application needs to adopt two heating device to realize the effective supply of raw materials, and the upper surface of raw materials owing to having covered the raw materials, along with the growth, the raw materials can sinter gradually together, can not provide effectual transmission path for the gaseous phase material that the growth needs to reduce the utilization ratio of raw and other materials, reduced growth rate.
There is an urgent need for an apparatus capable of growing large-sized SiC single crystals.
Disclosure of Invention
The invention aims to provide a device capable of growing large-size SiC single crystals.
The above object of the present invention is achieved by the following technical solutions.
The invention provides a device for silicon carbide single crystal growth, which comprises a graphite crucible main body, a graphite crucible cover and a seed crystal, wherein the seed crystal is fixed on the inner side of the graphite crucible cover; wherein,,
the apparatus further comprises a graphite ring positioned between the graphite crucible body and the graphite crucible cover;
the graphite ring is comprised of an expanded diameter section proximate to the graphite crucible cover and a constant diameter section distal from the graphite crucible cover, wherein the expanded diameter section has an inclined face inclined relative to the seed crystal and the inclined face extends toward the seed crystal in at least alignment with a peripheral edge of the seed crystal.
The inventors of the present application have unexpectedly found that when the graphite ring of the present invention is provided between the graphite crucible main body and the graphite crucible cover, a large-sized silicon carbide single crystal can be obtained. Without wishing to be bound by theory, this may be due to the fact that the graphite ring of the present invention has an expanded diameter section that can allow the vapor phase species of SiC to be transported as far as possible toward the central seed crystal by means of physical confinement, thereby reducing the likelihood of spontaneous nucleation of supersaturated vapor phase species on the graphite baffle to form polycrystalline regions; meanwhile, the baffle plate of the crucible is provided with a section of constant diameter part, so that the constant diameter growth of the large-size SiC crystal after the diameter expansion can be realized, and the difficulty of later crystal processing can be realized and reduced.
Preferably, in the apparatus for growing a silicon carbide single crystal according to the present invention, the inclined surface has an inclination angle of 30 to 89 ° with respect to the radial direction of the graphite crucible body (refer to angle θ in fig. 2).
The inventors of the present application have unexpectedly found that when the inclination angle of the inclined surface with respect to the radial direction of the graphite crucible main body is 30 to 89 °, a silicon carbide single crystal of a larger size can be obtained which is more effective. Too large an angle affects the expansion efficiency, too small an angle tends to form polycrystalline regions at the edges of the growing crystal, eroding the growing crystal.
Preferably, in the apparatus for growing a silicon carbide single crystal according to the present invention, the inner diameter of the constant diameter section is the same as the inner diameter of the graphite crucible body.
Preferably, in the apparatus for growing a silicon carbide single crystal according to the present invention, the inclined surface extends toward the seed crystal to cover a peripheral edge of the seed crystal by 10 to 30mm. Since more defects often exist at the edge of the seed crystal, the graphite ring covers the defects at the edge of the seed crystal in the growth process, so that the quality of the grown crystal can be improved.
Preferably, in the apparatus for growing a silicon carbide single crystal according to the present invention, the apparatus further comprises at least one graphite sleeve located within the graphite crucible body to divide the graphite crucible body into a raw material region surrounded by the graphite sleeve and the graphite crucible body and a non-raw material region surrounded by the inside of the graphite sleeve;
the side wall of the graphite sleeve is provided with a through hole, and the extending direction of the through hole forms an acute angle with the axis of the graphite sleeve so as to prevent raw materials in the raw material area from entering the non-raw material area.
The device of the present invention may further comprise a graphite sleeve as described above. The graphite sleeve can increase the utilization rate of raw materials, increase the growth speed and further reduce the cost of SiC single crystals. In the process of growing SiC crystals by PVT, gas phase materials are typically transported to the SiC seed crystal through the interstices between the SiC particles and the gaps between the feedstock and the graphite crucible. Along with the growth, the raw material particles can sinter together, so that the transportation of gas-phase substances is blocked, and the utilization rate of raw materials is reduced. In addition, as the size of the grown crystal increases, the difficulty in transporting the gas phase material from the crucible edge to the center of the seed crystal through the gap between the graphite crucible and the raw material increases, resulting in a decrease in the crystal growth rate and a decrease in the quality of the grown crystal. The increase in crystal size also increases the internal stress of the grown SiC crystal. Low utilization of raw materials, low growth rate, uneven transport of gas phase substances, result in an increase in SiC crystal cost and a decrease in crystal quality. The device of the present invention further comprising a graphite sleeve solves the above mentioned problems.
Preferably, in the apparatus for growing a silicon carbide single crystal according to the present invention, the height of the graphite sleeve is 20 to 70% of the distance of the seed crystal from the bottom wall of the graphite crucible main body.
Preferably, in the apparatus for growing a silicon carbide single crystal according to the present invention, the sum of the bottom areas of the graphite sleeves is 10 to 70% of the bottom area of the graphite crucible body.
Preferably, in the apparatus for growing silicon carbide single crystals of the present invention, the thickness of the wall of the graphite sleeve is 5-80mm.
Preferably, in the apparatus for growing a silicon carbide single crystal according to the present invention, the inner diameter of the graphite sleeve is 20% to 100% of the maximum size of the seed crystal.
Preferably, in the apparatus for growing a silicon carbide single crystal according to the present invention, the inner diameter of the upper top surface of the graphite sleeve is 20 to 80% of the inner diameter of the lower bottom surface.
Preferably, in the apparatus for growing a silicon carbide single crystal according to the present invention, the outer diameter of the upper top surface of the graphite sleeve is 20 to 80% of the outer diameter of the lower bottom surface.
Preferably, in the apparatus for growing a silicon carbide single crystal according to the present invention, the graphite sleeve is a cylindrical sleeve, a conical sleeve, or a truncated conical sleeve.
Preferably, in the apparatus for growing a silicon carbide single crystal according to the present invention, the outer diameter of the cylindrical sleeve is 1.1 to 5.5 times the inner diameter of the cylindrical sleeve.
Preferably, in the apparatus for growing a silicon carbide single crystal according to the present invention, the inner diameter of the cylindrical sleeve is 10 to 200mm.
Preferably, in the apparatus for growing a silicon carbide single crystal according to the present invention, the outer diameter of the cylindrical sleeve is 20 to 220mm.
Preferably, in the apparatus for growing a silicon carbide single crystal according to the present invention, an outer diameter of an upper top surface of the conical sleeve is the same as an inner diameter of the graphite crucible body.
Preferably, in the apparatus for growing a silicon carbide single crystal according to the present invention, the minimum distance between the through hole and the upper top surface of the graphite sleeve is 5 to 40% of the height of the graphite sleeve.
Preferably, in the apparatus for growing a silicon carbide single crystal according to the present invention, the minimum distance of the through hole from the upper top surface of the graphite sleeve is 10 to 100mm.
Preferably, in the apparatus for growing a silicon carbide single crystal according to the present invention, the minimum distance of the through hole from the lower bottom surface of the graphite sleeve is 10 to 100mm.
Preferably, in the apparatus for growing a silicon carbide single crystal according to the present invention, the distance between two adjacent through holes is 5 to 100mm.
Preferably, in the apparatus for growing a silicon carbide single crystal according to the present invention, the diameter of the through hole is 5 to 30mm.
Preferably, in the apparatus for growing a silicon carbide single crystal according to the present invention, an axis of the graphite sleeve overlaps with an axis of the graphite crucible main body.
In a specific embodiment of the present invention, the starting material required for growing SiC is preferably SiC, or Si, C, or SiC, si, C, or Si, C, V-containing species, or SiC, V-containing species;
in a specific embodiment of the present invention, the height of the feedstock filled in the graphite crucible (i.e., feedstock zone) outside the graphite sleeve is consistent with the graphite sleeve or is 1-5mm below the graphite sleeve;
in particular embodiments of the present invention, to prevent the feedstock from falling into the graphite sleeve in the feedstock zone, a barrier cap, such as a graphite sheet, may be employed to shield the top of the graphite sleeve as feedstock is added to the feedstock zone; when growing the single crystal, the blocking cover is removed.
In particular embodiments of the present invention, the graphite sleeve may be placed at any desired location in the graphite crucible, either centrally in the graphite crucible or offset to any side of the graphite crucible.
In a specific embodiment of the present invention, the side wall of the graphite sleeve needs to be perforated, and the number of through holes is preferably more than 2.
In a specific embodiment of the present invention, the growth process of a silicon carbide single crystal includes the steps of:
placing a plurality of graphite sleeves with through holes on the side walls into a graphite crucible; filling raw materials required by growth into a graphite crucible outside a graphite sleeve; adhering SiC seed crystal on the bottom cover of the crucible cover, screwing a graphite ring, and assembling the SiC seed crystal with the graphite crucible main body; and placing the graphite crucible tool loaded with the graphite sleeve and the growth raw materials in silicon carbide crystal growth equipment to grow the silicon carbide crystal.
In a specific embodiment of the present invention, a graphite sleeve is used (as shown in fig. 3) having a sidewall thickness at the lower bottom surface that is greater than the sidewall thickness at the upper bottom surface. Compared with a cylindrical sleeve with the same inner diameter, the thickness of the side wall at the lower bottom surface has better heat preservation effect, so that the temperature inside the graphite sleeve is increased, the temperature gradient is increased, the utilization rate of SiC raw materials can be further improved, and the crystal growth amount is increased.
In a specific embodiment of the present invention, a conical graphite sleeve is used in the present invention, the outer diameter of the upper bottom surface of which is the same as the inner diameter of the graphite crucible (as shown in fig. 4). The silicon carbide feedstock in the feedstock zone will decompose at high temperatures to compounds containing Si and C, as the SiC feedstock does not decompose according to Si: c=1:1, resulting in some graphitization of the feedstock to form graphite particles that remain in the crucible. These graphite particles may then be carried into the growing crystal by vapor phase species generated by SiC decomposition, which can affect the crystal quality. The conical graphite sleeve (shown in figure 4) can prevent graphite particles from being transmitted into SiC crystals, so that the crystal quality is improved.
The invention has the following beneficial effects:
(1) The inventive apparatus including the inventive graphite rings can grow SiC single crystals of large sizes, such as 8 inches or more.
(2) The device of the invention further comprising the graphite sleeve of the invention can increase the utilization rate of raw materials in SiC crystal growth, reduce the consumption of raw materials in growing SiC single crystals and reduce the growth cost. The device can provide sufficient and stable gas phase substances for SiC crystal growth, increase the utilization rate of raw materials and improve the crystal quality of the grown SiC single crystal.
Drawings
Embodiments of the present invention are described in detail below with reference to the attached drawing figures, wherein:
FIG. 1 is a schematic cross-sectional view of an apparatus for growing a silicon carbide single crystal in one embodiment of the invention;
FIG. 2 is a schematic cross-sectional view of a graphite crucible cover in an apparatus for growing a silicon carbide single crystal, in which the angle of the theta inclined plane is;
FIG. 3 is a schematic cross-sectional view of an apparatus for single crystal growth of silicon carbide in which 1 frustoconical graphite sleeve is disposed within a graphite crucible body in one embodiment of the present invention;
FIG. 4 is a schematic cross-sectional view of an apparatus for single crystal growth of silicon carbide in which 1 conical graphite sleeve is disposed within a graphite crucible body in one embodiment of the present invention;
FIG. 5 is a schematic cross-sectional view of an apparatus for growing a silicon carbide single crystal in which 2 cylindrical graphite sleeves are provided in a graphite crucible body in one embodiment of the present invention;
FIG. 6 is a physical view of a single crystal ingot of SiC grown using the apparatus of the invention in one embodiment of the invention;
wherein, the reference numerals:
1-an induction coil; 2-seed crystal; 3-graphite crucible cover; 4-graphite ring; 41-an expanded diameter section; 411-inclined plane; 42-isodiametric section; 5-a feedstock zone; 6-graphite sleeve; 61-through holes; 7-a graphite crucible body; 8-non-feed zone.
Detailed Description
Referring now to the drawings, illustrative aspects of the presently disclosed subject matter for a silicon carbide crystal growth apparatus will be described in detail. Although the drawings are provided to present some embodiments of the invention, the drawings are not necessarily to scale and certain features may be exaggerated, removed, or partially sectioned to better illustrate and explain the present disclosure. The position of part of components in the drawings can be adjusted according to actual requirements on the premise of not affecting the technical effect. The appearances of the phrase "in the drawings" or similar language in the specification do not necessarily refer to all figures or examples.
It should be noted that certain directional terms used hereinafter to describe the drawings, such as "transverse", "vertical", "front", "rear", "inner", "outer", "above", "below" and other directional terms, will be understood to have their ordinary meaning and refer to those directions as they would normally be referred to in viewing the drawings. Unless otherwise indicated, directional terms described herein are generally in accordance with conventional directions as understood by those skilled in the art.
Some embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following embodiments and features of the embodiments may be combined with each other without conflict.
Referring to fig. 1 to 5, the present invention provides an apparatus for silicon carbide crystal growth, comprising a graphite crucible body 7, a graphite crucible cover 3, a seed crystal 2, the seed crystal 2 being fixed inside the graphite crucible cover 3; wherein the device further comprises a graphite ring 4 positioned between the graphite crucible body 7 and the graphite crucible cover 3;
the graphite ring 4 is constituted by an enlarged diameter section 41 close to the graphite crucible cover 3 and an equal diameter section 42 distant from the graphite crucible cover 3, wherein the enlarged diameter section 41 has an inclined face 411 inclined with respect to the seed crystal 2 and the inclined face 411 extends toward the seed crystal 2 to be at least aligned with the peripheral edge of the seed crystal 2. Further, the inclination angle of the inclined surface 411 with respect to the radial direction of the graphite crucible body 7 may be 30 to 89 °, such as 30 °, 40 °, 50 °, 65 °, or 80 °.
Further, the inner diameter of the constant diameter section 42 is the same as the inner diameter of the graphite crucible body 7.
Further, the inclined surface 411 extends toward the seed crystal 2 to cover the periphery of the seed crystal 2 by 10 to 30mm, such as 15mm, 20mm or 25mm.
In an embodiment of the present invention, the apparatus of the present invention further comprises at least one graphite sleeve 6 (refer to fig. 1-5) located within the graphite crucible body 7 to divide the graphite crucible body 7 into a raw material zone 5 surrounded by the graphite sleeve 6 and the graphite crucible body 7 and a non-raw material zone 8 surrounded by the interior of the graphite sleeve 6. Of course, in other embodiments, more than one graphite sleeve 6 may be provided, such as 2 graphite sleeves 6 (see fig. 5). The side walls of the graphite sleeve 6 are provided with through holes 61, the direction of extension of the through holes 61 being at an acute angle, such as 30 °, 60 ° or 70 °, to the axis of the graphite sleeve to prevent the feedstock in the feedstock zone 5 from entering the non-feedstock zone 8. The height of the graphite sleeve 6 is 20-70%, such as 30%, 40%, 50% or 60%, of the distance of the seed crystal 2 from the bottom wall of the graphite crucible body 7. For example, the height of the graphite sleeve 6 may be 100mm. The distance of the seed crystal 2 from the bottom wall of the graphite crucible body 7 may be 150mm. The bottom area of the graphite sleeve 6 is 10-70%, such as 40%, 50%, 60% of the bottom area of the graphite crucible body. The thickness of the wall of the graphite sleeve 6 is 5-80mm. The inner diameter of the graphite sleeve 6 is 20% -100%, such as 50%, 60%, 70% of the maximum dimension of the seed crystal.
The minimum distance of the through holes 61 from the upper top surface of the graphite sleeve 6 is 5-40%, such as 10%, 20% or 30% of the height of the graphite sleeve 6; for example, the minimum distance of the through hole 61 from the upper top surface of the graphite sleeve 6 is 50mm; the minimum distance between the through hole 61 and the lower bottom surface of the graphite sleeve 6 is 40mm; the distance between two adjacent through holes is 5-100mm, such as 50mm. The diameter of the through hole 61 is 5-30mm, such as 20mm. In a specific embodiment, the axis of the graphite sleeve 6 may overlap with the axis of the graphite crucible body 7, i.e., the graphite sleeve 6 is placed at the center position of the graphite crucible body 7 (refer to fig. 1, 3-4).
The graphite sleeve 6 may be a cylindrical sleeve (refer to fig. 1 and 5), a conical sleeve (refer to fig. 4), or a frustoconical sleeve (refer to fig. 3). The outer diameter of the cylindrical sleeve is 1.1-5.5 times, such as 2 times, 3 times, 4 times and 5 times, the inner diameter of the cylindrical sleeve; for example, the inner diameter of the cylindrical sleeve is 180mm; the outer diameter of the cylindrical sleeve was 200mm.
In a particular embodiment, the graphite sleeve 6 may be a frustoconical sleeve (see fig. 3) with a wall thickness that tapers from bottom to top. The inner diameter of the upper top surface of the graphite sleeve 6 is 20-80% of the inner diameter of the lower bottom surface; the outer diameter of the upper top surface of the graphite sleeve 6 is 20-80% of the outer diameter of the lower bottom surface.
In one embodiment, the upper top surface of the conical sleeve has the same outer diameter as the inner diameter of the graphite crucible body 7 (see fig. 4).
Examples of single crystal growth of-SiC using the apparatus of the present invention:
the 6 inch commercial 4H-SiC is used as seed crystal, the C surface is used as crystal growth surface, and the C surface is bonded to the bottom cover of the split graphite crucible cover. And filling enough SiC powder raw materials outside a graphite sleeve of the graphite crucible main body, placing a graphite crucible cover adhered with seed crystals on the upper part of the graphite crucible, and placing the graphite crucible cover into an induction coil in a single crystal growth furnace after assembly.
Vacuumizing the growth furnace until the pressure is less than 10 -3 Pa, the following processes are carried out in sequence: (1) By Ar and N 2 The mixed gas is inflated to the single crystal growth furnace until the pressure reaches 30kPa,keeping the pressure unchanged, heating by adopting medium-frequency induction heating, setting the temperature of the raw material at 2400 ℃, keeping the temperature for 3 hours after the temperature reaches, and keeping the temperature in the furnace unchanged; (2) Reducing the pressure to 1200Pa through a growth furnace pressure control system, and keeping for 2 hours; (3) Maintaining the pressure at 1200Pa for 20 hours, and reducing the crucible by 20mm at a speed of 1 mm/h; (4) maintaining the pressure at 1200Pa for 100h; (5) Raising the pressure to 30kPa, reducing the crucible temperature to 1000 ℃ at a speed of 100 ℃/h, and keeping for 10 hours; then the temperature of the crucible is reduced to 800 ℃ at the speed of 10-800 ℃/h, and the temperature is kept for 10h; (6) Then turning off the power supply, and taking out the crystal after the SiC monocrystal and the crucible are cooled to room temperature; (7) 8-inch 4H-SiC single crystals were obtained.
FIG. 6 is a physical view of a SiC single crystal ingot having a diameter of 213mm obtained by growth using the apparatus of the present invention.
It should be noted that the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same. Although specific process parameters can be optimized and adjusted, the basic structure of the two main core guiding ideas and the growth device of the invention are clear. It should be understood by those skilled in the relevant art that the invention can be practiced with modification and equivalent arrangements without departing from the spirit and scope of the present invention, which is intended to be encompassed within the scope of the appended claims.
Claims (10)
1. An apparatus for silicon carbide single crystal growth comprises a graphite crucible main body, a graphite crucible cover and a seed crystal, wherein the seed crystal is fixed on the inner side of the graphite crucible cover; wherein,,
the apparatus further comprises a graphite ring positioned between the graphite crucible body and the graphite crucible cover;
the graphite ring is comprised of an expanded diameter section proximate to the graphite crucible cover and a constant diameter section distal from the graphite crucible cover, wherein the expanded diameter section has an inclined face inclined relative to the seed crystal and the inclined face extends toward the seed crystal in at least alignment with a peripheral edge of the seed crystal.
2. The apparatus for silicon carbide single crystal growth as claimed in claim 1, wherein the inclined surface has an inclination angle of 30 to 89 ° with respect to a radial direction of the graphite crucible body.
3. The apparatus for single crystal growth of silicon carbide according to claim 1, wherein an inner diameter of the constant diameter section is the same as an inner diameter of the graphite crucible body.
4. An apparatus for single crystal growth of silicon carbide according to claim 1, wherein the inclined surface extends toward the seed crystal to cover a periphery of the seed crystal by 10-30mm.
5. The apparatus for single crystal growth of silicon carbide according to claim 1, wherein the apparatus further comprises at least one graphite sleeve within the graphite crucible body to divide the graphite crucible body into a feedstock region surrounded by the graphite sleeve and the graphite crucible body and a non-feedstock region surrounded by the graphite sleeve interior;
the side wall of the graphite sleeve is provided with a through hole, and the extending direction of the through hole forms an acute angle with the axis of the graphite sleeve so as to prevent raw materials in the raw material area from entering the non-raw material area.
6. The apparatus for single crystal growth of silicon carbide as recited in claim 5, wherein the height of the graphite sleeve is 20-70% of the distance of the seed crystal from the bottom wall of the graphite crucible body.
7. The apparatus for silicon carbide crystal growth as claimed in claim 5, wherein the sum of the bottom areas of the graphite sleeves is 10-70% of the bottom area of the graphite crucible body;
preferably, the thickness of the wall of the graphite sleeve is 5-80mm;
preferably, the inner diameter of the graphite sleeve is 20% -100% of the largest dimension of the seed crystal.
8. The apparatus for silicon carbide crystal growth as claimed in claim 5, wherein the upper top surface inner diameter of the graphite sleeve is 20-80% of the lower bottom surface inner diameter;
preferably, the outer diameter of the upper top surface of the graphite sleeve is 20-80% of the outer diameter of the lower bottom surface;
preferably, the graphite sleeve is a cylindrical sleeve, a conical sleeve or a frustoconical sleeve.
9. The apparatus for silicon carbide crystal growth as claimed in claim 8, wherein the outer diameter of the cylindrical sleeve is 1.1-5.5 times the inner diameter of the cylindrical sleeve;
preferably, the inner diameter of the cylindrical sleeve is 10-200mm;
preferably, the outer diameter of the cylindrical sleeve is 20-220mm;
preferably, the upper top surface of the conical sleeve has the same outer diameter as the inner diameter of the graphite crucible body.
10. The apparatus for silicon carbide crystal growth as claimed in claim 5, wherein the minimum distance of the through hole from the upper top surface of the graphite sleeve is 5-40% of the height of the graphite sleeve;
preferably, the minimum distance between the through hole and the upper top surface of the graphite sleeve is 10-100mm;
preferably, the minimum distance between the through hole and the lower bottom surface of the graphite sleeve is 10-100mm;
preferably, the distance between two adjacent through holes is 5-100mm;
preferably, the diameter of the through hole is 5-30mm;
preferably, the axis of the graphite sleeve overlaps the axis of the graphite crucible body.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN117107345A (en) * | 2023-09-11 | 2023-11-24 | 宁波合盛新材料有限公司 | Silicon carbide crystal growth method and growth device thereof |
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