CN117431634A - Liquid phase growth method of silicon carbide single crystal - Google Patents
Liquid phase growth method of silicon carbide single crystal Download PDFInfo
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- CN117431634A CN117431634A CN202311401125.0A CN202311401125A CN117431634A CN 117431634 A CN117431634 A CN 117431634A CN 202311401125 A CN202311401125 A CN 202311401125A CN 117431634 A CN117431634 A CN 117431634A
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- 239000013078 crystal Substances 0.000 title claims abstract description 76
- 238000000034 method Methods 0.000 title claims abstract description 44
- 229910010271 silicon carbide Inorganic materials 0.000 title claims abstract description 44
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 title claims abstract description 41
- 239000007791 liquid phase Substances 0.000 title claims abstract description 17
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 33
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 23
- 239000010439 graphite Substances 0.000 claims abstract description 23
- 239000002994 raw material Substances 0.000 claims abstract description 22
- 239000000243 solution Substances 0.000 claims description 19
- 239000007788 liquid Substances 0.000 claims description 12
- 238000010438 heat treatment Methods 0.000 claims description 10
- 229910052710 silicon Inorganic materials 0.000 claims description 9
- 239000011259 mixed solution Substances 0.000 claims description 7
- 238000002156 mixing Methods 0.000 claims description 5
- 238000001816 cooling Methods 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 238000005086 pumping Methods 0.000 claims description 3
- 238000002425 crystallisation Methods 0.000 abstract description 5
- 230000008025 crystallization Effects 0.000 abstract description 5
- 238000010899 nucleation Methods 0.000 abstract description 4
- 230000006911 nucleation Effects 0.000 abstract description 4
- 230000002269 spontaneous effect Effects 0.000 abstract description 4
- 230000002035 prolonged effect Effects 0.000 abstract description 3
- 238000013461 design Methods 0.000 abstract description 2
- 238000004519 manufacturing process Methods 0.000 abstract description 2
- 230000008018 melting Effects 0.000 abstract description 2
- 238000002844 melting Methods 0.000 abstract description 2
- 239000007789 gas Substances 0.000 description 7
- 230000008569 process Effects 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 102000029749 Microtubule Human genes 0.000 description 1
- 108091022875 Microtubule Proteins 0.000 description 1
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 150000001721 carbon Chemical class 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000006184 cosolvent Substances 0.000 description 1
- 230000007123 defense Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000007429 general method Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 210000004688 microtubule Anatomy 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 238000010587 phase diagram Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000001226 reprecipitation Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/36—Carbides
-
- 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
- C30B19/00—Liquid-phase epitaxial-layer growth
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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 relates to the field of silicon carbide production, and particularly discloses a liquid phase growth method of silicon carbide single crystals; according to the invention, through changing the structural design of the original graphite crucible, the crystal quality and the surface morphology of the long-time growth of the SiC crystal are obviously improved, and compared with the original bucket structure during growth, the area of the low-temperature area of the surface is greatly reduced by using the crucible with a new structure. Further, spontaneous nucleation and crystallization of a non-seed crystal area of the surface low-temperature area are weakened, non-growth loss of Al in the raw material solution is restrained by introducing the melting A l, the total growth time of the raw material solution of a single furnace is prolonged, the utilization rate of raw materials is improved, and further the cost is reduced.
Description
Technical Field
The invention belongs to the technical field of silicon carbide production, and particularly relates to a liquid phase growth method of a silicon carbide single crystal.
Background
Silicon carbide (SiC), which is a third generation semiconductor, has superior properties to silicon (Si): the band gap of SiC (4H-SiC: eg=3.23 eV) is about 3 times that of Si (1.12 eV), and the critical breakdown field strength (4H-SiC: 3.0MV cm) －1 ) About Si (0.3 MV.cm) －1 ) 10 times the thermal conductivity (4H-SiC: 4.9 W.cm) －1 ·K －1 ) About Si (1.5 W.cm) －1 ·K －1 ) 3 times of (3). The performances mean that the SiC has unique application advantages in high-temperature, high-frequency and high-power electronic devices and radio-frequency microwave devices, so that the SiC has important application prospects in the fields of rail transit, new energy automobiles, high-voltage power grids, 5G communication, aerospace, national defense, military and the like. The preparation of high-quality, large-size and low-cost SiC single crystal substrates is a precondition for realizing large-scale application of SiC devices.
The method for growing SiC single crystal mainly comprises the following steps: the most mature and widespread physical vapor transport methods (physical vapor transport, PVT), high temperature chemical vapor deposition methods (high temperature chemical vapor deposition, HTCVD) and high temperature solution growth methods (high temperature solution growth, HTSG) are currently the dominant techniques of high temperature solution growth methods are top-seeded solution growth (top seeded solution growth, TSSG). The basic principle of the HTSG method is to use the dissolution and re-precipitation of Si and C elements in a high-temperature solution to realize the growth of SiC single crystals, which is different from two gas phase methods, and the technology widely adopted at present is the TSSG method. In patent CN 114703542a, a general method for producing a TSSG method using Cr as a cosolvent is described, and the method is characterized by a reflow step of bringing a seed crystal of 4H-type silicon carbide into contact with a raw material solution containing silicon and carbon and having an unsaturated carbon concentration, dissolving a part of the seed crystal, and growing a 4H-type silicon carbide single crystal from the seed crystal, wherein the growth surface of the seed crystal is a surface inclined at an angle of 60 ° or more and 68 ° or less in the <1-100> direction from any one of the (0001) surface and the (000-1) surface, and the 4H-SiC single crystal having a good morphology can be obtained without mixing of heterogeneous polytypes regardless of the presence or absence of doping.
With the development depth and the progress of technology, micropipes in SiC crystals grown by PVT method have been substantially eliminated (density less than 0.2cm －2 ) But the dislocation density is still relatively high, about 102-104 cm －2 This has a very detrimental effect on the performance and lifetime of the device. In addition, PVT method has the limitations of large diameter expansion difficulty, low yield, high cost and the like. Another method of growing SiC single crystals is HTCVD. The method uses SThe growth of SiC single crystal is realized by the principle that i source gas and C source gas are subjected to chemical reaction in a high-temperature environment of about 2100 ℃ to generate SiC, and the method has the great advantage that the long-time continuous growth of the crystal can be realized. By this method, 4 inch and 6 inch SiC single crystals have been successfully grown, and the growth rate can be as high as 2-3 mm/h. The HTCVD method requires not only a high growth temperature as in the PVT method but also gases such as SiH4, C3H8, and H2, and the growth cost of the method is high. The TSSG method can realize the growth of SiC single crystal at lower temperature (< 2000 ℃) and in a state close to thermodynamic equilibrium, and is easier to obtain high-quality SiC single crystal theoretically. In addition, the TSSG method has the advantages of no microtubule in the grown crystal, stronger controllability in the growth process, easy diameter expansion, easy realization of p-type doping and the like. Currently, 4 inch SiC single crystals have been grown successfully using TSSG methods. The method is hopeful to become a method for preparing SiC monocrystal with larger size, higher crystallization quality and lower cost after PVT method, thereby further promoting the rapid development of SiC industry.
The growth quality of the SiC crystal is high in the early stage of the growth of the SiC crystal by a liquid phase method which is stable for a long time, and the crystal is changed from single crystal to polycrystal in the late stage of the growth, because in the growth process, one of the crystal is easy to volatilize Al serving as the improvement of the crystal quality, and the concentration of the Al is reduced to half of the original concentration after the growth for 20 hours without additional treatment; also crystallization in low temperature regions where the surface is not seeded can result in growth mode transformation.
Disclosure of Invention
The invention aims to provide a liquid phase growth method of silicon carbide single crystal, which aims to solve the problems in the background technology.
In order to achieve the above purpose, the present invention provides the following technical solutions:
a liquid phase growth method of silicon carbide single crystal specifically comprises the following steps:
s1, mixing Si, cr, AI and other raw materials according to a molar ratio, and then placing the mixture into a high-purity graphite crucible;
s2, starting a vacuum pump, pumping high vacuum, then introducing Ar gas, starting a radio frequency power supply, and heating the crucible;
s3, heating the crucible to a target temperature, after the mixed solution is completely melted, lowering the seed crystal to a position 5mm above the liquid level, preheating for 1h, and contacting the seed crystal with the liquid level;
s4, after the seed crystal contacts the liquid level, the seed crystal moves according to a set rotating speed and a set pulling speed, and the crucible reversely rotates;
s5, after the growth is finished, pulling the crystal away from the liquid surface at a higher speed, and slowly cooling according to program setting.
Preferably, the raw materials such as Si, cr, AI and the like can be respectively added according to the proportion of 40% -60%, 35% -55% and 5%.
Preferably, in S1, a sufficient amount of AI is placed inside the AI slot.
Preferably, the crystal growth device for liquid phase growth of silicon carbide single crystal comprises:
the high-purity graphite crucible is externally provided with a radio-frequency heating coil;
the additional graphite structure is fixed inside the high-purity graphite crucible;
the crystal lifting shaft is hung above the middle of the high-purity graphite crucible.
Preferably, the high-purity graphite crucible is internally loaded with a raw material mixed solution, the additional graphite structure is internally loaded with a molten AI solution, and the seed crystal is fixedly arranged at the lower end of the crystal pulling shaft.
Compared with the prior art, the invention has the beneficial effects that:
(1) According to the invention, by changing the structure of the graphite crucible, the temperature field structure in the graphite crucible is changed, the area of a low-temperature area on the surface is reduced, and meanwhile, the molten Al tank is additionally added, so that saturated Al vapor volatilized from the molten Al tank can inhibit evaporation of Al in a raw material solution in the long-time growth process, the loss of Al in the long-time growth process is obviously reduced, and the problem of degradation of long-time growth of a liquid phase method is further solved.
(2) According to the invention, through changing the structural design of the original graphite crucible, the crystal quality and the surface morphology of SiC grown for a long time are obviously improved, and compared with the original bucket structure during growth, the area of a low-temperature area of the surface is greatly reduced by using the crucible with a new structure. The spontaneous nucleation crystallization of the non-seed crystal area of the surface low-temperature area is further weakened, the non-growth loss of Al in the raw material solution is restrained by introducing molten Al, the total growth time of the raw material solution of a single furnace is prolonged, the utilization rate of the raw materials is improved, and the cost is further reduced.
Drawings
FIG. 1 is a three-phase diagram of Si-Cr-C of the present invention;
FIG. 2 is a thermal field simulation of the device of the present invention;
FIG. 3 is a block diagram of a crystal growth apparatus according to the present invention;
in the figure: 1. a crystal pulling shaft; 2. seed crystal; 3. melting the AI solution; 4. a high purity graphite crucible; 5. an additional graphite structure; 6. a radio frequency heating coil; 7. mixing the raw materials to obtain a solution.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Examples:
referring to fig. 1-3, a liquid phase growth method of silicon carbide single crystal specifically comprises the following steps:
s1, mixing Si, cr, AI and other raw materials according to a molar ratio, and then placing the mixture into a high-purity graphite crucible;
s2, starting a vacuum pump, pumping high vacuum, then introducing Ar gas, starting a radio frequency power supply, and heating the crucible;
s3, heating the crucible to a target temperature, after the mixed solution is completely melted, lowering the seed crystal to a position 5mm above the liquid level, preheating for 1h, and contacting the seed crystal with the liquid level;
s4, after the seed crystal contacts the liquid level, the seed crystal moves according to a set rotating speed and a set pulling speed, and the crucible reversely rotates;
s5, after the growth is finished, pulling the crystal away from the liquid surface at a higher speed, and slowly cooling according to program setting.
The raw materials such as Si, cr, AI and the like can be respectively added according to the proportion of 40% -60%, 35% -55% and 5%.
In S1, a sufficient amount of AI is placed inside the AI slot.
The crystal growing device for liquid phase growth of the silicon carbide single crystal comprises:
the high-purity graphite crucible 4 is provided with a radio-frequency heating coil 6 outside the high-purity graphite crucible 4;
an additional graphite structure 5, the additional graphite structure 5 being fixed inside the high purity graphite crucible 4;
the crystal lifting shaft 1 is hung above the middle part of the high-purity graphite crucible 4.
The high-purity graphite crucible 4 is internally loaded with a raw material mixed solution 7, the additional graphite structure 5 is internally loaded with a molten AI solution 3, and the seed crystal 2 is fixedly arranged at the lower end of the crystal pulling shaft 1.
From the above, the upper opening of the new graphite crucible structure is smaller, so that the area of the contact part between the surface of the raw material mixed solution 7 and the gas can be effectively reduced, the low-temperature area of the surface of the solution is further reduced, and spontaneous nucleation is weakened to form a multiphase structure; the additional graphite structure 5 provided on the inner wall of the high purity graphite crucible 4 can provide molten AI, and the additional molten AI can ensure the relative stability of AI components, thus laying a foundation for the stable growth of crystals for a long time.
As shown in figure 2, spontaneous nucleation and crystallization of a non-seed crystal area of a surface low-temperature area are further weakened, non-growth loss of Al in the raw material solution is restrained by introducing molten Al, the total growth time of the raw material solution of a single furnace is prolonged, the utilization rate of raw materials is improved, and the cost is further reduced.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (5)
1. A liquid phase growth method of silicon carbide single crystal is characterized by comprising the following steps:
s1, mixing Si, cr, AI and other raw materials according to a molar ratio, and then placing the mixture into a high-purity graphite crucible;
s2, starting a vacuum pump, pumping high vacuum, then introducing Ar gas, starting a radio frequency power supply, and heating the crucible;
s3, heating the crucible to a target temperature, after the mixed solution is completely melted, lowering the seed crystal to a position 5mm above the liquid level, preheating for 1h, and contacting the seed crystal with the liquid level;
s4, after the seed crystal contacts the liquid level, the seed crystal moves according to a set rotating speed and a set pulling speed, and the crucible reversely rotates;
s5, after the growth is finished, pulling the crystal away from the liquid surface at a higher speed, and slowly cooling according to program setting.
2. A method for liquid phase growth of silicon carbide single crystal according to claim 1, wherein: the raw materials such as Si, cr, AI and the like can be respectively added according to the proportion of 40% -60%, 35% -55% and 5%.
3. A method for liquid phase growth of silicon carbide single crystal according to claim 2, wherein: in S1, a sufficient amount of AI is placed inside the AI slot.
4. A method for liquid phase growth of a silicon carbide single crystal according to claim 3, wherein: the crystal growing device for liquid phase growth of the silicon carbide single crystal comprises:
the high-purity graphite crucible is externally provided with a radio-frequency heating coil;
the additional graphite structure is fixed inside the high-purity graphite crucible;
the crystal lifting shaft is hung above the middle of the high-purity graphite crucible.
5. The liquid phase growth method of silicon carbide single crystal according to claim 4, wherein: the high-purity graphite crucible is internally provided with a raw material mixed solution, the inside of the additional graphite structure is provided with a molten AI solution, and the seed crystal is fixedly arranged at the lower end of the crystal pulling shaft.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311401125.0A CN117431634A (en) | 2023-10-26 | 2023-10-26 | Liquid phase growth method of silicon carbide single crystal |
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| CN202311401125.0A CN117431634A (en) | 2023-10-26 | 2023-10-26 | Liquid phase growth method of silicon carbide single crystal |
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