IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
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출원번호 |
US-0471866
(2012-05-15)
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등록번호 |
US-8512471
(2013-08-20)
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발명자
/ 주소 |
- Zwieback, Ilya
- Anderson, Thomas E.
- Gupta, Avinash K.
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출원인 / 주소 |
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대리인 / 주소 |
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인용정보 |
피인용 횟수 :
1 인용 특허 :
9 |
초록
▼
In a physical vapor transport growth technique for silicon carbide a silicon carbide powder and a silicon carbide seed crystal are introduced into a physical vapor transport growth system and halosilane gas is introduced separately into the system. The source powder, the halosilane gas, and the seed
In a physical vapor transport growth technique for silicon carbide a silicon carbide powder and a silicon carbide seed crystal are introduced into a physical vapor transport growth system and halosilane gas is introduced separately into the system. The source powder, the halosilane gas, and the seed crystal are heated in a manner that encourages physical vapor transport growth of silicon carbide on the seed crystal, as well as chemical transformations in the gas phase leading to reactions between halogen and chemical elements present in the growth system.
대표청구항
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1. A physical vapor transport growth technique for silicon carbide comprising: introducing a silicon carbide source powder and a silicon carbide seed crystal into a physical vapor transport growth system;controlling the SiC sublimation growth by separately introducing into the system a gas mixture c
1. A physical vapor transport growth technique for silicon carbide comprising: introducing a silicon carbide source powder and a silicon carbide seed crystal into a physical vapor transport growth system;controlling the SiC sublimation growth by separately introducing into the system a gas mixture containing gaseous halosilane; andheating the source powder, the seed crystal and the gas mixture containing halosilane in a manner that encourages physical vapor transport growth of silicon carbide on the seed crystal, as well as chemical transformations in the gas phase leading to reactions between halogen and chemical elements present in the growth system. 2. The growth technique of claim 1, further comprising introducing the gas mixture containing halosilane gas into the growth system in a manner that does not disturb vapor transport from the SiC source powder to the seed. 3. The growth technique of claim 1, wherein the reactions between the halogen and the chemical elements present in the growth system include reactions between halogen and boron. 4. The growth technique of claim 3, wherein the reactions between the halogen and the boron lead to the formation of volatile boron-halogen molecular associates. 5. The growth technique of claim 3, wherein the boron is in the form of at least one of the following: elemental boron, silicon-bound boron, or carbon-bound boron; and said at least one form includes a gaseous phase, a liquid phase, or a solid phase. 6. The growth technique of claim 4, wherein the volatile boron-halogen molecular associates are removed from the growth crucible by filtrating across the crucible wall, said removal assisted by a flow of the gas mixture in the system. 7. The growth technique of claim 2, wherein the gas mixture includes halosilane and hydrogen. 8. The growth technique of claim 7, wherein the reactions between the halogen and the chemical elements present in the growth system include reactions between halogen and silicon in the form of solid silicon carbide, as well as reactions between halogen and silicon in the form of vapors generated as a result of SiC sublimation, and the outcome of these reactions and stoichiometric ratios between gaseous products are affected by the presence of the hydrogen in the gas mixture. 9. The growth technique of claim 1, wherein the silicon carbide seed crystal has a polytype selected from the group consisting of the 3C, 4H, 6H, and 15R polytypes of silicon carbide. 10. The growth technique of claim 1, wherein the halosilane gas is tetrahalosilane. 11. The growth technique of claim 10, wherein the tetrahalosilane gas includes tetrachlorosilane (SiCl4) or tetrafluorosilane (SiF4). 12. The growth technique of claim 1, further comprising maintaining the total pressure in the sublimation system below atmospheric pressure. 13. The growth technique of claim 12, further comprising maintaining the total pressure in the physical vapor transport system below 200 Torr. 14. The growth technique of claim 1, further comprising heating the source powder to a temperature higher than the seed crystal. 15. The growth technique of claim 14, further comprising heating the source powder to a temperature between 10° C. and 200° C. higher than the seed crystal. 16. The growth technique of claim 1, further comprising introducing into the SiC growth system a gas mixture that includes hydrogen. 17. A method of silicon carbide crystal growth comprising: heating a silicon carbide source powder to sublimation in the presence of a silicon carbide seed crystal that is maintained at a lower temperature than the silicon carbide source powder to encourage physical vapor transport between the source powder onto the seed crystal to cause the seed crystal to grow; andduring sublimation of the source powder and sublimation growth of the seed crystal, introducing a gas mixture containing halosilane gas in the presence of the seed crystal and the silicon carbide source powder. 18. The method of claim 17, further comprising heating the seed crystal to a temperature between 10° C. and 200° C. lower than the source powder. 19. The method of claim 17, further comprising heating the source powder and introducing the halosilane gas at less than atmospheric pressure. 20. The method of claim 19, further comprising heating the source powder and introducing the halosilane gas at less than 200 Torr. 21. The method of claim 17, wherein the halosilane gas is tetrahalosilane. 22. The method of claim 21, wherein the tetrahalosilane gas includes tetrachlorosilane (SiCl4) or tetrafluorosilane (SiF4). 23. The method of claim 17, comprising heating the silicon carbide source powder in the presence of the silicon carbide seed crystal which has a polytype selected from the group consisting of the 4H, 6H, and 15R polytypes of silicon carbide. 24. The method of claim 17, further comprising during sublimation of the source powder and sublimation growth of the seed crystal, introducing a gas mixture containing hydrogen gas in the presence of the seed crystal and the silicon carbide source powder. 25. A system for bulk growth of silicon carbide comprising: a graphite crucible configured to receive a seed crystal and a silicon carbide source powder;an inlet for separately introducing a flow of a gas composition comprising halogen into the system in a manner whereupon the flow of said gas composition does not disturb vapor transport from the SiC source powder to the seed; andwalls of said graphite growth crucible allowing said gas flow to filter through without substantial increase in the gas pressure inside the crucible. 26. The system of claim 25, further comprising an RF heating coil positioned to inductively heat said graphite crucible and a power source for said RF heating coil. 27. The system of claim 25, further comprising a seed crystal having a polytype selected from the group consisting of the 3C, 4H, 6H, and 15R polytypes of silicon carbide. 28. The system of claim 25, wherein the halogen of the gas composition is halosilane gas. 29. The system of claim 28, wherein the halosilane gas is tetrahalosilane. 30. The system of claim 29, wherein the tetrahalosilane gas includes tetrachlorosilane (SiCl4) or tetrafluorosilane (SiF4). 31. The system of claim 25, wherein the halogen of the gas composition comprises a Cl-bearing gas or a F-bearing gas. 32. The system of claim 25, wherein the gas composition further comprises hydrogen. 33. The system of claim 25, further comprising a resistive heater positioned to heat said graphite crucible and a power source for said resistive heater. 34. A single crystal of silicon carbide comprising background boron impurity in the as-grown crystal in concentrations of ≦7·1015 cm−3. 35. The single crystal of claim 34, wherein the as-grown crystal has a polytype selected from the group consisting of the 4H, 6H, 3C and 15R polytypes of silicon carbide.
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