IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0664974
(2008-06-26)
|
등록번호 |
US-8449671
(2013-05-28)
|
국제출원번호 |
PCT/US2008/068342
(2008-06-26)
|
§371/§102 date |
20091216
(20091216)
|
국제공개번호 |
WO2009/003100
(2008-12-31)
|
발명자
/ 주소 |
- Wu, Ping
- Zwieback, Ilya
- Gupta, Avinesh K.
- Semenas, Edward
|
출원인 / 주소 |
|
대리인 / 주소 |
|
인용정보 |
피인용 횟수 :
0 인용 특허 :
5 |
초록
▼
A method of fabricating an SiC single crystal includes (a) physical vapor transport (PVT) growing a SiC single crystal on a seed crystal in the presence of a temperature gradient, wherein an early-to-grow portion of the SiC single crystal is at a lower temperature than a later-to-grow portion of the
A method of fabricating an SiC single crystal includes (a) physical vapor transport (PVT) growing a SiC single crystal on a seed crystal in the presence of a temperature gradient, wherein an early-to-grow portion of the SiC single crystal is at a lower temperature than a later-to-grow portion of the SiC single crystal. Once grown, the SiC single crystal is annealed in the presence of a reverse temperature gradient, wherein the later-to-grow portion of the SiC single crystal is at a lower temperature than the early-to-grow portion of the SiC single crystal.
대표청구항
▼
1. A method of fabricating a SiC single crystal comprising: (a) physical vapor transport (PVT) growing a SiC single crystal on a seed crystal in the presence of a temperature gradient, wherein an early-to-grow portion of the SiC single crystal is at a lower temperature than a later-to-grow portion o
1. A method of fabricating a SiC single crystal comprising: (a) physical vapor transport (PVT) growing a SiC single crystal on a seed crystal in the presence of a temperature gradient, wherein an early-to-grow portion of the SiC single crystal is at a lower temperature than a later-to-grow portion of the SiC single crystal; and(b) annealing the SiC single crystal in the presence of a reverse temperature gradient, wherein the later-to-grow portion of the SiC single crystal is at a lower temperature than the early-to-grow portion of the SiC single crystal. 2. The method of claim 1, wherein step (a) includes growing the SiC single crystal in the presence of an inert gas at a pressure between 1 and 200 torr at a temperature between 1900° C. and 2450° C. 3. The method of claim 2, wherein the inert gas comprises argon, or helium, or argon+nitrogen, or helium+nitrogen. 4. The method of claim 1, wherein step (a) includes: (1) PVT growing the SiC single crystal at a temperature T1 between 1900° C. and 2450° C. and a pressure P1 between 1 and 200 torr; and(2) following step (1), PVT growing the SiC single crystal at a temperature T2 that is higher than T1 and a pressure P2 that is lower than P1. 5. The method of claim 4, wherein T2 is 10 to 100 degrees C. higher than T1, and P2 is 10% to 60% lower than P1. 6. The method of claim 1, wherein step (b) includes annealing the SiC single crystal in the presence of an inert gas at a pressure between 300 and 600 torr at a temperature between 2100° C. and 2550° C. 7. The method of claim 6, wherein the inert gas comprises argon, or helium, or argon+nitrogen, or helium+nitrogen. 8. The method of claim 1, wherein: the early-to-grow part of the SiC single crystal grows on the SiC seed crystal; andthe later-to-grow part of the SiC single crystal is disposed at an end or side of the SiC single crystal opposite the early-to-grow part of the SiC single crystal. 9. The method of claim 1, wherein the temperature gradient of step (a) and the reverse temperature gradient of step (b) have substantially the same temperature difference over the SiC single crystal. 10. The method of claim 9, wherein the temperature difference is between 10° C. and 50° C. 11. A method of fabricating a SiC single crystal comprising: (a) providing a growth crucible that is charged with SiC source material at a bottom of the crucible and a SiC seed crystal at a top of the crucible;(b) heating the growth crucible such that: a temperature gradient forms therein with the SiC source material at a first, sublimation temperature and the SiC seed crystal at a second, lower temperature,the temperature gradient causes vapor from the SiC source material to condense on the SiC seed crystal to form the SiC single crystal, andduring growth of the SiC single crystal, the temperature gradient causes an early-to-grow part of the SiC single crystal to be at a lower temperature than a later-to-grow part of the SiC single crystal; and(c) following step (b), exposing the SiC single crystal to a reverse temperature gradient having temperatures suitable for annealing the SiC single crystal, whereupon a early-to-grow part of the SiC single crystal is at a higher temperature than the later-to-grow part of the SiC single crystal. 12. The method of claim 11, wherein: the temperature gradient includes temperatures between 1900° C. and 2450° C.; andthe reverse temperature gradient includes temperatures between 2100° C. and 2550° C. 13. The method of claim 12, wherein: the temperature gradient includes temperatures between 2000° C. and 2400° C.; andthe reverse temperature gradient includes temperatures between 2250° C. and 2450° C. 14. The method of claim 11, wherein: step (b) includes exposing the SiC single crystal to the temperature gradient in presence of a first inert gas at a pressure between 1 and 200 torr; andstep (c) includes exposing the SiC single crystal to the reverse temperature gradient in presence of a second inert gas at a pressure between 300 and 600 torr. 15. The method of claim 14, wherein: the first inert gas comprises argon, or helium, or argon+nitrogen, or helium+nitrogen; andthe second inert gas comprises argon, or helium, or argon+nitrogen, or helium+nitrogen. 16. The method of claim 11, wherein: the early-to-grow part of the SiC single crystal grows on the SiC seed crystal; andthe later-to-grow part of the SiC single crystal is disposed at an end or side of the SiC single crystal opposite the early-to-grow part of the SiC single crystal. 17. The method of claim 11, wherein the temperature gradient of step (b) and the reverse temperature gradient of step (c) have substantially the same temperature difference over the SiC single crystal. 18. The method of claim 17, wherein the temperature difference is between 10° C. and 50° C. 19. A method of fabricating a SiC single crystal comprising: (a) physical vapor transport (PVT) growing a SiC single crystal on a seed crystal for a first interval of time in the presence of a temperature gradient that has a maximum or minimum temperature of T1, wherein, during growth of the SiC single crystal, the temperature gradient causes an early-to-grow portion of the SiC single crystal to be at a lower temperature than a later-to-grow portion of the SiC single crystal; and(b) following step (a), changing said maximum or minimum temperature of the temperature gradient to a temperature T2 that is higher than T1 and PVT growing the SiC single crystal on the seed crystal for a second interval of time with said maximum or minimum temperature of the temperature gradient at temperature T2. 20. The method of claim 19, further including: (c) annealing the SiC single crystal in the presence of a reverse temperature gradient, wherein the later-to-grow portion of the SiC single crystal is at a lower temperature than the early-to-grow portion of the SiC single crystal.
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