US4243471A
Expired / Lapsed
US
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Method for directional solidification of silicon
Assignee: International Business Machines Corp
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Filing: 1978-05-02
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Granted: 1981-01-06
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Expires: 1998-05-02
Abstract
Abstract A method for growing silicon crystalline material by the directional solidification method without cracking the growth container. The container material must have an average thermal expansion coefficient of between about 3.0 to 4.3×10 -6 °C. -1 between about 20° and 650° C. The molten silicon is provided in the container and solidified sequentially from the enclosed regions to the open region of the container to form the crack-free silicon crystalline material.
Inventors
- 👤 Theodore F. Ciszek
- 👤 Guenter H. Schwuttke
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 05:57
CPC Classifications
C; C30; C30B; C30B29/00; C30B29/02; C30B29/06; C30B11/00; C30B11/002; Y; Y10; Y10S; Y10S117/00; Y10S117/90
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
74 words
Method for growing silicon crystal comprising: providing molten silicon in a graphite container; said container having an average thermal expansion coefficient of between about 3.0 to 4.3×10 6 °C. -1 between 20° and 650° C., density of about 1.8 grams per cubic centimeter and grain size of less than about 50 microns; and solidifying said molten silicon sequentially from the enclosed regions to the open region of said container to form crack-free silicon crystal.
Claim 2
Dependent Claim
74 words
Method for growing silicon crystal comprising: providing molten silicon in a graphite container; said container having an average thermal expansion coefficient of between about 3.0 to 4.3×10 6 °C. -1 between 20° and 650° C., density of about 1.8 grams per cubic centimeter and grain size of less than about 50 microns; and solidifying said molten silicon sequentially from the enclosed regions to the open region of said container to form crack-free silicon crystal.
Claim 3
Dependent Claim
31 words
The method of claim 1 wherein said container is a crucible and solidification is accomplished by lowering the system temperature at a rate of about 0.1 to 100° C. per minute.
Claim 4
Dependent Claim
28 words
The method of claim 1 wherein said container is a crucible and solidification is accomplished by removing said crucible from an RF heater to effect said sequential cooling.
Claim 5
Dependent Claim
30 words
The method of claim 1 wherein a silicon seed is positioned in said container to act as nucleation for growth of silicon crystal during said solidifying of said molten silicon.
Claim 6
Dependent Claim
19 words
The method of claim 8 wherein said container has a conical recess for said seed crystal to be positioned.
Claim 7
Dependent Claim
15 words
The method of claim 1 wherein the said carbon container has a subsequentially square cross-section.
Claim 8
Dependent Claim
76 words
Method for growing silicon crystal comprising: providing molten silicon in a vitreous carbon container; said container having an average thermal expansion coefficient of between about 3.0 to 4.3×10 6 °C. -1 between 20° C. and 650° C., density of about 1.5 grams per cubic centimeter and grain size of less than about 50 microns; and solidifying said molten silicon sequentially from the enclosed regions to the open region of said container to form crack-free silicon crystal.
Claim 9
Dependent Claim
76 words
Method for growing silicon crystal comprising: providing molten silicon in a vitreous carbon container; said container having an average thermal expansion coefficient of between about 3.0 to 4.3×10 6 °C. -1 between 20° C. and 650° C., density of about 1.5 grams per cubic centimeter and grain size of less than about 50 microns; and solidifying said molten silicon sequentially from the enclosed regions to the open region of said container to form crack-free silicon crystal.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-01-06 | 1984-07-07 | 1985-01-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-01-06 | 1988-07-07 | 1989-01-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-01-06 | 1992-07-07 | 1993-01-06 | $7700.00 | Window Closed / Lapsed |