US4547258A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Deposition of silicon at temperatures above its melting point
Assignee: Texas Instruments Inc
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Filing: 1982-12-22
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Granted: 1985-10-15
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Expires: 2002-12-22
Abstract
Abstract Liquid silicon is deposited on a high surface area column of silicon nitride particles, by hydrogen decomposition of trichlorosilane. This is accomplished in an environment heated to a temperature in excess of the melting point of silicon. After deposition, the liquid silicon flows by gravity to a collection point. Preferably a liquid transfer system moves the silicon directly to a crystal pulling operation. The liquid transfer to immediate pulling conserves energy and allows for continual withdrawal of melt from the reactor. The immediate pulling provides additional purification and the crystal thus pulled is preferably used as feedstock for a final crystal pulling operation.
Inventors
- 👤 David E. Witter
- 👤 Mohendra S. Bawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 12:35
CPC Classifications
C; C30; C30B; C30B15/00; C30B15/02; C01; C01B; C01B33/00; C01B33/02; C01B33/021; C01B33/027; C01B33/03; Y; Y10; Y10S; Y10S117/00; Y10S117/90
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
93 words
A process for producing silicon from a silicon bearing gas flow, comprising the steps of: providing a matrix of silicon nitride particles; forcing through a portion of said matrix of silicon nitride particles a stream of a silicon bearing gas mixture; said matrix of silicon nitride particles being heated to above the melting temperature of silicon while said gas flow is forced through said matrix; and collecting, at the bottom of said matrix of silicon nitride particles, liquid silicon which was deposited on said matrix of silicon nitride particles from said gas stream.
Claim 2
Dependent Claim
93 words
A process for producing silicon from a silicon bearing gas flow, comprising the steps of: providing a matrix of silicon nitride particles; forcing through a portion of said matrix of silicon nitride particles a stream of a silicon bearing gas mixture; said matrix of silicon nitride particles being heated to above the melting temperature of silicon while said gas flow is forced through said matrix; and collecting, at the bottom of said matrix of silicon nitride particles, liquid silicon which was deposited on said matrix of silicon nitride particles from said gas stream.
Claim 3
Dependent Claim
13 words
The process of claim 1, wherein said gas flow comprises trichlorosilane and hydrogen.
Claim 4
Dependent Claim
23 words
The process of claim 1, wherein said matrix is held at a temperature less than 50° C. above the melting point of silicon.
Claim 5
Dependent Claim
20 words
The process of claim 1, wherein said matrix of silicon nitride particles is contained in a reactor comprising silicon nitride.
Claim 6
Dependent Claim
15 words
The process of claim 4, wherein all of said reactor consists essentially of silicon nitride.
Claim 7
Dependent Claim
18 words
The process of claim 1, wherein said gas mixture further comprises a substantial percentage of an oxygen-bearing gas.
Claim 8
Dependent Claim
12 words
The process of claim 6, wherein said oxygen-bearing gas is nitrous oxide.
Claim 9
Dependent Claim
34 words
The process of claim 1, further comprising the step of: transporting said collected liquid silicon in the liquid state to an intermediate melt reservoir; and growing a rod of silicon from said melt reservoir.
Claim 10
Dependent Claim
33 words
The process of claim 8, further comprising the subsequent step of: incorporating said silicon rod into a final melt of silicon, and pulling a single large crystal of silicon from said final melt.
Claim 11
Dependent Claim
30 words
The process of claim 8, further comprising the step of: introducing a dopant impurity to said intermediate melt reservoir, prior to pulling said silicon rod from said intermediate melt reservoir.
Claim 12
Dependent Claim
28 words
The process of claim 8, wherein said step of transporting said liquid silicon to said intermediate melt reservoir comprises channeling said liquid silicon through piping comprising silicon nitride.
Claim 13
Dependent Claim
11 words
The process of claim 11, wherein said silicon rod is polycrystalline.
Claim 14
Dependent Claim
12 words
The process of claim 8, wherein said rod comprises substantially monocrystalline silicon.
Claim 15
Dependent Claim
49 words
The process of claim 13, further comprising an additional intermediate melt reservoir, said liquid silicon being selectively provided from said collection at the bottom of said matrix to alternate ones of said intermediate melt reservoirs; silicon-freezing valves being interposed between said collection point and each said intermediate melt reservoir.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-10-14 | 1989-04-15 | 1989-10-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-10-14 | 1993-04-15 | 1993-10-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-10-14 | 1997-04-15 | 1997-10-15 | $7700.00 | Window Closed / Lapsed |