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Patent US4741925A successfully refreshed from Google Patents.
US4741925A
Expired / Lapsed
US
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Method of forming silicon nitride coating
Assignee: Osram Sylvania Inc
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Filing: 1987-09-14
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Granted: 1988-05-03
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Expires: 2007-09-14
Abstract
Abstract A silicon nitride coating is deposited on the inside surface of a crucible by pyrolysis. Reactive gases are fed through a tube into the crucible. The crucible is rotated during deposition and the crucible walls are maintained at a temperature of at least about 1250° C.
Inventors
- 👤 Arun K. Chaudhuri
- 👤 Vinod K. Sarin
- 👤 Joseph M. Harris
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 02:13
CPC Classifications
C; C23; C23C; C23C16/00; C23C16/22; C23C16/30; C23C16/34; C23C16/345; C23C16/44; C23C16/46
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
113 words
The method of depositing a silicon nitride coating on the inside surface of a crucible comprising the steps of: disposing the crucible inside a reaction chamber; positioning a closed end tube axially within the crucible, the tube having a plurality of peripheral holes at the lower end thereof; introducing reactive gases into the tube and out through the peripheral holes to the inside surface of the crucible where the gases react to produce and deposit silicon nitride coating; rotating the crucible during deposition to obtain uniformity of coating; maintaining crucible temperature during deposition of at least about 1250° C. so that the coating deposited on the crucible surface is alpha crystalline silicon nitride.
Claim 2
Independent Claim
113 words
The method of depositing a silicon nitride coating on the inside surface of a crucible comprising the steps of: disposing the crucible inside a reaction chamber; positioning a closed end tube axially within the crucible, the tube having a plurality of peripheral holes at the lower end thereof; introducing reactive gases into the tube and out through the peripheral holes to the inside surface of the crucible where the gases react to produce and deposit silicon nitride coating; rotating the crucible during deposition to obtain uniformity of coating; maintaining crucible temperature during deposition of at least about 1250° C. so that the coating deposited on the crucible surface is alpha crystalline silicon nitride.
Claim 3
Dependent Claim
14 words
The method of claim 1 wherein the reactive gases comprise ammonia and silicon tetrachloride.
Claim 4
Dependent Claim
15 words
The method of claim 2 wherein a carrier gas is used for the silicon tetrachloride.
Claim 5
Dependent Claim
14 words
The method of claim 3 wherein the carrier gas comprises hydrogen, helium or argon.
Claim 6
Dependent Claim
21 words
The method of claim 1 wherein an enhancer gas is introduced with the reactive gases to smoothen the silicon nitride coating.
Claim 7
Dependent Claim
14 words
The method of claim 5 wherein the enhancer gas comprises hydrogen chloride or nitrogen.
Claim 8
Dependent Claim
23 words
The method of claim 1 including the step of maintaining a pressure of 10 to 30 torr within the reaction chamber during deposition.
Claim 9
Dependent Claim
19 words
The method of claim 1 including the step of depositing a layer of silicon on the silicon nitride coating.
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) | 1991-05-03 | 1991-11-02 | 1992-05-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-05-03 | 1995-11-02 | 1996-05-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-05-03 | 1999-11-02 | 2000-05-03 | $7700.00 | Window Closed / Lapsed |