US4289801A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for producing fine grained pyrolytic silicon nitride
Assignee: RTX Corp
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Filing: 1980-05-21
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Granted: 1981-09-15
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Expires: 2000-05-21
Abstract
Abstract Novel fine grained pyrolytic silicon nitride is produced by adding a substantial amount of methane to the normal reactant gases. Silicon tetrafluoride and ammonia in ratios of 60:40 to 10:90 may be employed with additions of methane in amounts equal to from 50 to 500% of the sum of silicon tetrafluoride and ammonia. When these reactant gases are passed over a heated substrate at a low pressure pyrolytic silicon nitride with a grain size of less than about 10 microns results.
Inventors
- 👤 Francis S. Galasso
- 👤 Malcolm Basche, deceased
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:49
CPC Classifications
C; C23; C23C; C23C16/00; C23C16/22; C23C16/30; C23C16/34; C23C16/345
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
112 words
A method for producing fine grain pyrolytic silicon nitride which comprises: providing reactant gases which comprise from 40 to 90% ammonia, balance silicon halide and an amount of methane equal to from about 50 to 500% of the reactant gases, mixing these gases and flowing them into a reaction chamber which contains a substrate, said reaction chamber and substrate being heated to from 1200° to 1900° C. and said reaction chamber being maintained at a partial pressure of less than 300 mm of Hg of reactant gases, so that fine grained pyrolytic silicon nitride free of carbon and having a grain size less than about 10 microns is deposited on the substrate.
Claim 2
Independent Claim
112 words
A method for producing fine grain pyrolytic silicon nitride which comprises: providing reactant gases which comprise from 40 to 90% ammonia, balance silicon halide and an amount of methane equal to from about 50 to 500% of the reactant gases, mixing these gases and flowing them into a reaction chamber which contains a substrate, said reaction chamber and substrate being heated to from 1200° to 1900° C. and said reaction chamber being maintained at a partial pressure of less than 300 mm of Hg of reactant gases, so that fine grained pyrolytic silicon nitride free of carbon and having a grain size less than about 10 microns is deposited on the substrate.
Claim 3
Dependent Claim
24 words
A method as in claim 1 wherein the ammonia is present in an amount equal to from 50 to 85% of the reactant gases.
Claim 4
Dependent Claim
23 words
A method as in claim 1 wherein the methane is added in amounts of from about 150 to 400% of the reactant gases.
Claim 5
Dependent Claim
20 words
A method as in claim 1 wherein the reaction chamber and substrate temperature is held between 1200° and 1600° C.
Claim 6
Dependent Claim
22 words
A method as in claim 1 wherein the reaction chamber partial pressure of reactant gases is less than 100 mm of Hg.
Claim 7
Dependent Claim
23 words
A method as in claim 1 wherein the reaction chamber partial pressure of reactant gas is from 1 to 10 mm of Hg.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-09-14 | 1985-03-16 | 1985-09-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-09-14 | 1989-03-16 | 1989-09-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-09-14 | 1993-03-16 | 1993-09-15 | $7700.00 | Window Closed / Lapsed |