Patent US4888142A successfully refreshed from Google Patents.
US4888142A
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Process for producing β-form Si3 N4
Assignee: Coorstek KK
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Filing: 1987-12-22
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Granted: 1989-12-19
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Expires: 2007-12-22
Abstract
Abstract Disclosed is a process for producing beta -form Si3N4 comprising firing amorphous or alpha -form Si3N4 of high chemical purity in a non-oxidizing atmosphere under an elevated pressure at a temperature of at least about 1600 DEG C., as well as a process for producing an article comprising such beta -form Si3N4.
Inventors
- 👤 Kenrou Hayashi
- 👤 Reiji Oguma
- 👤 Masayuki Tamura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 12:39
CPC Classifications
C; C30; C30B; C30B35/00; C30B35/002; C01; C01B; C01B21/00; C01B21/06; C01B21/068; C01B21/0687; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/593; C04B35/5935; C23; C23C; C23C16/00; C23C16/22; C23C16/30; C23C16/34; C23C16/345; C30B15/00; C30B15/10; C01P; C01P2002/00; C01P2002/02; C01P2006/00; C01P2006/80
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
114 words
A process for producing a β-form Si 3 N 4 article, comprising the steps of: depositing a Si 3 N 4 starting material comprising less than about 0.5% by weight of impurities on a substrate by chemical vapor deposition; firing the Si 3 N 4 deposit in a non-oxidizing atmosphere consisting essentially of one of N 2 , NH 3 and mixtures thereof under an elevated pressure of at least about 2 atm at a temperature of at least about 1700° C. so as to obtain a Si 3 N 4 article comprising at least about 60% by weight of β-form Si 3 N 4 ; and removing the substrate after the deposition step.
Claim 2
Dependent Claim
114 words
A process for producing a β-form Si 3 N 4 article, comprising the steps of: depositing a Si 3 N 4 starting material comprising less than about 0.5% by weight of impurities on a substrate by chemical vapor deposition; firing the Si 3 N 4 deposit in a non-oxidizing atmosphere consisting essentially of one of N 2 , NH 3 and mixtures thereof under an elevated pressure of at least about 2 atm at a temperature of at least about 1700° C. so as to obtain a Si 3 N 4 article comprising at least about 60% by weight of β-form Si 3 N 4 ; and removing the substrate after the deposition step.
Claim 3
Dependent Claim
21 words
A process according to claim 1, wherein said Si 3 N 4 starting material comprises α-form Si 3 N 4 .
Claim 4
Dependent Claim
21 words
A process according to claim 1, wherein said Si 3 N 4 starting material comprises amorphus Si 3 N 4 .
Claim 5
Dependent Claim
14 words
A process according to claim 1, wherein said non-oxidizing atmosphere comprises N 2 gas.
Claim 6
Dependent Claim
14 words
A process according to claim 1, wherein said non-oxidizing atmosphere comprises NH 3 gas.
Claim 7
Dependent Claim
21 words
A process according to claim 1, wherein said non-oxidizing atmosphere comprises a mixture of N 2 gas and NH 3 gas.
Claim 8
Dependent Claim
19 words
A process according to claim 1, wherein said elevated pressure in the firing is at least about 5 atm.
Claim 9
Dependent Claim
18 words
A process according to claim 1, wherein said temperature in the firing is less than about 1850° C.
Claim 10
Dependent Claim
11 words
A process according to claim 1, wherein said substrate comprises carbon.
Claim 11
Dependent Claim
12 words
A process according to claim 1, wherein said substrate comprises quartz glass.
Claim 12
Dependent Claim
11 words
A process according to claim 1, wherein said substrate comprises silicon.
Claim 13
Dependent Claim
22 words
A process according to claim 1, wherein said Si 3 N 4 article comprises less than about 0.5% by weight of impurities.
Claim 14
Dependent Claim
19 words
A process according to claim 8, wherein the firing step is maintained at a pressure of about 10 atm.
Claim 15
Dependent Claim
17 words
A process according to claim 1, wherein said impurities comprise Na, Ca, Fe, Al, Cr and Mn.
Claim 16
Dependent Claim
19 words
A process according to claim 14, wherein said impurities comprise an amount equal to less than 10 ppm each.
Claim 17
Dependent Claim
25 words
A process according to claim 15, wherein said Si 3 N 4 article comprises about 80% by weight of β-form Si 3 N 4 .
Claim 18
Dependent Claim
125 words
A process for producing a β-form Si 3 N 4 article, comprising the steps of: depositing a Si 3 N 4 starting material comprising less than about 0.5% by weight of impurities on a substrate selected from the group consisting of carbon, quartz glass and silicon by chemical vapor deposition; firing the Si 3 N 4 deposit in a non-oxidizing atmosphere consisting essentially of one of N 2 , NH 3 and mixtures thereof under an elevated pressure of at least about 2 atm at a temperature of at least about 1700° C. so as to obtain a Si 3 N 4 article comprising at least about 60% by weight of β-form Si 3 N 4 ; and removing the substrate after the deposition step.
Claim 19
Dependent Claim
125 words
A process for producing a β-form Si 3 N 4 article, comprising the steps of: depositing a Si 3 N 4 starting material comprising less than about 0.5% by weight of impurities on a substrate selected from the group consisting of carbon, quartz glass and silicon by chemical vapor deposition; firing the Si 3 N 4 deposit in a non-oxidizing atmosphere consisting essentially of one of N 2 , NH 3 and mixtures thereof under an elevated pressure of at least about 2 atm at a temperature of at least about 1700° C. so as to obtain a Si 3 N 4 article comprising at least about 60% by weight of β-form Si 3 N 4 ; and removing the substrate after the deposition step.
Claim 20
Dependent Claim
23 words
A process according to claim 11, wherein the starting material comprises amorphous or a-form Si 3 N 4 prepared by chemical vapor deposition.
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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) | 1992-12-18 | 1993-06-19 | 1993-12-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-12-18 | 1997-06-19 | 1997-12-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-12-18 | 2001-06-19 | 2001-12-19 | $7700.00 | Window Closed / Lapsed |