Patent US4769689A successfully refreshed from Google Patents.
US4769689A
Expired / Lapsed
US
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Stress relief in epitaxial wafers
Assignee: Nokia Bell Labs
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Filing: 1987-07-13
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Granted: 1988-09-06
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Expires: 2007-07-13
Abstract
Abstract The specification describes an epitaxial structure designed to reduce or eliminate the bowing of semiconductor wafers due to stresses caused by lattice mismatch between a heavily boron doped substrate and a lightly doped epitaxial layer. The lattice mismatch is reduced or eliminated by doping germanium into the substrate prior to epitaxial growth.
Inventors
- 👤 Wen Lin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 16:42
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/20; H10P14/36; H10P14/29; H10P14/2901; H10P14/2902; H10P14/2905
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
63 words
Expitaxial structure comprising a silicon substrae and an epitaxial layer on the silicon substrate, said substrate containing boron and germanium dopants, said substrate has p-type conductvity, said germanium dopant not changing said conductivity type, the respective amounts of boron (B) and germanium (Ge) contained in the substrate are approximately related by the expression: C.sub.GE =approximately 8C.sub.B where C is concentration in atomic %.
Claim 2
Dependent Claim
63 words
Expitaxial structure comprising a silicon substrae and an epitaxial layer on the silicon substrate, said substrate containing boron and germanium dopants, said substrate has p-type conductvity, said germanium dopant not changing said conductivity type, the respective amounts of boron (B) and germanium (Ge) contained in the substrate are approximately related by the expression: C.sub.GE =approximately 8C.sub.B where C is concentration in atomic %.
Claim 3
Dependent Claim
14 words
Structure of claim 1 in which C B is greater than 0.002 atomic %.
Claim 4
Dependent Claim
14 words
Structure of claim 1 in which C B is greater than 0.01 atomic %.
Claim 5
Dependent Claim
19 words
Structure of claim 1 in which the epitaxial layer is silicon with a thickness of greater than 3 μm.
References Cited (Backward Citations)
US3812519A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-09-06 | 1992-03-07 | 1992-09-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-09-06 | 1996-03-07 | 1996-09-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-09-06 | 2000-03-07 | 2000-09-06 | $7700.00 | Window Closed / Lapsed |