Patent US4871420A successfully refreshed from Google Patents.
US4871420A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Selective etching process
Assignee: Nokia Bell Labs
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Filing: 1988-02-10
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Granted: 1989-10-03
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Expires: 2008-02-10
Abstract
Abstract By adjusting the AC field conditions, i.e., by grounding the environment of a substrate being etched with a chlorine-containing plasma, a significant increase in etch selectivity is achieved. By applying a similar AC field adjustment to the reaction chamber surfaces, excellent etch uniformity is achieved in conjunction with excellent selectivity.
Inventors
- 👤 Frank B. Alexander, Jr.
- 👤 Pang-Dow Foo
- 👤 Ronald J. Schutz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 03:47
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/26; H10P50/264; H10P50/266; H10P50/267; H10P50/268; H10P50/24; H10P50/242
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
109 words
A process for fabricating a device comprising the steps of (1) in a vessel, etching a first material of a substrate by contact with chlorine-containing entities from a gas plasma while a second material of said substrate is also, during said etching, subjected to said entities; and (2) completing said device characterized in that said plasma is confined to a region that extends laterally from the periphery of said substrate a distance less than 20 percent of the effective diameter of said substrate, wherein said second material is substantially unaffected by said etching and wherein said confinement is accomplished by capacitively coupling the vicinity of said substrate to ground.
Claim 2
Dependent Claim
109 words
A process for fabricating a device comprising the steps of (1) in a vessel, etching a first material of a substrate by contact with chlorine-containing entities from a gas plasma while a second material of said substrate is also, during said etching, subjected to said entities; and (2) completing said device characterized in that said plasma is confined to a region that extends laterally from the periphery of said substrate a distance less than 20 percent of the effective diameter of said substrate, wherein said second material is substantially unaffected by said etching and wherein said confinement is accomplished by capacitively coupling the vicinity of said substrate to ground.
Claim 3
Dependent Claim
19 words
The process of claim 1 wherein said second material is a silicon oxide and said first material is silicon.
Claim 4
Dependent Claim
21 words
The process of claim 2 wherein said etching is accomplished in a reactor utilizing a hexagonal cathode to produce said plasma.
Claim 5
Dependent Claim
20 words
The process of claim 2 wherein said etching is accomplished in a reactor utilizing parallel electrodes to form said plasma.
Claim 6
Dependent Claim
34 words
The process of claim 2 wherein said plasma is confined to a region that is removed a distance of at least 20 percent of said substrate effective diameter from the surface of said vessel.
Claim 7
Dependent Claim
17 words
The process of claim 5 wherein the inner surfaces of said vessel are coated with a glass.
Claim 8
Dependent Claim
34 words
The process of claim 1 wherein said plasma is confined to a region that is removed a distance of at least 20 percent of said substrate effective diameter from the surfaces of said vessel.
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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) | 1992-10-02 | 1993-04-03 | 1993-10-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-10-02 | 1997-04-03 | 1997-10-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-10-02 | 2001-04-03 | 2001-10-03 | $7700.00 | Window Closed / Lapsed |