Patent US4569722A successfully refreshed from Google Patents.
US4569722A
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Ethylene glycol etch for processes using metal silicides
Assignee: Nokia Bell Labs
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Filing: 1984-11-23
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Granted: 1986-02-11
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Expires: 2004-11-23
Abstract
Abstract A novel etchant which comprises a mixture of ethylene glycol and hydrofluoric acid, preferably buffered hydrofluoric acid, has been found to control the etch rate of refractory metal silicides, in particular titanium silicide, in a manner such that titanium silicide may be used in place of tantalum silicide for interconnects and gates in semiconductor integrated circuits.
Inventors
- 👤 Alvaro Maury
- 👤 Louis C. Parrillo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 11:01
CPC Classifications
H; H10; H10W; H10W20/00; H10W20/01; H10W20/031; H10W20/064; H10W20/066; H10D; H10D64/00; H10D64/01; H10D64/013; H10D64/01302; H10D64/01304; H10D64/01306; H10D64/01308; H10D64/0131; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283; H10P50/60; H10P50/66; H10P50/663; H10P50/667
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
22 words
A method for removing oxide materials from refractory metal silicides using an etching solution consisting essentially of ethylene glycol and hydrofluoric acid.
Claim 2
Independent Claim
22 words
A method for removing oxide materials from refractory metal silicides using an etching solution consisting essentially of ethylene glycol and hydrofluoric acid.
Claim 3
Dependent Claim
15 words
The method of claim 1 wherein buffered hydrofluoric acid is used in the etching solution.
Claim 4
Dependent Claim
18 words
The method of claim 2 wherein the hydrofluoric acid is buffered to a 30:1 concentration (H 2 O:HF).
Claim 5
Dependent Claim
18 words
The method of claim 2 wherein the hydrofluoric acid is buffered to a 15:1 concentration (H 2 O:HF).
Claim 6
Dependent Claim
22 words
The method of claim 2 wherein the etching solution comprises 60% to 80% ethylene glycol and 40% to 20% buffered hydrofluoric acid.
Claim 7
Dependent Claim
18 words
The method of claim 5 wherein the etching solution comprises 70% ethylene glycol and 30% buffered hydrofluoric acid.
Claim 8
Dependent Claim
13 words
The method of claim 1 wherein the refractory metal silicide is titanium silicide.
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) | 1989-02-10 | 1989-08-12 | 1990-02-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-02-10 | 1993-08-12 | 1994-02-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-02-10 | 1997-08-12 | 1998-02-11 | $7700.00 | Window Closed / Lapsed |