US4554050A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Etching of titanium
Assignee: Nokia Bell Labs
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Filing: 1984-07-16
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Granted: 1985-11-19
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Expires: 2004-07-16
Abstract
Abstract The specification describes a technique for etching titanium using EDTA compounds. It is especially useful for selective etch processes such as those used to form titanium diffused waveguides in lithium niobate crystals.
Inventors
- 👤 William J. Minford
- 👤 Edmond J. Murphy
- 👤 Trudie C. Rice
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 02:29
CPC Classifications
C; C23; C23F; C23F1/00; C23F1/10; C23F1/14; C23F1/32; C23F1/38
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
28 words
Technique for etching titanium comprising the steps of: exposing a titanium surface to a solution comprising the ethylenediaminetetraacetic acid radical for a period sufficient to etch said surface.
Claim 2
Dependent Claim
28 words
Technique for etching titanium comprising the steps of: exposing a titanium surface to a solution comprising the ethylenediaminetetraacetic acid radical for a period sufficient to etch said surface.
Claim 3
Dependent Claim
45 words
Technique for selectively etching a titanium layer comprising the steps of applying to the titanium layer a photoresist or electron beam resist layer, patterning the resist layer, and subjecting the titanium regions exposed by the resist layer to a solution comprising the ethylenediaminetetraacetic acid radical.
Claim 4
Dependent Claim
45 words
Technique for selectively etching a titanium layer comprising the steps of applying to the titanium layer a photoresist or electron beam resist layer, patterning the resist layer, and subjecting the titanium regions exposed by the resist layer to a solution comprising the ethylenediaminetetraacetic acid radical.
Claim 5
Dependent Claim
21 words
Technique of claim 1 in which the solution contains ethylenediaminetetraacetic acid in the form of disodium ethylene diamine tetraacetic acid dihydrate.
Claim 6
Dependent Claim
12 words
Technique of claim 1 in which the solution contains an oxidation promoter.
Claim 7
Dependent Claim
17 words
Technique of claim 1 in which the solution is adjusted to have a pH greater than 9.
Claim 8
Dependent Claim
68 words
Method of manufacture of an optical waveguide comprising: forming a titanium layer on a crystal of lithium niobate, selectively masking said titanium layer, exposing the unmasked regions of the titanium layer to a solution comprising the ethylenediaminetetraacetic acid radical for a time sufficient to remove at least part of said unmasked regions, and heating the crystal to diffuse the remaining titanium into the crystal to form waveguiding regions.
Claim 9
Dependent Claim
68 words
Method of manufacture of an optical waveguide comprising: forming a titanium layer on a crystal of lithium niobate, selectively masking said titanium layer, exposing the unmasked regions of the titanium layer to a solution comprising the ethylenediaminetetraacetic acid radical for a time sufficient to remove at least part of said unmasked regions, and heating the crystal to diffuse the remaining titanium into the crystal to form waveguiding regions.
Claim 10
Dependent Claim
29 words
The technique of claim 6 in which the unmasked regions of titanium are slowly withdrawn from the solution during removal so that the titanium remaining has a varying thickness.
References Cited (Backward Citations)
US4080244A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-11-18 | 1989-05-20 | 1989-11-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-11-18 | 1993-05-20 | 1993-11-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-11-18 | 1997-05-20 | 1997-11-19 | $7700.00 | Window Closed / Lapsed |