US4421593A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Reverse etching of chromium
Assignee: Intersil Corp
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Filing: 1983-04-11
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Granted: 1983-12-20
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Expires: 2003-04-11
Abstract
Abstract A process for reverse etching a layer of chromium on a substrate is provided wherein a layer of resist is formed on the chromium and developed, thus exposing a portion of the chromium. The exposed chromium is passivated by backscattering from a suitable backing plate in a plasma, the resist is removed and the unpassivated chromium etched with a conventional liquid etchant. The pattern formed in the chromium layer is the opposite of that original formed in the resist material.
Inventors
- 👤 Bernard J. Curtis
- 👤 Martin Ebnoether
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 10:11
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/68; C; C23; C23F; C23F1/00; C23F1/02; G03F1/80
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
117 words
A process of reverse etching a layer of chromium on a substrate comprising: (a) forming a layer of resist material on the chromium layer; (b) irradiating and developing the resist layer thereby exposing a portion of the chromium layer; (c) plasma treating an assembly comprising said substrate and a backing plate comprised of a material resistant to liquids capable of etching chromium for a time sufficient to form a passivating coating on the exposed chromium by back-scattering material from said backing plate, but insufficient to remove all of said resist material; (d) removing the remaining resist material, thus exposing the unpassivated portion of the chromium layer; and (e) etching the unpassivated chromium layer with a liquid etchant.
Claim 2
Dependent Claim
117 words
A process of reverse etching a layer of chromium on a substrate comprising: (a) forming a layer of resist material on the chromium layer; (b) irradiating and developing the resist layer thereby exposing a portion of the chromium layer; (c) plasma treating an assembly comprising said substrate and a backing plate comprised of a material resistant to liquids capable of etching chromium for a time sufficient to form a passivating coating on the exposed chromium by back-scattering material from said backing plate, but insufficient to remove all of said resist material; (d) removing the remaining resist material, thus exposing the unpassivated portion of the chromium layer; and (e) etching the unpassivated chromium layer with a liquid etchant.
Claim 3
Dependent Claim
16 words
A process in accordance with claim 1, additionally including the step of removing said passivating coating.
Claim 4
Dependent Claim
16 words
A process in accordance with claim 1, wherein the resist material is a positive resist material.
Claim 5
Dependent Claim
22 words
A process in accordance with claim 1, wherein the irradiated portion of the resist layer is wet developed with a suitable solvent.
Claim 6
Dependent Claim
28 words
A process in accordance with claim 1, wherein the irradiated portion of the resist layer is dry developed in a plasma substantially inert with regard to the chromium.
Claim 7
Dependent Claim
26 words
A process in accordance with claim 1, wherein the plasma in step (c) is selected from the group consisting of oxygen, argon and sulfur hexafluoride plasmas.
Claim 8
Dependent Claim
14 words
A process in accordance with claim 6, wherein said plasma is an oxygen plasma.
Claim 9
Dependent Claim
14 words
A process in accordance with claim 6, wherein said plasma is an argon plasma.
Claim 10
Dependent Claim
14 words
A process in accordance with claim 1, wherein said backing plate is silicon dioxide.
Claim 11
Dependent Claim
13 words
A process in accordance with claim l, wherein said backing plate is niobium.
Claim 12
Dependent Claim
32 words
A process in accordance with claim 1, wherein the resist is removed in step (d) by plasma etching in a plasma inert to the passivated and unpassivated portions of the chromium layer.
Claim 13
Dependent Claim
30 words
A process in accordance with claim 1, wherein the resist is removed in step (d) with a solvent substantially inert to the passivated and unpassivated portions of the chromium layer.
Claim 14
Dependent Claim
25 words
A process in accordance with claim 1, wherein the unpassivated chromium is etched with an aqueous solution of a ceric ammonium salt and sulfuric acid.
Claim 15
Dependent Claim
14 words
A process in accordance with claim 13, wherein said salt is ceric ammonium nitrate.
Claim 16
Dependent Claim
14 words
A process in accordance with claim 13, wherein said salt is ceric ammonium sulfate.
Claim 17
Dependent Claim
20 words
A process in accordance with claim 9, wherein the passivating coating is removed by etching in a fluorocarbon plasma. .
References Cited (Backward Citations)
US3640812A
Cited
US3692655A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-12-19 | 1987-06-20 | 1987-12-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-12-19 | 1991-06-20 | 1991-12-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-12-19 | 1995-06-20 | 1995-12-20 | $7700.00 | Window Closed / Lapsed |