Patent US4048712A successfully refreshed from Google Patents.
US4048712A
Expired / Lapsed
US
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Processes for manufacturing semiconductor devices
Assignee: Leonardo SpA
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Filing: 1975-12-01
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Granted: 1977-09-20
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Expires: 1995-12-01
Abstract
Abstract A process for manufacturing MES-FET transistors with self-aligned Schottky barrier gate electrode, in which a layer of metal is deposited on a semiconductor slice, a resist geometry corresponding to the spacing of the drain and source ohmic contacts is defined, the excess metal is etched away with controlled underetching under said resist, a metal is then evaporated for forming the ohmic contacts, the metal remaining after said etching constituting the self-aligned gate electrode.
Inventors
- 👤 Marina Buiatti
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 03:05
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/01; H10D30/061; H10D30/0612; H10D30/80; H10D30/87; H10D64/00; H10D64/01; H10D64/012; H10D64/0124; H10D64/0125; Y; Y10; Y10S; Y10S148/00; Y10S148/139; Y10S148/143
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
147 words
A process of manufacturing a field effect transistor having a Schottky barrier gate electrode, comprising the steps of providing a substrate of semiconductor material, depositing on the exposed surface of said substrate a first metal layer, a part of which will form the Schottky junction gate electrode, applying on said metal layer a strip of photo-resist having a width greater than the final width of said gate electrode and corresponding to the desired spacing between two ohmic contacts of said field effect transistor, chemically etching said first metal layer to obtain a desired underetching with respect to said photo-resist strip, applying a second metal layer to said substrate by an evaporation process to form said ohmic contacts, the edges of said contacts being defined with precision by the edges of said resist strip, and removing said photo-resist strip from said gate electrode and alloying said ohmic contacts.
Claim 2
Dependent Claim
147 words
A process of manufacturing a field effect transistor having a Schottky barrier gate electrode, comprising the steps of providing a substrate of semiconductor material, depositing on the exposed surface of said substrate a first metal layer, a part of which will form the Schottky junction gate electrode, applying on said metal layer a strip of photo-resist having a width greater than the final width of said gate electrode and corresponding to the desired spacing between two ohmic contacts of said field effect transistor, chemically etching said first metal layer to obtain a desired underetching with respect to said photo-resist strip, applying a second metal layer to said substrate by an evaporation process to form said ohmic contacts, the edges of said contacts being defined with precision by the edges of said resist strip, and removing said photo-resist strip from said gate electrode and alloying said ohmic contacts.
Claim 3
Dependent Claim
19 words
A process as claimed in claim 1, wherein said first metal layer forming the gate electrode consists of aluminum.
Claim 4
Dependent Claim
16 words
A process as claimed in claim 1, wherein said substrate semiconductor material consists of gallium arsenide.
Claim 5
Dependent Claim
21 words
A process as claimed in claim 1, wherein the chemical etching is carried out by a diluted solution of hydrofluoric acid.
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) | 1980-09-19 | 1981-03-21 | 1981-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-09-19 | 1985-03-21 | 1985-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-09-19 | 1989-03-21 | 1989-09-20 | $7700.00 | Window Closed / Lapsed |