US4398340A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for making thin film field effect transistors
Assignee: United States Department of the Army
•
Filing: 1982-04-26
•
Granted: 1983-08-16
•
Expires: 2002-04-26
Abstract
Abstract A method for making thin film field effect transistors that utilize a semnductor material that is altered by acid etching and providing steps for producing the transistors such that the semiconductor material is protected from the acid solutions and therefore preventing the semiconductor material from being altered in the process of making the transistors.
Inventors
- 👤 Robert L. Brown
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 15:52
CPC Classifications
H; H10; H10D; H10D99/00; H10D30/00; H10D30/60; H10D30/67; H10D30/674; H10D30/675
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
165 words
A method for making thin film field effect transistors comprising providing a substrate that has a substantially flat surface thereon, mounting a thin metal film on said surface of said substrate, photolithographic and acid etching first and second connections from said thin metal film to define a predetermined gap between said first and second connections, depositing a layer of semiconductor material in said gap and overlapping portions of said first and second connections, depositing an impervious insulation layer that overlaps all sides of said semiconductor layer over said semiconductor and a portion of said first and second connections, depositing a metal layer as a gate over said insulation layer and photolithographic and acid etching said metal gate to a size that is substantially identical in width to the gap between said first and second connections to provide a thin film field effect transistor that has high frequency characteristics due to the materials of the transistor and the precision by which the transistor can be made.
Claim 2
Independent Claim
165 words
A method for making thin film field effect transistors comprising providing a substrate that has a substantially flat surface thereon, mounting a thin metal film on said surface of said substrate, photolithographic and acid etching first and second connections from said thin metal film to define a predetermined gap between said first and second connections, depositing a layer of semiconductor material in said gap and overlapping portions of said first and second connections, depositing an impervious insulation layer that overlaps all sides of said semiconductor layer over said semiconductor and a portion of said first and second connections, depositing a metal layer as a gate over said insulation layer and photolithographic and acid etching said metal gate to a size that is substantially identical in width to the gap between said first and second connections to provide a thin film field effect transistor that has high frequency characteristics due to the materials of the transistor and the precision by which the transistor can be made.
Claim 3
Dependent Claim
74 words
The method of making a thin film field effect transistor as set forth in claim 1, wherein said semiconductor material is selected from polycrystalline cadmium selenide and polycrystalline cadmium sulfide and wherein said semiconductor material is protected from acid etching of said first and second connections by being deposited after said first and second connections are acid etched and being protected by said impervious insulation layer from acid etching of said gate metal layer.
Claim 4
Dependent Claim
54 words
A method of making a thin film field effect transistor as set forth in claim 1, wherein said first and second connections and said gate have metal contacts deposited over a portion thereof to form connections adapting the first and second connections and the gate for ready connection to elements external to the transistor.
References Cited (Backward Citations)
US3258663A
Cited
US3520051A
Cited
US3470610A
Cited
US3616527A
Cited
US4252580A
Cited
US4372032A
Cited
US4331758A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-08-15 | 1987-02-14 | 1987-08-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-08-15 | 1991-02-14 | 1991-08-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-08-15 | 1995-02-14 | 1995-08-16 | $7700.00 | Window Closed / Lapsed |