US4005467A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High-power field-effect transistor and method of making same
Assignee: Thales SA
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Filing: 1975-08-22
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Granted: 1977-01-25
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Expires: 1995-08-22
Abstract
Abstract A field-effect transistor designed for high-power operation has a P + substrate, preferably of gallium arsenide, topped by an N layer which in turn is covered by a much thinner N + film, the layer and film being bisected by a serpentine trench so as to form a pair of interdigitated comb-shaped N + segments overlain by metallic deposits which constitute a source and a drain electrode. The trench, advantageously produced by ion bombardment which also has a passivating effect on the surface areas thus exposed, cuts deep enough into the N layer to leave a channel whose conductivity is controlled by a gate electrode substantially coextensive therewith on the opposite substrate face. The prismatic substrate body is peripherally bounded by a mesa flank which may be passivated by a deposit of low-melting glass.
Inventors
- 👤 Claude Vergnolle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:32
CPC Classifications
H; H10; H10D; H10D64/00; H10D64/20; H10D64/23; H10D64/251; H10D64/257; H10D30/00; H10D30/80; H10D30/83; H10D62/00; H10D62/10; H10D62/117; H10D62/17; H10D62/343; H10D62/80; H10D62/85
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
134 words
A field-effect transistor comprising: a monocrystalline semiconductive substrate of one conductivity type forming a body with an upper and a lower surface; a semiconductive layer of opposite conductivity type overlying said upper surface; a semiconductive film of a resistivity and a thickness substantially less than those of said layer and of said opposite conductivity type disposed on said layer, said layer and film being provided with a trench cutting through said film and partly into said layer to leave a channel of controllable conductivity, said trench subdividing said layer and film into two semiconductive segments bounded by passivated surface areas; a pair of metallic deposits respectively overlying said segments and forming a pair of main electrodes separated by said trench; and a metallic gate electrode on said lower surface in line with said channel.
Claim 2
Dependent Claim
134 words
A field-effect transistor comprising: a monocrystalline semiconductive substrate of one conductivity type forming a body with an upper and a lower surface; a semiconductive layer of opposite conductivity type overlying said upper surface; a semiconductive film of a resistivity and a thickness substantially less than those of said layer and of said opposite conductivity type disposed on said layer, said layer and film being provided with a trench cutting through said film and partly into said layer to leave a channel of controllable conductivity, said trench subdividing said layer and film into two semiconductive segments bounded by passivated surface areas; a pair of metallic deposits respectively overlying said segments and forming a pair of main electrodes separated by said trench; and a metallic gate electrode on said lower surface in line with said channel.
Claim 3
Dependent Claim
21 words
A field-effect transistor as defined in claim 1 wherein said trench and said gate electrode extend along substantially coextensive serpentine paths.
Claim 4
Dependent Claim
21 words
A field-effect transistor as defined in claim 1 wherein said passivated surface areas include the bottom and sides of said trench.
Claim 5
Dependent Claim
19 words
A field-effect transistor as defined in claim 1 wherein said substrate, layer and film consist essentially of gallium arsenide.
Claim 6
Dependent Claim
42 words
A field-effect transistor as defined in claim 1 wherein said body is peripherally scarped with formation of a surrounding mesa flank forming part of said passivated surface areas, said flank extending at least to a boundary between said substrate and said layer.
Claim 7
Dependent Claim
17 words
A field-effect transistor as defined in claim 5 wherein said flank is provided with an insulating coating.
Claim 8
Dependent Claim
26 words
A field-effect transistor as defined in claim 6 wherein said substrate, layer and film consist essentially of gallium arsenide, said coating consisting of a low-melting glass.
Claim 9
Dependent Claim
29 words
A field-effect transistor as defined in claim 7 wherein said substrate has P-type conductivity in regions underlying said trench and nearly intrinsic conductivity in zones underlying said semiconductive segments.
Claim 10
Dependent Claim
31 words
A field-effect transistor as defined in claim 1 wherein the bottom of said trench is spaced from said substrate by a distance corresponding to substantially half the width of said trench.
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) | 1980-01-25 | 1980-07-26 | 1981-01-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-01-25 | 1984-07-26 | 1985-01-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-01-25 | 1988-07-26 | 1989-01-25 | $7700.00 | Window Closed / Lapsed |