US4733283A
Expired / Lapsed
US
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GaAs semiconductor device
Assignee: Fujitsu Ltd
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Filing: 1986-09-19
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Granted: 1988-03-22
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Expires: 2006-09-19
Abstract
Abstract A method of manufacturing a GaAS semiconductor device of an E/D construction having a GaAs/AlGaAs heterojunction and utilizing a two-dimensional electron gas, which includes the steps of forming a heterojunction semiconductor substrate and etching a portion of the substrate to provide a gate portion of a depletion-mode FET. When the substrate of a semi-insulating GaAs layer, an undoped GaAs, an N-type AlGaAs layer providing an electron-supply layer, and a GaAs layer is formed, the GaAs layer is composed of a first GaAs layer, an etching stoppable AlGaAs layer, and a second GaAs layer, the first GaAs layer being formed on the N-type GaAs layer. The etching for provision of the gate portion is carried out by a dry etching method using an etchant of CCl 2 F 2 gas, so that the second GaAs layer can be etched but the AlGaAs layer cannot be etched. Thus, the thickness of the layers between a gate electrode of the depletion-mode FET and the GaAs/AlGaAs heterojunction plane is determined by the formation of the heterojunction substrate, and consequently a better uniformity of the threshold voltage of depletion-mode FET's is obtained.
Inventors
- 👤 Shigeru Kuroda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 14:20
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/80; H10D30/40; H10D30/47; H10D30/471; H10D30/475; H10D30/4755; H10D30/801; H10D84/00; H10D84/01; H10D84/02; H10D84/05; H10P; H10P50/00; H10P50/20; H10P50/24; H10P50/246; H10W; H10W10/00; H10W10/01; H10D84/80; H10D84/82; H10D84/83; H10D84/84; H10D84/86; Y; Y10; Y10S; Y10S438/00; Y10S438/97
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
219 words
A GaAs semiconductor device comprising an enhancement-mode FET and a depletion-mode FET which have a heterojunction and at least one of which utilizes a two-dimensional electron gas, said semiconductor device comprising: a semi-insulating GaAs substrate; an updoped GaAs layer formed on said semi-insulating GaAs substrate; an N-type AlGaAs layer formed on said undoped GaAs layer and including an exposed portion; a first N-type GaAs layer formed on said N-type AlGaAs layer and having a groove formed therein; an etching stoppable N-type AlGaAs layer formed on said first N-type GaAs layer; a second N-type GaAs layer formed on said etching stoppable N-type AlGaAs layer and having a groove formed therein; a gate electrode of said enhancement-mode FET self-aligningly filling the groove formed in said first GaAs layer and formed on an exposed portion of said N-type AlGaAs layer for providing an electron supply layer for said enhancement-mode FET; and a gate electrode of said depletion-mode FET for self-aligning filling a groove formed in said second N-type GaAs layer and formed on an exposed portion of said etching stoppable AlGaAs layer, said etching stoppable layer, said first GaAs layer and said N-type AlGaAs layer providing an electron supply layer for said depletion-mode FET, said gate electrode of said enhancement-mode FET and said gate electrode of said depletion-mode FET being formed simultaneously.
Claim 2
Dependent Claim
219 words
A GaAs semiconductor device comprising an enhancement-mode FET and a depletion-mode FET which have a heterojunction and at least one of which utilizes a two-dimensional electron gas, said semiconductor device comprising: a semi-insulating GaAs substrate; an updoped GaAs layer formed on said semi-insulating GaAs substrate; an N-type AlGaAs layer formed on said undoped GaAs layer and including an exposed portion; a first N-type GaAs layer formed on said N-type AlGaAs layer and having a groove formed therein; an etching stoppable N-type AlGaAs layer formed on said first N-type GaAs layer; a second N-type GaAs layer formed on said etching stoppable N-type AlGaAs layer and having a groove formed therein; a gate electrode of said enhancement-mode FET self-aligningly filling the groove formed in said first GaAs layer and formed on an exposed portion of said N-type AlGaAs layer for providing an electron supply layer for said enhancement-mode FET; and a gate electrode of said depletion-mode FET for self-aligning filling a groove formed in said second N-type GaAs layer and formed on an exposed portion of said etching stoppable AlGaAs layer, said etching stoppable layer, said first GaAs layer and said N-type AlGaAs layer providing an electron supply layer for said depletion-mode FET, said gate electrode of said enhancement-mode FET and said gate electrode of said depletion-mode FET being formed simultaneously.
Claim 3
Dependent Claim
25 words
A device according to claim 1, wherein a drain electrode of said enhancement-mode FET and a source electrode of said depletion-mode FET are in common.
Claim 4
Dependent Claim
19 words
A device according to claim 1, wherein all the electrodes of both said FET's are separated from each other.
Claim 5
Dependent Claim
44 words
The device of claim 1, comprising an isolation region for isolating said FETSs from each other, said isolation region extending to include the portion of said N-type AlGaAs layer underneath said depletion-mode GaAs FET, wherein only said enhancement-mode FET utilizes said two-dimensional electron gas.
Claim 6
Dependent Claim
29 words
The device of claim 1, comprising an isolation region for isolating said FETs, said isolation region extending to said substrate, wherein both said FETs utilize a two-dimensional electron gas.
Claim 7
Dependent Claim
20 words
The device of claim 1, comprising two source and drain electrodes of said FETs being provided by a single electrode.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1991-03-22 | 1991-09-21 | 1992-03-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-03-22 | 1995-09-21 | 1996-03-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-03-22 | 1999-09-21 | 2000-03-22 | $7700.00 | Window Closed / Lapsed |