US5019882A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Germanium channel silicon MOSFET
Assignee: International Business Machines Corp
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Filing: 1989-05-15
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Granted: 1991-05-28
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Expires: 2009-05-15
Abstract
Abstract An alloy layer comprising germanium and silicon is grown on top of a silicon substrate. The alloy layer is kept thin enough for proper pseudomorphic, dislocation free growth. A layer of silicon is applied to the alloy layer. The initial silicon layer is from two to three times as thick as the alloy layer. Approximately the upper two-thirds of the silicon layer is oxidized, either thermally, anodically or by plasma anodization. The silicon layer that remains between the silicon dioxide and the alloy layer is kept thin enough so that a parasitic channel does not form on the interface between the silicon and the silicon dioxide. The germanium alloyed channel is thus suitably bounded by silicon crystalline structures on both of the channel layer surfaces. The barrier heights between silicon dioxide and silicon are very large thus providing good carrie confinement. A suitably applied voltage will result in a region of high mobility charge carriers at the interface between the alloy layer and the upper silicon layer.
Inventors
- 👤 Paul M. Solomon
- 👤 Steven L. Wright
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:23
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/01; H10D30/021; H10D30/40; H10D30/47; H10D30/471; H10D30/473; H10D62/00; H10D62/80; H10D62/82; H10D62/822
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
90 words
A field effect transistor of the type wherein current in a channel between ohmic contacts is influenced by a potential applied to a gate disposed over said channel the improvement comprising: a substrate of a first monocrystalline semiconductor material, a strained, pseudomorphic, epitaxial channel layer of an alloy of said first semiconductor material and a second semiconductor material disposed on said substrate, an epitaxial layer of an oxidizable semiconductor material disposed on said channel layer, and, a gate oxide layer of said oxidizable semiconductor disposed on said oxidizable semiconductor layer.
Claim 2
Dependent Claim
90 words
A field effect transistor of the type wherein current in a channel between ohmic contacts is influenced by a potential applied to a gate disposed over said channel the improvement comprising: a substrate of a first monocrystalline semiconductor material, a strained, pseudomorphic, epitaxial channel layer of an alloy of said first semiconductor material and a second semiconductor material disposed on said substrate, an epitaxial layer of an oxidizable semiconductor material disposed on said channel layer, and, a gate oxide layer of said oxidizable semiconductor disposed on said oxidizable semiconductor layer.
Claim 3
Dependent Claim
16 words
A field effect transistor according to claim 1 wherein said first monocrystalline semiconductor material is silicon.
Claim 4
Dependent Claim
24 words
A field effect transistor according to claim 1 wherein said second semiconductor material is germanium and said alloy is Ge x Si 1-x .
Claim 5
Dependent Claim
15 words
A field effect transistor according to claim 1 wherein said oxidizable semiconductor material is silicon.
Claim 6
Dependent Claim
16 words
A field effect transistor according to claim 1 wherein said gate oxide layer is silicon dioxide.
Claim 7
Dependent Claim
28 words
A field effect transistor according to claim 1 wherein the content of said second semiconductor material in said alloy is sufficient to introduce strain in said channel layer.
Claim 8
Dependent Claim
27 words
A field effect transistor according to claim 1 wherein the content of said second semiconductor material in said alloy lies in a range of 1% to 99%.
Claim 9
Dependent Claim
21 words
A field effect transistor according to claim 1 wherein the content of said second semiconductor material in said alloy is 50%.
Claim 10
Dependent Claim
79 words
In a field effect transistor of the type wherein current in a channel between two ohmic contacts is influenced by a potential applied to a gate in proximity to said channel, the improvement comprising: a channel containing strained, pseudomorphic, epitaxial layer of a Ge x Si 1-x alloy disposed on a monocrystalline silicon substrate, an epitaxial layer of silicon disposed over Ge x Si 1-x layer, and a layer of silicon dioxide in contact with said layer of silicon.
Claim 11
Dependent Claim
79 words
In a field effect transistor of the type wherein current in a channel between two ohmic contacts is influenced by a potential applied to a gate in proximity to said channel, the improvement comprising: a channel containing strained, pseudomorphic, epitaxial layer of a Ge x Si 1-x alloy disposed on a monocrystalline silicon substrate, an epitaxial layer of silicon disposed over Ge x Si 1-x layer, and a layer of silicon dioxide in contact with said layer of silicon.
Claim 12
Dependent Claim
29 words
The invention of claim 1 wherein the Ge content of said channel containing layer is as high as possible to maintain said channel containing layer in the strained condition.
Claim 13
Dependent Claim
25 words
The invention of claim 9 wherein said silicon dioxide layer is about twice the thickness of either the channel containing layer or the silicon layer.
Claim 14
Dependent Claim
23 words
The invention of claim 9 wherein said channel containing layer and said silicon layer are about 10 nm and 2 nm thick, respectively.
Claim 15
Dependent Claim
14 words
The invention of claim 9 wherein said silicon dioxide layer is 10 nm thick.
Claim 16
Dependent Claim
23 words
The invention of claim 9 wherein the amount of Ge in said channel containing layer lies in a range between 1% to 99%.
Claim 17
Dependent Claim
16 words
The invention of claim 10 wherein the Ge content of said channel containing layer is 50%.
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) | 1994-05-27 | 1994-11-26 | 1995-05-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-05-27 | 1998-11-26 | 1999-05-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-05-27 | 2002-11-26 | 2003-05-28 | $7700.00 | Window Closed / Lapsed |