US4998152A
Expired / Lapsed
US
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Thin film transistor
Assignee: International Business Machines Corp
•
Filing: 1990-01-24
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Granted: 1991-03-05
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Expires: 2010-01-24
Abstract
Abstract Thin film field effect transistors are disclosed having direct or near direct contact of the source and drain electrodes to the channel region. Inverted gate and non-inverted gate types are fabricated by forming metallic source and drain electrodes within a layer of semiconductor material in contact with the channel region. The electrodes are formed by converting monocrystalline, polycrystalline or amorphous silicon regions to a refractory metal such as tungsten by using a non-self-limiting metal hexafluoride reduction process. The tungsten conversion process is isotropic and provides self-alignment of the source and drain electrodes with the gate in the non-inverted gate TFT. The process is low temperature, allowing the use of amorphous silicon as the semiconductor material. The transistors are especially useful for formation on large glass substrates for fabricating large flat panel displays.
Inventors
- 👤 John Batey
- 👤 Rajiv V. Joshi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 14:58
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/01; H10D30/021; H10D30/031; H10D30/0312; H10D30/0314; H10D30/0316; H10D30/0321; H10D30/60; H10D30/67; H10D30/6729; H10D30/6737; H10D30/674; H10D30/6741; H10D30/6743; H10D30/6744; H10D30/6746
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
98 words
A thin film inverted gate, field effect transistor comprising: a gate electrode layer disposed on a substrate; a first insulating layer disposed on said substrate and said gate electrode; a semiconductor layer disposed on said insulator layer; source and drain electrodes formed within said semiconductor layer, said electrodes comprising a refractory metal formed in place of all or a part of the semiconductor layer, said source and drain electrodes being spaced apart in the region above said gate electrode; a second insulator layer disposed on said semiconductor layer extending across the region between said source and drain electrodes.
Claim 2
Dependent Claim
98 words
A thin film inverted gate, field effect transistor comprising: a gate electrode layer disposed on a substrate; a first insulating layer disposed on said substrate and said gate electrode; a semiconductor layer disposed on said insulator layer; source and drain electrodes formed within said semiconductor layer, said electrodes comprising a refractory metal formed in place of all or a part of the semiconductor layer, said source and drain electrodes being spaced apart in the region above said gate electrode; a second insulator layer disposed on said semiconductor layer extending across the region between said source and drain electrodes.
Claim 3
Dependent Claim
24 words
The thin film transistor of claim 1 wherein the semiconductor layer is one of a monocrystalline state, a polycrystalline state and an amorphous state.
Claim 4
Dependent Claim
16 words
The thin film transistor of claim 2 wherein the semiconductor layer is made of amorphous silicon.
Claim 5
Dependent Claim
16 words
The thin film transistor of claim 2 wherein the semiconductor layer is made of polycrystalline silicon.
Claim 6
Dependent Claim
16 words
The thin film transistor of claim 2 wherein the semiconductor layer is made of monocrystalline silicon.
Claim 7
Dependent Claim
23 words
The thin film transistor of claim 2 wherein the source and drain electrodes formed within the semiconductor layer contact the first insulator layer.
Claim 8
Dependent Claim
33 words
The thin film transistor of claim 2 wherein the source and drain electrodes formed within the semiconductor layer are spaced from said first insulator layer by a thin layer of said semiconductor layer.
Claim 9
Dependent Claim
30 words
The thin film transistor of claim 7 wherein the spacing between the source and drain electrodes and the first insulator layer is in the range between 100 to 500 angstroms.
Claim 10
Dependent Claim
25 words
The thin film transistor of claim 8 wherein the space between the source and drain electrodes and the first insulator layer is about 100 angstroms.
Claim 11
Dependent Claim
49 words
The thin film transistor of claim 2 wherein the source and drain electrodes are formed within said semiconductor layer by a reduction reaction with a hexafluoride of said refractory metal and said semiconductor layer, said refractory metal being formed substantially free of the semiconductor material of said semiconductor layer.
Claim 12
Dependent Claim
13 words
The thin film transistor of claim 10 wherein the refractory metal is tungsten.
Claim 13
Dependent Claim
12 words
The thin film transistor of claim 11 wherein the substrate is glass.
Claim 14
Dependent Claim
79 words
A thin film field effect transistor comprising: a semiconductor layer disposed on a substrate; a gate insulator disposed on said semiconductor layer; a gate electrode layer disposed on said gate insulator layer; and source and drain electrodes formed within said semiconductor layer, said electrodes comprising a refractory metal formed in place of all or a part of the semiconductor layer, said source and drain electrodes being spaced apart in a portion of the region below said gate insulator layer.
Claim 15
Dependent Claim
79 words
A thin film field effect transistor comprising: a semiconductor layer disposed on a substrate; a gate insulator disposed on said semiconductor layer; a gate electrode layer disposed on said gate insulator layer; and source and drain electrodes formed within said semiconductor layer, said electrodes comprising a refractory metal formed in place of all or a part of the semiconductor layer, said source and drain electrodes being spaced apart in a portion of the region below said gate insulator layer.
Claim 16
Dependent Claim
24 words
The thin film transistor of claim 13 wherein the semiconductor layer is one of a monocrystalline state, a polycrystalline state and an amorphous state.
Claim 17
Dependent Claim
16 words
A thin film transistor of claim 13 wherein the semiconductor layer is made of amorphous silicon.
Claim 18
Dependent Claim
16 words
The thin film transistor of claim 14 wherein the semiconductor layer is made of polycrystalline silicon.
Claim 19
Dependent Claim
16 words
The thin film transistor of claim 14 wherein the semiconductor layer is made of monocrystalline silicon.
Claim 20
Dependent Claim
51 words
The thin film transistor of claim 14 wherein the source and drain electrodes are formed within said semiconductor layer by a reduction reaction with a hexafluoride of said refractory metal and said semiconductor layer, said refractory metal being formed with substantially no trace of the semiconductor material of said semiconductor layer.
Claim 21
Dependent Claim
13 words
The thin film transistor of claim 8 wherein the refractory metal is tungsten.
Claim 22
Dependent Claim
12 words
The thin film transistor of claim 9 wherein the substrate is glass.
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| 3.5 Years (Year 4) | 1994-03-04 | 1994-09-03 | 1995-03-05 | $2000.00 | Window Closed / Lapsed |
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