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US6351004B1
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Tunneling transistor applicable to nonvolatile memory
Assignee: Panasonic Holdings Corp
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Filing: 2000-10-16
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Granted: 2002-02-26
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Expires: 2020-10-16
Abstract
Abstract A tunneling transistor is provided as an effective means for miniaturization of a semiconductor integrated circuit having nonvolatile memory. An insulating layer is disposed on a silicon substrate. A source and a drain are disposed on the insulating layer, with an insulator of a few nanometers in thickness that provides a tunnel barrier being interposed between the source and the drain. A ferroelectric layer that exhibits spontaneous polarization is disposed directly above a region of the source that is adjacent to the insulator. With this construction, when the ferroelectric layer is polarized in a predetermined direction, at least a portion of the region of the source adjacent to the insulator forms a depletion region, with it being possible to vary the amount of current tunneling through the insulator depending on whether the ferroelectric layer is polarized or not.
Inventors
- 👤 Yasuhiro Shimada
- 👤 Shinichiro Hayashi
- 👤 Kiyoshi Uchiyama
- 👤 Keisuke Tanaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 01:55
CPC Classifications
H; H10; H10D; H10D8/00; H10D8/70; H10D30/00; H10D30/01; H10D30/021; H10D30/0415; H10D30/60; H10D30/701; H10D64/00; H10D64/01; H10D64/031; H10D64/033
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
68 words
A tunneling transistor having a source, a drain, and a gate, comprising: a tunnel barrier layer which forms a tunnel barrier between the source and the drain; and a ferroelectric layer which exhibits spontaneous polarization, wherein when the ferroelectric layer is polarized in a predetermined direction, the polarization induces formation of a depletion region within a region of the source that is adjacent to the tunnel barrier layer.
Claim 2
Dependent Claim
68 words
A tunneling transistor having a source, a drain, and a gate, comprising: a tunnel barrier layer which forms a tunnel barrier between the source and the drain; and a ferroelectric layer which exhibits spontaneous polarization, wherein when the ferroelectric layer is polarized in a predetermined direction, the polarization induces formation of a depletion region within a region of the source that is adjacent to the tunnel barrier layer.
Claim 3
Dependent Claim
40 words
The tunneling transistor of claim 1 , wherein the ferroelectric layer is interposed between the gate and the tunnel barrier layer, and the polarization of the ferroelectric layer is caused by an application of a predetermined bias to the gate.
Claim 4
Dependent Claim
31 words
The tunneling transistor of claim 2 , wherein the polarization of the ferroelectric layer induces complete depletion of the region of the source that is adjacent to the tunnel barrier layer.
Claim 5
Dependent Claim
25 words
The tunneling transistor of claim 1 , wherein the tunnel barrier layer is formed by interposing an insulating material between the source and the drain.
Claim 6
Dependent Claim
40 words
The tunneling transistor of claim 4 , wherein the source and the drain are made of a material selected from the group consisting of n-type silicon and p-type silicon, and the tunnel barrier layer is made of a silicon oxide.
Claim 7
Dependent Claim
58 words
The tunneling transistor of claim 2 , wherein the source and the drain are disposed adjacent to each other on a single substrate, the tunnel barrier layer is interposed between the source and the drain, and the ferroelectric layer and the gate are disposed in the stated order on the source, the tunnel barrier layer, and the drain.
Claim 8
Dependent Claim
73 words
The tunneling transistor of claim 2 , wherein the drain is disposed on a substrate, the tunnel barrier layer and the source are disposed in the stated order on the drain, and the ferroelectric layer and the gate are disposed, in the stated order, on part of an upper surface of the source which corresponds to part of a lower surface of the tunnel barrier layer that is in contact with the drain.
Claim 9
Dependent Claim
54 words
The tunneling transistor of claim 2 , further comprising: a floating electrode which is disposed adjacent to a surface of the ferroelectric layer on the side of the tunnel barrier layer; and an insulating layer which is disposed adjacent to a surface of the floating electrode on the side of the tunnel barrier layer.
Claim 10
Dependent Claim
34 words
The tunneling transistor of claim 8 , wherein the insulating layer has a permittivity such that a predetermined voltage is applied to the ferroelectric layer when the predetermined bias is applied to the gate.
Claim 11
Dependent Claim
61 words
The tunneling transistor of claim 9 , wherein the ferroelectric layer is made of at least one material selected from the group consisting of SrBi 2 Ta 2 O 9 and PZT(Pb(Zr 1−x Ti x )O 3 ), and the insulating layer is made of a material selected from the group consisting of SrTa 2 O 6 and SrTiO 3 .
Claim 12
Dependent Claim
20 words
The tunneling transistor of claim 10 , wherein the ferroelectric layer is formed by growing crystals on the floating electrode.
Claim 13
Dependent Claim
79 words
The tunneling transistor of claim 8 , wherein the drain is disposed on a substrate, the tunnel barrier layer and the source are disposed in the stated order on the drain, and the insulating layer, the floating electrode, the ferroelectric layer, and the gate are disposed, in the stated order, on part of an upper surface of the source which corresponds to part of a lower surface of the tunnel barrier layer that is in contact with the drain.
Claim 14
Dependent Claim
28 words
The tunneling transistor of claim 2 , wherein a barrier potential of the tunnel barrier layer is controlled by a level of a bias applied to the gate.
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) | 2005-02-25 | 2005-08-27 | 2006-02-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2009-02-25 | 2009-08-27 | 2010-02-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2013-02-25 | 2013-08-27 | 2014-02-26 | $7700.00 | Window Closed / Lapsed |