US5494891A
Expired / Lapsed
US
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Method for manufacturing three-terminal oxide superconducting devices
Assignee: Sumitomo Electric Industries Ltd
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Filing: 1994-12-06
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Granted: 1996-02-27
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Expires: 2014-12-06
Abstract
Abstract A superconducting device comprises a substrate, a non-superconducting layer formed in a principal surface of said substrate, an extremely thin superconducting channel formed of an oxide superconductor thin film on the non-superconducting layer. A superconducting source region and a superconducting drain region of a relatively thick thickness are formed of the oxide superconductor at the both sides of the superconducting channel separated from each other but electrically connected through the superconducting channel, so that a superconducting current can flow through the superconducting channel between the superconducting source region and the superconducting drain region. The superconducting device further includes a gate electrode through a gate insulator on the superconducting channel for controlling the superconducting current flowing through the superconducting channel, in which the superconducting channel is connected to the superconducting source region and the superconducting drain region at the higher portions than their one third height portions.
Inventors
- 👤 Takao Nakamura
- 👤 Michitomo Iiyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 02:17
CPC Classifications
H; H10; H10N; H10N60/00; H10N60/20; H10N60/205; H10N60/207; Y; Y10; Y10S; Y10S505/00; Y10S505/70; Y10S505/701; Y10S505/725; Y10S505/728
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
188 words
A method for manufacturing a three-terminal superconducting device, comprising the steps of: forming on a principal surface of a substrate a first oxide superconductor thin film; selectively etching a center portion of the first oxide superconductor thin film so that the portion of the first oxide superconductor thin film is completely removed and a surface of the substrate is exposed so as to form a superconducting source region and a superconducting drain region separately on the substrate; forming a non-superconductor layer having a thickness ranging from one third thickness to the same thickness of the superconducting source region and the superconducting region on the exposed surface of the substrate; forming a second extremely thin oxide superconductor thin film on the non-superconductor layer so that an extremely thin superconducting channel which is connected to the superconducting source region and the superconducting drain region at the higher portions than their one third height portions is formed on the non-superconductor layer; and forming a gate insulating layer and a gate electrode stacked on the gate insulating layer on a portion of the second oxide superconductor thin film above the non-superconductor layer.
Claim 2
Independent Claim
188 words
A method for manufacturing a three-terminal superconducting device, comprising the steps of: forming on a principal surface of a substrate a first oxide superconductor thin film; selectively etching a center portion of the first oxide superconductor thin film so that the portion of the first oxide superconductor thin film is completely removed and a surface of the substrate is exposed so as to form a superconducting source region and a superconducting drain region separately on the substrate; forming a non-superconductor layer having a thickness ranging from one third thickness to the same thickness of the superconducting source region and the superconducting region on the exposed surface of the substrate; forming a second extremely thin oxide superconductor thin film on the non-superconductor layer so that an extremely thin superconducting channel which is connected to the superconducting source region and the superconducting drain region at the higher portions than their one third height portions is formed on the non-superconductor layer; and forming a gate insulating layer and a gate electrode stacked on the gate insulating layer on a portion of the second oxide superconductor thin film above the non-superconductor layer.
Claim 3
Dependent Claim
47 words
A method as claimed in claim 1, wherein the non-superconductor layer is formed so as to have a thickness which is approximately half that of the first oxide superconductor thin film so that the superconducting channel, the gate insulating layer and the gate electrode are self aligned.
Claim 4
Dependent Claim
31 words
A method as claimed in claim 2, wherein the gate insulating layer is formed so as to cover the side surfaces of the superconducting source region and the superconducting drain region.
Claim 5
Dependent Claim
32 words
A method as claimed in claim 1, wherein the non-superconductor layer is formed so as to have almost the same thickness as those of the superconducting region and the superconducting drain region.
Claim 6
Dependent Claim
65 words
A method as claimed in claim 1, wherein the first oxide superconductor thin film is etched by an isotropic etching process so as to form a vacancy having a shape of a trapezoid between the superconducting source region and the superconducting drain region, widths of the superconducting source region and the superconducting drain region being narrower at the lower portions and narrowest at the bottom.
Claim 7
Dependent Claim
52 words
A method as claimed in claim 1, wherein the method further includes the step of heating the substrate to a temperature of 350° to 400° C. under a pressure lower than 1×10 -9 Torr after etching the first oxide superconductor thin film in order to clean the exposed surface of the substrate.
Claim 8
Dependent Claim
19 words
A method as claimed in claim 1, wherein the gate electrode is formed of a material which includes silicon.
Claim 9
Dependent Claim
16 words
A method as claimed in claim 7, wherein the gate electrode is formed of polycrystalline silicon.
Claim 10
Dependent Claim
57 words
A method as claimed in claim 7, wherein the method further comprises the step of heating the substrate so that silicon diffuses from the gate electrode into the superconducting source region and the superconducting drain region so as to form an insulating region isolating the gate electrode from the superconducting source region and the superconducting drain region.
Claim 11
Dependent Claim
33 words
A method as claimed in claim 9, wherein the method further comprises the step of forming a metal layer on the gate insulating layer which prevents silicon from diffusing into the superconducting channel.
Claim 12
Dependent Claim
29 words
A method as claimed in claim 1, wherein the non-superconductor layer is formed of an oxide having a crystal structure which is similar to that of the oxide superconductor.
Claim 13
Dependent Claim
23 words
A method as claimed in claim 11, wherein the non-superconductor layer is formed of Pr 1 Ba 2 Cu 3 O 7- ε.
Claim 14
Dependent Claim
35 words
A method as claimed in claim 1, wherein the method further comprises the step of forming a metal source electrode on the superconducting source region and a metal drain electrode on the superconducting drain region.
Claim 15
Dependent Claim
21 words
A method as claimed in claim 1, wherein the oxide superconductor is formed of high-T c (high critical temperature) oxide superconductor.
Claim 16
Dependent Claim
44 words
A method as claimed in claim 14, wherein the oxide superconductor is formed of an oxide superconductor material selected from the group consisting of a Y--Ba--Cu--O compound oxide superconductor material, a Bi--Sr--Ca--Cu--O compound oxide superconductor material, and a T1--Ba--Ca--Cu--O type compound oxide superconductor material.
Claim 17
Dependent Claim
36 words
A method as claimed in claim 1, wherein the substrate is formed of a material selected from the group consisting of a MgO (100) substrate, a SrTiO 3 (100) substrate and a CdNdAlO 4 (001) substrate.
Claim 18
Dependent Claim
26 words
The method as claimed in claim 1, wherein a thickness of the extremely thin oxide superconductor thin film is less than or equal to 5 nanometers.
Claim 19
Dependent Claim
21 words
The method as claimed in claim 14, wherein the high-T c oxide superconductor is a high-T c copper-oxide compound oxide superconductor.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-02-26 | 1999-08-28 | 2000-02-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-02-26 | 2003-08-28 | 2004-02-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-02-26 | 2007-08-28 | 2008-02-27 | $7700.00 | Window Closed / Lapsed |