EP0480814A2
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EP
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Superconducting device having an extremely thin superconducting channel formed of oxide superconductor material and method for manufacturing the same
Assignee: Sumitomo Electric Industries Ltd
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Filing: 1991-10-08
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Granted: —
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Expires: 2011-10-08
Abstract
Abstract A superconducting device comprises a superconducting channel constituted of an oxide superconductor thin film formed on a substrate, a superconductor source electrode and a superconductor drain electrode formed at opposite ends of the superconducting channel, so that a superconducting current can flow through the superconducting channel between the source electrode and the drain electrode. A gate electrode is located through an insulating layer on the superconducting channel so as to control the superconducting current flowing through the superconducting channel. The oxide superconductor thin film of the superconducting channel is formed of a c -axis oriented oxide superconductor crystal, and the oxide superconductor thin film of the superconductor source electrode and the superconductor drain electrode are formed of an a-axis oriented oxide superconductor crystal. The superconducting channel is continuous to the superconductor source electrode and the superconductor drain electrode.
Inventors
- 👤 Takao Nakamura
- 👤 Hiroshi Inada
- 👤 Michitomo Iiyama
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 14:21
CPC Classifications
H; H10; H10N; H10N60/00; H10N60/20; H10N60/205; H10N60/207; Y; Y10; Y10S; Y10S505/00; Y10S505/70; Y10S505/701; Y10S505/702; Y10S505/703; Y10S505/725; Y10S505/729
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
142 words
A superconducting device comprising a substrate, a superconducting channel constituted of an oxide superconductor thin film formed on said substrate, a superconductor source electrode and a superconductor drain electrode formed at opposite ends of the superconducting channel, so that a superconducting current can flow through said superconducting channel between said superconductor source electrode and said superconductor drain electrode, and a gate electrode located through an insulating layer on the superconducting channel so as to control the superconducting current flowing through the superconducting channel, said oxide superconductor thin film of said superconducting channel being formed of a c -axis oriented oxide superconductor crystal, and said oxide superconductor thin film of said superconductor source electrode and said superconductor drain electrode being formed of an a-axis oriented oxide superconductor crystal, said superconducting channel being continuous to said superconductor source electrode and said superconductor drain electrode.
Claim 2
Dependent Claim
41 words
A superconducting device claimed in Claim 1 wherein said oxide superconductor thin film of said superconductor source electrode and said superconductor drain electrode is formed of the same material as that of said oxide superconductor thin film of said superconducting channel.
Claim 3
Dependent Claim
71 words
A superconducting device claimed in Claim 1 wherein said c -axis oriented oxide superconductor thin film of said superconducting channel is formed to extend over a principal surface of said substrate and on a projecting insulating region formed on said principal surface, and said superconductor source electrode and said superconductor drain electrode are located on said c -axis oriented oxide superconductor thin film at both sides of said projecting insulating region.
Claim 4
Dependent Claim
61 words
A superconducting device claimed in Claim 3 wherein said c -axis oriented oxide superconductor thin film is shallowly recessed at both sides of said projecting insulating region, and said superconductor source electrode and said superconductor drain electrode are located on the shallowly recessed portions of said c -axis oriented oxide superconductor thin film at both sides of said projecting insulating region.
Claim 5
Dependent Claim
39 words
A superconducting device claimed in Claim 4 wherein said shallowly recessed portions of said c -axis oriented oxide superconductor thin film formed at both sides of said projecting insulating region have a depth of not less than ten nanometers.
Claim 6
Dependent Claim
66 words
A superconductor device claimed in Claim 1 wherein said superconductor source electrode and said superconductor drain electrode are located on a planer principal surface of said substrate separately from each other, and said c -axis oriented oxide superconductor thin film of said superconducting channel is formed on said planer principal surface of said substrate to extend between said superconductor source electrode and said superconductor drain electrode.
Claim 7
Dependent Claim
50 words
A superconducting device claimed in Claim 6 wherein said gate electrode is formed of a normal conductor material located on said superconducting channel, and a source electrode and a drain electrode formed of a normal conductor material are formed on said superconductor source electrode and said superconductor drain electrode, respectively.
Claim 8
Dependent Claim
46 words
A superconducting device claimed in Claim 1 wherein the oxide superconductor thin film is formed of a material selected from the group consisting of a Y-Ba-Cu-O type compound oxide superconductor material, a Bi-Sr-Ca-Cu-O type compound oxide superconductor material, and a Tl-Ba-Ca-Cu-O type compound oxide superconductor material.
Claim 9
Dependent Claim
38 words
A superconducting device claimed in Claim 1 wherein the substrate is formed of a material selected from the group consisting of a MgO (100) substrate, a SrTiO₃ (100) substrate and a CdNdAlO₄ (001) substrate, and a semiconductor substrate.
Claim 10
Dependent Claim
41 words
A superconducting device claimed in Claim 1 wherein the substrate is formed of a silicon substrate and a principal surface of the silicon substrate is coated with insulating material layers which are formed of a MgAl₂O₄ layer and a BaTiO₃ layer.
Claim 11
Independent Claim
162 words
A method of manufacturing a superconducting device, comprising the step of preparing a substrate having a projecting insulating region formed on a principal surface thereof, forming a c -axis oriented oxide superconductor thin film on the principal surface of the substrate including the projection so that a thickness of the oxide superconductor thin film on said projecting insulating region is thinner than that of the oxide superconductor thin film on the substrate other than said projecting insulating region, providing a gate electrode through a gate insulator on a portion of said c -axis oriented oxide superconductor thin film on said projecting insulating region, shallowly recessing said c -axis oriented oxide superconductor thin film at both sides of said projecting insulating region, and forming a superconductor source electrode and a superconductor drain electrode of an a-axis oriented oxide superconductor thin film on the shallowly recessed portions of said c -axis oriented oxide superconductor thin film at both sides of said projecting insulating region.
Claim 12
Dependent Claim
81 words
A method claimed in Claim 11 wherein said c -axis oriented oxide superconductor thin film is formed so that the thickness of the oxide superconductor thin film on said projecting insulating region is not greater than five nanometers, and said shallowly recessed portions of said c -axis oriented oxide superconductor thin film is formed by etching said c -axis oriented oxide superconductor thin film at both sides of said projecting insulating region by a depth of not less than ten nanometers.
Claim 13
Dependent Claim
111 words
A method claimed in Claim 11 wherein said shallowly recessed portions of said c -axis oriented oxide superconductor thin film is formed by forming a refractory metal mask on said gate electrode and etching said c -axis oriented oxide superconductor thin film by using said refractory metal mask as a mask, and said superconductor source electrode and said superconductor drain electrode of the a-axis oriented oxide superconductor thin film are formed on the shallowly recessed portions of said c -axis oriented oxide superconductor thin film at both sides of said projecting insulating region by depositing an a-axis oriented oxide superconductor thin film by using said refractory metal mask as a mask.
Claim 14
Independent Claim
174 words
A method of manufacturing a superconducting device, comprising the step of preparing a substrate having a planar principal surface thereof, forming a superconductor source electrode and a superconductor drain electrode of an a-axis oriented oxide superconductor thin film on said planar principal surface of said substrate separately from each other, forming on said principal surface of said substrate a c -axis oriented oxide superconductor thin film which is thinner than said a-axis oriented oxide superconductor thin film, so that a superconducting channel is formed between said superconductor source electrode and said superconductor drain electrode, providing a gate electrode through a gate insulator on said c -axis oriented oxide superconductor thin film between said superconductor source electrode and said superconductor drain electrode, removing a portion of said c -axis oriented oxide superconductor thin film on each of said superconductor source electrode and said superconductor drain electrode, and forming a source electrode and a drain electrode of a normal conductor material on an exposed portion of said superconductor source electrode and said superconductor drain electrode, respectively.
Claim 15
Dependent Claim
135 words
A method claimed in Claim 14 wherein said superconductor source electrode and said superconductor drain electrode are formed by depositing a crystal disturbing layer on a selected position of said principal surface of said substrate, uniformly depositing an a-axis oriented oxide superconductor thin film on said principal surface of said substrate so as to cover said crystal disturbing layer so that a portion of the a-axis oriented oxide superconductor thin film deposited on said crystal disturbing layer becomes non-superconductive, and selectively removing a non-superconductive portion of said a-axis oriented oxide superconductor thin film deposited on said crystal disturbing layer and said crystal disturbing layer, so that two portions of the a-axis oriented oxide superconductor thin film are formed separately from each other so as to form said superconductor source electrode and said superconductor drain electrode.
Claim 16
Dependent Claim
15 words
A method claimed in Claim 15 wherein said crystal disturbing layer is formed by SiO₂.
Claim 17
Dependent Claim
57 words
A method claimed in Claim 16 wherein said non-superconductive portion of said a-axis oriented oxide superconductor thin film deposited on said SiO₂ layer and said SiO₂ layer are selectively removed by a dry etching process utilizing the etching speed difference due to difference in crystallizability between said a-axis orientated oxide superconductor thin film and said non-superconducting portion.
References Cited (Backward Citations)
No citation records indexed.
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