US4253230A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Silicon barrier Josephson junction configuration
Assignee: United States Department of the Navy
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Filing: 1979-02-09
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Granted: 1981-03-03
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Expires: 1999-02-09
Abstract
Abstract A planar, silicon barrier, Josephson junction and method of forming the jtion which does not require expensive high-resolution, lithography techniques such as electron beam or x-ray. The method includes an etching mask-etch process which forms the basic structure configuration using a (110)-cut silicon wafer. Subsequent to the etching process the mask is removed and a superconducting film is deposited on the previously formed silicon surface to produce a single crystal silicon barrier with good electrical properties.
Inventors
- 👤 Kenneth L. Davis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 21:44
CPC Classifications
H; H10; H10N; H10N60/00; H10N60/01; H10N60/0912; Y; Y10; Y10S; Y10S505/00; Y10S505/825; Y10S505/917; Y10S505/922; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49014
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
182 words
A method of forming a planar, silicon barrier, Josephson junction comprising: fabricating from a silicon bulk material a single crystal of silicon having a (110)-cut surface; growing or depositing a protective layer on the (110)-cut surface of said silicon wafer; forming an etch pattern in said protective layer to expose a portion of the surface of said silicon wafer; etching away the exposed silicon defined by said pattern to a desired depth thereby forming a channel on opposite sides of a silicon barrier said channel having smooth straight side surfaces with a smooth bottom of exposed silicon in the surface of said wafer; oxidizing said exposed silicon surfaces to a desired thickness; etching away all the oxidized areas thereby forming a narrow barrier of a desired thickness; cleaning all oxide off the silicon barrier surfaces; depositing a layer of superconducting film on the bottom of said channel and on top of said wafer surface; forming an etch pattern on said superconducting layer to remove the superconductor film from the top of said wafer surface thereby completing the formation of said Josephson junction.
Claim 2
Independent Claim
182 words
A method of forming a planar, silicon barrier, Josephson junction comprising: fabricating from a silicon bulk material a single crystal of silicon having a (110)-cut surface; growing or depositing a protective layer on the (110)-cut surface of said silicon wafer; forming an etch pattern in said protective layer to expose a portion of the surface of said silicon wafer; etching away the exposed silicon defined by said pattern to a desired depth thereby forming a channel on opposite sides of a silicon barrier said channel having smooth straight side surfaces with a smooth bottom of exposed silicon in the surface of said wafer; oxidizing said exposed silicon surfaces to a desired thickness; etching away all the oxidized areas thereby forming a narrow barrier of a desired thickness; cleaning all oxide off the silicon barrier surfaces; depositing a layer of superconducting film on the bottom of said channel and on top of said wafer surface; forming an etch pattern on said superconducting layer to remove the superconductor film from the top of said wafer surface thereby completing the formation of said Josephson junction.
Claim 3
Dependent Claim
18 words
A method as claimed in claim 1 in which: said protective layer is silicon dioxide (SiO 2 ).
Claim 4
Dependent Claim
20 words
A method as claimed in claim 1 in which: said protective layer is silicon nitride (Si 3 N 4 ).
Claim 5
Dependent Claim
19 words
A method as claimed in claim 2 wherein: said silicon is etched away with a KOH and water mixture.
Claim 6
Dependent Claim
19 words
A method as claimed in claim 3 wherein: said silicon is etched away with a KOH and water mixture.
Claim 7
Dependent Claim
24 words
A method as claimed in claim 1 in which: said superconducting film is selected from one of the following: lead, indium, tin or niobium.
Claim 8
Dependent Claim
33 words
A method as claimed in claim 1 which includes: doping said silicon with impurities subsequent to forming said channels and said barrier, said doping being done prior to oxidizing said exposed silicon surfaces.
Claim 9
Dependent Claim
32 words
A method as claimed in claim 1 which includes: doping said silicon with impurities subsequent to etching away said oxidized areas, said doping being done prior to cleaning said silicon barrier surfaces.
Claim 10
Dependent Claim
34 words
A method as claimed in claim 3 in which: said silicon nitride is etched away subsequent to etching away all the oxide areas and prior to cleaning all oxide off the silicon barrier surface.
Claim 11
Dependent Claim
27 words
A method as claimed in claim 3 in which: said silicon nitride is etched away subsequent to depositing said superconducting film on the bottom of said channel.
Claim 12
Independent Claim
233 words
A method for forming a planar, silicon barrier, Josephson junction comprising: fabricating from a silicon bulk material a single crystal of silicon having a (110)-cut surface; growing or depositing a protective layer on the (110)-cut surface of said wafer; forming an etch pattern in said protective layer to expose a portion of the surface of said silicon wafer; etching away the exposed silicon defined by said pattern, using first etchant, to a desired depth froming a channel having smooth vertical surfaces and a smooth flat bottom surface; doping the exposed silicon surfaces with boron in which the dopant diffuses to a controlled depth within the exposed silicon; forming an etch pattern in said protective layer to expose a second portion of the surface of said silicon wafer directly opposite said doped channel; etching the second exposed surface of said silicon using a second etchant, to a level coplanar with the surface of the boron-doped layer in the bottom surface of said channel thereby leaving stand a doped front upright portion which is perpendicular to the wafer surface; cleaning all oxide off the exposed silicon surfaces; depositing a layer of superconducting film on the surface of said silicon wafer and on the bottom of said channels; and forming an etch pattern on said superconducting layer to remove the superconductor film from the top of said wafer, thereby completing the formation of said Josephson junction.
Claim 13
Independent Claim
233 words
A method for forming a planar, silicon barrier, Josephson junction comprising: fabricating from a silicon bulk material a single crystal of silicon having a (110)-cut surface; growing or depositing a protective layer on the (110)-cut surface of said wafer; forming an etch pattern in said protective layer to expose a portion of the surface of said silicon wafer; etching away the exposed silicon defined by said pattern, using first etchant, to a desired depth froming a channel having smooth vertical surfaces and a smooth flat bottom surface; doping the exposed silicon surfaces with boron in which the dopant diffuses to a controlled depth within the exposed silicon; forming an etch pattern in said protective layer to expose a second portion of the surface of said silicon wafer directly opposite said doped channel; etching the second exposed surface of said silicon using a second etchant, to a level coplanar with the surface of the boron-doped layer in the bottom surface of said channel thereby leaving stand a doped front upright portion which is perpendicular to the wafer surface; cleaning all oxide off the exposed silicon surfaces; depositing a layer of superconducting film on the surface of said silicon wafer and on the bottom of said channels; and forming an etch pattern on said superconducting layer to remove the superconductor film from the top of said wafer, thereby completing the formation of said Josephson junction.
Claim 14
Dependent Claim
30 words
A method of forming a planar, silicon barrier, Josephson junction as claimed in claim 7 in which: said protective layer on said silicon surface is silicon dioxide (SiO 2 ).
Claim 15
Dependent Claim
32 words
A method of forming a planar, silicon barrier, Josephson junction as claimed in claim 11 in which: said protective layer on said silicon surface is silicon nitride (Si 3 N 4 ).
Claim 16
Dependent Claim
18 words
A method as claimed in claim 12 in which: said first etchant is a KOH and water mixture.
Claim 17
Dependent Claim
18 words
A method as claimed in claim 13 in which: said first etchant is a KOH and water mixture.
Claim 18
Dependent Claim
16 words
A method as claimed in claim 12 wherein: said first etchant is an ethylene diamine-pyrocatechol-water mixture.
Claim 19
Dependent Claim
16 words
A method as claimed in claim 14 wherein: said second etchant is an ethylene diamine-pyrocatechol-water mixture.
Claim 20
Dependent Claim
16 words
A method as claimed in claim 15 wherein: said second etchant is an ethylene diamine-pyrocatechol-water mixture.
Claim 21
Dependent Claim
33 words
A method as claimed in claim 11 which includes: doping said silicon with impurities after said silicon surface has been etched with said second etchant and before said silicon barrier surfaces are cleaned.
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) | 1984-03-02 | 1984-09-01 | 1985-03-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-03-02 | 1988-09-01 | 1989-03-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-03-02 | 1992-09-01 | 1993-03-03 | $7700.00 | Window Closed / Lapsed |