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FABRICATION OF HIGH Tc LAYERED SUPERCONDUCTOR INSULATOR SUPERCONDUCTOR TUNNEL JUNCTIONS

IP.com Disclosure Number: IPCOM000036946D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Koch, RH: AUTHOR [+3]

Abstract

Disclosed is a method of fabricating high Tc ceramic tunnel junctions using planar sandwich, complete wafer processing. The entire MULTILAYER STRUCTURE IS GROWN IN SITU, AND THEN THE JUNCTIONS AR e patterned when the completed structure is removed to atmosphere.

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FABRICATION OF HIGH Tc LAYERED SUPERCONDUCTOR INSULATOR SUPERCONDUCTOR TUNNEL JUNCTIONS

Disclosed is a method of fabricating high Tc ceramic tunnel junctions using planar sandwich, complete wafer processing. The entire MULTILAYER STRUCTURE IS GROWN IN SITU, AND THEN THE JUNCTIONS AR e patterned when the completed structure is removed to atmosphere.

SIS (superconductor-insulator-superconductor) tunnel junctions are formed using the high Tc PHASE OF THE YBACUO COMPOUND. IN SITU plasma oxidation of the base YBaCuO material is used to create the tunnel barrier. A large area, unpatterned thin film of the YBaCuO material is first formed in a vapor deposition system at elevated substrate (375oC) temperature. The sample is then cooled to 100oC, and a plasma discharge established in an oxygen atmosphere. Oxidation times are varied controllably with a typical time being 900 seconds. Upon completion of the plasma oxidation, the substrate temperature is returned to 375oC. The counter-electrode is then deposited, completing the multilayered structure without breaking vacuum. This technique preserves the smoothness of the interface by introducing two NOVEL STEPS IN THE PROCESSING: (1) A GROWN IN SITU PLASMA OXIDE AS the tunnel barrier, and (2) the full wafer concept.

It is found that the plasma oxide provides a suitable native barrier, whereas the oxides of the constituent metals do not provide sufficient insulation. Another important step is related to the patterning of the s...