Fabrication technology for lead-alloy Josephson devices for high-density integrated circuits

Journal Article · Sat Mar 01 00:00:00 EST 1986 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.336437· OSTI ID:6125091

Imamura, T; Hoko, H; Tamura, H; Yoshida, A; Suzuki, H; Morohashi, S; Ohara, S; Hasuo, S; Yamaoka, T

Fabrication technology for lead-alloy Josephson devices was evaluated from the viewpoint of application to large-scale integrated circuits. Metal and insulating layers used in the circuits were evaluated, and optimization of techniques for deposition or formation of these layers was investigated. Metallization of the Pb-In-Au base electrode and the Pb-Bi counterelectrode was studied in terms of optimizing the deposited films, to improve the reliability of junction electrodes. The formation of the oxide barrier was studied by in situ ellipsometry. SiO/sub x/ deposited in oxygen was developed as the insulation layer with less defect density than conventional SiO. A liftoff technique using toluene soaking was developed, and patterns with a minimum line width of 2 m were consistently reproduced. The characteristics of each element in the circuits were evaluated for test vehicles. For the junction, the following items were evaluated: controllability of the critical current I/sub c/, junction quality, I/sub c/ uniformity, junction yield, and thermal cycling and storage stability. For the peripheral elements, integrity of lines and contacts, and characteristics of resistors were evaluated. 8-kbit memory cell arrays with a full vertical structure were fabricated to evaluate these technologies in combination. The continuity of each metal layer and insulation between metal layers were evaluated with an autoprober at room temperature. For selected chips, cell characteristics have been measured, and their I/sub c/ uniformity and production yields for cells are discussed. Normal operation of the memory cells was confirmed for all of the 24 accessible cells on a chip.

• Research Organization: Fujitsu Limited, 10-1 Morinosato-Wakamiya, Atsugi 243-01, Japan
• OSTI ID: 6125091
• Journal Information: J. Appl. Phys.; (United States), Vol. 59:5
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
INTEGRATED CIRCUITS
JOSEPHSON JUNCTIONS
FABRICATION
PERFORMANCE
ELECTRIC CURRENTS
ELECTRODES
ELLIPSOMETRY
GOLD ALLOYS
INDIUM ALLOYS
LAYERS
LEAD ALLOYS
SILICA
STABILITY
ALLOYS
CHALCOGENIDES
CURRENTS
ELECTRONIC CIRCUITS
JUNCTIONS
MEASURING METHODS
MICROELECTRONIC CIRCUITS
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
SILICON COMPOUNDS
SILICON OXIDES
SUPERCONDUCTING JUNCTIONS
420201* - Engineering- Cryogenic Equipment & Devices