Title :
Fabrication of sub-micron whole-wafer SIS tunnel junctions for millimeter wave mixers
Author :
Huq, S.E. ; Blamire, M.G. ; Evetts, J.E. ; Hasko, D.G. ; Ahmed, H.
Author_Institution :
Cambridge Univ., UK
fDate :
3/1/1991 12:00:00 AM
Abstract :
As part of a program for the development of a space-qualified submillimeter-wave mixer operating in the region of one terahertz, the authors have developed processes for the fabrication of submicron whole-wafer tunnel junctions. Using the self-aligned whole-wafer process (SAWW) with electron beam lithography they have been able to reliably fabricate high-quality (Vm>20 mV) submicron tunnel junctions from whole-wafer Nb/AlOx/Nb structures. In particular, it is shown that the junction quality is independent of size down to 0.3 μm2 junction area. The problems of film stress, anodization, registration for electron beam lithography, and lift-off, which limit the yield of good quality submicron-scale junctions are addressed
Keywords :
aluminium compounds; mixers (circuits); niobium; solid-state microwave devices; superconducting junction devices; 1 THz; EHF; MM-waves; Nb-AlOx-Nb; SAWW; SIS tunnel junctions; THF; anodization; electron beam lithography; film stress; junction area; junction quality; lift-off; millimeter wave mixers; registration; self-aligned whole-wafer process; space-qualified submillimeter-wave mixer; sub-MM-waves; submicron whole-wafer tunnel junctions; whole wafer processing; Capacitance; Electron beams; Fabrication; Frequency; Josephson junctions; Lithography; Niobium; Superconducting device noise; Superconducting devices; Superconducting films;
Journal_Title :
Magnetics, IEEE Transactions on
