LTS JOSEPHSON-JUNCTION CRITICAL-CURRENT UNIFORMITIES FOR LSI APPLICATIONS

Manufacturing yields of large scale superconducting circuits depend st rongly on the uniformity of junction critical currents. We report on j unction manufacturing tolerances based on extensive measurements of Nb - and NbN-based junction arrays and individual junctions. Transient wa veforms induced by switching of a single junction have sufficient ampl itude to switch other junctions in a series array. We have measured th e effect of sympathetic switching and developed damping structures to dissipate switching transients. Comparisons of critical current distri butions measured on individual junctions with critical current distrib utions determined from series junction arrays will be presented. In ad dition, the validity of using series arrays of large numbers of juncti ons to assess the critical current uniformity will be discussed.