High-T/sub c/ superconductor-normal-superconductor junctions with polyimide-passivated ambient-temperature edge formation

Superconductor-Normal-Superconductor (SNS) edge Josephson Junctions (JJs) continue to be a focus of high-T/sub c/ superconductor (HTS) electronics development. The ability to form clean edges in HTS materials is essential for successful SNS edge JJs as well as crossovers and via contacts. We report a novel SNS JJ fabrication process in which a YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta///SrTiO/sub 3/ base electrode/insulator bilayer coated with a polyimide passivation layer is rotated during Ar ion milling through a reflowed photoresist mask to form omnidirectional edges. No sample cooling is used during milling. YBa/sub 2/Cu/sub 2.8/Co/sub 0.2/O/sub 7-/spl delta// normal layers and YLa/sub 0.05/Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// counter-electrodes completed the SNS JJ´s. Devices fabricated using this polyimide passivation layer have significantly smaller spreads in critical current and resistance than those processed without it.