Fabrication of superconductor-normal metal-superconductor Josephson junctions with integrated high-T/sub c/ groundplanes

We describe the fabrication of superconductor-normal metal-superconductor YBa/sub 2/Cu/sub 3/O/sub x/ (YBCO) edge junctions with a cobalt-doped YBCO barrier. The process includes an integrated high-T/sub c/ groundplane with a low /spl epsiv//sub r/ interlevel dielectric layer of Sr/sub 2/AlNbO/sub 6/ (SAN). We have used groundplanes of both sputtered YBCO and YBCO and NdBa/sub 2/Cu/sub 3/O/sub x/ (NBCO) deposited by thermal coevaporation. Junction to groundplane isolations of >3.5/spl times/10/sup 8/ /spl Omega//spl middot/cm have been measured with a groundplane T/sub c/ as high as 90 K. The proper functioning of the groundplane was verified by measuring the inductance of identical SQUIDs on and off the groundplane. The SQUID inductance on the groundplane was as low as 1.2 pH//spl square/ at 70 K. The spreads in the junction critical currents are comparable for devices on and off the groundplane Groundplane and junction uniformity issues such as film morphology, and edge and barrier formation will be discussed.