An improved multi-layer fabrication process for YBa2Cu3O7-x-based circuits

Improved via connections i n structures of YBa,Cu,07.,/SrTi0,/YBa,Cu,0,, (YBCO /STO/ YBCO) multilayers have been made using a combined HF wet-etching and ion-mil l ing process. The critical current density Jc of the via is as high as 2 x l o 6 A/cm2 at 76 K, and i s dominated by edge contacts in the ab-plane. YBCO and Sr,AlNbO, (SAN) multilayer test circuits were also made with this process. The 4" crossovers in a SAN test chip had a critical temperature Tc of 88 K and Jc of 1.5 x lo6 A/cm2 at 81 K, very close to those of the planar f i l m , showing no evidence of weak links in the YBCO crossing low angle SAN steps.