Development of multilayer process with upper wiring layer for HTS circuit application

The properties of YbBCO and LuBCO thin films were examined with the aim of applying them to an upper wiring layer for HTS SFQ circuit. c-Axis oriented films could be prepared for both the materials at a relatively low temperature of 640°C. However, there was a little difference in their superconducting properties, and YbBCO films exhibited better properties with a sharp transition at about 82K. Multilayer structures with four-HTS layers were fabricated using YbBCO for upper wiring layer and CeO2 as insulating layer. It was also confirmed that junctions exhibited RSJ-type I–V curves after deposition of the upper wiring layer.