Double-sided sputtering deposition ofYBa2Cu3O7-δ thin films on 2'LaAlO3 wafers for microwave applications

摘要

Superconducting yttrium barium copper oxide films were prepared on 2" lanthanum aluminate substrates by sputtering from a cylindrical and stoichiometric target. The deposition parameters were studied in order to obtain in a reproducible manner a sufficiently low value of the surface resistance for microwave applications. The typical value at 10 GHz and 77 K was 0.35 mΩ down to 0.2 mΩ. The purpose of this work was the subsequent deposition of YBa2Cu3O7-z on the LaAlO3 backside without degradation of the first deposit. The fabrication of the subsequent deposit was made with the same deposition parameters as the first film after turning over the substrate at room temperature. The physical and structural properties of both side deposits were analyzed (RBS, ion channeling, MEB, XRD, Rs and electrical resistivity). Although the first film underwent a second thermal process during the subsequent deposition, the surface resistance value was not degraded. This unexpected result is discussed in the frame of the mechanism of oxygenation in YBa2Cu3O7-x film by changing the conditions of sample cooling. An example of a microwave filter using this double-sided structure is presented