Double-sided sputtering deposition of YBa2Cu3O7-delta thin films on 2" LaAlO3 wafers for microwave applications.

Superconducting Yttrium Barium Copper Oxide films were prepared oil 2 " Lan thanum Aluminate substrates by sputtering from a cylindrical and stoichiome tric 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 77K was 0.35 m Ome ga down to 0.2 m Omega. The purpose of this work was the subsequent deposit ion of YBa2Cu3O7-z on the LaAlO3 backside,without degradation of the first deposit. The fabrication of the subsequent deposit was made with the same d eposition parameters as the first plm after fuming over the substrate at ro om temperature. The physical and structural properties of both side deposit s were analyzed (RBS, ion channeling, MEB, XRD, Rs and electrical resistivi ty). 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 iii the frame of mechanism of oxygenation in YBa2Cu3O7-z film by changing the conditions of sample cooling. An example of microwave filter using this double-sided structure is presented.