EFFECTS OF PROCESSING ON ELECTRICAL-PROPERTIES OF YBA2CU3O7 FILMS .1.POSTDEPOSITION ANNEAL PROCESS

The effects of several patterning process steps on the critical curren t density J(c) and microwave surface resistance R(s) of alpha-axis ori ented films of YBa2Cu3O7 on LaAlO3 are described. The films were prepa red by cosputtering from Y, BaF2, and Cu targets, followed by annealin g in water-saturated O2. J(c) and R(s) parameters were measured by mut ual inductance and parallel plate resonator techniques, respectively, so that the films did not require patterning for the measurement. Appl ication of a polymer film followed by stripping in acetone caused mode st degradation, while stripping with an O2 plasma resulted in no chang e in the parameters. Brief ion milling, as well as baking at 185-degre es-C with polymer film present, caused severe degradation; other treat ments had intermediate effects. The degree of degradation suggests tha t the surface damage results in secondary effects that penetrate well into the film. A formula is derived for the change in R(s) due to a su rface layer, providing a quantitative comparison to experiment.