Effects of processing on electrical properties of YBa₂Cu₃O₇ films. II. In situ deposition processes

The effects of several patterning process steps on the critical current J_c and surface resistance R_s of YBa₂Cu₃O₇ films are described. Included are two off‐axis sputtering processes and a metalorganic chemical‐vapor deposition (MOCVD) process, all producing in situ superconducting films with c‐axis epitaxial orientation. J_c and R_s parameters were measured by mutual inductance and parallel plate resonator techniques, respectively, so that the films did not require patterning for the measurement. Applying a polymer film and stripping, either with acetone or with an O₂ plasma, resulted in no change in R_s. Brief ion milling, as well as baking at 185 °C with polymer film present, caused moderate degradation (∼25 μΩ) for films deposited on MgO (both sputtered and MOCVD). The damage caused by ion milling sputtered films on LaAlO₃ was considerably greater (∼100 μΩ); photoresist developer also had a significant effect. The degree of degradation in R_s for these films suggests that the surface damage results in secondary effects that penetrate well into the film. This damage was not removed by annealing in O₂; in fact it was made substantially worse. J_c was increased slightly by all processes, by an amount ranging from 5% to 50%.