Optimization of YBa2Cu3O7−δ submicrometer structure fabrication

Abstract
We present a study of the sputter etching step in the fabrication sequence of YBa2Cu3O7−δ submicrometer structures down to 200 nm linewidth. We identify oxygen effusion as the main reason for process‐induced degradation of superconductivity. Oxygen reloading by plasma oxidation after pattern transfer efficiently recovers both the transition temperature Tc and the critical current density jc of the YBa2Cu3O7−δ submicrometer structures. Liquid‐nitrogen cooling of the substrate is shown to efficiently suppress oxygen effusion during sputter etching. Critical current densities above 106 A/cm2 at 77 K are obtained for 0.75 μm wide and 10 μm long bridges.