OPTIMIZATION OF YBA2CU3O7-DELTA SUBMICROMETER STRUCTURE FABRICATION

We present a study of the sputter etching step in the fabrication sequence of YBa2Cu3O7-delta 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 T(c) and the critical current density j(c) of the YBa2Cu3O7-delta submicrometer structures. Liquid-nitrogen cooling of the substrate is shown to efficiently suppress oxygen effusion during sputter etching. Critical current densities above 10(6) A/cm2 at 77 K are obtained for 0.75 mum wide and 10 mum long bridges.