Wet etch process for patterning insulators suitable for epitaxial high Tc superconducting thin film multilevel electronic circuits

A wet etch process is described for patterning insulators suitable for multilayer epitaxial high Tc superconductor-insulator-superconductor structures down to micrometer-scale dimensions. A solution of 7 percent HF in water gives convenient etch rates for SrTiO3 and MgO insulators (about 1500 A/min for single crystals), and easily stops on thin high Tc superconducting layers, due to the high selectivity of this etchant between these insulators and the cuprate superconductors. Using entirely wet etching patterning processes, 5-turn (20-turn) coils with zero resistance at 89 K (79 K) and critical currents at 77 K of 2.5 mA (6 microamperes) have been fabricated. (Author)