Chemical Etching of High-Tc Superconducting Y-Ba-Cu-O Films in Phosphoric Acid Solution

Abstract

Chemical etching properties of a high-Tc Y-Ba-Cu-O film with a phosphoric acid (H3PO4) solution were closely investigated. With an appropriate stirring, the etching developed in proportion to the time. The etching rate R was dependent on the dilution γ of H3PO4: R (µm/s)≃2γ for γ≤0.5, and otherwise it decreased superlinearly with increasing γ. A 2 µm wide Y-Ba-Cu-O line was fabricated using this technique with a positive-type photoresist such as AZ-1350J. Nosign of degradation of the superconductivity was found in the 50 µm wide etched lines. Rather, they showed an extreme enhancement of the onset temperature after this procedure.