Microlithography of high-temperature superconducting films: laser ablation vs. wet etching

Narrow lines and microbridge structures have been etched in sputtered superconducting films of Y-Ba-Cu-O by variations of two methods. The first uses standard photolithography followed by wet etching in weak acid. The second uses a maskless process involving focused pulsed YAG (yttrium-aluminium-garnet) laser together with a computer-controlled x-y stage to produce local ablation of the superconducting film. Issues relating to limits of resolution, annealing of films, and degradation of superconducting properties are critically discussed for the two approaches.>