DI-CARBOXYLIC-ACID-BASED AND TRI-CARBOXYLIC-ACID-BASED ETCHES FOR PROCESSING HIGH-TEMPERATURE SUPERCONDUCTING THIN-FILMS AND RELATED MATERIALS

The development of passive and active electronics from high-temperature superconducting thin films depends on the development of process technology capable of producing appropriate feature sizes without degrading the key superconducting properties. We present a new class of chelating etches based on di- and tri-carboxylic acids that are compatible with positive photoresists and can produce submicron feature sizes while typically producing increases in the microwave surface resistance at 94 GHz by less than 10%. This simple etching process works well for both the Y-Ba-Cu-O and Tl-Ba-Ca-Cu-O systems. In addition, we demonstrate that the use of chelating etches with an activator such as HF allows the etching of related oxides such as LaAlO3, which is a key substrate material, and Pb(Zr0.53Ti0.47)O3 (PZT) which is a key ferroelectric material for HTS and other applications such as nonvolatile memories.