Digital laser etching of Bi-Sr-Ca-Cu-O superconducting thin films

A gas-laser-etching of Bi-Sr-Ca-Cu-O thin films was performed by digitally counting an etch process loop. Laser irradiation and NF3 gas-supply were done separately. At one laser fluence range the etch depth was independent of the laser fluence, suggesting that the etching was limited by the amounts of adsorption gas molecules. The way that the etch depth depends on the etching loop count was intensively investigated. The depth was saturated after the etching of a few loops. The surfaces of the etched area were flattened and smoothened. Possible models that explain the etch depth saturation and surface flattening were discussed.