Laser patterning of superconducting YBa₂Cu₃O_7-x films

The authors investigated the use of laser dry etching for patterning thin films of superconducting YBa₂Cu₃O_7-x. A second harmonic of a single-mode CW Q-switched Nd:YAG laser with a duration of 80 ns and repetition rate of 500 Hz was used. A schematic diagram of a patterned sample, which was prepared for a four-probe resistivity measurement, and the surface morphology of the etched pattern are shown. The edge is quite sharp within 0.2 μm. For the typical result, the laser intensity was approximately 2 J/cm². The resulting 4-μm-wide microbridge had an onset temperature of 95 K and zero resistance of 90 K, which was the same as that of the original film. The temperature dependence of the critical current density was approximately 10⁶ A/cm² at 30 K.