Surface etching of YBCO films by xenon difluoride
We have demonstrated that xenon difluoride (XeF2) etches thin films of YBa2Cu3O7−x, the superconducting form of yttrium–barium–copper–oxide (YBCO), during dry etch processing. Both c-axis and mixed a/c-axis YBCO films show evidence of such etching with a axis being more reactive. Profiles of YBCO films examined by ESCA show that the surfaces of both etched and unetched films are barium rich at the expense of yttrium. After XeF2 etching, fluorine was found to be present to a depth of at least 40 nm. Despite the etching and the presence of fluorine in the YBCO films, the superconducting transition temperature, Tc, was unaffected by the XeF2 treatment.