PREPARATION OF THIN-FILMS OF Y1BA2CU3O7-X BY MAGNETRON SPUTTERING TECHNIQUES

The discovery of superconductivity at temperatures above 77 K has produced much interest in developing thin film circuits using these materials. The most successful techniques applied to growing thin films of the 90 K superconductor, Y1Ba2Cu3O7-x, include evaporation, sputtering, and laser ablation. We have been studying three variations of sputtering: a 3 metal co-sputtering technique requiring a post-anneal at high temperatures, an in situ process using an inverted cylindrical magnetron sputter gun, 1 adn another in situ process using a planar target in an off-axis geometry. 2 Our films are grown primarily on magnesium oxide (MgO) substrates because it is readily available, inexpensive, and its low dielectric constant permits convenient microwave circuit design. We find that our co-sputter process with post-anneal produces films with depressed T(c)'s and J(c)'s. The inverted cylindrical magnetron sputtering has yielded the best films with complete transitions as high as 87 K and J(c) = 4 x 10(6) A/cm2 at 4 K. Our off-axis results are not quite as good, with 79 K complete transitions. In this paper, we discuss these and other results, as well as some of the problems we have encountered with these sputtering techniques.