TIME-DEPENDENCE AND SPATIAL-DISTRIBUTION OF THE DEPOSITION RATE OF YBA2CU3O7 THIN-FILMS IN 90-DEGREES OFF-AXIS SPUTTERING

We have examined the time dependence and spatial distribution of the d eposition rate of YBa2Cu3O7 (YBCO) thin films in 90 degrees off-axis r adio frequency planar magnetron sputtering throughout the life of a ta rget. We have found that although the amount of YBCO sputtered from th e target is constant, the amount of YBCO deposited on the substrate de creases linearly over time. Furthermore, the time dependence of the de position rate changes at different positions on the substrate. The cha nges in the deposition rate at any point along the substrate as a func tion of time can be explained by the change in the angular distributio n of the sputtered particles that is caused by changes in the target e rosion groove geometry, and the decrease in the kinetic energy of sput tered particles that is indicated by the decrease in the self-bias vol tage over time. (C) 1997 American Vacuum Society. [S0734-2101(97)02806 -6].