Off-axis unbalanced magnetron sputtering of YBa2Cu3O7 thin films

Abstract

An unbalanced magnet assembly is used in DC off-axis sputtering to grow YBa2Cu3O7 superconducting thin films. The assembly with a stronger central magnet than the annular magnet directs plasma to bombard the off-axis substrate, resulting in deteriorated thin films. In contrast, the assembly with a weaker central magnet directs plasma away from the off-axis substrate and results in a film with a higher transition temperature and a smoother surface. Furthermore, the latter type of unbalanced DC magnetron sputtering gives a higher deposition rate and enables the grown film to be uniform in composition on static substrates over a range of 8 cm in length. These results reveal the feasibility of using the unbalanced magnetron for thin film growth.