Target presputtering effects on stoichiometry and deposition rate of Y-Ba-Cu-O thin films grown by dc magnetron sputtering

Abstract
Y-Ba-Cu-O thin films have been grown from stoichiometric compound targets using dc magnetron sputtering. Initially, the film composition was strongly off-stoichiometric and the deposition rate very low. However, after extensive presputtering, stoichiometric films, with respect to the metal content, were deposited at a rate of 2–2.5 Å/s. The long presputtering time (20–30 h) needed is due to a slowly changing oxygen content on the target surface. This is caused not only by preferential sputtering effects, but also by bulk diffusion in the target. The presputtering time is significantly decreased if the target is annealed in an argon atmosphere prior to use. Oxygen adsorbed on the target surface during venting of the chamber will also affect the process significantly.