Composition changes in sputter deposition of Y-Ba-Cu-O films

The mechanism of the composition change in sputter deposition of Y-Ba-Cu-O film from a YBa₂Cu₃O_7-x target has been investigated using an RF planar magnetron sputtering apparatus. Film composition changes significantly not only with the substrate temperature T_s and sputtering gas pressure, but also with the substrate position. A significant lack of Cu and Ba content is observed in film deposited with the substrate just above the erosion area of the target. When bombardment of the substrate surface by negative ions emitted from the target is suppressed by inserting a shield plate between the target and substrate, the Cu and Ba content in the film increases. These results indicate not only that the sticking probability of the sputtered particles changes with T _s and incident particle energy, but also that high-energy-particle bombardment of the substrate surface, which originates in the negative oxygen ions emitted from the target, influences the film composition