Composition Distribution of Compound Oxide Films Deposited by Magnetron Sputtering.

In this study, the mechanism of composition deviation of compound oxide films deposited by magnetron sputtering is examined. Composition distributions of SrTiO3 films and SrRuO3 films were analyzed on a substrate plane. On the area directly facing the erosion area of the target, not only were the ratios of Ti in SrTiO3 films and Ru in SrRuO3 films in excess of other areas, but also the amount of deposited Ti and Ru atoms was increased. The composition profiles were explained through simulations using angular distribution functions of sputtered atoms. Assuming the angular distribution of Ti in SrTiO3 films as a summation of a homogenous fraction and a highly preferential forward direction fraction, the unique Ti composition profile is represented. This result can be interpreted as a small amount of negative metal (or metal oxide) ions that emerged from the erosion area of the target and enriched the area directly facing the erosion area. Such negative ions are one of the main origins of composition deviation.