COLLISION DOMINATED PREFERENTIAL SPUTTERING OF TANTALUM OXIDE

Tantalum oxide was used as a model system in order to identify the mechanisms responsible for preferential sputtering. After bombarding Ta2O5 with low energy ions (1.5 keV He+ and 1 keV Ar+) at different angles of incidence, the surface composition was analysed by means of AES (Auger Dectron Spectroscopy) and ISS (Ion Scattering Spectroscopy). The experiments were simulated with the binary collision code TRIDYN. The good agreement between the results obtained by the two experimental techniques (AES and ISS) and between experiment and computer simulation confirms that in this mass and energy range preferential sputtering of tantalum oxide is governed by collision processes. The preferential sputtering effects (e.g. steady-state surface composition and characteristic fluence) caused by the different component sputtering yields can be explained qualitatively and quantitatively in the frame of a simple sputtering model. Individual mechanisms of sputtering are discussed in detail. Compositional depth profiles obtained both experimentally and by computer simulation are related to the distribution of deposited energy.