Dynamic alterations of the surface composition during sputtering of silicides

The temporal development of composition alterations in the surface region of NiSi, MoSi, and PtSi due to bombardment with Ar+ ions of energy between 2 and 5 keV is studied by 1 keV AES depth profiling. In all cases an enrichment of the heavier (metal) component some nm below the surface is observed. By comparing this result with recent Monte-Carlo calculations it is concluded that the mass difference between components plays the dominant role in the build-up of the composition alterations. This conclusion is supported by trends in the metal peak depth and maximum concentration as well as in surface composition data. The studies show that the composition changes observed are due to a superposition of several sputter mechanisms. (author)