Computer simulation of atomic mixing during ion bombardment

Abstract

The atomic mixing in the target under ion bombardment is assumed to result from cascades of atomic collision events. Computer simulations have been applied to collision cascades to estimate the depth resolution of surface analysis with an ion probe. The Monte Carlo method based on a single scattering model has been used mainly in the calculation under the assumptions of random collision process, no diffusion and no target saturation processes. High-energy collisions are characterized by a Lenz-Jensen or a Thomas-Fermi potential, while a Born-Mayer potential is used in the low energy region. The simulations have been performed for the bombardment of Ar ions withE ₀=5 keV and 10 keV at angles of incidence θ=0° and 60° on Si targets. The depth resolutions [the definition of which is explained by (15) in the text] are about 140Å for the Lenz-Jensen cross section and about 80Å for the Thomas-Fermi one for θ=0° atE ₀=5 keV, and decrease by 20–40% at θ=60° and increase by 70–90% forE ₀=10 keV.