Atomic scale simulation of physical sputtering of silicon oxide and silicon nitride thin films

Molecular dynamics simulations of energetic ion bombardments were carried out to investigate physical sputtering process. Bombardments of several ion species (He+, Ne+, Ar+, Kr+, Xe+) on a modeled amorphous silicon oxide substrate were simulated to find out the effect of plasma ion species on sputtering. Reflection characteristics of ions, fraction of energy deposited on substrate, and sputtering yield were obtained for each species, which collide on the surface at incident angle (φi) of 60° and with incident energy (Ei) of 100 eV. Simulations of Ar+ bombardments on SiO2 and Si3N4 substrates were carried out to compare the sputtering yield of two substrates at various incident angles (φi=0°φi=0°, 30°, 45°, 60°, 75°, 85°) and with incident energies (Ei=100 and 200 eV). The sputtering yield of silicon nitride was more than twice of that of silicon oxide in this range of incident energy. The preferential sputtering of O or N atoms rather than Si atoms was also observed in the physical sputtering of these multi-component substrates (SiO2 and Si3N4).