Molecular dynamics simulation of energetic ion bombardment onto a-Si 3N 4 surfaces

Abstract

Energetic ion (Ar +) bombardment onto a silicon nitride substrate was modeled using molecular dynamics simulation. An empirical potential energy function developed by Vashishta was used to describe the interactions in substrate atoms. An amorphous surface configuration was prepared by simulating the surface evolution due to successive ion impacts and structure relaxation at high temperature. We considered Ar + ion bombardment on this amorphous surface, for various incident angles ( φ i=0°, 30°, 45°, 60°, 75° and 85°) and incident energies ( E i=100 and 200 eV). The reflection characteristics of impact ions can be obtained, in addition the plasma sputtering process can also be investigated with these atomic scale simulations. The sputtering yield had its maximum in the range of incident angle, 60°< φ i<75°, and nonstoichiometric surface atom removal (Si sput : N sput=1 : 2.5) was observed.