An investigation on the removal characteristics of compound materials during ion beam sputtering using the Kinetic Monte Carlo method

Ion beam sputtering has been extensively adopted for optical surface processing. Due to differences between atoms in terms of atomic mass, surface binding energy and surface coverage fraction, the removal characteristics of the solid compound materials will be diverse. This paper first developed a quasi-atomistic model of the binary compound target and simulated ion beam sputtering processes using the Kinetic Monte Carlo (KMC) method. Furthermore, the effect of atomic differences on the removal characteristics was investigated. Finally, contrastive analysis between simulations and experiments of fused silica using an Ar+ ion beam was performed. The simulation results indicated that the competition between two types of preferential sputtering could cause the surface composition, removal amount and removal rate to oscillate in the early stage and to be relatively stable after a period of time. Compared with the fused silica experiments, the stable removal rate error of the KMC model considering the preferential sputtering is 5.9%; however, the stable removal rate error of the KMC model without regard to the preferential sputtering is 12.6%.