Prediction of SiO2 sputtering yield using molecular dynamics simulation

The surface of processed wafers during the plasma etching process is exposed to a shower of relatively high energy particles, and the surface reaction that evaporates the upper surface layer is induced by the collision. The surface profile evolution during plasma etching needs to be known in order to control the fine details of features of semiconductor devices. The process is a complex combination of factors such as incident particle kinetic energy, incident angle and substrate conditions. In this study, we performed molecular dynamics simulations of Ar⁺ ions bombarding a SiO₂ substrate and observed the sputtering yield as the incident angle and energy changes. The primary goal is to verify the process as a reliable source of microscopic sputtering yield data. We inserted 10 ps of relaxation right after each bombardment to allow the concentrated heat to diffuse into the bulk region, which gave us similar results to a previous study (Abrams and Graves, J. Vac. Sci. Tech. A vol. 16, pp. 3006-3019, 1998), and we observed the surface evolution during the process. These efforts predicted a different sputtering yield from the previous study, but the overall patterns of reaction product trajectories were similar