| Ion-surface interactions are an essential part of plasma processing which is used extensively in microelectronics fabrication. As device dimensions continue to shrink, understanding at the atomic scale becomes progressively more important. In this work, the interaction of low energy (25–200 eV) Ar+ ions with surfaces was studied using the molecular dynamics (MD) methodology, with the aid of massively parallel computation.; Simulations of Ar+ impact on silicon and Cl-passivated silicon surfaces were performed to study atomic layer etching (ALET) of silicon. Simulation results on depth of damage layer, Si sputtering yield, and sputtering threshold (37.5 eV), were in agreement with available experimental data. Three main types of sputtering pathways were identified based on the kind of energetic species formed right after initial ion impact. A new mapping of sputtering events based on position-from-impact (PFI) was devised, which provided a convenient way to delineate and classify sputtering mechanisms.; Molecular dynamics was also applied to study the formation of ultrathin oxide films formed on Si by exposure to thermal energy O atoms. A novel multibody potential which stabilized the Si/SiO2 interface was used for this purpose. Oxide growth was found to follow Langmuir-type kinetics with unity initial sticking coefficient of O and saturation coverage of around four monolayers, in good agreement with experimental data. Then, etching of an ultrathin oxide film on silicon by 100 eV Ar+ ions was simulated to study ion assisted surface cleaning. Ion irradiation was found to promote the restructuring of the surface into distinct oxide islands, as observed experimentally. Island formation was accompanied with an increase in surface roughness. Finally, the evolution of the surface state with ion dose was predicted quantitatively. |
