Etching of SiC by energetic F2: Molecular dynamics simulation

Molecular dynamics (MD) simulations were performed to investigate F₂ continuously bombarding silicon carbide (SiC) surfaces with energies in the range of 50-200 eV at normal incidence and room temperature. The Tersoff-Brenner form potential was used. The simulation results show that the uptake of F atoms, the etch yields of C and Si from the initial substrate, and the surface structure profile are sensitive to the incident energy. Like occurrence in Si etching, steady-state etching is observed and an F-containing reaction layer is formed through which Si and C atoms are removed. A carbon-rich surface layer after bombarding by F₂ is observed which is in good agreement with experiments. In the reaction layer, SiF in SiF₂ species are dominant; with increasing incident energy, the total fraction of SiF and SiF₂ increases, while the amount of SiF₃ and SiF₄ decreases. Finally, etching mechanisms are discussed.