SF 6 Plasma Etching of Silicon: Evidence of Sequential Multilayer Fluorine Adsorption

It is shown, from the diffusion model for fluorine-based plasma etching of silicon, how the anisotropy evolution, as a function of the partial pressure of atomic fluorine, may account for adsorption and desorption mechanisms on silicon surfaces. In addition to the anisotropy-isotropy transition, sequential multilayer adsorption is demonstrated experimentally. Etching mechanisms are discussed in the light of the observed results.