Comparison of models for silicon etching in CF4 + O2 plasma

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Abstract The plasma chemical etching (PCE) of Si in CF4 + O2 plasma is considered. The concentrations of plasma components are calculated using values extrapolated from experimental data. Resulting calculations of plasma components are used for the calculation of Si etching rates. The concentrations of the adsorbed layer and surface components, obtained from analysis of PCE of silicon, are used for the comparison of site-balance and adsorbed-layer models. It is found that adsorbed-layer model predicts higher concentration of SiO2 molecules on the surface than site-balance model. The difference in SiO2 concentration is important during ion-beam-assisted etching and reactive ion etching processes as the models predict different etching rates due to different sputtering yields of Si atoms and SiO2 molecules.