ETCHING YIELDS OF SIO2 BY LOW-ENERGY CF(X+) AND F+ IONS

Etching yields of SiO2 by mass-separated F+, CF+, CF2+, CF3+, and Ar+ ions have been measured at low ion energies ranging from 80 to 350 eV. CF3+ and CF2+ ions have higher etching yields than CF+ and F+ ions. At low ion energies, SiO2 cannot be etched and some film deposition is observed on the SiO2 surface. For example, in the case of CF+ ions, SiO2 can be etched at ion energies above 200 eV. This film deposition is caused by reactions of CF(x)+ ions at the SiO2 surface, and neutrals coming from the ion source also have some effect on this deposition.