Etching yields Of SiO2 have been determined for F+, CFx+, (x=1,2,3) ion irradiation with energy ranging from 250 to 2000 eV using a mass-analyzed ion-beam apparatus that can irradiate a single species ion to sample surfaces under an ultrahigh vacuum condition. The etching yield of CFx+ X (x = 1,2,3) was enhanced by the chemical effects of the ions, and both carbon and fluorine atoms from the incident ions were significant reactants. For lower energies, the etching yield increased with increasing ion energy. Above 1000 eV, the etching yield was gradually saturated with increasing ion energy. In the low ion energy region, steady etching did not occur, and an amorphous fluorinated carbon (a-C:F) film was deposited on the SiO2 surface. The ion energy region in which a-C:F film deposition occurred decreased with increasing fluorine atoms in incident CFx+ (x = 1,2,3) ions. (C) 2004 American Vacuum Society.