Chemical and Physical Sputtering in F+ Ion Beam Etching of Si

Silicon etching was performed by a mass-selected, low-energy, F+ ion beam in an ultrahigh vacuum and the amount of etched Si was measured by the “in situ” quartz crystal oscillator microbalance technique. Through this method, it was possible to derive separate chemical and physical sputtering yields for Si over the incident ion energy range of 100 eV∼3000 eV. The chemical sputtering yield was found to be larger than the physical one when the incident ion energy became less than 200 eV.