Transitional change to amorphous fluorinated carbon film deposition under energetic irradiation of mass-analyzed carbon monofluoride ions on silicon dioxide surfaces

We have studied both the etching of SiO 2 film and the growth of an amorphous fluorinated carbon (a-C:F) film by mass-analyzed fluorocarbon ion irradiation. This experiment was done in an ultrahigh vacuum with a pressure of 10 −7 Pa even during irradiation. When using a carbon monoflouride ( CF 1 + ) ion with an energy of 300 eV to irradiate, it was found that SiO 2 film a few nm thick was initially etched away. Then, an a-C:F film was continuously deposited on the SiO 2 surface as the ion dose exceeded about 5×10 16 cm −2 . Using in situ x-ray photoelectron spectroscopy analysis, it was determined that carbon accumulates on the surface at this early stage as the ion dose increases, so that this transition is resulted by the surface modification on which the CF 1 + ion itself irradiates the SiO 2 surface. Especially in highly ionized fluorocarbon plasmas, surface conditions such as the carbon concentration affect possibly etching performance.