Measurement of adsorbed F atoms on a HF treated Si surface using infrared reflection absorption spectroscopy

Si(111) surface treated with HF solution was studied using Fourier transform infrared reflection absorption spectroscopy for the observation of Si–Fx bond absorption and x-ray photoelectron spectroscopy for the identification of the adsorbates on the Si surface. Two absorption peaks were observed in the range of 905–925 cm−1, and they were assigned to Si–F2 symmetric stretching mode at 918 cm−1 and Si–H2 bending mode at 910 cm−1. The absorption peak of Si–F2 distinctly decreased with de-ionized water rinse, though the Si–H2 peak hardly changed. The absorption peak of Si–F was not observed in all spectra. This result indicates that F atoms selectively adsorbed at a step region rather than on a terrace region on Si(111) surface after HF treatment.