Si(111) surface treated with HF solution was studied using Fourier transform infrared reflection absorption spectroscopy for the observation of Si–Fxbond 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–F2symmetric stretching mode at 918 cm−1and Si–H2bending mode at 910 cm−1. The absorption peak of Si–F2distinctly decreased with de‐ionized water rinse, though the Si–H2peak 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. ©1995 American Institute of Physics.