Behavior of fluorine on silicon (100) surfaces etched with NH4F aqueous solutions

Abstract

The bonding states and the behavior of F atoms on Si(100) surfaces exposed to air after etching with NH4F aqueous solutions were studied using X-ray photoelectron spectroscopy. F1s spectra from the Si surfaces could be separated into two Gaussian curves corresponding to respective Si–F and Si–F2 bonds, similar to the spectra from Si surfaces dipped into HF aqueous solutions. The majority of F atoms were in the Si–F2 bonding state. During the growth of native oxide on Si surfaces exposed to air, F1s peak intensities increased to a maximum and then decreased with increasing exposure time. The binding energies of both separated F1s components shifted toward higher binding energies. These results suggest that F atoms are distributed not only on the Si surface, but also beneath the Si surface, and move to the surface of the native oxide film formed by exposure to air. © 2000 Scripta Technica, Electron Comm Jpn Pt 2, 83(7): 41–47, 2000