Reactivity of a fluorine passivated silicon surface

Abstract

Fluorine-terminated Si(100) surfaces have been prepared by dosing with XeF2. The reactivity of these surfaces towards reoxidation by water vapor or molecular oxygen has been analyzed in situ using x-ray photoelectron spectroscopy. Whereas the fluorine-terminated surface is quite stable in dry oxygen, significantly stronger reactivity is observed with water vapor. Reaction with water molecules creates Si–OF surface species, presumably via an insertion reaction, and leads to loss of fluorine and to growth of a thin oxide. It is inferred that the hydrogen-terminated, HF-cleaned surface, which exhibits some surface fluorine, is oxidatively attacked in water or air at Si–F defect sites.