The F2 treatment of a hydrogen-terminated Si(100) surface in a vacuum
chamber was chosen to generate a densely fluorinated silicon surface.
It was confirmed by IR-attenuated total reflection and X-ray photoelec
tron spectroscopy measurements that the Si-H bonds on the surface were
replaced with the Si-F bonds and that 1.0 monolayer of the Si-F bonds
was formed after 1 x 10(4) L exposure. Mass spectrometry measurements
of the volatile reaction products indicated that the Si-F bonds were
produced by the following reaction: {SiH(surface)+F2 (gas)-->Si-F(surf
ace)+HF(gas)}. The variation of thus prepared surface in water was als
o studied. The 1.0 monolayer of Si-F bonds was found to be replaced wi
th the 0.7 monolayer of Si-H bonds and the 0.2-0.3 monolayer of Si-OH
bonds after dipping into water for 1 min. The replacement of the Si-F
bonds with the Si-H bonds was considered to be the back-bond-breaking
reaction by water. Such a reaction between water and the surface Si-F
was observed for the first time.