Chemistry Reference
In-Depth Information
The formation of oxide on HF-treated silicon surface in water is postulated by
Graf
et al
.
663
to follow the process illustrated in Fig. 2.22. The initial appearance of
Si-OH groups is due to the fast exchange reaction of SiF:
Due to the strong electronegativity of OH groups, the Si-SiOH back bond is weakened
and is attacked by water:
The Si-H bond so formed is slowly replaced by water according to the reaction
Finally, oxide is formed through a bridging reaction of Si-OH groups:
In nonaqueous solutions the formation of oxide on the surface of silicon requires the
presence of water.
395,692
In solvents such as acetonitrile, nitromethane, and dimethyl sul-
foxide, the HF-cleaned silicon surface gradually evolves from a H-terminated passive
surface to a silicon oxide-covered surface due to the residual water (~10ppm) present
