Chemistry Reference
In-Depth Information
treated in HF solution is much slower. For example, in one case the HF-treated surface
is covered with an oxide of 2-3 Å after exposure to air for 1 hour;
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in another, it takes
about 1 week for a monolayer to form.
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The slow growth of native oxide on the HF-treated surface is attributed to the
hydrogen termination which passivates the surface. The formation of the first mono-
layer of oxide requires the breakup of the Si-H bonds. According to Graf
et al
.,
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the oxide growth on HF-treated Si in air follows two distinct stages as shown in Fig.
2.16. There is an incubation period initially, during which the oxide grows very little.
Afterwards, the growth shows a logarithmic dependence on time with a rate of ~5
Å/decade. Another study reported similar growth kinetics as shown in Fig. 2.17.
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