In situ optical monitoring of the initial oxidation processes on Si[001] by reflectance difference spectroscopy (RDS)

We have reported that the reflectance difference (RD) signal for the single-domain SiO/sub 2/-Si[001] interface changes sign in a oscillatory manner, and the half period of the oscillation correspond to progression of oxidation by one monolayer. The significance of this result is that we can now count the number of the oxidized Si layers in situ during the oxidation reaction. With this technique, we can measure, for example, the depth variation of the activation energy of the oxidation reaction in a layer-resolved manner. Comparison of such experimental data with the latest first-principle calculations should advance our understanding of this rather complex but technologically important reaction. The obtained RD spectra exhibit a spectral lineshape of the energy-derivative type, which is of interest from the viewpoint of surface optics.