Real‐time observation of ultrathin silicon oxide film growth using rapid ellipsometry

We have studied plasma oxidation of silicon by a radio frequency discharge using rapid ellipsometry. The change rate of the ellipsometric parameter Δ immediately after starting the discharge increases as the plasma density increases. An anomalous time dependence of the optical phase shift (Δ) is observed in the initial stage of silicon surface oxidation, and the behavior is explained based on a model calculation, which considers a change in refractive index during silicon oxide film growth. The effect of silicon wafer surface orientation on the oxidation rate in the plasma oxidation has been also investigated. The result shows that the plasma oxidation rate on Si(111) is larger than that on Si(100).