High-speed retardation modulation ellipsometer

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Abstract
Construction and performance of a high-speed retardation modulation ellipsometer are described. An ADP four-crystal electrooptic modulator is used for the retardation modulation and a high-speed digitizer for the simultaneous detection of the transmitted light intensity and the modulation voltage. The ellipsometer can acquire the necessary data for determining a data point (Ψ,Δ) in 4 μsec and repeat the data acquisition for fifty data points at intervals of 4 μsec–160 msec. In such conditions, precision represented in terms of an average of root mean squares is 0.05° in Ψ and 0.15° in Δ when a BaK1 standard optical glass is used as a sample at the present stage. An example is given of the application to rapid growth of anodic films on a semiconductor GaAs wafer.