Design and operation of an automated, high-temperature ellipsometer

A computer-assisted, ellipsometric system performs in situ measurements on substrates and thin films in various atmospheres, at temperatures up to 1450 K. A laser is used as the light source. The light flux exiting from a rotating analyzer is measured at 512 equally spaced intervals, to yield a flux ellipse that is used for further analysis. Data acquisition and data reduction are under control of an IBM System/7 computer. Ab initio calibration of the optical components using a fixed angle of incidence is possible; the cell windows are considered as small-retardation wave plates. Effects of non-ideality of polarizer and analyzer were negligible. Refractive indices of silicon (nSi*) and thermally grown silicon dioxide (nSiO2) are reported as functions of temperature up to 1350 K.