THIN FILM COMPOSITIONAL ANALYSIS USING NULL OR FIXED WAVELENGTH ELLIPSOMETRY.

The chemical composition of an insulating film on a semiconducting substrate is estimated using null or fixed wavelength ellipsometry. Multiple-wavelength-angle-of-incidence ellipsometry, together with the effective medium approximation, were used to evaluate both the composition and the geometrical structure of an insulating film made of silicon nitride and silicon oxide on a GaAs substrate. The general applicability of the technique for null or fixed wavelength ellipsometers is critically assessed and compared with the more commonly used fixed-angle-of-incidence spectroscopic ellipsometric method.