Ellipsometric Liquid Immersion Method For Determination Of All Optical Parameters Of System - Nonabsorbing Film On An Absorbing Substrate

A method for obtaining all the optical parameters of a system of an absorbing substrate with a nonabsorbing surface film from a series of ellipsometric measurements is described. It utilizes the fact that the reflectance of such a system at normal incidence remains essentially constant for a small but finite range of surface-film thicknesses. Furthermore, it hinges on the fact that the ellipsometric parameters Δ and ψ, measured on one sample in two different ambients, are compatible with only one choice of the complex refractive n 2 − i k 2 of the substrate and the refractive index n 1 of the film. Results on cleaved samples of silicon are reported.