Spectroscopic ellipsometry of multilayer dielectric coatings

Multilayer dielectric coatings deposited by e-beam evaporation have been ch aracterised by the phase modulated spectroscopic ellipsometer (PMSE). Measu rements have been done on various multilayer thin films devices e.g., high reflectivity mirror, narrow band filter, beam combiner, beam splitter, etc. consisting of several bilayers of TiO2/SiO2. Results have been shown here for the first two samples. The measured Ellipsometry spectra are fitted wit h theoretical spectra generated assuming appropriate models regarding the s ample structures. Optical constants of the substrates and the SiO2 films ha ve been supplied and trial dispersion relations have been used for the opti cal constants of the TiO2 layers. The fittings have been done by minimising the squared difference (chi (2)) between the measured and calculated value s of the ellipsometric parameters (psi and Delta) and accurate information have been derived regarding the thickness and refractive indices of the dif ferent layers. (C) 2001 Elsevier Science Ltd. All rights reserved.