SPECTROELLIPSOMETRIC CHARACTERIZATION OF THIN SILICON-NITRIDE FILMS

An empirical dielectric function (EDF) has been used to represent the spectra in the effective optical constants of Si-rich nitride (SiNx) t hin films processed by PECVD. A good correlation was found between the EDF parameters and the film composition results from Auger spectrosco py. It is shown that the EDF approach allows one to use a simple optic al model of the film stack and extrapolate the spectra in the optical constants of SINx outside the measured wavelength range. This advantag e gives a feasibility of using the EDF to characterize optical propert ies of thin films in the Deep-UV region, below 230 nm, which is outsid e the spectral range of most commercial ellipsometers. (C) 1998 Elsevi er Science S.A.