Optical characterization of non-stoichiometric silicon nitride films

Characterizations of non stoichiometric silicon nitride films prepared by PECVD method onto silicon single crystal substrates are performed using variable angle spectroscopic ellipsometry and spectroscopic reflectometry and Rutherford backscattering spectrometry (RBS). The optical characterization employs a dispersion model based on the parametrization of the density of electronic states of the valence and conduction bands. The thin overlayers onto the upper boundaries of the films are taken into account. The values of the dispersion parameters of the SiNx films and thicknesses of these films and overlayers are determined. The ratios of Si and N atomic fractions in the individual films are evaluated using RBS. The results from the optical method and RBS are correlated.