Spectroscopic ellipsometry of inhomogeneous thin films exhibiting thickness non-uniformity and transition layers

In this paper the complete optical characterization of an inhomogeneous polymer-like thin film of SiO x C y H z exhibiting a thickness non-uniformity and transition layer at the boundary between the silicon substrate and this film is performed using variable angle spectroscopic ellipsometry. The Campi-Coriasso dispersion model was utilized for describing the spectral dependencies of the optical constants of the SiO x C y H z thin film and transition layer. The multiple-beam interference model was used for expressing inhomogeneity of the SiO x C y H z thin film. The thickness non-uniformity of this film was taken into account by means of the averaging of the elements of the Mueller matrix performed using the thickness distribution for the wedge-shaped non-uniformity. The spectral dependencies of the optical constants of the SiO x C y H z thin film at the upper and lower boundaries together with the spectral dependencies of the optical constants of the transition layer were determined. Furthermore, the thickness values of the SiO x C y H z film and transition layer, profiles of the optical constants of the SiO x C y H z thin film and the rms value of local thicknesses corresponding to its thickness non-uniformity were determined. Thus, all the parameters characterizing this complicated film were determined without any auxiliary methods.