Characterization of the Optical Properties and Composition of TiNx Thin Films by Spectroscopic Ellipsometry and Xray Photoelectron Spectroscopy

Abstract

Thin films of TiNx with 0.34<x<1.19 were deposited on silicon substrates by a filtered arc deposition process. Spectroscopic ellipsometry (SE) in the energy region 1.5–3.5 eV was used to measure the optical properties of the films. X-ray photoelectron spectroscopy (XPS) was used to determine the relative atomic concentration and the chemical states of the elements. The dielectric function ε(ω) measured by ellipsometry gives the optical response of TiNx films and valuable information on their chemical composition, which is also verified by XPS. The plasma energy ωp of TiNx films was found to depend strongly on the N/Ti ratio and this is correlated with the value of x as determined by XPS and Rutherford backscattering spectroscopy (RBS). The results show that, via the calibration, spectroscopic ellipsometry may be used to estimate the stoichiometry of deposited TiNx films.