Optical characterization of TiN thin films

In this work we demonstrate the combined use of spectroscopic ellipsometry (performed from 420-720 nm at 65° angle of incidence) and spectroscopic reflectometry (performed from 200-800 nm at normal incidence) for the characterization of thin TiN films deposited on thick oxide films on silicon. By simultaneously analyzing both reflectance and ellipsometric spectra acquired from the same physical location on the sample surface we are able to precisely determine both the TiN and oxide film thicknesses, as well as the optical constants of the TiN film. The key to this analysis is the use of the Lorentz oscillator dispersion model to parameterize the optical constants of the TiN thin film such that these optical constants can be varied in the analysis by varying a relatively small number of parameters in the Lorentz oscillator dispersion model