Film thickness dependence on the optical properties of sputtered and UHV deposited Ti thin films

Titanium films of different thicknesses were deposited on glass substrates, using planar magnetron sputtering at 313 K substrate temperature. Their optical properties were measured by spectrophotometry in the spectral range of 200-2500 nm. Kramers-Kronig method was used for the analysis of the reflectivity curves of Ti films to obtain the optical constants of the films. In order to compare the influence of thickness of Ti films prepared using two different PVD methods, namely sputtering and electron gun depositions on the optical properties of Ti films, the optical results of Savaloni and Kangarloo (2007) for Ti films produced using electron gun deposition under UHV condition at 313 K substrate temperature are incorporated in this work. The analysis of the residual stress in the sputter deposited films using sin(2) psi technique and the nano-strain in the E. Gun deposited films obtained from X-ray diffraction line broadening analysis (Warren-Averbach method) showed consistency with the results obtained for optical functions and agreed well with the predictions of both structural zone model (SZM) and effective medium approximation (EMA) results. Therefore, a direct correlation between the optical properties and the processes involved in the evolution of thin films is established. The optical data, in particular the conductivity results for sputter deposited Ti films show more agreement with those of bulk sample (Lynch et al., 1975), while those of UHV E. Gun deposited films are more consistent with those of thin film sample (Johnson and Christy, 1974). (C) 2010 Elsevier Ltd. All rights reserved.