Spectro-ellipsometric studies of sputtered amorphous titanium dioxide thinfilms: Simultaneous determination of refractive index, extinction coefficient, and void distribution

Amorphous titanium dioxide thin films were deposited onto silicon substrate s by using RF magnetron sputtering, and the index of refraction, the extinc tion coefficient, and the void distribution of these films were simultaneou sly determined from the analyses of their ellipsometric spectra. In particu lar, our novel strategy, which combines the merits of multi-sample fitting, the dual dispersion function, and grid search, was proven successful in de termining the optical constants over a wide energy range, including the ene rgy region where the extinction coefficient was large. Moreover, we found t hat the void distribution was dependent on the deposition conditions, such as the sputtering power, the substrate temperature, and the substrate surfa ce.