  In spectroscopic ellipsometry, the optical properties of materials are
obtained indirectly by generally assuming dielectric function and optical
models. This ellipsometry analysis, which typically requires numerous model
parameters, has essentially been performed by a try-and-error approach, making
this method as a rather time-consuming characterization technique. Here, we
propose a fully automated spectroscopic ellipsometry analysis method, which can
be applied to obtain dielectric functions of light absorbing materials in a
full measured energy range without any prior knowledge of model parameters. The
developed method consists of a multiple-step grid search and the following
non-linear regression analysis. Specifically, in our approach, the analyzed
spectral region is gradually expanded toward higher energy while incorporating
an additional optical transition peak whenever the root-mean-square error of
the fitting analysis exceeds a critical value. In particular, we have
established a unique algorithm that could be employed for the ellipsometry
analyses of different types of optical materials. The proposed scheme has been
applied successfully for the analyses of MoOx transparent oxides and the
complex dielectric function of a MoOx layer that exhibits dual optical
transitions due to band-edge and deep-level absorptions has been determined.
The developed method can drastically reduce a time necessary for an
ellipsometry analysis, eliminating a serious drawback of a traditional
spectroscopic ellipsometry analysis method.
