An Approach for Measuring the Ellipsometric Parameters of Isotropic and Anisotropic Thin Films Using the Stokes Parameter Method

A method is proposed for extracting the ellipsometric parameters of isotropic and anisotropic thin films from the Stokes parameters obtained for five different input polarization lights, namely four linearly polarized lights and one right-hand circular polarized light. In the proposed approach, the genetic algorithm in curve fitting is used to extract the refractive index and thickness properties of the isotropic or anisotropic sample from the experimental results obtained for the variation of the ellipsometric parameters with the incident angle. Finally, the experimental values of the ellipsometric parameters and the simulated values are compared. It is shown that for a typical isotropic thin film, the average standard deviations of Ψ
pp
and Δ
pp
are 0.020° and 0.464°, respectively. Meanwhile, for a typical anisotropic thin film, the average standard deviations of Ψ
pp
, Ψ
ps
, Ψ
sp
, Δ
pp
, Δ
ps
, and Δ
sp
are found to be 0.014°, 0.047°, 0.041°, 0.312°, 0.402°, and 0.571°, respectively. Overall, the results presented in this study confirm that the proposed method provides a straightforward and reliable means of extracting the ellipsometric parameters of isotropic and anisotropic materials by Stokes parameters using five independent input polarization lights. Specially, the ellipsometric parameters of anisotropic thin film expressed by Stokes parameters or Mueller elements are explicitly presented.