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

作者：Lo Yu Lung^*; Hsieh Wen Hsiang; Chung Yi Fan; Tsai Shiou An

来源：Journal of Lightwave Technology, 2012, 30(14): 2298-2306.

DOI：10.1109/JLT.2012.2196977

• Anisotropic thin film
• ellipsometer
• genetic algorithm (GA)
• isotropic thin film
• Mueller matrix
• stokes vector.

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 Psi(pp) and Delta(pp) are 0.020 degrees and 0.464 degrees, respectively. Meanwhile, for a typical anisotropic thin film, the average standard deviations of Psi(pp), Psi(ps), Psi(sp), Delta(pp), Delta(ps), and Delta(sp) are found to be 0.014 degrees, 0.047 degrees, 0.041 degrees, 0.312 degrees, 0.402 degrees, and 0.571 degrees, 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.

• 出版日期2012-7-15