Convergence and precision characteristics of finite difference time domain method for the analysis of spectroscopic ellipsometry data at oblique incidence

The finite difference time domain (FDTD) method presents attractive advantages for analysis of the spectroscopic ellipsometry (SE) response of complex, non-planar samples including generality and suitability to address complex structures as well as non-linear effects and/ or non-periodic morphologies. However, it is imperative to advance our understanding, and more importantly, to design strategies to improve the computational time of FDTD method calculations. In a previous report we show the ability to simulate the SE response of prototypical samples based on far-field projections of near-field simulation based on the FDTD method with accuracy equivalent to similar to 0.5 monolayer precision in film thickness up to 70 degrees angle of incidence (AoI). In this contribution, we provide a refined strategy that results in similar to 3 orders of magnitude improvement in the determination of the SE data as estimated by the chi(2) figure of merit for modeling of SE data at angles as large as 80. AoI with respect to the standard solution. Significantly the proposed strategy also provides improvement in the computation time that speeds up by a factor similar to 4x at 70 degrees AoI but that can be as large as similar to 20x for 40 degrees AoI. (C) 2016 Elsevier B. V. All rights reserved.