Characterization of curved surface layer by Mueller matrix ellipsometry

Abstract

The authors apply Mueller matrix ellipsometry to characterize the curved surface layers, by utilizing the noticeable anisotropy observed from the measured data. The authors demonstrate that this anisotropy is introduced by the curved surface shape as well as the misalignment between the illumination spot and the surface vertex. An optical model is proposed to expound the anisotropy, and is applied to evaluate the curved thin thermal oxide layer on a silicon sphere crown. After incorporating the proposed optical model in the parameter extraction, the experimental results show that not only will the accuracy of the oxide layer thickness measurement at an arbitrary location on the surface be improved, the curvature radius as well as the position of detection can also be determined directly.