13 November 2014 A 2-dimensionalal thickness measurement ellipsometer based on the the the liquid crystal variable retarder
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Abstract
A 2-dimensional thickness measurement ellipsometer based on the liquid crystal variable retarder (LCVR) is proposed and setup in order to provide precise, real-time measurement in a manufacturing environment. Images are collected sequentially by CCD camera with respect to pre-determined polarization state of incident light derived by the LCVR attached with compensator. A phase-shifting algorithm and a Fourier series approach algorithm are used to obtain full-field distributions of the ellipsometric parameters, and then a polarization model (ambient-film-substract) is used to calculate the thickness of a thin film in two dimensions precisely and quickly. Theoretically, the speed and precision of this method benefit from applying voltage on the LCVR to produce polarization modulation that is able to avoid mechanical vibrations that could affect the accuracy of the measurements. The experimental results verify the ability and performance of the 2-dimensional thickness measurement ellipsometer.
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Fangfang Meng, Xuejian Wu, Yan Li, "A 2-dimensionalal thickness measurement ellipsometer based on the the the liquid crystal variable retarder", Proc. SPIE 9276, Optical Metrology and Inspection for Industrial Applications III, 92761U (13 November 2014); doi: 10.1117/12.2071875; https://doi.org/10.1117/12.2071875
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