Coaxial spectroscopic imaging ellipsometry for volumetric thickness measurement

We propose spectroscopic imaging ellipsometry that can measure spectral ellipsometric signals in the entire field of view simultaneously without areal scanning or operation of polarization devices. The proposed imaging ellipsometry is configured in a coaxial optical structure so that the high magnification objective lens is applicable and the spatial resolution is highly increased. Without the operation of polarization components and to efficiently obtain the spectral data in the object plane, the ellipsometric parameters are encoded into the high frequency in the spectral domain and are measured by an imaging Michelson interferometer. The volumetric thickness measurement by the proposed method was verified by comparing the thickness results of the SiO2/Si sample that has four different thicknesses with commercial ellipsometer results. (C) 2020 Optical Society of America

Automated summary

The proposed spectroscopic imaging ellipsometry allows for measuring spectral ellipsometric signals in the entire field of view simultaneously using a coaxial optical structure. By encoding ellipsometric parameters into high frequency in the spectral domain and measuring them with an imaging Michelson interferometer, the method eliminates the need for operating polarization components. The effectiveness of volumetric thickness measurement was confirmed by comparing results with a commercial ellipsometer on SiO2/Si samples with varying thicknesses.