Polarization state change calibration and system verification of a Mueller matrix spectroscopic ellipsometer based on reflective objectives

The Mueller matrix spectroscopic ellipsometer is a non-destructive measurement method that utilizes the polarization properties of light and is widely used to measure the critical dimensions created after semiconductor processing. However, for critical dimension measurement, it should use a reflective objective so that its focal length does not change according to each wavelength, and the size of the beam incident on the sample keeps sufficiently small. At this point, there is a limitation in that the polarization state changes depending on the angle of the beam incident from the reflective objective and the degree of coating on the mirror surface. In this investigation, we propose a method to extract the polarization state changes that occur in the reflective objectives.