Rapid angular ellipsometry method using spatial polarization modulation and detection

Owing to its nanometer accuracy and noninvasive properties, ellipsometry has an important role in the film thickness measurement and optical critical dimension (OCD) method for measuring gratings and semiconductor devices with periodic structures. Currently, commercial ellipsometers frequently take ∼10s to complete a measurement owing to the necessity for mechanically rotating polarized elements, which limits its efficiency. In this paper, we propose a new, to the best of our knowledge, ellipsometry setup that combines a vortex waveplate and a polarized camera to achieve polarization modulation and detection spatially. The measuring speed of the proposed system is determined by the frame rate of the polarized camera. A sample can be rotated to acquire its angular Mueller matrix within 3 s. The theoretical principle is described in this paper. The proposed system was calibrated, and a maximum error of 0.6% was observed when measuring the Mueller matrix of different samples. This proposed method is a simple and rapid method for measuring angular Mueller matrices and will further increase the efficiency of OCD methods and other ellipsometry applications.