Performance measurement technique for 193-nm depolarizer

Abstract

Herein, a performance measurement technique for 193-nm depolarizers, which is an area that still lacks research, is proposed and demonstrated. Utilizing a reflective fused-quartz Brewster wedge plate as a polarizer, a large beam at 193 nm is effectively polarized with a large separation angle, which is not possible with traditional polarization prisms. A pre-polarizing and beam-splitting structure is used to reduce power drift. A statistical method that makes full use of repeated measurements and priori knowledge (polarization decomposition and Malus' law) is developed to significantly improve measurement accuracy. Verification, functional, and repeatability tests are conducted. The experimental results are in good agreement with the theoretical analysis. This technique exhibits excellent accuracy and precision. It can be used for offline measurement of the depolarizer used in 193-nm immersion lithography, which is of considerable significance. Furthermore, the results provide important insights for related works on high-accuracy polarization measurement at ultra-short wavelengths.