Polarization simulation and analysis of residual birefringence in optical materials for a hyper-NA lithography illumination system

摘要

A polarization simulation and analysis method was carried out for a hyper numerical apertures (NA) lithography illumination system which is affected by residual birefringence in optical materials. The lens is divided into multiple small annuli according to the finite element method, and the retardation distribution is obtained by setting the residual birefringence of each annulus. Finally, the polarized ray tracing is cleverly changed to geometric ray tracing. A hyper-NA lithography illumination system is modeled, and the residual birefringence is set between 0.1 nm/cm and 1 nm/cm. The simulation result shows that the degree of polarization performance degradation is proportional to the magnitude of residual birefringence, and the tolerance of residual birefringence in lens materials is below 1 nm/cm for the system. The polarization simulation and analysis method provides a powerful tool to calculate the polarized parameters of the system, which is helpful for selecting lens material of the hyper-NA illumination system. (C) 2019 Optical Society of America