Study on pellicle optimization and polarization aberration induced by pellicle in hyper numerical aperture lithography

In hyper numerical aperture (NA) lithography imaging, the incident angle of imaging rays on pellicle varies in a wide range, so it is difficult to enhance the transmittance of oblique incidence employing the conventional pellicle optimization methods. A novel pellicle optimization method is developed based on the film optics theory, which maximizes the average transmittance within the whole incident angles range. The transmission properties and phase characteristics of pellicle are studied using Johns matrix representation. The corresponding Johns pupil is obtained to analyze the polarization aberration induced by pellicle. The results show that, compared with the conventional pellicle optimization methods, the novel method enhances the transmittance of oblique incidence and decreases the pellicle-induced polarization aberration more effectively. The novel method provides the essential theoretical basis and technical support for pellicle setting in hyper NA lithography imaging.