Impact of non-uniform polarized illumination on hyper-NA lithography

Abstract

Conventional top-hat model of polarized illumination loses its accuracy in lithography simulation which cannot meet the requirements of 45nm node lithography and beyond. The simulation error of top-hat model in evaluating lithography performance cannot be neglected anymore. In this paper, we apply a Gaussian model to represent the non-uniform degree of polarization (NU-DOP) distribute across the pupil and evaluate its impact on the CD uniformity under various conditions. The result shows that the model can accurately evaluate the non-uniform property of polarized illuminator. When the mean NU-DOP approaches to 1, the effect of non-uniformity becomes more pronounced. Furthermore, the non-uniform of DOP distribution causes more CD error at defocus position.