Polarization aberration in-situ measurement in lithography tools

Polarization aberration of projection optics should be measured, controlled and compensated accurately in high numerical-aperture image optical system, such as lithography tools for technical node of 14-5 nm. In this paper, we develop a three-step eigenvalue calibration method for polarization aberration measurement in-situ accurately. The whole system and subsystems can be calibrated by using the wide-view-angle quarter-wave plate as one of the reference samples. In addition, an experimental tool is developed to implement the proposed method, which is of significant importance to quantify and improve the properties of the projection optics in lithography.