A novel method of partial coherence measuring for the illuminationsystem and its defocus performance analysis

摘要

Partial coherence (generally represented by is one of the important parameters of lithographic toolto assess the performance of pupil fill. In this paper, a novel method of partial coherence measurementfor the illumination system is proposed. Statistical results of measured by the proposed method areanalyzed. The dependence of partial coherence on the defocus, which is the distance from the measuringposition to the best image plane, is also investigated. The simulation results prove the effectiveness ofthis method, and with the defocus increasing, the measured partial coherence decreases. Generally, ifthree times of the standard deviation is required to be 1 × 10-3, the amount of defocus should be lessthan 96 μ.