Multiscale measurement for infrared suppression ratio of SPFs-integrated EUV collectors by a weighted harmonic mean integral

Infrared (IR) suppression is essential for extreme ultraviolet (EUV) lithography systems. This study establishes a method for predicting the global infrared suppression ratio (IRSR) of EUV collectors from local IRSR values, based on a weighted harmonic mean integral framework. To enable reliable local IRSR measurement, the challenge of spectral leakage inherent in finite-spot illumination on large-period gratings is analyzed and overcome by identifying optimal illumination conditions that balance spatial resolution and signal integrity. A dedicated optical system is implemented to execute this localized measurement strategy. The proposed method enables detailed assessment of IRSR performance and uniformity across the collector surface, offering practical insights for manufacturing tolerance specification and optimization of the collector-SPFs collaborative design.