title: Measurement technique for in situ characterizing aberrations of projection optics in lithographic tools.
abstract: As the feature size decreases, degradation of image quality caused by wavefront aberrations of projection optics in lithographic tools has become a serious problem in the low-k1 process. We propose a novel measurement technique for in situ characterizing aberrations of projection optics in lithographic tools. Considering the impact of the partial coherence illumination, we introduce a novel algorithm that accurately describes the pattern displacement and focus shift induced by aberrations. Employing the algorithm, the measurement condition is extended from three-beam interference to two-, three-, and hybrid-beam interferences. The experiments are performed to measure the aberrations of projection optics in an ArF scanner.
authors.affiliation: Information Optics Laboratory, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China. wf@ustc.edu
authors.forename: Fan
authors.initials: F
authors.lastname: Wang
authors.forename: Xiangzhao
authors.initials: X
authors.lastname: Wang
authors.forename: Mingying
authors.initials: M
authors.lastname: Ma