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Evaluation of Pupil-Filtering in High-Numerical Aperture I-Line Lens

1993; Institute of Physics; Volume: 32; Issue: 12S Linguagem: Inglês

10.1143/jjap.32.5845

1347-4065

Hiroshi Fukuda, Yasushi Kobayashi, Katsunobu Hama, Tsutomu Tawa, Shinji Okazaki,

Advanced optical system design

The pupil-filtering lens system for optical lithography experimentally evaluated in this study is based on an i-line stepper lens with a numerical aperture (NA) of 0.5, and its pupil function can be set arbitrarily to change the image characteristics. With the previously proposed super-FLEX filter, the depth of focus was three times that of the system without the filter, and the resolution for window patterns was 20% higher. Image characteristics of the filter, such as the edge-enhancing effect and the proximity effect, are discussed and were experimentally evaluated. The optical and mechanical tolerances required for this system are shown to be within ranges that are attainable in practical stepper systems.