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Proceedings Paper

Innovative image formation: coherency controlled imaging
Author(s): Koichi Matsumoto; Naomasa Shiraishi; Yuichiro Takeuchi; Shigeru Hirukawa
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Paper Abstract

Two types of innovative imaging systems are studied. One is the system with non-incoherent effective source and the other is the system with non-coherent pupil function. When the optics are configured in such a way that a certain pattern would be illuminated by a group of waves diffracted by the pattern itself or an exactly the same pattern, the effective source can be made no longer incoherent. Then the coherence of the effective source can be a new parameter to improve image quality. The simulation shows that the contrast of L/S pattern imaging under the off-axis illumination, for instance, can be boosted up to 99.5% with this system, while to only 90.6% with conventional optics. A new pupil filter is proposed; the area of which is divided into some annular zones to be made mutually incoherent. Then the phase difference becomes less crucial and large DOF can be achieved. The simulation shows that this filter is effective for the exposure of contact hole patterns.

Paper Details

Date Published: 17 May 1994
PDF: 10 pages
Proc. SPIE 2197, Optical/Laser Microlithography VII, (17 May 1994); doi: 10.1117/12.175475
Show Author Affiliations
Koichi Matsumoto, Nikon Corp. (Japan)
Naomasa Shiraishi, Nikon Corp. (Japan)
Yuichiro Takeuchi, Nikon Corp. (Japan)
Shigeru Hirukawa, Nikon Corp. (Japan)

Published in SPIE Proceedings Vol. 2197:
Optical/Laser Microlithography VII
Timothy A. Brunner, Editor(s)

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