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Proceedings Paper

Quasi-telecentricity: the effects of unbalanced multipole illumination
Author(s): Stephen P. Renwick
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Paper Abstract

Telecentricity has long been recognized as an important property of lithography-tool optics. "Shift" telecentricity error, an angular misalignment of the illuminator and projection lens, manifests itself as an unwanted translation of the aerial image through focus. At best focus, no effect is visible. Generally, litho tool acceptance tests measure directly the translation through focus, although it is also possible to use pupil-imaging techniques to observe the error by measuring offset of the pupil fill with respect to the projection lens NA. Even with a perfectly aligned system (i.e. a perfectly centered pupil fill), it is still possible to induce a translation through focus. This arises especially in multipole pupil fill patterns (dipole, quadrupole, etc.) which have one pole brighter than the others. We refer to this effect as "quasi-telecentricity." With the tight pitches and extreme polar illumination patterns coming into increasing use, this effect will become more important in the next few years. We have calculated the size of the effect and placed limits on the illumination patterns that can be used for this type of printing.

Paper Details

Date Published: 26 March 2007
PDF: 11 pages
Proc. SPIE 6520, Optical Microlithography XX, 65202W (26 March 2007); doi: 10.1117/12.712752
Show Author Affiliations
Stephen P. Renwick, Nikon Precision, Inc. (United States)

Published in SPIE Proceedings Vol. 6520:
Optical Microlithography XX
Donis G. Flagello, Editor(s)

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