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Proceedings Paper

Wafer edge-shot algorithm for wafer scanners
Author(s): Tsuneyuki Hagiwara; Masato Hamatani; Hideyuki Tashiro; Etsuya Morita; Shinichi Okita; Naoto Kondo
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Paper Abstract

The requirement for the higher resolution is pushing up the NA of the projection lens, so the DOF becomes shallower and the focus budget becomes tight. On the other hand, the requirement for the higher through-put is still demanding. To achieve the best throughput, the alternate scanning exposure sequence is inevitable to current wafer scanners. To realize the alternative scanning exposure, it is necessary to perform precise focusing control even at the partial shot on the wafer edge region. A wafer edge stepwise focusing algorithm is developed. This algorithm utilizes multi-points focusing sensors and dynamically switches the focusing sensors during alternating scan exposure of the partial site on the wafer edge region. Thus the amount of the defocus on the wafer edge region is minimized. The actual performance of the wafer edge stepwise focusing algorithm is discussed. This algorithm can be used with or without pitching motion control of the wafer leveling stage. The influence of the pitching motion control to the focusing performance is also discussed.

Paper Details

Date Published: 30 July 2002
PDF: 12 pages
Proc. SPIE 4691, Optical Microlithography XV, (30 July 2002); doi: 10.1117/12.474628
Show Author Affiliations
Tsuneyuki Hagiwara, Nikon Corp. (Japan)
Masato Hamatani, Nikon Corp. (Japan)
Hideyuki Tashiro, Nikon Corp. (Japan)
Etsuya Morita, Nikon Precision Inc. (United States)
Shinichi Okita, Nikon Corp. (Japan)
Naoto Kondo, Nikon Corp. (Japan)

Published in SPIE Proceedings Vol. 4691:
Optical Microlithography XV
Anthony Yen, Editor(s)

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