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Proceedings Paper

Method of Zernike coefficients extraction for optics aberration measurement
Author(s): Yoshihiro Shiode; Shuuichi Okada; Hiroki Takamori; Hideki Matsuda; Sachiko Fujiwara
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Paper Abstract

With recent progress in resolution enhancement techniques, requirements for exposure tools, specifically optics aberration, are becoming severer. Some simple ways to allow aberration measurements to be performed on exposure tools have been reported and made commercially available. These methods, however, do not seem to go much beyond monitoring of aberration changes while the accuracy of absolute values is left unclear. This paper describes a new approach of optics aberration measurement. With this approach, an optimum effective light source and patterns to be measured have been designed for analysis of Zernike polynomials that represent the wavefront of optics. By measuring the shift of images printed from the patterns with the light source, specific Zernike coefficients can be extracted. This new technique can also be applied to any conventional lens aberration tests using SEM. Same as the above Zernike coefficients extraction, just measuring the displacement of the images that are formed from optimum mask patterns with an optimum light source will provide a conventional SEM value. Simulations to compare the new technique with the conventional SEM showed a very good correlation with each other as expected. Experimental results are discussed to determine the accuracy of the new technique.

Paper Details

Date Published: 30 July 2002
PDF: 12 pages
Proc. SPIE 4691, Optical Microlithography XV, (30 July 2002); doi: 10.1117/12.474530
Show Author Affiliations
Yoshihiro Shiode, Canon Inc. (Japan)
Shuuichi Okada, Canon Inc. (Japan)
Hiroki Takamori, Canon Inc. (Japan)
Hideki Matsuda, Canon Inc. (Japan)
Sachiko Fujiwara, Canon Inc. (Japan)

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

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