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Proceedings Paper

Automated aberration extraction using phase wheel targets
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Paper Abstract

An approach to in-situ wavefront aberration measurement is explored. The test is applicable to sensing aberrations from the image plane of a microlithography projection system or a mask inspection tool. A set of example results is presented which indicate that the method performs well on lenses with a Strehl ration above 0.97. The method uses patterns produced by an open phase figure1 to determine the deviation of the target image from its ideal shape due to aberrations. A numerical solution in the form of Zernike polynomial coefficients is reached by modeling the object interaction with aberrated pupil function using the nonlinear optimization routine over the possible deformations to give an accurate account of the image detail in 2-D. The numerical accuracy for the example below indicated superb performance of the chosen target shapes with only a single illumination setup.

Paper Details

Date Published: 12 May 2005
PDF: 10 pages
Proc. SPIE 5754, Optical Microlithography XVIII, (12 May 2005); doi: 10.1117/12.606460
Show Author Affiliations
Lena Zavyalova, Rochester Institute of Technology (United States)
Anatoly Bourov, Rochester Institute of Technology (United States)
Bruce W. Smith, Rochester Institute of Technology (United States)

Published in SPIE Proceedings Vol. 5754:
Optical Microlithography XVIII
Bruce W. Smith, Editor(s)

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