15 March 2006 Practical approach to full-field wavefront aberration measurement using phase wheel targets
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Abstract
An automated aberration extraction method is presented which allows extraction of lithographic projection lens' aberration signature having only access to object (mask) and image (wafer) planes. Using phase-wheel targets on a two-level 0/π phase shift mask, images with high sensitivity to aberrations are produced. Zernike aberration coefficients up to 9th order have been extracted by inspection of photoresist images captured via top-down SEM. The automated measurement procedure solves a multi-dimensional optimization problem using numerical methods and demonstrates improved accuracy and minimal cross-correlation. Starting with a detailed procedure analysis, recent experimental results for 193-nm projection optics in commercial full field exposure tools are discussed with an emphasis on the performance of the aberration measurement approach.
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Lena V. Zavyalova, Lena V. Zavyalova, Bruce W. Smith, Bruce W. Smith, Anatoly Bourov, Anatoly Bourov, Gary Zhang, Gary Zhang, Venugopal Vellanki, Venugopal Vellanki, Patrick Reynolds, Patrick Reynolds, Donis G. Flagello, Donis G. Flagello, "Practical approach to full-field wavefront aberration measurement using phase wheel targets", Proc. SPIE 6154, Optical Microlithography XIX, 61540Y (15 March 2006); doi: 10.1117/12.657928; https://doi.org/10.1117/12.657928
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