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High-order aberration measurement technique based on quadratic Zernike model with optimized source

 
: Yang, J.; Wang, X.; Li, S.; Duan, L.; Yan, G.; Xu, D.; Bourov, A.Y.; Erdmann, A.

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Optical engineering 52 (2013), No.5, Art. 053603
ISSN: 0091-3286
ISSN: 0036-1860
ISSN: 1560-2303
English
Journal Article
Fraunhofer IISB ()

Abstract
In this paper, we propose an aberration metrology (AM) of a lithographic projection lens based on aerial images (AI) by using a quadratic relationship model (Quad) between the aerial-image intensity distribution and the Zernike coefficients. The proposed method (AMAI-Quad) uses principal component analysis and multiple linear regression analyses for model generation. The quadratic model is, then, used to extract Zernike coefficients by a nonlinear least-squares minimizing technique. The best linear constrain condition is estimated by optimizing the illumination settings. Compared with earlier techniques, based on a linear relationship between Zernike coefficients and AIs, the new method can extend the orders of Zernike coefficients measured. The application of AMAI-Quad to AIs, computed by lithography simulators PROLITH and Dr.LiTHO, demonstrated an extension of measurement range to 90m? and an enhancement of measurement accuracy by more than 30 percent.

: http://publica.fraunhofer.de/documents/N-283917.html