11 June 2013 In situ aberration measurement technique based on an aerial image with an optimized source
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Abstract
An in situ aberration measurement technique based on an aerial image with an optimized source is proposed. A linear relationship between the aerial image and Zernike coefficients is established by the principal components and regression matrices, which are obtained in a modeling process through principal component analysis (PCA) and regression analysis. The linear relationship is used to extract Zernike aberrations from the measured aerial image in a retrieval process. The characteristics of regression matrix are analyzed, and the retrieval process of Zernike coefficients is optimized. An evaluation function for the measurement accuracy of Zernike aberrations is proposed, and then a fast procedure to optimize the illumination source is designed. Parameters of the illumination source are optimized according to the evaluation function and applied in our method. The simulators Dr.LiTHO and PROLITH are used to validate the method. Compared to the previous aberration measurement technique based on principal component analysis of an aerial image (AMAI-PCA), the number terms of Zernike coefficients that can be measured are increased from 7 to 27, and the measurement accuracy of Zernike aberrations is improved by more than 20%.
© 2013 Society of Photo-Optical Instrumentation Engineers (SPIE) 0091-3286/2013/$25.00 © 2013 SPIE
Guanyong Yan, Xiangzhao Wang, Sikun Li, Jishuo Yang, Dongbo Xu, Lifeng Duan, Anatoly Y. Bourov, and Andreas Erdmann "In situ aberration measurement technique based on an aerial image with an optimized source," Optical Engineering 52(6), 063602 (11 June 2013). https://doi.org/10.1117/1.OE.52.6.063602
Published: 11 June 2013
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Cited by 1 scholarly publication.
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KEYWORDS
In situ metrology

Image processing

Principal component analysis

Process modeling

Lithography

Matrices

Optical engineering

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