13 March 2012 In-situ measurement of lens aberrations in lithographic tools using CTC-based quadratic aberration model
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Abstract
With ever decreasing of feature sizes, the measurement of lens aberration has become increasingly important for the imaging quality control of projection lithographic tools. In this paper, we propose a method for in-situ aberration measurement based on a quadratic aberration model, which represents the bilinear relationship between the aerial image intensity and the Zernike coefficients. The concept of cross triple correlation (CTC) is introduced, so that the quadratic model can be calculated in a fast speed with the help of fast Fourier transform (FFT). We then develop a method for the Zernike coefficients characterization using the genetic optimization algorithm from the through focus aerial images of a nine contacts mask pattern. Simulation results demonstrate that this method is simple to implement and will have potential applications for in-situ metrology of lens aberration in lithographic tools.
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Xiaofei Wu, Shiyuan Liu, Shuang Xu, Xinjiang Zhou, Wei Liu, "In-situ measurement of lens aberrations in lithographic tools using CTC-based quadratic aberration model", Proc. SPIE 8326, Optical Microlithography XXV, 832629 (13 March 2012); doi: 10.1117/12.916190; https://doi.org/10.1117/12.916190
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