7 April 2016 Measurement of asymmetric side wall angles by coherent scanning Fourier scatterometry
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We propose a measurement technique which enables the precise determination of side wall angles (SWAs) with absolute values below 1°. Our simulations show that a differentiation between asymmetric SWAs is also possible. The grating structure under investigation has a grating period on the order of a few micrometers. Each grating line consists of a fine sub-grating with 40 nm period and 20 nm critical dimension. Our approach is based on coherent high-NA Fourier scatterometry, extended by a lateral scan over the sample. Additionally, a 180°-shearing element allows for coherent superposition of the higher diffraction orders.
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M. L. Gödecke, M. L. Gödecke, S. Peterhänsel, S. Peterhänsel, K. Frenner, K. Frenner, W. Osten, W. Osten, "Measurement of asymmetric side wall angles by coherent scanning Fourier scatterometry", Proc. SPIE 9778, Metrology, Inspection, and Process Control for Microlithography XXX, 97780G (7 April 2016); doi: 10.1117/12.2218824; https://doi.org/10.1117/12.2218824

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