13 March 2018 Measurement of pattern roughness and local size variation using CD-SEM: current status
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Measurement of line edge roughness (LER) is discussed from four aspects: edge detection, PSD prediction, sampling strategy, and noise mitigation, and general guidelines and practical solutions for LER measurement today are introduced. Advanced edge detection algorithms such as wave-matching method are shown effective for robustly detecting edges from low SNR images, while conventional algorithm with weak filtering is still effective in suppressing SEM noise and aliasing. Advanced PSD prediction method such as multi-taper method is effective in suppressing sampling noise within a line edge to analyze, while number of lines is still required for suppressing line to line variation. Two types of SEM noise mitigation methods, "apparent noise floor" subtraction method and LER-noise decomposition using regression analysis are verified to successfully mitigate SEM noise from PSD curves. These results are extended to LCDU measurement to clarify the impact of SEM noise and sampling noise on LCDU.
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Hiroshi Fukuda, Hiroshi Fukuda, Takahiro Kawasaki, Takahiro Kawasaki, Hiroki Kawada, Hiroki Kawada, Kei Sakai, Kei Sakai, Takashi Kato, Takashi Kato, Satoru Yamaguchi, Satoru Yamaguchi, Masami Ikota, Masami Ikota, Yoshinori Momonoi, Yoshinori Momonoi, "Measurement of pattern roughness and local size variation using CD-SEM: current status ", Proc. SPIE 10585, Metrology, Inspection, and Process Control for Microlithography XXXII, 105850H (13 March 2018); doi: 10.1117/12.2299633; https://doi.org/10.1117/12.2299633

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