19 March 2015 Overlay target selection for 20-nm process on A500 LCM
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Persistently shrinking design rules and increasing process complexity require tight overlay control thereby making it imperative to choose the most suitable overlay measurement technique and complementary target design. In this paper we describe an assessment of various target designs from FEOL to BEOL on 20-nm process. Both scatterometry and imaging based methodology were reviewed for several key layers on A500LCM tool, which enables the use of both technologies. Different sets of targets were carefully designed and printed, taking into consideration the process and optical properties of each layer. The optimal overlay target for a given layer was chosen based on its measurement performance.
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Vidya Ramanathan, Vidya Ramanathan, Lokesh Subramany, Lokesh Subramany, Tal Itzkovich, Tal Itzkovich, Karsten Gutjhar, Karsten Gutjhar, Patrick Snow, Patrick Snow, Chanseob Cho, Chanseob Cho, Lipkong Yap, Lipkong Yap, "Overlay target selection for 20-nm process on A500 LCM", Proc. SPIE 9424, Metrology, Inspection, and Process Control for Microlithography XXIX, 942424 (19 March 2015); doi: 10.1117/12.2086016; https://doi.org/10.1117/12.2086016

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