3 April 2008 Optimization of high order control including overlay, alignment, and sampling
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Overlay requirements for semiconductor devices are increasing faster than anticipated. Overlay becomes much harder to control with current methods and therefore novel techniques are needed. In this paper, we present our investigation methods for High Order Control, and the candidates for improvement. This paper will present the study for each components of high order control. High order correction is one component for high order control and several correction methods were compared for this study. High order alignment is another important component for higher order control instead of using conventional linear model for the alignment. Alignment and overlay measurement sampling decision becomes a more critical issue for sampling efficiency and accuracy. Optimal sampling for high order was studied for high order control. Using all these studies, various applications for optimal high order control have also been studied. This study will show the general approach for high order control with theory and actual experimental data.
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Dongsub Choi, Dongsub Choi, Chulseung Lee, Chulseung Lee, Changjin Bang, Changjin Bang, Daehee Cho, Daehee Cho, Myunggoon Gil, Myunggoon Gil, Pavel Izikson, Pavel Izikson, Seunghoon Yoon, Seunghoon Yoon, Dohwa Lee, Dohwa Lee, } "Optimization of high order control including overlay, alignment, and sampling", Proc. SPIE 6922, Metrology, Inspection, and Process Control for Microlithography XXII, 69220P (3 April 2008); doi: 10.1117/12.772274; https://doi.org/10.1117/12.772274

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