24 March 2016 Overlay metrology performance prediction fidelity: the factors enabling a successful target design cycle
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Overlay metrology performances highly depend on the detailed design of the measured target. Hence performing simulations is an essential tool for optimizing target design. We demonstrate for scatterometry overlay (SCOL) three key factors which enable consistency in ranking between simulated and measured metrology performance for target design. The first factor, to enable high fidelity simulations for the purpose of target design, is stack and topography verification of model inputs. We report in detail the best known film metrology methods required to achieve model integrity. The second factor is the method of calculation of metrology performance metrics based on target cell reflectivities from electro-magnetic (EM) simulations. These metrics enable ranking of different designs, and subsequent choice of the best performing designs among all simulated design options, the ranking methodology being the third factor. We apply the above steps to a specific stack, where five different designs have been considered. Simulated versus measured values are compared. A good agreement between simulation and measurement is achieved.
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Inna Tarshish-Shapir, Inna Tarshish-Shapir, Eitan Hajaj, Eitan Hajaj, Greg Gray, Greg Gray, Jeffery Hodges, Jeffery Hodges, Jianming Zhou, Jianming Zhou, Sarah Wu, Sarah Wu, Sam Moore, Sam Moore, Guy Ben-Dov, Guy Ben-Dov, Chen Dror, Chen Dror, Ze'ev Lindenfeld, Ze'ev Lindenfeld, David Gready, David Gready, Mark Ghinovker, Mark Ghinovker, Mike Adel, Mike Adel, "Overlay metrology performance prediction fidelity: the factors enabling a successful target design cycle", Proc. SPIE 9778, Metrology, Inspection, and Process Control for Microlithography XXX, 97782J (24 March 2016); doi: 10.1117/12.2219181; https://doi.org/10.1117/12.2219181

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