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24 March 2016 Lithography aware overlay metrology target design method
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We present a metrology target design (MTD) framework based on co-optimizing lithography and metrology performance. The overlay metrology performance is strongly related to the target design and optimizing the target under different process variations in a high NA optical lithography tool and measurement conditions in a metrology tool becomes critical for sub-20nm nodes. The lithography performance can be quantified by device matching and printability metrics, while accuracy and precision metrics are used to quantify the metrology performance. Based on using these metrics, we demonstrate how the optimized target can improve target printability while maintaining the good metrology performance for rotated dipole illumination used for printing a sub-100nm diagonal feature in a memory active layer. The remaining challenges and the existing tradeoff between metrology and lithography performance are explored with the metrology target designer’s perspective. The proposed target design framework is completely general and can be used to optimize targets for different lithography conditions. The results from our analysis are both physically sensible and in good agreement with experimental results.
© (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Myungjun Lee, Mark D. Smith, Joonseuk Lee, Mirim Jung, Honggoo Lee, Youngsik Kim, Sangjun Han, Michael E. Adel, Kangsan Lee, Dohwa Lee, Dongsub Choi, Zephyr Liu, Tal Itzkovich, Vladimir Levinski, and Ady Levy "Lithography aware overlay metrology target design method", Proc. SPIE 9778, Metrology, Inspection, and Process Control for Microlithography XXX, 97781L (24 March 2016);

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