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20 March 2020 OPO residuals improvement with imaging metrology for 3D NAND
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In the latest 3D NAND devices there is a larger focus on measurement accuracy control, coupled with more traditional minimization of Total Measurement Uncertainty (TMU). Measurement inaccuracy consumes an increasingly significant part of the overlay (OVL) budget, requiring control and optimization.

In this paper we will show the improvement in imaging OVL measurement accuracy using wave tuning (WT) capability combined with advanced algorithms to address 3D NAND process challenges. In addition to new OVL target designs that take advantage of WT capability, we also demonstrate improvement in OVL model residuals through optimization of measurement bandwidth, focus position and number of grab frames. Improvements in precision and tool-to-tool matching are also realized through both optimization of the region of interest (ROI) and splitting measurement areas using a dual-recipe technique.
© (2020) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Shlomit Katz, Anna Golotsvan, Yoav Grauer, Efi Megged, Greg Gray, Fiona (Shuk Fan) Leung, Pek Beng Ong, Shi Lei, Jeremy (Shi-Ming) Wei, Wayne (Wei) Zhou, and Linfei Gao "OPO residuals improvement with imaging metrology for 3D NAND", Proc. SPIE 11325, Metrology, Inspection, and Process Control for Microlithography XXXIV, 113252J (20 March 2020);

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