OPO residuals improvement with imaging metrology for 3D NAND
Abstract
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.
- Publication:
-
Metrology, Inspection, and Process Control for Microlithography XXXIV
- Pub Date:
- March 2020
- DOI:
- 10.1117/12.2551874
- Bibcode:
- 2020SPIE11325E..2JK