Robustness improvement in imaging-based overlay metrology for high topography layers by Talbot targets

Brian Watson; Shlomit Katz; Richard Housley; Kar Wui Thong; Nikhil Aditya Kumar Roy; Yoav Grauer; Diana Shapirov; Raviv Yohanan; Greg Gray; Yonglei Li; Daniel Chalom

doi:10.1117/12.2583831

22 February 2021 Robustness improvement in imaging-based overlay metrology for high topography layers by Talbot targets

Brian Watson, Shlomit Katz, Richard Housley, Kar Wui Thong, Nikhil Aditya Kumar Roy, Yoav Grauer, Diana Shapirov, Raviv Yohanan, Greg Gray, Yonglei Li, Daniel Chalom

Author Affiliations +

Proceedings Volume 11611, Metrology, Inspection, and Process Control for Semiconductor Manufacturing XXXV; 1161133 (2021) https://doi.org/10.1117/12.2583831
Event: SPIE Advanced Lithography, 2021, Online Only

Conference Poster

Abstract

As 3D NAND devices increase memory density by adding layers, scaling and increasing bits-per-cell, new overlay (OVL) metrology challenges arise. On product overlay (OPO) may decrease for critical thick layers such as thick deck-to-deck alignment, whereas high aspect ratio (Z-axis) structures introduce stress, tilt and deformation that require accurate and robust OVL measurements. Advanced imaging metrology (AIM®) targets, that consist of two side-byside periodic gratings in the previous and current layers, are typically used to measure OVL with Imaging Based Overlay (IBO) metrology systems. In this paper, we present a new approach that utilizes the Talbot effect in AIM to produce multiple contrast planes along the Z-axis, which enables a common focus position for both layers at a similar focus plane, resulting in improved measurement robustness. We will present Talbot effect theory, target design steps by metrology target design (MTD) simulator, actual measurement results on an advanced 3D NAND device and conclusions for such targets.

Conference Presentation

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Brian Watson, Shlomit Katz, Richard Housley, Kar Wui Thong, Nikhil Aditya Kumar Roy, Yoav Grauer, Diana Shapirov, Raviv Yohanan, Greg Gray, Yonglei Li, and Daniel Chalom "Robustness improvement in imaging-based overlay metrology for high topography layers by Talbot targets", Proc. SPIE 11611, Metrology, Inspection, and Process Control for Semiconductor Manufacturing XXXV, 1161133 (22 February 2021); https://doi.org/10.1117/12.2583831

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