Global tilt measurement on irregular PIL supporting patterns in 3D NAND memory

Yung-Yi Lin; Tien-Jung Lee; Hsiao-Fei Su; Yen-Hung Liu; Chao-Yu Cheng; Christopher Liman; Boxue Chen; Zhengquan Tan; Ming-Tsung Wu; Min-Hsuan Huang; Yao-Yuan Chang; Hong-Ji Lee; Nan-Tzu Lian

doi:10.1117/12.3010532

9 April 2024 Global tilt measurement on irregular PIL supporting patterns in 3D NAND memory

Yung-Yi Lin, Tien-Jung Lee, Hsiao-Fei Su, Yen-Hung Liu, Chao-Yu Cheng, Christopher Liman, Boxue Chen, Zhengquan Tan, Ming-Tsung Wu, Min-Hsuan Huang, Yao-Yuan Chang, Hong-Ji Lee, Nan-Tzu Lian

Author Affiliations +

Proceedings Volume 12955, Metrology, Inspection, and Process Control XXXVIII; 129552Z (2024) https://doi.org/10.1117/12.3010532
Event: SPIE Advanced Lithography + Patterning, 2024, San Jose, California, United States

Conference Poster

Abstract

3D NAND flash memory stacks cells vertically in multiple layers. One of the critical processes in chip-making is slit trench landing control since the word-line gate replacement of silicon nitride films and the isolation of plural memory blocks are through the means of slit structure. However, during the gate of silicon nitride removal in slit trenches, the architecture of memory blocks may collapse due to the lack of sufficient supporting patterns surrounding the slit trenches. For better silicon nitride removal control, there are various irregular patterns of dummy pillars (PIL) designed in as supporting structures to provide better mechanical property, which can prevent memory blocks from collapsing while removing silicon nitride in gate replacement processing. Hence, an effective measurement is needed to indicate the bottom shifting of PIL during the etching recipe optimization. In this work, we demonstrate the deployment of small angle X-ray scattering (SAXS) technology with global tilt extraction (GTE) that successfully predicts PIL landing location displacement, which matches destructive gauging data. GTE is a modeless method to determine global tilt, i.e., center line shifting (CLS) of the bottom relative to the topmost on the target pattern. GTE is proven to be a reliable method for in-line process monitoring as well as for use in PIL etching recipe optimization for 3D NAND development.

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

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Yung-Yi Lin, Tien-Jung Lee, Hsiao-Fei Su, Yen-Hung Liu, Chao-Yu Cheng, Christopher Liman, Boxue Chen, Zhengquan Tan, Ming-Tsung Wu, Min-Hsuan Huang, Yao-Yuan Chang, Hong-Ji Lee, and Nan-Tzu Lian "Global tilt measurement on irregular PIL supporting patterns in 3D NAND memory", Proc. SPIE 12955, Metrology, Inspection, and Process Control XXXVIII, 129552Z (9 April 2024); https://doi.org/10.1117/12.3010532

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