Laser self-reference technique for high-precision lithographic alignment

Shuonan Shan; Zijian Zhong; Tianshi Lu; Xinghui Li

doi:10.1117/12.3036345

8 November 2024 Laser self-reference technique for high-precision lithographic alignment

Shuonan Shan, Zijian Zhong, Tianshi Lu, Xinghui Li

Proceedings Volume 13234, Advanced Laser Processing and Manufacturing VIII; 1323407 (2024) https://doi.org/10.1117/12.3036345
Event: SPIE/COS Photonics Asia, 2024, Nantong, Jiangsu, China

Abstract

Achieving nanometer-level alignment precision in lithography is essential for the advancement of semiconductor manufacturing. This study introduces an innovative laser self-reference technique that leverages the interference of two coherent beams on a reflective grating with a matching period. By incorporating a wedge-shaped beam splitter, a reference interference fringe is generated, establishing a direct correlation between the incident interference pattern and the reference grating, thus enabling real-time spatial alignment monitoring. A theoretical model was developed to elucidate the phase relationship. The experimental apparatus comprised a high-precision laser system, a piezoelectric transducer (PZT) for minute phase adjustments, and a high-speed CMOS camera for instantaneous analysis. The technique was evaluated using three displacement inversion algorithms, with the image phase correlation algorithm outperforming the others, achieving control of deviations to below 3.2 nm. Laser self-referencing technology not only provides a nanoscale alignment method, but also meets the fine control required for multi-layer grating manufacturing, improving the quality and reliability of the lithography process, and addressing a critical challenge in the production of semiconductor chips.

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

Citation Download Citation

Shuonan Shan, Zijian Zhong, Tianshi Lu, and Xinghui Li "Laser self-reference technique for high-precision lithographic alignment", Proc. SPIE 13234, Advanced Laser Processing and Manufacturing VIII, 1323407 (8 November 2024); https://doi.org/10.1117/12.3036345

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