Optical and SEM-based overlay metrology study on process-induced overlay inaccuracy

Cheuk Wun Wong

doi:10.1117/12.3010935

10 April 2024 Optical and SEM-based overlay metrology study on process-induced overlay inaccuracy

Cheuk Wun Wong

Proceedings Volume 12955, Metrology, Inspection, and Process Control XXXVIII; 129550S (2024) https://doi.org/10.1117/12.3010935
Event: SPIE Advanced Lithography + Patterning, 2024, San Jose, California, United States

Abstract

This paper characterizes, studies and breaks down different components of OL inaccuracy and NZO for a back-end-of-line (BEOL) metal layer on an advanced node testsite. In this study, NZO is characterized by measuring SEM OL and OM OL at the same locations across the wafer and at various process steps. To understand the root-cause of the NZO, process-induced OL shift on both SEM OL and OM OL from ADI, to AEI and finally to CMP are characterized and discussed. It shows that process-induced OL shift is a major contributor to OL inaccuracy and NZO and is affected by the CD and pitch of the measured feature. This paper also studies OL difference between kerf (where OM OL marks are typically located) and in-die (where actual device are located) overlay. Lastly, OL delta between the two OL measurement techniques was studied by measuring the same OL mark with both SEM OL and OM OL tools. This paper concludes with a breakdown of key contributors to OL inaccuracy and NZO. It provides recommendations and future work on utilizing SEM OL in conjunction with OM OL to address the challenging overlay inaccuracy and NZO requirement for advanced logic node.

Conference Presentation

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

Citation Download Citation

Cheuk Wun Wong "Optical and SEM-based overlay metrology study on process-induced overlay inaccuracy", Proc. SPIE 12955, Metrology, Inspection, and Process Control XXXVIII, 129550S (10 April 2024); https://doi.org/10.1117/12.3010935

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