High-Precision Localization Algorithm for Target Symmetry Center in Image-Based Overlay Metrology

Liu, Wuhao; Song, Maoxin; Shi, Shuming; Ling, Mingchun; Qin, Hengwei; Guan, Hengrui; Wang, Jun; Hong, Jin

doi:10.3390/mi17050626

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Open AccessArticle

High-Precision Localization Algorithm for Target Symmetry Center in Image-Based Overlay Metrology

by

Wuhao Liu

^1,2

,

Maoxin Song

^2,*,

Shuming Shi

²,

Mingchun Ling

^2,*,

Hengwei Qin

^1,2,

Hengrui Guan

²,

Jun Wang

² and

Jin Hong

²

¹

School of Environmental Science and Optoelectronic Technology, University of Science and Technology of China, Hefei 230026, China

²

Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China

^*

Authors to whom correspondence should be addressed.

Micromachines 2026, 17(5), 626; https://doi.org/10.3390/mi17050626

Submission received: 17 April 2026 / Revised: 18 May 2026 / Accepted: 19 May 2026 / Published: 20 May 2026

(This article belongs to the Special Issue Emerging Technologies and Applications for Semiconductor Industry)

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Abstract

Achieving high-precision overlay target center localization is critical for image-based overlay (IBO) metrology in advanced semiconductor manufacturing. This paper proposes a novel IBO target localization algorithm based on symmetry center matching. Leveraging the symmetry design of the IBO optical system as a physical prior, the algorithm reformulates center localization as a global correlation optimization problem. The grayscale projection profile of a single-sided edge is extracted, spatially mirrored, and used as a reference template for sliding correlation matching against the opposite edge. The symmetry center is then determined from the peak of the Pearson correlation coefficient curve. Simulation results demonstrate a center localization accuracy better than 0.00013 pixels (3

σ

), with repeatability precision remaining within 0.012 pixels (3

σ

) under stringent noise and blur conditions. Experimental validation yields object-space repeatability precision of 0.129 nm (3

σ

) and 0.144 nm (3

σ

) in the X and Y directions, respectively, surpassing the 0.32 nm measurement uncertainty requirement for advanced process nodes. The average single-frame processing time is approximately 0.07 s, demonstrating that the proposed algorithm simultaneously satisfies the demands of high precision and high throughput.

Keywords: overlay metrology; center localization; correlation

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MDPI and ACS Style

Liu, W.; Song, M.; Shi, S.; Ling, M.; Qin, H.; Guan, H.; Wang, J.; Hong, J. High-Precision Localization Algorithm for Target Symmetry Center in Image-Based Overlay Metrology. Micromachines 2026, 17, 626. https://doi.org/10.3390/mi17050626

AMA Style

Liu W, Song M, Shi S, Ling M, Qin H, Guan H, Wang J, Hong J. High-Precision Localization Algorithm for Target Symmetry Center in Image-Based Overlay Metrology. Micromachines. 2026; 17(5):626. https://doi.org/10.3390/mi17050626

Chicago/Turabian Style

Liu, Wuhao, Maoxin Song, Shuming Shi, Mingchun Ling, Hengwei Qin, Hengrui Guan, Jun Wang, and Jin Hong. 2026. "High-Precision Localization Algorithm for Target Symmetry Center in Image-Based Overlay Metrology" Micromachines 17, no. 5: 626. https://doi.org/10.3390/mi17050626

APA Style

Liu, W., Song, M., Shi, S., Ling, M., Qin, H., Guan, H., Wang, J., & Hong, J. (2026). High-Precision Localization Algorithm for Target Symmetry Center in Image-Based Overlay Metrology. Micromachines, 17(5), 626. https://doi.org/10.3390/mi17050626

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High-Precision Localization Algorithm for Target Symmetry Center in Image-Based Overlay Metrology

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