Scatterometry-based overlay metrology

Hsu-Ting Huang; Gayathri Raghavendra; Apo Sezginer; Kenneth Johnson; Fred E. Stanke; Michelle L. Zimmerman; Cristina Cheung; Makoto Miyagi; Bhanwar Singh

doi:10.1117/12.483668

2 June 2003 Scatterometry-based overlay metrology

Hsu-Ting Huang, Gayathri Raghavendra, Apo Sezginer, Kenneth Johnson, Fred E. Stanke, Michelle L. Zimmerman, Cristina Cheung, Makoto Miyagi, Bhanwar Singh

Author Affiliations +

Proceedings Volume 5038, Metrology, Inspection, and Process Control for Microlithography XVII; (2003) https://doi.org/10.1117/12.483668
Event: Microlithography 2003, 2003, Santa Clara, California, United States

Abstract

Scatterometry provides a new, vibration-tolerant technique of overlay metrology. Gauge repeatability and reproducibility is improved by an order of magnitude over imaging-based overlay metrology. To measure the overlay of patterned layers A and B by scatterometry, one line grating is placed in layer A and another in layer B. The two gratings overlap when they are viewed in the direction that is normal to the wafer. The line gratings in layers a and b are of equal pitch and their lines are parallel. In one method, overlay is measured by fitting the optical properties of the target with spectra calculated using a model of the target and rigorous coupled wave analysis. A faster and simpler method obtains overlay by applying a linear estimator to a difference of spectra. Optical properties of targets were measured by a normal incidence spectroscopic reflectometer. Test wafers representing three overlay applications were fabricated: contact mask to shallow-trench, first metal mask to contact, and gate-mask to shallow-trench. Overlay measured by scatterometry agree with imaging-based measurements and offsets intentionally written to the reticle.

Citation Download Citation

Hsu-Ting Huang, Gayathri Raghavendra, Apo Sezginer, Kenneth Johnson, Fred E. Stanke, Michelle L. Zimmerman, Cristina Cheung, Makoto Miyagi, and Bhanwar Singh "Scatterometry-based overlay metrology", Proc. SPIE 5038, Metrology, Inspection, and Process Control for Microlithography XVII, (2 June 2003); https://doi.org/10.1117/12.483668

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