New optical metrology technique for measuring the shape of a lithography photo mask

Guillermo Castro Luis; Kiril Ivanov Kurtev; Miguel Jiménez; Juan M. Trujillo-Sevilla; Jose Manuel Ramos-Rodríguez; Jan O. Gaudestad

doi:10.1117/12.3011886

9 April 2024 New optical metrology technique for measuring the shape of a lithography photo mask

Guillermo Castro Luis, Kiril Ivanov Kurtev, Miguel Jiménez, Juan M. Trujillo-Sevilla, Jose Manuel Ramos-Rodríguez, Jan O. Gaudestad

Author Affiliations +

Proceedings Volume 12955, Metrology, Inspection, and Process Control XXXVIII; 129553L (2024) https://doi.org/10.1117/12.3011886
Event: SPIE Advanced Lithography + Patterning, 2024, San Jose, California, United States

Conference Poster

Abstract

Wafer overlay errors due to non-flatness and thickness variations of a mask need to be minimized to achieve a very accurate on-product-overlay (OPO). Due to the impact of overlay errors inherent in all reflective lithography systems, EUV reticles will need to adhere to flatness specifications below 10nm, which metric is not possible to achieve using current tooling infrastructure; current metric is showing Peak-to-Valley (PV) flatness of around 60nm. In this paper, we present a new method to generate a very high-resolution photomask shape measurement of an entire optical photomask used in DUV lithography, by measuring both from front side and backside, a technique based on detecting the wave front phase of the reflected light from a quartz photomask. We introduce Wave Front Phase Imaging (WFPI), a new method for measuring flatness that generates a shape map based on local slope. It collects 810 thousand (K) data points on an 86.4mm× 86.4mm area with a spatial resolution of 96μm.

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

Citation Download Citation

Guillermo Castro Luis, Kiril Ivanov Kurtev, Miguel Jiménez, Juan M. Trujillo-Sevilla, Jose Manuel Ramos-Rodríguez, and Jan O. Gaudestad "New optical metrology technique for measuring the shape of a lithography photo mask", Proc. SPIE 12955, Metrology, Inspection, and Process Control XXXVIII, 129553L (9 April 2024); https://doi.org/10.1117/12.3011886

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