Image-based alignment sensor unaffected by aberration

Michio Ohashi

doi:10.1117/12.2610608

26 May 2022 Image-based alignment sensor unaffected by aberration

Michio Ohashi

Proceedings Volume 12053, Metrology, Inspection, and Process Control XXXVI; 120531K (2022) https://doi.org/10.1117/12.2610608
Event: SPIE Advanced Lithography + Patterning, 2022, San Jose, California, United States

Conference Poster

Abstract

Accurate alignment sensors are needed for tight overlay requirements. The interplay of alignment sensor lens aberrations and process variations (such as layer thickness variation or line width variation) can produce position measurement errors. We propose a new method called TIAS (two-beam imaging alignment sensor) where we can achieve high accuracy even in the presence of lens aberrations. It has added benefits of high image contrast and greater depth of focus. We confirmed the aberration robustness of TIAS by our experiment. TIAS technique is not only applicable to alignment sensing but also to image-based overlay (IBO) measurement.

Citation Download Citation

Michio Ohashi "Image-based alignment sensor unaffected by aberration", Proc. SPIE 12053, Metrology, Inspection, and Process Control XXXVI, 120531K (26 May 2022); https://doi.org/10.1117/12.2610608

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