1 April 2010 Application of model-based library approach to photoresist pattern shape measurement in advanced lithography
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Abstract
The model-based library (MBL) matching technique was applied to measurements of photoresist patterns exposed with a leading-edge ArF immersion lithography tool. This technique estimates the dimensions and shape of a target pattern by comparing a measured SEM image profile to a library of simulated line scans. In this study, a double trapezoid model was introduced into MBL library, which was suitable for precise approximation of a photoresist profile. To evaluate variously-shaped patterns, focus-exposure matrix wafers were exposed under three-illuminations. The geometric parameters such as bottom critical dimension (CD), top and bottom sidewall angles were estimated by MBL matching. Lithography simulation results were employed as a reference data in this evaluation. As a result, the trends of the estimated sidewall angles are consistent with the litho-simulation results. MBL bottom CD and threshold method 50% CD are also in a very good agreement. MBL detected wide-SWA variation in a focus series which were determined as in a process window by CD values. The trend of SWA variation, which is potentiality to undergo CD shift at later-etch step, agreed with litho-simulation results. These results suggest that MBL approach can achieve the efficient measurements for process development and control in advanced lithography.
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Naoki Yasui, Naoki Yasui, Miki Isawa, Miki Isawa, Toru Ishimoto, Toru Ishimoto, Kohei Sekiguchi, Kohei Sekiguchi, Maki Tanaka, Maki Tanaka, Mayuka Osaki, Mayuka Osaki, Chie Shishido, Chie Shishido, Norio Hasegawa, Norio Hasegawa, Shaunee Cheng, Shaunee Cheng, } "Application of model-based library approach to photoresist pattern shape measurement in advanced lithography", Proc. SPIE 7638, Metrology, Inspection, and Process Control for Microlithography XXIV, 76382O (1 April 2010); doi: 10.1117/12.846504; https://doi.org/10.1117/12.846504
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