18 March 2015 Evaluation of compact models for negative-tone development layers at 20/14nm nodes
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Abstract
With the introduction of negative tone develop (NTD) resists to production lithography nodes, multiple NTD resist modeling challenges have surpassed the accuracy limits of the existing modeling infrastructure developed for the positive polarity process. We report the evaluation of two NTD resist modeling algorithms. The new modeling terms represent, from the first principles, the NTD resist mechanisms of horizontal shrink and horizontal development bias. Horizontal shrink describes the impact of the physical process of out-gassing on remaining resist edge location. Horizontal development bias accounts for the differential in the peak and minimum development rate with exposure intensity observed in NTD formulations. We review specific patterning characteristics by feature type, modeling accuracy impact presented by these NTD mechanisms, and their description in our compact models (Compact Model 1, CM1). All the new terms complement the accuracy advantage observed with existing CM1 resist modeling infrastructure. The new terms were tested on various NTD layers. The results demonstrate consistent model accuracy improvement for both calibration and verification. Furthermore, typical NTD model fitting challenges, such as large SRAF-induced wafer CD jump, can be overcome by the new NTD terms. Finally, we propose a joint-tuning approach for the calibration of compact models for the NTD resist.
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Ao Chen, Yee Mei Foong, Dong Qing Zhang, Hongxin Zhang, Angeline Chung, David Fryer, Yunfei Deng, Dmitry Medvedev, Yuri Granik, "Evaluation of compact models for negative-tone development layers at 20/14nm nodes", Proc. SPIE 9426, Optical Microlithography XXVIII, 94261P (18 March 2015); doi: 10.1117/12.2085711; https://doi.org/10.1117/12.2085711
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