Characterization of the photoacid diffusion length

Shuhui Kang; Vivek M. Prabhu; Wen-li Wu; Eric K. Lin; Kwang-Woo Choi; Manish Chandhok; Todd R. Younkin; Wang Yueh

doi:10.1117/12.813555

1 April 2009 Characterization of the photoacid diffusion length

Shuhui Kang, Vivek M. Prabhu, Wen-li Wu, Eric K. Lin, Kwang-Woo Choi, Manish Chandhok, Todd R. Younkin, Wang Yueh

Proceedings Volume 7273, Advances in Resist Materials and Processing Technology XXVI; 72733U (2009) https://doi.org/10.1117/12.813555
Event: SPIE Advanced Lithography, 2009, San Jose, California, United States

Abstract

The photoacid diffusion length is a critical issue for extreme ultraviolet (EUV) lithography because it governs the critical dimension (CD), line-edge-roughness (LER), and line-width-roughness (LWR) of photoresist materials. Laboratorybased experimental methods that complement full lithographic testing would enable a rapid screening of materials and process conditions. This paper provides an approach to characterize the photoacid diffusion length by applying a bilayer stack technique. The method involves quantitative measurements of the deprotection kinetics as well as film thickness at each process step: radiation exposure, post-exposure bake, and development. Analogous to a contrast curve, by comparing the film thickness of the bilayer before and after development, the photoacid diffusion length was deduced in a commercial EUV photoresist and compared to EUV lithography. Further, by combining the experiments with kinetics modeling, the measured photoacid diffusion length was predicted. Lastly, based upon the measured kinetics parameters, a criterion was developed that next-generation resists must meet to achieve a 16 nm photoacid diffusion length. These guidelines are discussed in terms of correlations and contributions from the photoacid and resist properties. In particular, the trapping kinetics of the photoacid provides a route to reduce LER and the CD at low dose.

Citation Download Citation

Shuhui Kang, Vivek M. Prabhu, Wen-li Wu, Eric K. Lin, Kwang-Woo Choi, Manish Chandhok, Todd R. Younkin, and Wang Yueh "Characterization of the photoacid diffusion length", Proc. SPIE 7273, Advances in Resist Materials and Processing Technology XXVI, 72733U (1 April 2009); https://doi.org/10.1117/12.813555

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