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Proceedings Paper

Characterization of the photoacid diffusion length
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Paper 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.

Paper Details

Date Published: 1 April 2009
PDF: 11 pages
Proc. SPIE 7273, Advances in Resist Materials and Processing Technology XXVI, 72733U (1 April 2009); doi: 10.1117/12.813555
Show Author Affiliations
Shuhui Kang, National Institute of Standards and Technology (United States)
Vivek M. Prabhu, National Institute of Standards and Technology (United States)
Wen-li Wu, National Institute of Standards and Technology (United States)
Eric K. Lin, National Institute of Standards and Technology (United States)
Kwang-Woo Choi, Intel Corp. (United States)
Manish Chandhok, Intel Corp. (United States)
Todd R. Younkin, Intel Corp. (United States)
Wang Yueh, Intel Corp. (United States)


Published in SPIE Proceedings Vol. 7273:
Advances in Resist Materials and Processing Technology XXVI
Clifford L. Henderson, Editor(s)

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