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Journal of Micro/Nanolithography, MEMS, and MOEMS

Characterizing acid diffusion lengths in chemically amplified resists from measurements of deprotection kinetics
Author(s): Abhijit A. Patil; Yogendra Narayan Pandey; Manolis Doxastakis; Gila E. Stein
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Paper Abstract

The acid-catalyzed deprotection of glassy poly(4-hydroxystyrene-co-<italic<tert</italic<butyl acrylate) films was studied with infrared absorbance spectroscopy and stochastic simulations. Experimental data were interpreted with a simple description of subdiffusive acid transport coupled to second-order acid loss. This model predicts key attributes of observed deprotection rates, such as fast reaction at short times, slow reaction at long times, and a nonlinear dependence on acid loading. Fickian diffusion is approached by increasing the postexposure bake temperature or adding plasticizing agents to the polymer resin. These findings demonstrate that acid mobility and overall deprotection kinetics are coupled to glassy matrix dynamics. To complement the analysis of bulk kinetics, acid diffusion lengths were calculated from the anomalous transport model and compared with nanopattern line widths. The consistent scaling between experiments and simulations suggests that the anomalous diffusion model could be further developed into a predictive lithography tool.

Paper Details

Date Published: 16 December 2014
PDF: 7 pages
J. Micro/Nanolith. 13(4) 043017 doi: 10.1117/1.JMM.13.4.043017
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 13, Issue 4
Show Author Affiliations
Abhijit A. Patil, Univ. of Houston (United States)
Yogendra Narayan Pandey, Univ. of Houston (United States)
Manolis Doxastakis, Argonne National Lab. (United States)
Gila E. Stein, Univ. of Houston (United States)

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