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Characterizing acid diffusion lengths in chemically amplified resists from measurements of deprotection kinetics

[+] Author Affiliations
Abhijit A. Patil

University of Houston, Department of Chemical and Biomolecular Engineering, 4800 Calhoun Road, Houston, Texas 77204, United States

Yogendra Narayan Pandey

University of Houston, Department of Chemical and Biomolecular Engineering, 4800 Calhoun Road, Houston, Texas 77204, United States

Manolis Doxastakis

Institute for Molecular Engineering, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, United States

Gila E. Stein

University of Houston, Department of Chemical and Biomolecular Engineering, 4800 Calhoun Road, Houston, Texas 77204, United States

J. Micro/Nanolith. MEMS MOEMS. 13(4), 043017 (Dec 16, 2014). doi:10.1117/1.JMM.13.4.043017
History: Received September 4, 2014; Accepted November 13, 2014
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Abstract.  The acid-catalyzed deprotection of glassy poly(4-hydroxystyrene-co-tertbutyl 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.

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© 2014 Society of Photo-Optical Instrumentation Engineers

Citation

Abhijit A. Patil ; Yogendra Narayan Pandey ; Manolis Doxastakis and Gila E. Stein
"Characterizing acid diffusion lengths in chemically amplified resists from measurements of deprotection kinetics", J. Micro/Nanolith. MEMS MOEMS. 13(4), 043017 (Dec 16, 2014). ; http://dx.doi.org/10.1117/1.JMM.13.4.043017


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