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Proceedings Paper

Amplification of the index of refraction of aqueous immersion fluids by ionic surfactants
Author(s): Kwangjoo Lee; Joy Kunjappu; Steffen Jockusch; Nicholas J. Turro; Tatjana Widerschpan; Jianming Zhou; Bruce W. Smith; Paul Zimmerman; Will Conley
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Paper Abstract

In order to find new immersion liquids to improve the resolution of 193 nm immersion photolithography, we have attempted to discover aqueous system possessing an index of refraction greater than that of water using aqueous surfactant systems. The index of refraction (RI) of both cationic and anionic surfactant systems were examined in the presence of wide range of inorganic salts, and parameters such as size of surfactants, concentrations, and temperature were varied. The refractive index (RI) was found to be increased in the presence of both anionic and cationic surfactants compared to those of water and also increased as a function of surfactant concentration. However the refractive index tends to increase much more strongly as a function of salt concentration. In our study, a maximum RI enhancement was observed from 6.5 M CdCl2 in 8.2 mM aqueous SDS solution. The effect of micellar properties such as the critical micelle concentration (cmc) and degree of ionization were systematically studied for aqueous SDS system in the presence of CdCl2. The correlation on index of refraction between empirical data and theoretical prediction were performed using the concept of molar refraction. Wavelength dependence of RI from theoretical prediction based on empirical equation was examined for various concentration of CdCl2 system and the results are reported in the paper.

Paper Details

Date Published: 4 May 2005
PDF: 17 pages
Proc. SPIE 5753, Advances in Resist Technology and Processing XXII, (4 May 2005); doi: 10.1117/12.606105
Show Author Affiliations
Kwangjoo Lee, Columbia Univ. (United States)
Joy Kunjappu, Columbia Univ. (United States)
Steffen Jockusch, Columbia Univ. (United States)
Nicholas J. Turro, Columbia Univ. (United States)
Tatjana Widerschpan, Univ. Karlsruhe (Germany)
Jianming Zhou, Rochester Institute of Technology (United States)
Bruce W. Smith, Rochester Institute of Technology (United States)
Paul Zimmerman, Intel Corp. (United States)
SEMATECH, Inc. (United States)
Will Conley, Freescale Semiconductor, Inc. (United States)
SEMATECH, Inc. (United States)

Published in SPIE Proceedings Vol. 5753:
Advances in Resist Technology and Processing XXII
John L. Sturtevant, Editor(s)

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