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Proceedings Paper

Laser durability studies of high index immersion fluids: fluid degradation and optics contamination effects
Author(s): V. Liberman; M. Rothschild; S. T. Palmacci; P. A. Zimmerman; A. Grenville
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Paper Abstract

An extension of water-based immersion lithography involves replacing water with a higher index transparent oil. Understandably, potential lens contamination is a major concern for an all-organic immersion fluid. We have constructed an experimental system for controlled irradiation of high index fluids, including capabilities for in-situ cleaning of potential deposits. We present results of laser-irradiation of several high index immersion fluid candidates. Using properly developed exposure metrics, we discuss implications for fluid lifetimes in an immersion system, with and without in-situ purification. Using our in-situ metrology, we are able to decouple bulk fluid degradation from window photocontamination for several fluids. We find a significant variation in optics contamination rate depending on the fluid tested. Even the slowest observed contamination rates would require some remediation strategies to remove the built-up deposit from the final element surface. We also present results of irradiation of model hydrocarbon compound fluids. Irradiation of these materials leads to fundamental understanding of underlying photochemistry, and also provides guidance in designing future generation high index fluids.

Paper Details

Date Published: 27 March 2007
PDF: 10 pages
Proc. SPIE 6520, Optical Microlithography XX, 652035 (27 March 2007); doi: 10.1117/12.723958
Show Author Affiliations
V. Liberman, Lincoln Lab., Massachusetts Institute of Technology (United States)
M. Rothschild, Lincoln Lab., Massachusetts Institute of Technology (United States)
S. T. Palmacci, Lincoln Lab., Massachusetts Institute of Technology (United States)
P. A. Zimmerman, Intel Corp./International SEMATECH (United States)
A. Grenville, Intel Corp./International SEMATECH (United States)

Published in SPIE Proceedings Vol. 6520:
Optical Microlithography XX
Donis G. Flagello, Editor(s)

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