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Proceedings Paper

Prevention of MoSi multilayer reflection loss in EUVL tools
Author(s): Hans Meiling; Bas Mertens; Frank Stietz; Marco Wedowski; Roman Klein; Ralph Kurt; Eric Louis; Andrey E. Yakshin
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Paper Abstract

Extreme ultraviolet lithography requires vacuum conditions in the optical train. In order to maintain sufficient energy throughput, reflection reduction of multilayer mirrors due to contamination has to be minimized. We report on oxidation and carbonization experiments on MoSi mirrors under exposure with EUV radiation from a synchrotron. To mimic the effects of EUV radiation we also exposed samples using an electron gun. The oxidation rate was found to be ~0.015 nm/h per mW/mm2 of EUV radiation under vacuum conditions that are typical for a high throughput EUVL system, I.e. 10-6 mbar H2O. This oxidation can to a large extend be suppressed by using smart gas blend strategies during exposure, e.g. using ethanol. A deposition rate of 0.25 nm/h was found when the hydrocarbon pressure of Fomblin was reduced to 10(superscript -9 mbar. We demonstrate that carbonization can be suppressed by admitting oxygen during electron gun exposure.

Paper Details

Date Published: 20 December 2001
PDF: 12 pages
Proc. SPIE 4506, Soft X-Ray and EUV Imaging Systems II, (20 December 2001); doi: 10.1117/12.450949
Show Author Affiliations
Hans Meiling, ASML (Netherlands)
Bas Mertens, TNO (Netherlands)
Frank Stietz, Carl Zeiss (Germany)
Marco Wedowski, Carl Zeiss (Germany)
Roman Klein, Physikalisch Technische Bundesanstalt (Germany)
Ralph Kurt, Philips Research Labs. (Netherlands)
Eric Louis, FOM-Institute for Plasma Physics Rijnhuizen (Netherlands)
Andrey E. Yakshin, FOM-Institute for Plasma Physics Rijnhuizen (Netherlands)

Published in SPIE Proceedings Vol. 4506:
Soft X-Ray and EUV Imaging Systems II
Daniel A. Tichenor; James A. Folta, Editor(s)

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