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Proceedings Paper

Accelerated lifetime metrology of EUV multilayer mirrors in hydrocarbon environments
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Paper Abstract

The ability to predict the rate of reflectivity loss of capped multilayer mirrors (MLMs) under various conditions of ambient vacuum composition, intensity, and previous dose is crucial to solving the mirror lifetime problem in an EUV stepper. Previous measurements at NIST have shown that reflectivity loss of MLMs exposed under accelerated conditions of dose and pressure can be a very complicated function of these variables. The present work continues this effort and demonstrates that reflectivity loss does not scale linearly for accelerated exposure doses over the range of 0-350 J/mm2 either for partial pressures of MMA in the range 10-8-10-7 Torr or acetone in the range 10-7-10-6 Torr. We suggest that this nonlinear scaling may be the result of a varying damage rate as the surface of the growing contamination layer moves through the EUV standing wave created by exposure of any MLM to resonant radiation. To further investigate the potential influence of these resonance effects, we report new measurements showing large variations of the secondary electron yield as a function of thickness of carbon deposited on top of a MLM.

Paper Details

Date Published: 20 March 2008
PDF: 11 pages
Proc. SPIE 6921, Emerging Lithographic Technologies XII, 692117 (20 March 2008); doi: 10.1117/12.772627
Show Author Affiliations
S. B. Hill, NIST (United States)
N. S. Faradzhev, NIST (United States)
C. Tarrio, NIST (United States)
T. B. Lucatorto, NIST (United States)
T. E. Madey, Rutgers Univ. (United States)
B. V. Yakshinskiy, Rutgers Univ. (United States)
E. Loginova, Rutgers Univ. (United States)
S. Yulin, Fraunhofer-Institut für Angewandte Optik und Feinmechnik, Jena (Germany)

Published in SPIE Proceedings Vol. 6921:
Emerging Lithographic Technologies XII
Frank M. Schellenberg, Editor(s)

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