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Proceedings Paper

Investigation of plasma-induced erosion of multilayer condenser optics
Author(s): Richard J. Anderson; Dean A. Buchenauer; K. A. Williams; W. M. Clift; L. E. Klebanoff; N. V. Edwards; O. R. Wood II; S. Wurm
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Paper Abstract

Experiments are presented that investigate the mechanistic cause of multilayer erosion observed from condenser optics exposed to EUV laser-produced plasma (LPP) sources. Using a Xe filament jet source excited with Nd-YAG laser radiation (300 mJ/pulse), measurements were made of material erosion from Au, Mo, Si and C using coated quartz microbalances located 127 mm from the plasma. The observed erosion rates were as follows: Au=99nm/106 shots, Mo= 26nm/106 shots, Si=19nm/106 shots, and C=6nm/106 shots. The relative ratio Au:Mo:Si:C of erosion rates observed experimentally, 16:4:3:1 compares favorably with that predicted from an atomic sputtering model assuming 20 kV Xe ions, 16:6:4:1. The relative agreement indicates that Xe-substrate sputtering is largely responsible for the erosion of Mo/Si multilayers on condenser optics that directly face the plasma. Time-of-flight Faraday cup measurements reveal the emission of high energy Xe ions from the Xe-filament jet plasma. The erosion rate does not depend on the repetition rate of the laser, suggesting a thermal mechanism is not operative. The Xe-filament jet erosion is ~20x that observed from a Xe spray jet. Since the long-lived (millisecond time scale) plasma emanating from these two sources are the same to within ~30%, sputtering from this long-lived plasma can be ruled out as an erosion agent.

Paper Details

Date Published: 6 May 2005
PDF: 12 pages
Proc. SPIE 5751, Emerging Lithographic Technologies IX, (6 May 2005); doi: 10.1117/12.599859
Show Author Affiliations
Richard J. Anderson, Sandia National Labs. (United States)
Dean A. Buchenauer, Sandia National Labs. (United States)
K. A. Williams, Sandia National Labs. (United States)
W. M. Clift, Sandia National Labs. (United States)
L. E. Klebanoff, Sandia National Labs. (United States)
N. V. Edwards, International SEMATECH (United States)
O. R. Wood II, International SEMATECH (United States)
S. Wurm, International SEMATECH (United States)

Published in SPIE Proceedings Vol. 5751:
Emerging Lithographic Technologies IX
R. Scott Mackay, Editor(s)

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