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Proceedings Paper

Characterization of prototype optical surfaces and coatings for the EUV reticle imaging microscope
Author(s): H. Glatzel; J. Daniel; K. Khajehnouri; T. Roff; S. Sporer; S. Wong; M. Kriese; Y. Platonov; J. Rodriguez
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Paper Abstract

To perform actinic inspection of patterned EUV reticles with diffraction-limited resolution at 13.5 nm wavelength aspheric optical surfaces with surface figure errors and roughnesses well below 1 nm had to be developed. The 3D surface topologies of prototype optical components were characterized over spatial periods ranging from the clear apertures down to 25 nanometers over 6 orders of magnitude by using a portfolio of instruments. 3D topography maps were Fourier analyzed and averaged Power Spectral Densities (PSDs) computed over the entire spatial frequency range. A good fit to the PSD was achieved with a linear function on a log-log scale. RMS values were computed over several spatial period ranges. All optical surfaces were coated with high-reflectivity coatings to maximize optical throughput at 13.5 nm for the average angle-of-incidence of each optic. The spectral reflectivity of the HR coatings, consisting of Molybdenum-Silicon bi-layers (40 periods) were measured using synchrotron instruments at the NIST/DARPA EUV Reflectometry Facility and the Center for X-Ray Optics at Lawrence Berkeley National Laboratory. Total variations (PV) of peak-position within the clear-apertures ranged from 0.005 nm to 0.020 nm, with the one exception being a highly-curved convex surface yielding a PV variation of 0.040 nm. Peak reflectivity variation was typically 0.2% to 1% PV over the clear aperture, with some of the variation being instrument precision. One optic was coated with Ruthenium only, approximately 16nm thick, with less than ±0.1 nm variation in thickness. Detailed information on the spectral reflectivity for the coatings is discussed.

Paper Details

Date Published: 6 May 2005
PDF: 8 pages
Proc. SPIE 5751, Emerging Lithographic Technologies IX, (6 May 2005); doi: 10.1117/12.619290
Show Author Affiliations
H. Glatzel, Tinsley Labs. (United States)
J. Daniel, Tinsley Labs. (United States)
K. Khajehnouri, Tinsley Labs. (United States)
T. Roff, Tinsley Labs. (United States)
S. Sporer, Tinsley Labs. (United States)
S. Wong, Tinsley Labs. (United States)
M. Kriese, Osmic, Inc. (United States)
Y. Platonov, Osmic, Inc. (United States)
J. Rodriguez, Osmic, Inc. (United States)

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

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