The surface topography of optics fabricated for Extreme Ultraviolet Lithography has been measured using a combination of phase-measuring interferometry and atomic force microscopy. Power Spectral Densities were computed over spatial frequencies extending from 2.0{times}10{sup {minus}8} nm{sup {minus}1} to 7.7{times}10{sup {minus}2} nm{sup {minus}1}. Roughness values for frequencies greater than 1.0{times}10{sup {minus}6} were 0.64 nm rms for a spherical optic and 0.95 nm rms for an aspheric optic. These values are significantly larger than 0.088 nm rms, which as obtained using a spherical optic representative of current limits in surface polishing technology. 9 refs., 4 figs.
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Lawrence Livermore National Lab., CA (United States)
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California
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The surface topography of optics fabricated for Extreme Ultraviolet Lithography has been measured using a combination of phase-measuring interferometry and atomic force microscopy. Power Spectral Densities were computed over spatial frequencies extending from 2.0{times}10{sup {minus}8} nm{sup {minus}1} to 7.7{times}10{sup {minus}2} nm{sup {minus}1}. Roughness values for frequencies greater than 1.0{times}10{sup {minus}6} were 0.64 nm rms for a spherical optic and 0.95 nm rms for an aspheric optic. These values are significantly larger than 0.088 nm rms, which as obtained using a spherical optic representative of current limits in surface polishing technology. 9 refs., 4 figs.
Gaines, D.P.; Sweeney, D.W.; DeLong, K.W.; Vernon, S.P.; Baker, S.L.; Tichenor, D.A. et al.Surface characterization of optics for EUV lithography,
report,
May 28, 1996;
California.
(digital.library.unt.edu/ark:/67531/metadc675715/:
accessed September 20, 2017),
University of North Texas Libraries, Digital Library, digital.library.unt.edu;
crediting UNT Libraries Government Documents Department.