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Proceedings Paper

Smoothing of substrate roughness by carbon-based layers prepared by pulsed laser deposition (PLD)
Author(s): Stefan Braun; Beatrice Bendjus; Thomas Foltyn; Maik Menzel; Jurgen Schreiber; Andreas Leson
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Paper Abstract

In order to obtain high reflectance of EUV and X-ray multilayer mirrors, highly polished substrate surfaces with rms roughness σrms = 0,1-0.2 nm are necessary. However, the simultaneous achievement of low micro-roughness and precise surface figure is very challenging and often not accomplished. Therefore deposition techniques capable to deposit layers with smoothing properties are very desirable. One potential method that enables the formation of such layers is the pulsed laser deposition (PLD). This technique generates particles with high kinetic energies of up to several 100 eV. We investigated the deposition of carbon based smoothing layers by PLD on numerous substrates with roughness between σrms = 0.15 and 0.75 nm using different laser power densities and film thicknesses. Besides pure carbon layers we also used metal/carbon (metal = Ni, W, Pt) multilayers with respect to their capabilities to smooth surface roughness. As a general trend it turns out that a better smoothing can be obtained with higher laser power densities, whereby diamond-like carbon films are created. Furthermore, the intrinsic stress of the smoothing layers has been investigated. Due to the high kinetic energy of the impinging particles during the film growth, the layers show compressive stress. The degree of the stress depends on the concrete metal that is combined with carbon in the multilayer stack. Up to now the lowest compressive stress is obtained with Ni/C multilayers.

Paper Details

Date Published: 18 October 2004
PDF: 10 pages
Proc. SPIE 5533, Advances in Mirror Technology for X-Ray, EUV Lithography, Laser, and Other Applications II, (18 October 2004); doi: 10.1117/12.560358
Show Author Affiliations
Stefan Braun, Fraunhofer-Institut fur Werkstoff-und Strahltechnik (Germany)
Beatrice Bendjus, Fraunhofer-Institut fur Zerstorungsfreie Prufverfahren (Germany)
Thomas Foltyn, Fraunhofer-Institut fur Werkstoff-und Strahltechnik (Germany)
Maik Menzel, Fraunhofer-Institut fur Werkstoff-und Strahltechnik (Germany)
Jurgen Schreiber, Fraunhofer-Institut fur Zerstorungsfreie Prufverfahren (Germany)
Andreas Leson, Fraunhofer-Institut fur Werkstoff-und Strahltechnik (Germany)

Published in SPIE Proceedings Vol. 5533:
Advances in Mirror Technology for X-Ray, EUV Lithography, Laser, and Other Applications II
Ali M. Khounsary; Udo Dinger; Kazuya Ota, Editor(s)

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