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Low-stress coatings for sputtered-sliced Fresnel zone plates and multilayer Laue lenses

 
: Braun, Stefan; Kubec, Adam; Gawlitza, Peter; Menzel, Maik; Leson, Andreas

:

Hudec, R. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
EUV and x-ray optics: Synergy between laboratory and space IV : 13-14 April 2015, Prague, Czech Republic
Bellingham, WA: SPIE, 2015 (Proceedings of SPIE 9510)
ISBN: 978-1-62841-631-2 (ISBN)
Paper 95100L, 9 pp.
Conference "EUV and X-Ray Optics - Synergy between Laboratory and Space" <4, 2015, Prague>
English
Conference Paper
Fraunhofer IWS ()
internal stress reduction; MoSi2; WSi2; multilayer Laue lens; X-ray focusing; microscopy

Abstract
The application of thin film coating processes for the fabrication of diffractive X-ray optical elements like sputtered-sliced zone plates or multilayer Laue lenses (MLL) is a very promising approach for X-ray focusing down to spot sizes of < 10 nm. However, for practical useful focal length in the order of several millimeters or a few centimeters, multilayer thicknesses of several 10 mu m up to a few 100 mu m are necessary in order to have large enough numerical apertures of the lenses. Currently one of the main challenges is to coat low-stress multilayers with large total thicknesses in the order of 100 mu m. Usually sputter deposition results in thin films with significant compressive stress. With new material combinations such as Mo/MoSi2/Si/MoSi2 and W/WSi2/Si/WSi2 the overall stress can be reduced to almost zero if the individual thicknesses are properly adapted. In the case of these four-layer-systems only the period thickness d(p) follows the zone plate law. In case of Mo/MoSi2/Si/MoSi2, stress-free multilayers are obtained with d(Mo) = 0.5*d(p), d(MoSi2) = 0.16*d(p) and d(Si) = 0.34*d(p).

: http://publica.fraunhofer.de/documents/N-350007.html