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Proceedings Paper

Two magnification steps EUV microscopy with a Schwarzschild objective and an adapted zone plate lens
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Paper Abstract

Due to the short wavelength microscopy with extreme ultraviolet (EUV) light is optimally suited for detecting defects e.g. on mask blanks for EUV lithography. In this work the use of a zone plate lens as a second magnification step in EUV microscopy with a multilayer coated Schwarzschild objective is suggested. The zone plate has to be adapted to the optical system and to have a magnification high enough to match the resolution of the Schwarzschild objective to the detector pixel size. The resulting zone plate should have only a few tens of zones and about 1 μm resolution which reduces fabrication demands. Furthermore, this combination enables a scan and zoom procedure where first the measurements are carried out just with a Schwarzschild objective allowing only a small magnification but larger object field. Then, in areas of interest, the second magnification step is switched on by inserting a zone plate in front of the detector and refocusing the sample. The paper addresses regulations for the zone plate design, simulations of the whole optical system and corresponding demonstration experiments on test structures.

Paper Details

Date Published: 30 April 2009
PDF: 8 pages
Proc. SPIE 7360, EUV and X-Ray Optics: Synergy between Laboratory and Space, 736005 (30 April 2009); doi: 10.1117/12.822986
Show Author Affiliations
Larissa Juschkin, RWTH Aachen Univ. (Germany)
Ralf Freiberger, RWTH Aachen Univ. (Germany)


Published in SPIE Proceedings Vol. 7360:
EUV and X-Ray Optics: Synergy between Laboratory and Space
René Hudec; Ladislav Pina, Editor(s)

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