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Proceedings Paper

Cooled EUV collector optics for LPP and DPP sources
Author(s): X. Bozec; L. Moine; R. Wevers; S. Djidel; R. Mercier Ythier; R. Geyl; V. Patoz
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Paper Abstract

For several years Sagem has invested in technologies and engineering to develop innovative solutions for collecting optics for LPP and DPP EUV sources. Among the technological challenges for collecting mirrors, thermal control plays a very important role in avoiding degradation of in band EUV reflectivity and maintaining far field optical performance during scanner operation. Sagem proposes solutions based on a metallic mirror with embedded cooling circuits to stabilize the temperature of the mirror during source operation. Results of simulation as well as first technology validations obtained on prototypes will be shown to demonstrate the performance of the cooled mirror design. Another critical performance about the collector is the HSFR (micro roughness) requirements of the optical surface for limiting scattering and optimizing the in band EUV reflectivity. Thanks to the specific polishing process, HSFR values of below 2 Angstroms have been achieved on demonstrator metallic mirrors with high departure aspheres. Reflectivity measurements performed after coating of these parts with MoSi multilayers confirm that the obtained polishing quality is compliant with polishing specifications for high performance EUV optics. Finally, upcoming developments at Sagem in the field of EUV collecting optics will be presented.

Paper Details

Date Published: 29 March 2011
PDF: 10 pages
Proc. SPIE 7969, Extreme Ultraviolet (EUV) Lithography II, 79690A (29 March 2011); doi: 10.1117/12.876981
Show Author Affiliations
X. Bozec, Sagem (France)
L. Moine, Sagem (France)
R. Wevers, Sagem (France)
S. Djidel, Sagem (France)
R. Mercier Ythier, Sagem (France)
R. Geyl, Sagem (France)
V. Patoz, Sagem (France)

Published in SPIE Proceedings Vol. 7969:
Extreme Ultraviolet (EUV) Lithography II
Bruno M. La Fontaine; Patrick P. Naulleau, Editor(s)

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