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Proceedings Paper

Suppression of long wavelength reflection from extreme-UV multilayer optics
Author(s): Q. Huang; A. J. R. van den Boogaard; R. van de Kruijs; E. Zoethout; V. V. Medvedev; E. Louis; F. Bijkerk
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Paper Abstract

Plasma based radiation sources optimized to emit 13.5 nm Extreme UV radiation also produce a significant amount of light at longer wavelengths. This so called out-of-band (OoB) radiation is detrimental for the imaging capabilities of an EUV lithographic imaging system, particularly the deep ultraviolet (DUV) and ultraviolet (UV) parts of the light (λ=100-400 nm). To suppress these wavelengths while maintaining the high efficiency of the mirror for EUV light, several methods have been developed, including phase-shift gratings (PsG) and anti-reflection layers (SPE layer). PsG’s use the diffraction properties of a quarter-wavelength high multilayer grating to filter out the DUV/UV light, while the SPE layer works as an anti-reflection coating. Both methods have achieved a suppression factor of 10 - 30 around the target wavelength. To achieve a full band suppression effect, a new scheme based on surface pyramid structures was developed. An average suppression ofmore than 10 times can be achieved with a relative EUV efficiency of 89% (compared to standard multilayer (ML)) in theory. Different methods were discussed and their results are presented.

Paper Details

Date Published: 27 September 2013
PDF: 5 pages
Proc. SPIE 8848, Advances in X-Ray/EUV Optics and Components VIII, 88480N (27 September 2013); doi: 10.1117/12.2023889
Show Author Affiliations
Q. Huang, FOM Institute DIFFER (Netherlands)
A. J. R. van den Boogaard, FOM Institute DIFFER (Netherlands)
R. van de Kruijs, FOM Institute DIFFER (Netherlands)
E. Zoethout, FOM Institute DIFFER (Netherlands)
V. V. Medvedev, FOM Institute DIFFER (Netherlands)
E. Louis, FOM Institute DIFFER (Netherlands)
Univ. Twente (Netherlands)
F. Bijkerk, FOM Institute DIFFER (Netherlands)
Univ. Twente (Netherlands)

Published in SPIE Proceedings Vol. 8848:
Advances in X-Ray/EUV Optics and Components VIII
Ali Khounsary; Shunji Goto; Christian Morawe, Editor(s)

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