Spectral purity enhancement for the EUV Lithography Systems by suppressing UV reflection from multilayers

Qiushi Huang, Meint de Boer, Jonathan Barreaux, Daniel Mathijs Paardekooper, Toine van den Boogaard, Robbert van de Kruijs, Erwin Zoethout, Eric Louis, Fred Bijkerk

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

3 Citations (Scopus)
1 Downloads (Pure)


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 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). Both methods have achieved a suppression factor of 10 - 30 around the target wavelength. To achieve a full band suppression effect with a minimum loss of EUV light, a new scheme based on surface pyramid structures was developed. An average suppression of more than 10 times was achieved with a relative EUV efficiency of 82.2% by using the Si pyramids structure (compared to a flat multilayer (ML)). Recently, we have successfully produced a pyramid structure consisting of multilayers which greatly improves the relative EUV efficiency to 94.2%.
Original languageEnglish
Title of host publicationExtreme Ultraviolet (EUV) Lithography V
EditorsObert R. Wood, Eric M. Panning
Place of PublicationSan Jose, CA
Number of pages5
Publication statusPublished - 2014
EventSPIE Conference on Extreme Ultraviolet (EUV) Lithography V, 2014 - San Jose, United States
Duration: 24 Feb 201427 Feb 2014
Conference number: 5

Publication series

NameProceedings of SPIE
ISSN (Print)0277-786X


ConferenceSPIE Conference on Extreme Ultraviolet (EUV) Lithography V, 2014
Country/TerritoryUnited States
CitySan Jose


  • Spectral purity
  • EUV multilayer
  • Diffraction
  • Pyramid


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