Suppression of long wavelength reflection from extreme-UV multilayer optics

Qiushi Huang, Toine van den Boogaard, Robbert Wilhelmus Elisabeth van de Kruijs, E. Zoethout, Viacheslav Medvedev, Eric Louis, Frederik Bijkerk

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

2 Citations (Scopus)
4 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 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.
Original languageEnglish
Title of host publicationAdvances in X-Ray/EUV Optics and Components VIII
EditorsAli Khounsary, Shunji Goto, Christian Morawe
Place of PublicationBellingham, WA
Publication statusPublished - 25 Aug 2013
EventSPIE Optical Engineering + Applications 2013 - San Diego Convention Center, San Diego, United States
Duration: 25 Aug 201329 Aug 2013

Publication series

NameProceedings of SPIE
ISSN (Print)0277-786X


ConferenceSPIE Optical Engineering + Applications 2013
Country/TerritoryUnited States
CitySan Diego


  • IR-88103
  • METIS-299274


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