Optical element for full spectral purity from IR-generated EUV light sources

Toine van den Boogaard, Eric Louis, F.A. van Goor, Frederik Bijkerk

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

16 Citations (Scopus)


Laser produced plasma (LLP) sources are generally considered attractive for high power EUV production in next generation lithography equipment. Such plasmas are most efficiently excited by the relatively long, infrared wavelengths of CO2-lasers, but a significant part of the rotational-vibrational excitation lines of the CO2 radiation will be backscattered by the plasma's critical density surface and consequently will be present as parasitic radiation in the spectrum of such sources. Since most optical elements in the EUV collecting and imaging train have a high reflection coefficient for IR radiation, undesirable heating phenomena at the resist level are likely to occur. In this study a completely new principle is employed to obtain full separation of EUV and IR radiation from the source by a single optical component. While the application of a transmission filter would come at the expense of EUV throughput, this technique potentially enables wavelength separation without loosing reflectance compared to a conventional Mo/Si multilayer coated element. As a result this method provides full spectral purity from the source without loss in EUV throughput. Detailed calculations on the principal of functioning are presented
Original languageEnglish
Title of host publicationAlternative Lithographic Technologies
Subtitle of host publication24–26 February 2009, San Jose, California, United States
EditorsFrank M. Schellenberg, Bruno M. La Fontaine
Place of PublicationBellingham, WA
ISBN (Print)9780819475244
Publication statusPublished - 24 Feb 2009
EventSPIE Advanced Lithography 2009 - San Jose Convention Center, San Jose, United States
Duration: 22 Feb 200927 Feb 2009

Publication series

NameProceedings of SPIE
ISSN (Print)0277-786X


ConferenceSPIE Advanced Lithography 2009
Country/TerritoryUnited States
CitySan Jose


  • EUVLithography
  • EUV Source
  • Mo/Si Multilayers
  • Infrared
  • Blazed Grating
  • IR-77751
  • METIS-266559
  • Spectral Purity
  • Out of Band Radiation

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