Surface chemistry of Ru: Relevance to optics lifetime in EUVL

R. Wasielewski, B. V. Yakshinskiy, Mohamed Nejib Hedhili, A. Ciszewski, T. E. Madey*

*Corresponding author for this work

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

    17 Scopus citations

    Abstract

    Ruthenium capping layers ∼2 nm thick are used to protect and extend the lifetimes of Si/Mo multilayer mirrors used in extreme ultraviolet lithography (EUVL) applications. In the present work, we use ultrahigh vacuum surface science methods to address two aspects of Ru surface chemistry: (a) use of atomic hydrogen to remove oxygen from O-covered Ru, and (b) the effects of a model background hydrocarbon gas (methyl methacrylate, MMA) on the accumulation of carbon on a Ru(101̄0) single crystal surface. Atomic H is very effective in removing O from Ru even at 300K; the interpretation is that H reacts directly with adsorbed O to make OH, and a subsequent H atom reacts with OH to make H 2O, which desorbs at 300K. MMA adsorbs strongly on Ru in the first monolayer and dissociates upon heating; H 2 and CO desorption products are seen upon heating from 300 to 600K, while a fractional monolayer of C remains on the surface. Physisorbed multilayers of MMA form at temperatures below ∼170K. Thermal desorption of MMA dosed onto O-covered Ru shows that MMA reacts and completely removes an adsorbed O monolayer upon heating. Electron bombardment of MMA/Ru causes polymerization and also can induce accumulation of carbon - all depends on electron fluence, partial pressure of MMA, and substrate temperature.

    Original languageEnglish (US)
    Title of host publicationEMLC 2007
    Subtitle of host publication23rd European Mask and Lithography Conference
    DOIs
    StatePublished - Nov 5 2007
    EventEMLC 2007: 23rd European Mask and Lithography Conference - Grenoble, France
    Duration: Jan 22 2007Jan 25 2007

    Publication series

    NameProceedings of SPIE - The International Society for Optical Engineering
    Volume6533
    ISSN (Print)0277-786X

    Other

    OtherEMLC 2007: 23rd European Mask and Lithography Conference
    CountryFrance
    CityGrenoble
    Period01/22/0701/25/07

    Keywords

    • Atomic H
    • EUV optics contamination
    • EUV optics lifetime
    • Electron induced reactions
    • Extreme ultraviolet lithography (EUVL)
    • Hydrogen
    • Methyl methacrylate (MMA)
    • Oxygen
    • Ru(101̄0)
    • Ruthenium

    ASJC Scopus subject areas

    • Electronic, Optical and Magnetic Materials
    • Condensed Matter Physics
    • Computer Science Applications
    • Applied Mathematics
    • Electrical and Electronic Engineering

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