Metrology related to the multilayer mirrors in an extreme-ultraviolet stepper

C. Tarrio, S. B. Hill, Ivan Ermanoski, T. B. Lucatorto, T. E. Madey, M. Chandhok, M. Fang

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Abstract

    Extreme-ultraviolet (EUV) lithography is slated for introduction in the 2012 time frame for volume production of chips with 32-nm design rules. NIST has a program to perform metrology on the multilayer mirrors used to focus the 13.5 nm EUV radiation employed in the stepper. This program includes accurate mirror reflectivity measurements and accelerated lifetime testing. One of the major obstacles to attaining high volume manufacturing is lifetime of the mirrors comprising the projection system. Ongoing endurance testing of Ru-capped multilayer mirrors at the National Institute of Standards and Technology synchrotron facility has revealed that the damage resulting from EUV irradiation does not in general depend on the exposure conditions in an intuitive way. Previous exposures of Ru-capped multilayers to EUV radiation in the presence of water vapor demonstrated that the mirror damage rate actually decreases with increasing water pressure. We will present results of recent exposures showing that the reduction in damage for partial pressures of water up to 5×10 -6Torr is not the result of a spatially uniform decrease in reflectivity across the Gaussian intensity distribution of the incident EUV beam. Instead, under a range of water partial pressures, we observe a drop in the damage rate in the center of the exposure spot where the intensity is greatest, while the reflectivity loss in the wings of the intensity distribution appears to be independent of water partial pressure. An investigation is underway to find the cause of the non-Gaussian damage profile. Preliminary results and hypotheses will be discussed. In addition to high-resolution reflectometry of the EUV-exposure sites, the results of surface analysis such as XPS will be presented. Although the observations presented here are based on exposures of Ru-capped samples, unless novel capping layers are similarly characterized, direct application of accelerated testing results could significantly overestimate mirror lifetime in the production environment.

    Original languageEnglish (US)
    Title of host publicationCHARACTERIZATION AND METROLOGY FOR NANOELECTRONICS
    Subtitle of host publication2007 International Conference on Frontiers of Characterization and Metrology
    Pages428-431
    Number of pages4
    DOIs
    StatePublished - Oct 22 2007
    EventCHARACTERIZATION AND METROLOGY FOR NANOELECTRONICS: 2007 International Conference on Frontiers of Characterization and Metrology - Gaithersburg, MD, United States
    Duration: Mar 27 2007Mar 29 2007

    Publication series

    NameAIP Conference Proceedings
    Volume931
    ISSN (Print)0094-243X
    ISSN (Electronic)1551-7616

    Other

    OtherCHARACTERIZATION AND METROLOGY FOR NANOELECTRONICS: 2007 International Conference on Frontiers of Characterization and Metrology
    CountryUnited States
    CityGaithersburg, MD
    Period3/27/073/29/07

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    Keywords

    • Extreme ultraviolet
    • Lifetime testing
    • Lithography
    • Multilayer optics

    ASJC Scopus subject areas

    • Physics and Astronomy(all)

    Cite this

    Tarrio, C., Hill, S. B., Ermanoski, I., Lucatorto, T. B., Madey, T. E., Chandhok, M., & Fang, M. (2007). Metrology related to the multilayer mirrors in an extreme-ultraviolet stepper. In CHARACTERIZATION AND METROLOGY FOR NANOELECTRONICS: 2007 International Conference on Frontiers of Characterization and Metrology (pp. 428-431). (AIP Conference Proceedings; Vol. 931). https://doi.org/10.1063/1.2799412