Balancing of residual stress in thin film iridium by utilizing chromium as an underlayer

S. Massahi*, L. M. Vu, D. D.M. Ferreira, F. E. Christensen, N. Gellert, P. L. Henriksen, S. Svendsen, A. S. Jegers, M. Collon, B. Landgraf, D. Girou, A. Thete, B. Shortt, I. Ferreira, M. Bavdaz

*Corresponding author for this work

    Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

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    Abstract

    As part of the thin film development for the Athena X-ray telescope and X-ray optics in general, we investigated the residual stress in iridium and chromium thin films deposited using direct current magnetron sputtering. Residual stresses in thin films can affect the performance and adhesion properties of the fabricated thin film coated X-ray optics. We characterized the thin films using X-ray reflectometry to determine the thin film thicknesses and stylus profilometry to determine the residual film stresses. To counterbalance the compressive stress identified in the iridium thin films, we introduced a chromium thin film layer for which the residual stress is tensile beneath the iridium film. However, chromium thin films are known to exhibit a grainy growth resulting in a high surface roughness which was also observed in this work. In this paper, we evaluated the effect on the iridium surface roughness when introducing a chromium underlayer and discussed the effect on the X-ray optics performance.

    Original languageEnglish
    Title of host publicationSpace Telescopes and Instrumentation 2020: Ultraviolet to Gamma Ray
    EditorsJan-Willem A. den Herder, Shouleh Nikzad, Kazuhiro Nakazawa
    Number of pages17
    Volume11444
    PublisherSPIE - International Society for Optical Engineering
    Publication date2020
    Article number114444N
    ISBN (Electronic)9781510636750, 9781510636767
    DOIs
    Publication statusPublished - 2020
    EventSpace Telescopes and Instrumentation 2020: Ultraviolet to Gamma Ray - Online event
    Duration: 14 Dec 202018 Dec 2020

    Conference

    ConferenceSpace Telescopes and Instrumentation 2020: Ultraviolet to Gamma Ray
    LocationOnline event
    Period14/12/202018/12/2020
    SeriesProceedings of SPIE - The International Society for Optical Engineering
    Volume11444
    ISSN0277-786X

    Keywords

    • Athena mission
    • Atomic force microscopy
    • DC magnetron sputtering
    • Residual thin film stress
    • Silicon Pore Optics
    • Stylus profilometry
    • X-ray optics
    • X-ray reflectometry

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