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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