Energetic Sn+ irradiation effects on ruthenium mirror specular reflectivity at 13.5-nm

• Published in: Applied physics. A, Materials science & processing Materials science & processing, 2010-07, Vol.100 (1), p.231-237
• Main Authors: Allain, J. P., Nieto-Perez, M., Hendricks, M. R., Zink, P., Metzmacher, C., Bergmann, K.
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Condensed Matter Physics; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Lenses, prisms, and mirrors; Machines; Manufacturing; Nanotechnology; Optical and Electronic Materials; Optical elements, devices, and systems; Optics; Physics; Physics and Astronomy; Processes; Surfaces and Interfaces; Thin Films
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-010-5581-8

Sn + irradiations of Ru single-layer mirrors (SLM) simulate conditions of fast-Sn ion exposure in high-intensity 13.5 nm lithography lamps. Ultra-shallow implantation of Sn is measured down to 1–1.5 nm depth for energies between 1–1.3 keV at near-normal incident angles on Ru mirror surfaces. The Sn surface concentration reaches an equilibrium of 55–58% Sn/Ru for near-normal incidence and 36–38% for grazing incidence at approximately 63 degrees with respect to the mirror surface normal. The relative reflectivity at 13.5 nm at 15-degree incidence was measured in-situ during Sn + irradiation. For near-normal Sn + exposures the reflectivity is measured to decrease between 4–7% for a total Sn fluence of 10 16 cm −2 . Theoretical Fresnel reflectivity modeling shows for the same fluence assuming all Sn atoms form a layer on the Ru mirror surface, that the reflectivity loss should be between 15–18% for this dose. Ex-situ absolute 13.5 nm reflectivity data corroborate these results, indicating that implanted energetic Sn atoms mixed with Ru reflect 13.5-nm light differently than theoretically predicted by Fresnel reflectivity models.