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Proceedings Paper

Optical, chemical, depth, and magnetic characterization of Mg/Co-based nanometric periodic multilayers
Author(s): P. Jonnard; K. Le Guen; M.-H. Hu; J.-M. André; S. K. Zhou; H. Ch. Li; J. T. Zhu; Z. S. Wang; N. Mahne; A. Giglia; S. Nannarone; A. Verna; C. Meny; A. Galtayries; I. Estève; M. Walls
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Paper Abstract

We have developed and elaborated a series of Mg/Co-based periodic multilayers to build efficient mirrors for the extreme ultraviolet (EUV) range. For s-polarized light and at 45° of grazing incidence, the reflectivity of as-deposited Mg/Co is 42.6% at 25.1 nm. X-ray emission spectroscopy and nuclear magnetic resonance measurements do not indicate any noticeable interdiffusion at the interfaces between layers. Scanning transmission electronic microscopy images attest the high structural quality of the stack. X-ray reflectivity (XRR) curves in the hard x-ray and EUV domains confirm this description and estimate a weak interfacial roughness (~ 0.5 nm). Taking advantage of the magnetic character of Co, we have performed resonant magnetic reflectivity measurements by scanning the photon energy around the Co L absorption edge for opposite circular polarizations. The magnetization profile of the Co layers within Co/Mg determined with an expected depth resolution of one monolayer confirms the interface abruptness. Scanning electron microscopy images and XRR curves give evidence of the thermal stability of Mg/Co up to 300 °C. From that value, a strong change in the sample morphology due to the delamination of the multilayer from the substrate occurs. This should account for the drastic reflectivity drop observed above this temperature. Starting from Mg/Co, we have inserted a Zr layer at one or at the other interface or at both interfaces to estimate the effect of the introduction of a third material within the period. We have found that Mg/Co/Zr is more efficient (50% of reflectivity) than Mg/Zr/Co and Mg/Zr/Co/Zr (~ 40%). Through time-of-flight secondary ion mass spectrometry depth profiling and NMR measurements, we have assigned this difference to an intermixing process when Co layers are deposited onto Zr layers.

Paper Details

Date Published: 4 October 2011
PDF: 7 pages
Proc. SPIE 8168, Advances in Optical Thin Films IV, 816818 (4 October 2011); doi: 10.1117/12.895316
Show Author Affiliations
P. Jonnard, Lab. de Chimie Physique-Matière Rayonnement, CNRS, Univ. Pierre et Marie Curie (France)
K. Le Guen, Lab. de Chimie Physique-Matière Rayonnement, CNRS, Univ. Pierre et Marie Curie (France)
M.-H. Hu, Lab. de Chimie Physique-Matière Rayonnement, CNRS, Univ. Pierre et Marie Curie (France)
J.-M. André, Lab. de Chimie Physique-Matière Rayonnement, CNRS, Univ. Pierre et Marie Curie (France)
S. K. Zhou, Tongji Univ. (China)
H. Ch. Li, Tongji Univ. (China)
J. T. Zhu, Tongji Univ. (China)
Z. S. Wang, Tongji Univ. (China)
N. Mahne, Lab. Nazionale TASC, CNR (Italy)
A. Giglia, Lab. Nazionale TASC, CNR (Italy)
S. Nannarone, Lab. Nazionale TASC, CNR (Italy)
A. Verna, Lab. Nazionale TASC, CNR (Italy)
C. Meny, Institut de Physique et Chimie des Matériaux de Strasbourg, CNRS (France)
A. Galtayries, Lab. de Physico-Chimie des Surfaces, CNRS, Ecole Nationale Superieure de Chimie ParisTech (France)
I. Estève, Institut de Minéralogie et de Physique des Milieux Condensés, CNRS, Univ. Paris 6 et 7 (France)
M. Walls, Lab. de Physique des Solides, CNRS, Univ. Paris-Sud 11 (France)

Published in SPIE Proceedings Vol. 8168:
Advances in Optical Thin Films IV
Michel Lequime; H. Angus Macleod; Detlev Ristau, Editor(s)

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