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Proceedings Paper

Metal fluoride coatings prepared by ion-assisted deposition
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Paper Abstract

ArF lithography technology requires minimization of optical losses due to scattering and absorption. Consequently, it is necessary to optimize the coating process of metal fluorides. The properties of metal fluoride thin films are mainly affected by the deposition methods, their parameters (temperature and deposition rate) and the vacuum conditions. A substrate temperature of more than 300°C is a condition for high density and low water content of metal fluorides. Therefore, a substrate temperature of 150°C results in inhomogeneous films with high water content. Until now, the best results were achieved by boat evaporation. This paper will demonstrate that most of the common metal fluorides like MgF2, AlF3, and even LaF3 can be deposited by electron beam evaporation. In comparison to other deposition methods, the prepared thin films have the lowest absorption in the VUV spectral range. Furthermore, metal fluoride thin films were prepared by ion assistance. It will be demonstrated, that they have less water content, high packing density, and low absorption in the VUV spectral range. In this study, single layers of LaF3 and AlF3 and antireflection coatings were prepared by electron beam evaporation with and without ion-assistance. The mechanical, structural, and optical properties were examined and discussed.

Paper Details

Date Published: 25 September 2008
PDF: 10 pages
Proc. SPIE 7101, Advances in Optical Thin Films III, 71010L (25 September 2008); doi: 10.1117/12.797422
Show Author Affiliations
Martin Bischoff, Friedrich-Schiller-Univ. (Germany)
Fraunhofer Institute Applied Optics and Precision Engineering (Germany)
Maik Sode, Friedrich-Schiller-Univ. (Germany)
Dieter Gäbler, Fraunhofer Institute Applied Optics and Precision Engineering (Germany)
Helmut Bernitzki, Jenoptik Laser, Optik, Systeme GmbH (Germany)
Christoph Zaczek, Carl Zeiss SMT AG (Germany)
Norbert Kaiser, Fraunhofer Institute Applied Optics and Precision Engineering (Germany)
Andreas Tünnermann, Friedrich-Schiller-Univ. (Germany)
Fraunhofer Institute Applied Optics and Precision Engineering (Germany)


Published in SPIE Proceedings Vol. 7101:
Advances in Optical Thin Films III
Norbert Kaiser; Michel Lequime; H. Angus Macleod, Editor(s)

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