Long term tests of resonator optics in ArF excimer lasers

verfasst von: Nils Beermann, Holger Blaschke, Henrik Ehlers, Detlev Ristau, Dirk Wulff Molder, Sigrid Jukresch, Ansgar Matern, Martin Bischoff, Dieter Gäbler, Norbert Kaiser
Abstract: The aim of this work is the optimization of the resonator optics of excimer laser systems to achieve longer lifetimes and to reduce the cost of ownership. The degradation after long-term exposure to high photon fluxes (typically 80 mJ/cm²) at the ArF laser wavelength of 193 nm was analyzed. Based on the investigations, a model describing the process of the deterioration of the out-coupling partial reflector was developed. It was found that contamination of the optics by the laser's discharge electrodes leads to absorption losses on the surface facing the inside of the resonator. As a consequence, the laser irradiation causes a temperature gradient in the CaF₂-substrates which leads to crystal cleavage and braking of the optics. Defects on the outward surface are the origin for the growth of Calcite crystals and organic compounds by photo induced chemical reactions of the substrate material and contaminations in the purge gas. It was demonstrated that the lifetime of the resonator optics can be substantially increased by adapted optical designs and coatings.
Externe Organisation(en): Laser Zentrum Hannover e.V. (LZH)
Korth Kristalle GmbH
Coherent GmbH
Fraunhofer-Institut für Angewandte Optik und Feinmechanik IOF
Typ: Aufsatz in Konferenzband
Publikationsdatum: 21.04.2009
Publikationsstatus: Veröffentlicht
Peer-reviewed: Ja
ASJC Scopus Sachgebiete: Elektronische, optische und magnetische Materialien, Physik der kondensierten Materie, Angewandte Informatik, Angewandte Mathematik, Elektrotechnik und Elektronik
Elektronische Version(en): https://doi.org/10.1117/12.816706 (Zugang: Unbekannt)

BibTeX

@inproceedings{b6f01b383cb3456b9f8365cb2dc2cc10,
title = "Long term tests of resonator optics in ArF excimer lasers",
abstract = "The aim of this work is the optimization of the resonator optics of excimer laser systems to achieve longer lifetimes and to reduce the cost of ownership. The degradation after long-term exposure to high photon fluxes (typically 80 mJ/cm2) at the ArF laser wavelength of 193 nm was analyzed. Based on the investigations, a model describing the process of the deterioration of the out-coupling partial reflector was developed. It was found that contamination of the optics by the laser's discharge electrodes leads to absorption losses on the surface facing the inside of the resonator. As a consequence, the laser irradiation causes a temperature gradient in the CaF2-substrates which leads to crystal cleavage and braking of the optics. Defects on the outward surface are the origin for the growth of Calcite crystals and organic compounds by photo induced chemical reactions of the substrate material and contaminations in the purge gas. It was demonstrated that the lifetime of the resonator optics can be substantially increased by adapted optical designs and coatings.",
keywords = "ArF laser, Degradation, Optical coatings, Partial reflector, Resonator optics, Substrate",
author = "Nils Beermann and Holger Blaschke and Henrik Ehlers and Detlev Ristau and Molder, {Dirk Wulff} and Sigrid Jukresch and Ansgar Matern and Martin Bischoff and Dieter G{\"a}bler and Norbert Kaiser",
year = "2009",
month = apr,
day = "21",
doi = "10.1117/12.816706",
language = "English",
isbn = "9780819473653",
series = "Proceedings of SPIE - The International Society for Optical Engineering",
booktitle = "XVII International Symposium on Gas Flow, Chemical Lasers, and High-Power Lasers",
note = "XVII International Symposium on Gas Flow, Chemical Lasers, and High-Power Lasers ; Conference date: 15-09-2008 Through 19-09-2008",
}