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Proceedings Paper

Pulsed UV laser Raman and fluorescence spectroscopy of large-area fused silica photomask substrates
Author(s): Christian Muehlig; Sylvia Bark-Zollmann; Dieter Grebner; Wolfgang Triebel
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Paper Abstract

Large area photomask substrates of fused silica and a size of up to 9 inches by 9 inches are locally evaluated by laser induced fluorescence and H2 measurements. Using a narrow-bandwidth KrF excimer laser, pulsed UV Raman spectroscopy is applied to measure the content of molecular hydrogen as an indicator of laser durability. Due to expeditious H2 measurements, this technique allows to determine the local H2 concentrations across an entire 6 inch by 6 inch photomask substrate within one hour. ArF excimer laser induced fluorescence (LIF) measurements are applied to correlate the H2 concentration and the laser induced defect formation in fused silica. In most cases the NBOH defect density, determine by the intensity of the peak at (lambda) equals 650 nm in the LIF spectrum, shows a symmetric curve across the substrate diagonals with its lowest values in the center. The associated H2 concentrations are found to show a maximum in the center. Furthermore, pulsed UV Raman spectroscopy is used to monitor the H2 concentration during irradiation with several 105 pulses of high KrF laser fluence. At first a rise in the H2 concentration is observed. After a maximum value further irradiation leads to a drop of molecular hydrogen within the illuminated volume.

Paper Details

Date Published: 5 July 2000
PDF: 7 pages
Proc. SPIE 4000, Optical Microlithography XIII, (5 July 2000); doi: 10.1117/12.389054
Show Author Affiliations
Christian Muehlig, Institut fuer Physikalische Hochtechnologie e.V. (Germany)
Sylvia Bark-Zollmann, Institut fuer Physikalische Hochtechnologie e.V. (Germany)
Dieter Grebner, Institut fuer Physikalische Hochtechnologie e.V. (Germany)
Wolfgang Triebel, Institut fuer Physikalische Hochtechnologie e.V. (Germany)

Published in SPIE Proceedings Vol. 4000:
Optical Microlithography XIII
Christopher J. Progler, Editor(s)

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