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Proceedings Paper

Absorption measurement of DUV optical materials at 193 and 157 nm by laser-induced deflection
Author(s): Christian Muehlig; Siegfried Kufert; Wolfgang Triebel; Ute Natura; Frank Coriand
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Paper Abstract

Under 193 nm excimer laser irradiation the laser induced deflection technique (LID) is applied to investigate directly the bulk absorption α of high quality fused silica and calcium fluoride. Fused silica samples are characterized by their fluence H dependent absorption α(H). Their small signal absorption coefficients α 0 are extrapolated by an appropriate fitting model. All investigated standard samples with high H2 content fulfill the requirement for optical lithography which is determined by an α0 of less than (formula available in paper). Prolonged direct absorption measurements at relatively high fluences of 10 and 20 mJ/cm2 by the LID technique are compared to state of the art marathon durability tests for H2 poor fused silica at a H = 1.3 mJ/cm2. The very good agreement of the results demonstrates that the measurement time for durability tests of fused silica can be reduced considerably by increasing the applied fluencs H. Calcium fluoride is investigated by both, direct bulk absorption (LID) and conventional transmission measurements. A very good agreement is found by comparing the results of both experiments. For investigations at 157 nm laser irradiation a new compact LID measurement device is introduced. Calibration measurements show that the sensitivity is significantly increased compared to the previous setup. The detection limit of the new setup is estimated to α values of (formula available in paper) for calcium fluoride and fused silica, respectively.

Paper Details

Date Published: 4 November 2003
PDF: 10 pages
Proc. SPIE 5188, Advanced Characterization Techniques for Optics, Semiconductors, and Nanotechnologies, (4 November 2003); doi: 10.1117/12.506795
Show Author Affiliations
Christian Muehlig, Institut fuer Physikalische Hochtechnologie e.V. (Germany)
Siegfried Kufert, Institut fuer Physikalische Hochtechnologie e.V. (Germany)
Wolfgang Triebel, Institut fuer Physikalische Hochtechnologie e.V. (Germany)
Ute Natura, Schott Lithotec AG (Germany)
Frank Coriand, Schott Lithotec AG (Germany)

Published in SPIE Proceedings Vol. 5188:
Advanced Characterization Techniques for Optics, Semiconductors, and Nanotechnologies
Angela Duparre; Bhanwar Singh, Editor(s)

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