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Proceedings Paper

Interferometric testing of photomask substrate flatness
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Paper Abstract

Conventional interferometric testing of the flatness of photomask substrates is rendered difficult by the long coherence length of the HeNe laser sources typically used in commercially available phase measuring interferometers appropriate for flatness testing. The Ritchey-Common configuration allows testing of flats in a spherical wavefront; this paper shows that, under appropriate conditions, high resolution surface flatness maps of photomask substrates may be obtained using instrumentation currently available in many optical shops.

Paper Details

Date Published: 22 August 2001
PDF: 8 pages
Proc. SPIE 4344, Metrology, Inspection, and Process Control for Microlithography XV, (22 August 2001); doi: 10.1117/12.436725
Show Author Affiliations
Christopher J. Evans, National Institute of Standards and Technology (United States)
Robert E. Parks, Optical Perspectives Group (United States)
Lianzhen Shao, Tucson Optical Research Corp. (United States)
Tony L. Schmitz, National Institute of Standards and Technology (United States)
Angela D. Davies, National Institute of Standards and Technology (United States)


Published in SPIE Proceedings Vol. 4344:
Metrology, Inspection, and Process Control for Microlithography XV
Neal T. Sullivan, Editor(s)

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