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Interferometric Testing of Photomask Blank Flatness

Published

Author(s)

Christopher J. Evans, R E. Parks, L Z. Shao, Tony L. Schmitz, Angela Davies

Abstract

Conventional interferometric testing of the flatness of photomask blanks 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 spherical wavefront; this paper shows that, under appropriate conditions, high resolution surface flatness maps of photomask blanks may be obtained using instrumentation currently available in many optical shops.
Proceedings Title
SPIE International Symposium on Microlithography
Volume
4344
Conference Dates
February 26-28, 2001
Conference Location
Santa Clara, CA
Conference Title
International Symposium on Microlithography

Keywords

flatness, interfermetry, photomasks, Ritchey-Common test

Citation

Evans, C. , Parks, R. , Shao, L. , Schmitz, T. and Davies, A. (2001), Interferometric Testing of Photomask Blank Flatness, SPIE International Symposium on Microlithography, Santa Clara, CA (Accessed April 21, 2024)
Created February 28, 2001, Updated February 19, 2017