Interferometric testing of photomask substrate flatness

Christopher J. Evans; Robert E. Parks; Lianzhen Shao; Tony L. Schmitz; Angela D. Davies

doi:10.1117/12.436725

22 August 2001 Interferometric testing of photomask substrate flatness

Christopher J. Evans, Robert E. Parks, Lianzhen Shao, Tony L. Schmitz, Angela D. Davies

Proceedings Volume 4344, Metrology, Inspection, and Process Control for Microlithography XV; (2001) https://doi.org/10.1117/12.436725
Event: 26th Annual International Symposium on Microlithography, 2001, Santa Clara, CA, United States

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.

Citation Download Citation

Christopher J. Evans, Robert E. Parks, Lianzhen Shao, Tony L. Schmitz, and Angela D. Davies "Interferometric testing of photomask substrate flatness", Proc. SPIE 4344, Metrology, Inspection, and Process Control for Microlithography XV, (22 August 2001); https://doi.org/10.1117/12.436725

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