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Interferometric Testing of Photomask Substrate 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
Metrology, Inspection and Process Control for Microlithography, Conference | 15th | Metrology, Inspection and Process Control for Microlithography XV | SPIE
Volume
4344
Conference Dates
February 1, 2001
Conference Title
Proceedings of SPIE--the International Society for Optical Engineering

Keywords

flatness, interferometry, photomasks, Ritchey-Common test

Citation

Evans, C. , Parks, R. , Shao, L. , Schmitz, T. and Davies, A. (2001), Interferometric Testing of Photomask Substrate Flatness, Metrology, Inspection and Process Control for Microlithography, Conference | 15th | Metrology, Inspection and Process Control for Microlithography XV | SPIE (Accessed April 16, 2024)
Created August 1, 2001, Updated February 19, 2017