Interferometric Testing of Photomask Blank Flatness
Christopher J. Evans, R E. Parks, L Z. Shao, Tony L. Schmitz, Angela Davies
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.
SPIE International Symposium on Microlithography
February 26-28, 2001
Santa Clara, CA
International Symposium on Microlithography
flatness, interfermetry, photomasks, Ritchey-Common test
, Parks, R.
, Shao, L.
, Schmitz, T.
and Davies, A.
Interferometric Testing of Photomask Blank Flatness, SPIE International Symposium on Microlithography, Santa Clara, CA
(Accessed June 9, 2023)