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An important parameter in the production of flat panel displays is the waviness, or micro-corrugation, of the substrate surface. It describes surface deviations in the mid spatial frequency range between roughness and global shape. Typically, the waviness has to be determined to an accuracy in the 5 nm-range. A technique is presented to measure the waviness optically in a non-contact fashion along a profile 14' long. Thus large panel substrates can be measured. Special issues to consider are: (1) suppression of the light reflected from the back surface of the panel substrate, (2) large required dynamic range due to the overall shape of the panel of more than 100 micrometers , (3) the flexibility of the panel substrates requiring well designed fixturing to avoid bending and pick-up of vibrations. The described technique is based on an extension of a phase- shifting white-light Mach-Zehnder interferometer which has been used successfully in the characterization of thin glass disk substrates.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Klaus R. Freischlad "Large flat panel profiler", Proc. SPIE 2862, Flatness, Roughness, and Discrete Defect Characterization for Computer Disks, Wafers, and Flat Panel Displays, (4 November 1996);


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