2 January 1986 Accurate Mask-To-Wafer Gap Measurements In The EBP Lithography Tool
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Abstract
We describe a new mask-to-wafer gap measurement technique, that has been implemented into the Electron-Beam Proximity Printing (EBP) lithography tool. In the EBP gap-measurement mode the parallel e-beam of 1 mm diameter performs scanning inclination about a perio-dic chip-registration pattern in the mask, resulting in the image of that mask pattern scanning across the wafer surface. Detection of strong scattering or reflection of electrons, when that image overlaps corresponding registration patterns on the wafer surface, reveals the image excursion in the wafer plane, which in turn is an accurate measure for the mask-wafer gap. An accuracy of + 1% for absolute mask-wafer gap data and - more important for application in EBP lithography - an accuracy of + 0.3% for relative mask-wafer gap variations was readily obtained over a gap range 560 μm to 1400 μm.
© (1986) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
W. Z apka, W. Haug, H. Bohlen, "Accurate Mask-To-Wafer Gap Measurements In The EBP Lithography Tool", Proc. SPIE 0565, Micron and Submicron Integrated Circuit Metrology, (2 January 1986); doi: 10.1117/12.949727; https://doi.org/10.1117/12.949727
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