1 February 1991 Submicrometer lithographic alignment and overlay strategies
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Inter-mask-level alignment and overlay measurements are becoming more challenging as new generations of lithography progress to critical dimensions well below a micrometer. Registration requirements are typically a small fraction (. 20%) of the critical dimension. Despite the importance of alignment to the realization of future generations of lithography, relatively little effort has been expended in contrast to the large body of work on new source and photoresist technologies. Moire techniques are shown to be an effective technique for alignment and overlay registration to well below a micrometer. Initial experiments are presented for several promising moire metrology techniques which are shown to be sufficiently precise to resolve two gratings with periods differing by less than 0.1 nm. A high-resolution Si-based optical position sensor, which relies on electronic transport mechanisms, rather than optical phase information, is also discussed in the context of submicrometer alignment.
© (1991) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Saleem H. Zaidi, Saleem H. Zaidi, S. Sohail H. Naqvi, S. Sohail H. Naqvi, Steven R. J. Brueck, Steven R. J. Brueck, } "Submicrometer lithographic alignment and overlay strategies", Proc. SPIE 1343, X-Ray/EUV Optics for Astronomy, Microscopy, Polarimetry, and Projection Lithography, (1 February 1991); doi: 10.1117/12.23197; https://doi.org/10.1117/12.23197

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