4 August 1993 Evaluation of the error in automatic measurement of interlevel alignment
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Abstract
As device densities continue to increase, lithographic requirements will continue to expand through the 90's. Although progress is being made in the resolution requirements in the 0.5 micron regime, resolution is not the only critical issue in submicron lithography. Interlevel alignment, or overlay registration, is also an area of vital concern. Various optical instruments are currently available to automatically determine interlevel alignment of photomask layers in integrated circuit manufacturing. It will be shown that the accuracy of those alignment instruments that use an optical column can be affected by mark design and the magnification in the optical column. The mathematical relationship between the alignment structure layout and the magnification of the optical system, and the resulting error is developed. Experimental data is then taken and found to agree with the mathematical prediction. From the mathematical relationship, an optimum structure layout is determined.
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David C. Watkins, David C. Watkins, Lowell M. Bramer, Lowell M. Bramer, } "Evaluation of the error in automatic measurement of interlevel alignment", Proc. SPIE 1926, Integrated Circuit Metrology, Inspection, and Process Control VII, (4 August 1993); doi: 10.1117/12.148960; https://doi.org/10.1117/12.148960
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