14 September 2001 Optimal lens assignment through measured aberrations
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The effect of aberrations on process window optimization is investigated for typical memory patterns. A possibility of change of optimum NA and sigma by aberration level of lens is demonstrated. In order to extend low k1 imaging up to production line, customized lens and layer arrangement is suggested based on process latitude calculation with measured lens aberration. In-situ interferometer (ISI) was used for aberration measurement, of which the measurement accuracy was confirmed by comparison with Phase Measuring Interferometer (PMI). CD distribution of two critical layers of typical SRAM and DRAM patterns for required process latitudes of device patterns, depth of focus and dose latitude, were investigated and aberrations of DUV steppers and scanners were measured and used for calculation. In order to minimize aberration induced patterning errors, ranking of tools based on error calculation with measured aberration and customizations of NA and illumination settings for given device patterns were performed. Also, layout optimization for low aberration sensitivity was performed.
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Nakgeuon Seong, Nakgeuon Seong, Young S. Kang, Young S. Kang, Hanku Cho, Hanku Cho, Joo-Tae Moon, Joo-Tae Moon, } "Optimal lens assignment through measured aberrations", Proc. SPIE 4346, Optical Microlithography XIV, (14 September 2001); doi: 10.1117/12.435630; https://doi.org/10.1117/12.435630

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