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13 March 2018 Higher order intra-field alignment for intra-wafer lens and reticle heating control
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Before each wafer exposure, the photo lithography scanner’s alignment system measures alignment marks to correct for placement errors and wafer deformation. To minimize throughput impact, the number of alignment measurements is limited. Usually, the wafer alignment does not correct for intrafield effects. However, after calibration of lens and reticle heating, residual heating effects remain. A set of wafers is exposed with special reticles containing many alignment marks, enabling intra-field alignment. Reticles with a dense alignment layout have been used, with different defined intra-field bias. In addition, overlay simulations are performed with dedicated higher order intra-field overlay models to compensate for wafer-to-wafer and across-wafer heating.
© (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Charlie Chen, En-Chuan Lio, Hsiao Lin Hsu, Jia Hung Chang, Sho Shen Lee, Patrick Lomtscher, Boris Habets, Georg Erley, Norman Birnstein, Steven Tottewitz, and Rex Liu "Higher order intra-field alignment for intra-wafer lens and reticle heating control", Proc. SPIE 10585, Metrology, Inspection, and Process Control for Microlithography XXXII, 105851R (13 March 2018);

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