Alberto Lopez-Gomez,1 Stefan Buhl,1 Eric Jehnes,1 Patrick Lomtscher,1 Manuela Gutsch,1 Xaver Thrun,1 Clemens Utzny,1 Philip Groeger,1 Johannes Kowalewski1
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The semiconductor industry has been largely using the mean+3sigma overlay dispositioning metric for over 20 years now. As technology shrink progresses, this metric does not represent the most accurate overlay condition on the wafer. The continuous usage of the traditional metric leads to non-optimal rework decisions and potential yield loss in high-volume manufacturing (HVM). We propose an alternative overlay dispositioning metric that reduces rework without compromising accuracy or sampling. The proposed metric is called ‘number-of-dies-within-spec’. It is obtained by first evaluating the overlay model on a dense grid, followed by comparing the grid values against the spec limits. Based on that, each die can be evaluated, and dies below the spec are counted to obtain the wafer key performance indicator (KPI) “number-of-dies-within-spec”. This paper shows the rework gain for two layers when using our proposed metric against the traditional mean+3sigma dispositioning.
(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.
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Alberto Lopez-Gomez, Stefan Buhl, Eric Jehnes, Patrick Lomtscher, Manuela Gutsch, Xaver Thrun, Clemens Utzny, Philip Groeger, Johannes Kowalewski, "An alternative to M+3S overlay dispositioning metric: number-of-dies-within-spec," Proc. SPIE 12955, Metrology, Inspection, and Process Control XXXVIII, 129553T (9 April 2024); https://doi.org/10.1117/12.3022117