This study is a joint investigation in a high-volume manufacturing environment of the portion of overlay associated with displacement induced by a single process across many chambers. Displacement measurements are measured by Coherent Gradient Sensing (CGS) interferometry, which generates high-density displacement maps (>3 million points on a 300 mm wafer) such that the stresses induced die-by-die and process-by-process can be tracked in detail. The results indicate the relationship between displacement and overlay shows the ability to forecast overlay values before the lithographic process. Details of the correlation including overlay/displacement range, and lot-to-lot displacement variability are considered.
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Jeffrey Mileham, Yasushi Tanaka, Doug Anberg, David M. Owen, Byoung-Ho Lee, Eric Bouche, "Study of correlation between overlay and displacement measured by Coherent Gradient Sensing (CGS) interferometry," Proc. SPIE 9778, Metrology, Inspection, and Process Control for Microlithography XXX, 97782W (24 March 2016);