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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Semiconducting wafers
Overlay metrology
Lithography
Distortion
Data modeling
Scanners
Interferometry