Definition
Overlay is the positional accuracy with which a newly patterned semiconductor layer is placed relative to a previous layer or existing wafer features.
Application
Controlled during DUV and EUV lithography to align successive device layers, support scanner matching, and reduce yield loss from layer-placement error.
Related concepts
Evidence and further reading
- Evidence from asml.comhttps://www.asml.com/en/products/duv-lithography-systems/twinscan-nxt-2150i
- Evidence from asml.comhttps://www.asml.com/en/products/duv-lithography-systems/twinscan-nxt2100i