Changing technology requirements of mask metrology

Upcoming semiconductor technology nodes will still be based on optical lithography by ArF water immersion technology because there are still too many open issues preventing extreme ultraviolet (EUV) lithography from being introduced into high volume production. Several kinds of multi-patterning technology are considered to overcome the optical resolution issue by 193nm high NA illumination and still achieve <32nm half-pitch. Mask registration metrology must be adapted to provide useful and comprehensive data on the mask contribution to wafer overlay.