Novel overlay correction by synchronizing scan speed to intra-die fingerprint on lithography scanner

Abstract

Intra-die overlay is becoming one of the key challenges in high accuracy overlay. While recent progress of overlay metrology has made it viable to monitor intra-die overlay signature by nondestructive methods, traditional intra-field correction does not work well enough to reduce intra-die overlay error of lithography process. In this paper, we demonstrated for the first time that the intra-die overlay correction does work by synchronizing scan speed to intra-die fingerprint and this method is actually applicable to treat both lot-to-lot and intra-wafer variation of intra-die overlay.