A Novel Multiple Layers Overlay Run-to-Run Control Using New Algorithm Metrics for Logic Process

For On-Product Overlay (OPO) control in high volume manufacturing, process induced variations such as lot-to-lot (L2L) have been a continuous challenge. We have demonstrated the use of Feedforward control to improve L2L variation in our previous study. In this paper, we investigated a novel run-to-run control strategy to split X and Y overlay controls using different control methods respectively. Depending on the intrinsic character of overlay and alignment tree, Feedforward control is applicable and beneficial to either single overlay direction or both directions but from different pre-layers. Accordingly, the automation design of supporting different control strategy for an individual layer using ASML Litho InSight product is demonstrated.