Patent ID: 8687167

Claim:
A lithographic apparatus comprising: an illumination system configured to condition a radiation beam; a support configured to support a patterning device, the patterning device being capable of imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam; a substrate table configured to hold a substrate; a projection system configured to project the patterned radiation beam onto a target portion of the substrate, an alignment apparatus configured to align the substrate according to an alignment strategy, prior to the projection of the patterned radiation beam onto a target portion of the substrate; and a scanning control module configured to control at least one of the support, substrate table, and projection system by periodically retrieving measurements that define baseline control parameters from one or more monitor wafers to determine a parameter drift from the baseline control, the one or more wafers having been initially exposed using a first alignment strategy; wherein the apparatus is configured to, when exposing a production substrate using a second alignment strategy different from the first alignment strategy, adjust a correction made for the parameter drift, thereby being substantially closer to the correction that would have been made had the second alignment strategy been used in exposure of the one or more monitor wafers; wherein the scanning control module is further configured to determine a difference between effects of the second and first alignment strategies during exposure of a substrate and to use the difference to adjust the correction.