Abstract: The present invention relates to the activation of a software upgrade in a lithographic apparatus that transfers a pattern onto a substrate. The time and date of the activation of a software upgrade is compared with the time and date of the exposure of the first layer of a substrate or of a “lot” of substrates. If the activation date and time is later than the first exposure date and time, software-functionality types is not mixed on a single lot or substrate and the old software-functionality is used for that lot or substrate. If, on the other hand, the activation date and time of the software-functionality update is earlier than the first exposure of the lot or substrate, the lot or substrate has not yet been affected by the old software-functionality and the new, updated software-functionality may be used to control the pattern transfer onto all of the substrate layers.

Abstract: In calibration of overlay performance of an immersion lithographic apparatus, two sets of overlay data are obtained from exposures carried out using normal and reversed meanders. The two data sets can then be used to eliminate effects due to wafer cooling.

Abstract: In calibration of overlay performance of an immersion lithographic apparatus, two sets of overlay data are obtained from exposures carried out using, for example, normal and reversed meanders. The two data sets can then be used to eliminate effects due to substrate cooling.