ASML Holding N.V.
Method for estimating overlay

Abstract:

The present invention provides a method for determining overlay. The method comprises obtaining an initial overlay estimate relating to a first set of targets and data about a second set of targets, wherein the data for a target comprises an intensity measurement of the target for each of a group of different wavelengths. The method further comprises using the initial overlay estimate to filter data relating to the second set of targets and using the filtered data to estimate overlay on the substrate.