ASML Holding N.V.
Lithographic method and lithographic apparatus

Abstract:

A method includes exposing number of fields on a substrate, obtaining data about a field and correcting exposure of the field in subsequent exposures. The method includes defining one or more sub-fields of the field based on the obtained data. Data relating to each sub-field is processed to produce sub-field correction information. A subsequent exposure of the one or more sub-fields is corrected using the sub-field correction information. By controlling a lithographic apparatus by reference to data of a particular sub-field within a field, overlay error can be reduced or minimized for a critical feature, rather than being averaged over the whole field. By controlling a lithographic apparatus with reference to a sub-field rather than only the whole field, a residual error can be reduced in each sub-field.