Patent ID: 8504333

Claim:
A device manufacturing method, comprising: performing a first process of a lithographic process to a substrate; providing a representation of a model of a variation of a plurality of properties of the substrate across the substrate wherein providing the representation of the model of variation comprises: identifying a plurality of available sample positions on the substrate for measurement of the plurality of properties of the substrate; defining an initial representation of the model of a variation of the plurality of properties of the substrate across the substrate, wherein the initial representation of the model of variation is configured to represent the variation of the plurality of properties of the substrate across the substrate when provided with measurements of the plurality of properties of the substrate at the available sample positions on the substrate; analyzing the initial representation of the model of variation in order to determine the samples positions of the available sample positions having greater effect on the model of variation, wherein analyzing comprises: ranking the available sample positions at least based on the effect of the measurements from each of the available sample positions on the model of the variation; selecting, from the available sample positions, a subset of sample positions that are identified in the analysis of the initial representation of the model as having greatest effect on the model; defining a revised representation of the model of the variation of the plurality of properties of the substrate across the substrate, wherein the revised representation of the model is configured to represent the variation of the plurality of properties of the substrate across the substrate when provided with measurements of the plurality of properties of the substrate at the subset of sample positions; and performing a second process of a lithographic process to a substrate, wherein the performance of the second process is controlled using the revised representation of the model of variation.