Patent Document ID: 20130054186
Application ID: 13570765
Patent Flag: 0

Claim One:
1. A method of determining an overlay error comprising: measuring scattering properties of a first target comprising a first structure and a second structure; constructing a model of the first structure using the measured scattering properties, the model comprising a first model structure corresponding to the first structure; modifying the model by overlaying the first model structure with an intermediate model structure; calculating a first defect-induced overlay error between the first model structure and the intermediate model structure in the modified model; further modifying the model by replacing the intermediate model structure with a second model structure, corresponding to the second structure; calculating a second defect-induced overlay error between the first model structure and the second model structure, the first and second model structures being overlaid with respect to each other in the further modified model; and determining an overlay error in a second target using the calculated second defect-induced overlay error.