Various computer-implemented methods are provided. One method for sorting
defects in a design pattern of a reticle includes searching for defects
of interest in inspection data using priority information associated with
individual defects in combination with one or more characteristics of a
region proximate the individual defects. The priority information
corresponds to modulation levels associated with the individual defects.
The inspection data is generated by comparing images of the reticle
generated for different values of a lithographic variable. The images
include at least one reference image and at least one modulated image. A
composite reference image can be generated from two or more reference
images. The method also includes assigning one or more identifiers to the
defects of interest. The identifier(s) may include, for example, a defect
classification and/or an indicator identifying if the defects of interest
are to be used for further processing.