Correlating SEM and optical images for wafer noise nuisance identification

A high-resolution inspector system for inspecting a semiconductor sample, comprising at least one processor and memory that are operable for performing the following operations:

• providing a plurality of locations corresponding to a plurality of candidate defect events on a semiconductor sample from an optical inspector operable to acquire a plurality of acquired optical images from which such candidate defect events are detected at their corresponding locations across the sample;
• acquiring high-resolution images of the plurality of candidate defect events at their corresponding locations on the sample;
• correlating each of a first set of modelled optical images, which have been modeled from a first subset of the acquired high-resolution images, with a corresponding one of a first set of the acquired optical images, to identify a plurality of surface noise events, as shown in the first set of high-resolution images, as sources for the corresponding candidate defect events in the first set of acquired optical images, wherein the correlating of each of the first set of modelled optical images results in identification of the surface noise events as sources if the corresponding modelled and acquired optical images are substantially identical;
• and
• correlating each of a second set of modelled optical images, which have been modeled from a second subset of the acquired high-resolution images, with a corresponding one of a second set of the acquired optical images so that noise events are not identified as sources and, instead, subsurface events are identified as sources for the corresponding candidate defect events in the second set of acquired optical images.