Various methods and systems for detection of selected defects particularly
in relatively noisy inspection data are provided. One method includes
applying a spatial filter algorithm to raw inspection data acquired
across an area on a substrate to determine a first portion of the raw
inspection data that has a higher probability of being a selected type of
defect than a second portion of the raw inspection data. The selected
type of defect includes a non-point defect. The method also includes
generating a raw two-dimensional map illustrating the first portion of
the raw inspection data. In addition, the method includes searching the
raw two-dimensional map for an event that has spatial characteristics
that approximately match spatial characteristics of the selected type of
defect. The method further includes determining if the event corresponds
to a defect having the selected type.