Disclosed is a method of inspecting a sample. The sample is scanned in a
first direction with at least one particle beam. The sample is scanned in
a second direction with at least one particle beam. The second direction
is at an angle to the first direction. The number of defects per an area
of the sample are found as a result of the first scan, and the position
of one or more of the found defects is determined from the second scan.
In a specific embodiment, the sample includes a test structure having a
plurality of test elements thereon. A first portion of the test elements
is exposed to the beam during the first scan to identify test elements
having defects, and a second portion of the test elements is exposed
during the second scan to isolate and characterize the defect.