Patent ID: 7280200

Claim:
A system for inspecting an edge of a semiconductor wafer, comprising: a light source configured to project at least one first beam of light at a predetermined angle relative to a surface of the semiconductor wafer, the first light beam being projected to scan at least a portion of the wafer edge, thereby producing at least one second beam of light reflected from the wafer edge; a light detector configured to detect the second light beam reflected from the wafer edge; and a processor operative: to convert the detected second light beam to actual edge data representative of the scanned wafer edge portion, the scanned wafer edge portion having radial and tangential dimensions, the actual edge data includin actual edge datum points disposed in the radial dimension and actual edge datum points disposed in the tangential dimension; to determine at least one radial threshold for use in at least one comparison of nearest neighboring datum points disposed in the radial dimension of the scanned wafer edge portion; to deternine at least one tangential threshold for use in at least one comparison of nearest neighboring datum points disposed in the tangential dimension of the scanned wafer edge portion; to compare at least two nearest neighboring datum points disposed in the radial dimens ion to obtain first nearest neighbor comparison data, and to compare the first nearest neighbor comparison data to the at least one radial threshold to detect the wafer edge; to compare at least two nearest neighboring datum points disposed in the tangential dimension to obtain second nearest neighbor comparison data, and to compare the second nearest neighbor comparison data to the at least one tangential threshold; and in the event the second nearest neighbor comparison data exceeds the at least one tangential threshold, to designate the at least two nearest neighboring datum points disposed in the tangential dimension as corresponding to a wafer edge defect.