Correction of overlay offset between inspection layers in integrated circuits

The present invention relates to the manufacturing of integrated circuits. More specifically, the present invention relates to identifying defects in integrated circuits being manufactured on a wafer. A first method for determining the offset between the origins of the coordinate systems used for inspection of at least two different defect inspections of a wafer with integrated circuits disposed on it, comprises creating a database containing location data for defects disposed on at least two inspection layers of an integrated circuit wafer; defining maximum offsets for interlayer defects; defining minimum spacings for intralayer defects; for all defects having spacings larger than the minimum spacings searching the database for interlayer defect pairs having offsets smaller than the maximum offsets; calculating an actual offset for each interlayer defect pair; determining whether the actual offsets are randomly distributed; identifying dense zones for the actual offsets if they are not randomly distributed; and developing an estimate of the offset between the origins of the at least two layers and a confidence value for the estimate for said actual offsets. A second method comprises identifying from the database at least one die having a number of defects nd wherein 0 nd k where k is an integer less than or equal to 5, identifying all interlayer defect pairs on the at least one die, and calculating an actual offset for each interlayer defect pair in place of defining maximum offsets for interlayer defects and defining minimum spacings for intralayer defects.