Patent ID: 7975245

Claim:
A computer-implemented method for determining if actual defects are potentially systematic defects or potentially random defects, comprising: comparing a number of actual defects in a group to a number of randomly generated defects in a group, wherein the actual defects are detected on a wafer, and wherein a portion of a design on the wafer proximate a location of each of the actual defects in the group and each of the randomly generated defects in the group is substantially the same; and determining if the actual defects in the group are potentially systematic defects or potentially random defects based on results of said comparing, wherein said determining comprises determining that the actual defects in the group are potentially systematic defects if the number of the actual defects in the group is greater than the number of the randomly generated defects in the group and determining that the actual defects in the group are potentially random defects if the number of the actual defects in the group is not greater than the number of the randomly generated defects in the group, and wherein said comparing and said determining are performed using a computer system.