Patent ID: 7415386

Claim:
A method for analyzing a sample of wafers, comprising the steps of: (a) identifying F failure metrics that are applicable to at least one circuit pattern on each wafer within the sample of wafers, where F is an integer; (b) identifying Z spatial and/or reticle zones on each wafer, where Z is an integer; (c) providing values for each of the F failure metrics, for each of the Z zones on each wafer; (d) defining a point for each respective wafer in an N-dimensional space, where N=F*Z, and each point has coordinates corresponding to values of the F failure metrics in each of the Z zones of the corresponding wafer; and (e) clustering the sample of wafers into a plurality of clusters of wafers using a computer, so that the wafers within each cluster are close to each other in the N-dimensional space, thereby identifying the plurality of clusters of wafers from the sample of wafers so that within each individual cluster, the wafers have a similar distribution of defects.