ON THE EFFECT OF DEFECT CLUSTERING ON TEST TRANSPARENCY AND IC TEST OPTIMIZATION

We recently proposed a wafer-based testing approach which for the firs t time employs defect clustering information on the wafer to optimize test cost and defect levels in the shipped product. Preliminary analys is of this approach had implicitly assumed that the probability that a test detects a faulty circuit is independent of the number of faults in that circuit. This assumption may be optimistic. In this correspond ence, we study the effect of clustering and test transparency on defec t distributions in individual dice, and its impact on the fault detect ion capabilities of a given test set. We show here that significant de fect-level improvements in the shipped product can indeed be achieved by exploiting defect clustering in optimization testing.