On the effect of defect clustering on test transparency and IC test optimization

We recently proposed a wafer-based testing approach which for the first time employs defect clustering information on the wafer to optimize test cost and defect levels in the shipped product. Preliminary analysis 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 correspondence, we study the effect of clustering and test transparency on defect distributions in individual dice, and its impact on the fault detection capabilities of a given test set. We show here that significant defect-level improvements in the shipped product can indeed be achieved by exploiting defect clustering in optimization testing