Observation Point Placement for Improved Logic Diagnosis based on Large Sets of Candidate Faults

Abstract

Multiple defects are prevalent in early stages of yield improvement for a new technology. When a logic diagnosis procedure is applied to a faulty unit that contains a multiple defect, it sometimes produces a large set of candidate faults. Such a set includes extra candidates that do not match the defect present in the faulty unit. An earlier study indicates that a logic diagnosis procedure may prefer certain faults as candidate faults, causing them to appear as extra candidates in many sets of candidate faults. This points to the possibility of using a small number of observation points to eliminate extra candidates that appear often. This paper takes advantage of this observation to improve the quality of diagnosis by placing observation points. Experimental results for benchmark circuits demonstrate the effectiveness of observation points in reducing large sets of candidate faults.