A CMOS fault extractor for inductive fault analysis

The inductive fault analysis (IFA) method is presented and a description is given of the CMOS fault extraction program FXT. The IFA philosophy is to consider the causes of faults (manufacturing defects) and then simulate these causes to find the faults that are likely to occur in a circuit. FXT automates IFA for a CMOS technology by generating a list of faults that are likely to occur in a CMOS circuit. The realistic faults generated by FXT are used to evaluate fault models, find the realistic fault coverage of test sets, and guide future testing research. How well various fault models characterize the realistic faults can be quantitatively measured because FXT's fault list includes the relative likelihood of occurrence (weight) of each extracted fault. The value of IFA and FXT is demonstrated by the analysis of five commercial CMOS circuits. This analysis shows that the traditional SSA fault model characterizes fewer than half of the faults extracted by FXT; graph-theoretic techniques provide little improvement in the percentage of realistic faults modeled.>