Generation of Compact Single-Detect Stuck-At Test Sets Targeting Unmodeled Defects

Abstract

We present a new method to generate compact stuck-at test sets that offer high defect coverage. The proposed method first selects the most effective patterns from a large N-detect pattern repository, by using a new output deviation-based metric. Then it embeds complete coverage of stuck-at faults within these patterns, and also uses the proposed metric to further improve their unmodeled defect coverage. Simulation results are presented for ISCAS and IWLS benchmark circuits by using two surrogate fault models, the transition-delay and the bridging fault model, respectively, to measure defect coverage. The results show that the proposed method provides considerably higher transition-fault coverage and coverage ramp-up compared to another recently published method with similar test length. Moreover, in all cases, the proposed method either outperforms or is as effective as the competing approach in terms of bridging-fault coverage. In many cases, higher transition-fault coverage is obtained even than much larger N-detect test sets for several values of N. Finally, our results provide the insight that, instead of using N-detect testing with as large N as possible, it is more efficient to combine the output deviations metric with multi-detect testing to get high-quality, compact test sets.