Testing Resistive Opens and Bridging Faults Through Pulse Propagation

This paper addresses the problems related to resistive opens and bridging faults that lie out of the most critical paths. These faults cannot be detected by traditional delay fault testing because the induced delay defects are not large enough to result in timing violations when the test rate is equal to the nominal operating frequency. In spite of this problem, resistive opens and bridgings should be detected because they may give rise to reliability problems. To detect them, we propose a testing method that is based on the propagation of pulses within the faulty circuit and that exploits the degraded capability of faulty paths to propagate pulses. The effectiveness of our method is analyzed at the transistor level and compared with the use of reduced clock periods to detect the same class of faults. Results show similar performance in the case of resistive opens and better performance in the case of bridgings. Moreover, the proposed approach is not affected by possible problems in the clock distribution.