Hazard Initialized LOC Tests for TDF Undetectable CMOS Open Defects

Hazards have been known to have the potential to invalidate tests for stuck-open faults in CMOS circuits. In this paper we show that hazards can also predictably allow the detection of stuck-open faults that may be undetectable by traditional TDF launch-on-capture (LOC) scan delay tests. Importantly, the detected open faults are not redundant, and can in fact be activated in normal functional operation leading to functional errors. We identify such defects in benchmark circuits and present a LOC test selection method capable of predictably detecting the open defects through initialization by a hazard.