As most of us know, PVC (passive voltage contrast) is a popular technique used to determine open or short issue on failure analysis field [1]. And SPM (scanning probe microscopy) is another powerful technique for measuring characterization of dielectric or judging gate-oxide integrity of device [2]. In this paper, a judicious and effective ratiocinating method that coupled PVC with SPM would be discussed for revealing some special invisible defect modes, which were imperceptible to observe and very difficult to identify out by means of traditional PFA skills. And two such examples, whose failure position could not be caught exactly not only for the most sensitive PVC but high-resolution current mapping of SPM, would be presented to certify the benefit and excellence of this ratiocinating method. After our experiment, to apply such ratiocinating method could provide a good thinking in profile and help to reason the fault model. Simultaneously, the specific failure mechanism and defect location could be deduced before, the conclusive PFA. Thus failure analysis turn-around time would not be wasted and yield-improving strategy could be proposed as soon as possible. So the application is successful.
