Failure analysis of complicated case by functional OBIRCH method

There are many kinds of failure mode in failure analysis (FA). Some is simple and some is complicated to analyze. During analysis period, if an abnormal leakage current path is found, OBIRCH can be used to analyze the current path and find the defect location which induces the leakage current. But sometimes, the failure mode is very complicated. We cannot get the leakage current by measure IV-Curves at static state. In this situation, due to leakage current cannot be found at static state, basic operating of OBIRCH is not enough for analysis. We must try to find a setup condition which can reveal the leakage current path, and OBIRCH can be used base on the setup condition to find the defect location. The above is functional OBIRCH method. In this paper, a real case is shared. This case is analyzed by functional OBIRCH method, an abnormal hot spot is observed at a MOSFET and physical analysis finally found Gate Oxide Rupture (GOX) at the hot spot location.