Functional OBIRCH strategy in analyzing complex functional failures including logic failures

OBIRCH (Optical Beam Induced Resistance Change) analysis was usually used to analyze direct leakage or short failure. But when met complex functional failures, we only know the leakage existed and higher current was consumed, but we couldn´t confirm the leakage path or which device was the main failed one. An efficient method was presented by performing OBIRCH analysis in function mode with different kinds of setup condition to trace the abnormal current. It could detect the current path and indicate the failed device directly without much microprobe work. It was also helpful in analyzing the logic failures without test pattern.