It is difficult to localize the soft defect on analog and mixed-signal ICs only by OBIRCH, because OBIRCH laser scanning module could not synchronize with the IC under functional test, and the failure modes on analog and mixed-signal ICs are complicated. In this paper, a dynamic synchronization method is proposed to localize the soft defect precisely only with an OBIRCH tool on analog and mixed-signal ICs. The methodology and system configuration are presented. A case is studied successfully on an analog and mixed-signal IC using this method.

As semiconductor technology continues to advance to smaller dimensions and more complex circuit designs, it is becoming more challenging to locate the resistive short directly between two metal lines (signals) due to a metal bridge defect. Especially these two metal lines are very long and relevant to many functional modules. After studying the failed circuit model, we found there should be a tiny leakage between one of the bridged signals and one of common power signals (such as VDD and GND) on a failed IC compared with the reference one, if there is a metal bridge defect between these two bridged signals. The tiny leakage between one of the bridged signals and one of power signals is an indirect leakage that is a mapping of the direct resistive short between these two bridged signals. The metal bridge defect could be pinpointed with the tiny leakage between one of the bridged signals and one of power signals by Lock-in IR-OBIRCH. It is an easier and faster way to locate the metal bridge defects. In this paper, the basic and simple circuit model with a metal bridge defect will be presented and two cases will be studied to demonstrate how to localize a metal bridge defect by the tiny leakage between one of the bridged signals and one of power signals.

Lock-in IR-OBIRCH analysis, as a kind of static thermal laser stimulation (S-TLS) technique, is very effective to isolate a fault for the parametric failure cases. However, its capability is limited to localize a defect when the IC is operated under a defined operating condition. Whereas the dynamic thermal laser stimulation (D-TLS) technique is good at locating a fault while the IC is operated under some functions to activate the failure. In this paper, a novel method is presented to realize DTLS just by Lock-in IR-OBIRCH assisted with a Current Detection Probe Head. Two cases are studied to demonstrate the effectiveness of this method.