Power metallization degradation monitoring on power MOSFETs by means of concurrent degradation processes

An on-chip solution for health monitoring of semiconductor power switches subjected to thermo-mechanical metal fatigue degradation is proposed. The fatigue detection relies on the correlation between the progress of the main failure mechanism, which is critical to the functionality of the device, and a parallel degradation of a non-critical sensing structure using a different mechanism. Both mechanisms are driven by the same cyclic thermo-mechanical load. This study specifically develops a sensing structure for detecting power metallization aging through electrically detectable ratcheting behavior in the routing metal layer underneath. Experiments have been carried out on a dedicated test structure with electrical sensing of the health monitoring structure. Meanwhile, the main degradation progress was observed via scanning electron microscopy in regular intervals. Results show that the proposed approach will reliably work only for detecting degradation driven by repeated high overload events.