Study of the spatial distribution of breakdown spots in MOS devices in case of important edge effect anomalies

The breakdown spots spatial distribution in metal gate/high-K/III-V semiconductor capacitors caused by severe electrical stress is investigated. The spots appear as a random point pattern on the top electrode and are the consequence of important thermal effects occurring at the very moment of the formation of filamentary leakage current paths across the gate oxide stack. The damage is permanent, easily detectable without any image or sample treatment and accumulates with the application of successive stresses. It is shown using spatial statistics techniques that despite the distribution of spots is anomalous in the periphery of the devices, they follow a Poisson process within the structure far from the edges.