Unipolar recovery of dielectric breakdown in fully silicided high- κ gate stack devices and its reliability implications

We report observations of unipolar recovery of dielectric breakdown in fully silicided NiSi-gate HfSiON- SiO_x bilayer dielectric based high- κ metal-insulator-semiconductor (MIS) gate stack, analogous to resistive switching in metal-insulator-metal (MIM) nonvolatile memory devices. The dependence of the recovery voltage on breakdown hardness and filament location is analyzed and the physics behind MIS recovery, governed by joule heating induced oxygen vacancy trap passivation, is explained using failure analysis and statistical investigations. The observed MIS recovery phenomenon can be a tool to design for reliability in novel metal gate high- κ gate stacks.