Conductive atomic force microscope characterization of weak spots in irradiated ultra-thin gate oxides

The electrical conduction of fresh, electrically stressed and irradiated thin SiO2 gate oxides has been analyzed at a nanometer scale with C-AFM. Current images in irradiated oxides reveal the existence of leaky sites with a density compatible with the ion fluence during irradiation. At a more detailed analysis, one weak spot showed an electrical conduction that can be attributed to SBD. The others show a leaky behavior similar to RILC. The results demonstrate that the ions that hit the gate area during irradiation can damage the oxide in such a way that when a low field electrical stress is applied, RILC or SBD are triggered.