Nanoscale Bias-Annealing Effect in Postirradiated Thin Silicon Dioxide Films Observed by Conductive Atomic Force Microscopy

This paper investigated the reliability of thin silicon dioxide (SiO₂) subjected to irradiation followed by stress, using conductive atomic force microscopy (C-AFM). The I-V characteristics of localized spots on thin oxide films were measured before and after Co⁶⁰gamma-ray irradiation. The oxide films were then subjected to a ramped voltage stress simultaneously during the I-V measurements. By taking advantage of a small contact area, we report for the first time the nanoscale postirradiation bias-annealing effect in thin SiO₂ film using C-AFM. Based on the number of fluctuating current peaks appearing in the I-V curves of the pre- and posttreatment oxide films, as well as the calculated effective barrier height from the Fowler-Nordheim tunneling theory, we found that the trapped charge in the oxide films, but not the charge at the interface caused by Co⁶⁰gamma-ray irradiation, can be effectively annealed out by a postirradiation ramped voltage.