Latent reliability degradation of ultra-thin oxides after heavy ion and /spl gamma/-ray irradiation

We studied the effects of heavy ion and /spl gamma/-ray irradiation on radiation-induced leakage current (RILC) and time-dependent dielectric breakdown (TDDB) life distributions of ultra-thin oxides (<3.5 nm). Thermal annealing experiments were carried out on irradiated devices to study the nature of RILC. TDDB experiments were also performed on irradiated devices with thermal annealing. Our results show that gamma irradiation had a minimal effect on intrinsic TDDB lifetime of ultra-thin oxides. However, heavy ion irradiation induced RILC and substantially reduced the lifetime of ultra-thin oxide films. Thermal annealing experiments suggests that RILC is due to trapped holes. Removal of RILC (and holes) do not improve TDDB lifetime.