Observation of latent reliability degradation in ultrathin oxides after heavy-ion irradiation

Constant voltage time-dependent-dielectric-breakdown distributions were obtained for both unirradiated and irradiated 3.0 and 3.2 nm thick SiO2 films subjected to Co-60 gamma irradiation and heavy ions of 823 MeV Xe-129 (linear energy transfer=59 MeV-cm(2)/mg). The gamma irradiation had no effect on oxide lifetime. The heavy ion irradiation substantially reduced oxide life even though the devices were biased at 0.0 V during irradiation. The reduction of oxide lifetime under constant-voltage stress conditions was a strong function of the heavy ion fluence. (C) 2002 American Institute of Physics.