Electrical Stresses on Ultra-Thin Gate Oxide SOI MOSFETs after Irradiation

We present the first experimental data about the wear-out of a 0.1um partially depleted SOI CMOS technology after heavy ion irradiation. We show that accelerated life tests based on high electric fields yield significant differences between irradiated and non-irradiated devices, even though no or only minor changes are visible in the characteristics of the devices after irradiation. Firstly, the time to breakdown of the front gate oxide is significantly lower in the irradiated samples. The degradation kinetics of the threshold voltage and transconductance peak are strongly affected by ion strikes. In particular, a sudden shift of the threshold voltage and an acceleration in the degradation of the transconductance peak are observed upon the application of an electrical stress which have no correspondence in non-irradiated devices. An acceleration in the degradation of the parasitic back transistor is observed as well. These phenomena are interpreted in terms of latent damage left by the irradiation in the oxides that make up SOI devices