Effects of ionizing radiation on n-channel MOSFET´s fabricated in zone-melting-recrystallized Si films on SiO2

We have investigated the effects of irradiation with 1.5 MeV electrons on the electrical characteristics of n-channel MOSFET´s fabricated in zone-melting-recrystallized Si films on SiO2-coated Si substrates. With a -15 V bias applied to the Si substrate during irradiation and device operation, the subthreshold leakage current remains below 0.2 pA/µm (channel width) for ionizing doses up to 10⁶rad(Si). The negative substrate bias also reduces the shift of threshold voltage to less than 0.3 V for devices with 50 nm-thick gate oxide.