Irradiation response of mobile protons in buried SiO2 films

We have performed current-voltage, capacitance-voltage and electron-paramagnetic-resonance (EPR) characterization of silicon-on-insulator (SOI) samples, subjected to a wide variety of irradiation and anneal treatments. By comparing transport properties and interfacial reaction mechanisms, we provide evidence for an intrinsic difference in the response of mobile protons in these oxides, depending on whether they are generated by irradiation or by H₂ annealing. A radiation effects study of SOI buried oxides containing annealing induced mobile protons is presented to gain insight into the mechanisms behind these fundamental differences. Electrical characterization shows that, for these devices, the initial interface trap and mobile proton densities are largely unaffected by the irradiation. However, if the irradiation is carried out in the presence of positive bias applied to the top Si, the protons become trapped in shallow levels. These proton traps are activated by the irradiation and are located near the oxide/substrate interface. These results may lead to improved radiation hardness of buried oxides for nonvolatile memory and other applications