Effect of X-ray radiation on MOSFET´s (SIMOX) LF excess noise

The behavior of hardened n-MOS and p-MOS transistors (silicon on insulator (SOI)-SIMOX technology) was investigated. These elementary components have been irradiated by X-ray radiation after an electrical characterization. In addition to such electrical parameters as the threshold voltage, the transconductance, and the leakage drain current, it is interesting to observe the channel noise level shift before and after irradiation at different doses. The particular interest of this analysis is found in the behavior of SOI-SIMOX technology transistors. This approach based on LF excess noise measurements is a new way to evaluate and understand the radiation-induced mechanisms. The major effects of ionizing radiation on MOS transistors are identified as the increase of the fixed oxide charge and of the interface state density, both mechanisms stemming from ionizing effects in the thin gate oxide. These densities control the channel current fluctuations and then the channel noise current