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

This study is related to the behaviour of hardened n-MOS and p-MOS transistors (SOI-SIMOX technology). These elementary components have been irradiated by X-ray radiation after an electrical characterization. In addition to the electrical parameters such as the threshold voltage V/sub t/, the transconductance g/sub m/ and the leakage drain current I/sub df0/, it appears 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 behaviour of SOI-SIMOX technology transistors. This approach, on the basis of 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). Of course, these densities control the channel current fluctuations and then the channel noise current.<
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