Application of a new MOS-transistor model to total dose radiation effects in CMOS-devices

Electrical properties of irradiated MOS-devices are investigated experimentally and analysed by the use of a new model for the IV-characteristics of a MOS-transistor. In addition to the established effects, hole trapping and formation of interface states, it was observed, by measuring electrical properties of the bipolar configurations included in the MOS-structures, that minority carrier traps are created in the bulk or transition regions. According to the new model, the radiation induced decrease of the subthreshold slope is mainly caused by the latter effect while the interface states causes a bend or a knee on the subthreshold slope. The latter property was predominant in a second MOS-technology investigated. The new model also predicts the radiation induced decrease of the transistor constant as well as the substrate bias properties. The minority carrier traps may occur in n-channel as well as p-channel devices and influences the subthreshold slopes and transistor constants in the same way in both kind of devices