Total-dose characterization of CMOS/SOI-ZMR technology

The authors present the total dose radiation characterization of an unhardened SOI (silicon on insulator)/ZMR technology of CNET/CNS (Centre National d´Etudes des Telecommunications). Various bias conditions are applied to the front gate oxide and buried oxide during gamma irradiation in order to define the worst and best case configurations for different devices: transistors, capacitors, and ring oscillators. The authors compare the radiation responses of transistors with different structures to allow clear separation of device conduction on top channel, back channel, and edge channel along the sidewalls of the island. The MOS structure with body contact shows improved subthreshold characteristics before and after dose radiation. A good correlation is observed between n-substrate capacitor and p-channel transistors irradiated at -5-V back-gate bias. Radiation-induced kink effects are observed on PMOS transistors for a positive back-gate bias (+5 V) during irradiation. The observed phenomena have been confirmed by the 2-D numerical device simulator TITAN. Satisfactory total dose response of a ring oscillator is obtained. The results obtained highlight the potential of unhardened SOI-ZMR technology for radiation-tolerant device applications (D⩽100 krad)