SPICE Models of Fluorine-Ion-Irradiated CMOS Devices

CMOS image sensors are attractive for space applications due to their low-power and system-on-chip features. The typical active pixel sensor (APS) is composed of a photodiode and several transistors. Using Fluorine +7 ions with an energy of 17 MeV, the effects of radiation are investigated on photodiodes and transistors manufactured using a standard 0.35-mum CMOS process. Simulation results show that the range of these ions overlaps with the active region of the device. Thus, the proximity effect of the ions on the performance of the device can be important. The tested photodiode showed a leakage current increase after it was irradiated with fluorine ions. The ideality factor of recombination current is observed to increase up to 4. Moreover, an increase in leakage current and absolute threshold voltage was observed in fluorine-ion-irradiated nMOS and pMOS transistors. In this paper, behavioral SPICE models are developed to analyze the contribution of these components to an overall increase in dark current of a CMOS APS.