Degradation in super-junction MOSFET under successive exposure of heavy ion strike and gamma ray irradiation

Abstract

The degradation of 200 V super-junction MOSFET under successive exposure of heavy ion strike and gamma ray irradiation is investigated for the first time in this paper. Compared with the device purely irradiated with gamma ray, the MOSFET subjected to superimposed irradiation stress, e.g. irradiated with heavy ion strike first and then irradiated with gamma ray, exhibits more serious deterioration in static characteristics, such as threshold voltage and transconductance. Moreover, the devices under superimposed irradiation stress exhibits very different dynamic characteristics, such as more obviously increased gate charges and improved reverse recovery. In addition, the degradation mentioned above caused by the extra oxide traps and interface strain bonds generated by heavy ion strike can be attenuated with applying negative gate voltage bias during the whole experiments, which provides a solution to avoid this potential threat in aerospace application.