Effect of grade doping buffer layer on SEE failure in VDMOSFET

Single event burnout (SEB) is a common single event effect (SEE) occur in VDMOSFET, previous studies have indicated the strong relationship between the device's secondary breakdown voltage and the SEB threshold voltage. This paper presents a grade doping buffer layer structure to improve the device's secondary breakdown voltage so that enhance the resistance to SEE. Through detailed simulation, it has been verified that optimized grade doping buffer layer can decrease the peak value of the electric field, significantly improve the parasitic bipolar turn-on current and the SEB threshold voltage. Moreover, compared to non-buffer layer and constant doping buffer layer structure, the optimized grade doping buffer structure is a more effective structure in SEE hardened VDMOSFET.