Comparison of 14-MeV Neutron-Induced Damage in Si and SiC Power MOSFETs

The comparison of the single event burnout (SEB) performance between 900-V Si and silicon carbide (SiC) MOSFETs is conducted using 14-MeV neutron irradiation. A SEB is observed for the Si MOSFET biased at 83% of the rated voltage, while no SEB occurs for the SiC MOSFET biased at 94% of the rated voltage. For the 900-V class power MOSFET, the planar SiC device seems more SEB hardened than the Si planar super-junction device. The linear energy transfer (LET) values and ranges of the secondary ions produced by the nuclear reaction of 14-MeV neutrons are obtained for Si and SiC devices. The maximum LET value of the secondary ions induced by 14-MeV neutrons can reach 9.85 MeV $\cdot $ cm2/mg in the SiC device, which is high enough to induce SEB according to the previous heavy ion irradiation data. The mechanisms by which relatively low-energy neutrons are unable to induce SEB are related to the low range of the secondary ions. Most of the secondary ions have a range of less than $3~\mu $ m. It is interesting to note that the SEB damages caused by 14-MeV neutrons in Si devices are located in the transition region between the cell area and the gate pad, which means that this region is more sensitive to SEB than the cell region for super-junction Si MOSFETs. This is verified by the TCAD simulation.