Analysis of neutron-induced single-event burnout in SiC power MOSFETs

Abstract

The triggering mechanism of single-event burnout (SEB) in SiC power MOSFETs was studied by white neutron irradiation experiments and device simulations. Electron–hole pairs generated along a recoil ion trajectory resulted in a highly localized SEB current. This dynamic current led to an increase in the electron density in the vicinity of the n−/n+ interface, which resulted in a shift in the peak electric field strength. Finally, a local short-circuit occurred between the drain and source electrodes by punch-through of the electric field in the n+ source diffusion region.A cross-sectional view of the SEB damage showed that melting of the SiC occurred and cracks were formed in the n− drift region due to the highly localized SEB current. This indicates that the maximum lattice temperature reached the sublimation temperature of SiC. The location of the simulated peak lattice temperature agreed closely with the position of the observed SEB damage. This demonstrated that the main mechanism triggering SEB in SiC power MOSFETs is not parasitic npn-transistor action, but a shift in the peak electric field and the punch-through in the n+ source diffusion region, similar to the case for SiC power diodes.