Single event burnout of SiC MOSFET induced by atmospheric neutrons

Abstract

The mechanisms responsible for atmospheric neutron induced single event burnout (SEB) in commercial silicon carbide (SiC) power MOSFETs were investigated and analyzed. Firstly, based on the atmospheric neutron irradiation spectrometer (ANIS) at the China spallation neutron source (CSNS), accelerated neutron irradiation experiments were carried out to evaluate the dependence of the sensitivity of atmospheric neutrons induced SEB on the drain bias voltage (VDS) in SiC MOSFET. Secondly, microscopic detection and analysis of the burned-out devices were performed at the wafer level by combining microscopy, focused ion beam (FIB) and scanning electron microscope (SEM) to reveal SEB mechanisms inside the semiconductor device. Locally melted morphologies were observed both in the source contact and in the deeper SiC device. Since the melting point of the contact metal is much lower than that of SiC, it is the region where the burnout occurs initially, followed by the vicinity of the n−-drift/n+-drain interface. In addition, combined with the Geant4 calculation and TCAD simulation, the spatiotemporal evolution of the internal electric field and the maximum lattice temperature inside the device after ion incidence were simulated and analyzed. Results show that the strong impact ionization of the carriers induced by the local electric field causes a large amount of energy dissipation in a short time, which eventually leads to thermal damage to the device.