Cosmic Ray Failure Mechanism and Critical Factors for 3.3kV Hybrid SiC Modules

The cosmic ray failure mechanism for a 3.3kV IGBT has been investigated. It could be clarified that the dynamic avalanche current dominates the catastrophic self-heating, and the impact of the parasitic bipolar action is negligible for a 3.3kV IGBT unlike a lower voltage class IGBT. For practical use, the integral over the electric field with a specific threshold value was proposed as an index for the robustness for a High Voltage (HV) IGBT such as a 3.3kV class device. The cosmic ray robustness of a 3.3kV SiC Schottky Barrier Diode (SBD) was also investigated: it was found that the failure rate is almost the same as that of 3.3kV class Si devices.