Ensuring the reliability of power electronic devices with regard to terrestrial cosmic radiation

Terrestrial cosmic radiation is a significant factor for the reliability of power electronic devices, for voltage classes that range from about 300 V to beyond 6500 V. As such, cosmic radiation-induced device failure concerns power diodes, MOSFETs and IGBT, irrespective of the base semiconductor material, Silicon, SiC or GaN. Though the basic mechanism of failure varies with device type, failure is invariably initiated by the creation of ionizing spallation fragments following a collision of a high-energy neutron with a substrate nucleus. This paper summarizes the results of device simulations and dedicated experiments to substantiate our knowledge about failure mechanisms. It will discuss the possibilities of failure rate prediction for different device types and classes. Main focus of this paper is the presentation and discussion of methods for the determination of failure rates by accelerated testing. Results of nucleon irradiation test are compared with storage tests. The effect of bias voltage and temperature, which are the main stressors, is discussed.