Hot spots induced by reverse leakage current flow through the semiconductor-dielectric interface from device PN junction periphery

A commercial power silicon diode die was used in a suitable devised experiment with infrared imaging microscope. At 500 V applied reverse voltage, hot spots have been revealed near the junction periphery at 220°C temperature. These hot spots are attributed to non-uniform leakage current flow at the junction periphery. At higher applied voltage these small overheated regions can initiate reverse electrical characteristic instability followed by failure. Further advance in the junction passivation process from device technology is required to provide high quality semiconductor-dielectric interface. This could enable reliable operation of some power silicon devices above 200°C junction temperature.