Filament-induced thermomigration of an aluminum drop at the cathode-side of high-voltage power diodes

This paper shows how a buried aluminum eutectic drop at the cathode-side of a high-voltage power diode can affect the device behavior. The aluminum drop driven by thermo-migration, moves from the contact metallization some micrometers into the chip and forms a buried eutectic. Thermomigration [1] becomes stronger as the temperature gradient increases. High temperature gradients can be achieved at the cathode side if a single filament is triggered. Simulation results show that an early surface-punch-through at a spike may reduce the reverse-recovery ruggedness of the power diode. Such a detrimental filamentation can be avoided by a well-defined fabrication process of the device.