Behavior of Avalanche-Induced Current Filament of High Voltage IGBTs at Over-voltage

When the avalanche effect occurs at the over-voltage of IGBTs, the behavior that the devices represent dominate the device robustness against the avalanche. With the increase of avalanche effect, current crowding (current filament) can arise, which is a root reason leading to the device destruction. In this paper, the avalanche breakdown characteristics of high voltage IGBTs are studied, and then the relations between the avalanche breakdown curves and the avalanche-generated current filaments are reveled. The results show the higher
$\mathrm{a}_{\mathrm{p}\mathrm{n}\mathrm{p}}$
can cause a stronger negative differential resistance effect in avalanche breakdown curve, leading to the formation of a stronger filament with a slower moving speed, consequently weakening the device robustness against the avalanche.