3D TCAD studies of Snapback Driven Failure in Punch-through TVS Diodes under System Level ESD Stress Conditions

This paper explains the ESD failure dynamics of TVS diode, reported for the first time. The failure is universal to TVS diode structure designed as ESD protecting element. This work gives the detailed physical insights into failure mechanisms, using 2D & 3D TCAD simulations. Failure at very low currents due to non-uniform bipolar turn on, for longer pulse duration, is explained. 2D simulation shows the non -uniformity due to current crowding while 3D simulation supports the failure dependency with thermally driven filamentation. Finally, three device engineering schemes are proposed to improve the phenomena of low current ESD failure under longer pulse duration, through which non-uniform bipolar turn-on is limited.