On the failure mechanism and current instabilities in RESURF type DeNMOS device under ESD conditions

We present 3D device modeling of RESURF or non-STI type DeNMOS device under ESD conditions. The impact of base push-out, pulse-to-pulse instability and electrical imbalance on the various phases of filamentation is discussed. A new phenomenon called “week NPN action” and the cause of early and fast failure is identified. A modification of the device is proposed which achieved an improvement of ~5X in failure threshold (I_T2) and ~2X in ESD window without degrading its I/O performance.