A Robust Dual Directional SCR without Current Saturation Effect for ESD Applications

A robust dual directional SCR (RDDSCR) is proposed to suppress the current saturation effect in conventional dual directional SCR (DDSCR). By introducing a new current path with low resistance, the self-heating effect in NWELL regions of RDDSCR can be well avoided. The ESD I-V characteristics of RDDSCR and DDSCR are measured with the transmission line pulsing (TLP) tester. Moreover, TCAD simulation is also carried out to explore the physics mechanism in depth. Compared with DDSCR, the new RDDSCR possesses an improvement in failure current of 16.5% and an increase in holding voltage of about 2V. Furthermore, the influence of the external resistance on ESD performance of RDDSCR is also studied, where the resistance value of zero  has been demonstrated to be a better option. Compared with the existing optimization methods, RDDSCR method has been proven to be more efficient in inhibiting current saturation effect of DDSCR without any compromise on turn-on characteristic.