New DDSCR structure with high holding voltage for robust ESD applications*

Abstract

A novel dual direction silicon-controlled rectifier (DDSCR) with an additional P-type doping and gate (APGDDSCR) is proposed and demonstrated. Compared with the conventional low-voltage trigger DDSCR (LVTDDSCR) that has positive and negative holding voltages of 13.371 V and 14.038 V, respectively, the new DDSCR has high positive and negative holding voltages of 18.781 V and 18.912 V in a single finger device, respectively, and it exhibits suitable enough positive and negative holding voltages of 14.60 V and 14.319 V in a four-finger device for ±12-V application. The failure current of APGDDSCR is almost the same as that of LVT-DDSCR in the single finger device, and the four-finger APGDDSCR can achieve positive and negative human-body model (HBM) protection capabilities of 22.281 kV and 23.45 kV, respectively, under 40-V voltage of core circuit failure, benefitting from the additional structure. The new structure can generate a snapback voltage on gate A to increase the current gain of the parasitic PNP in holding voltage. Thus, a sufficiently high holding voltage increased by the structure can ensure that a multi-finger device can also reach a sufficient holding voltage, it is equivalent to solving the non-uniform triggering problem of multi-finger device. The operating mechanism and the gate voltage are both discussed and verified in two-dimensional (2D) simulation and experiemnt.