Novel Symmetrical Dual-Directional SCR With p-Type Guard Ring for High-Voltage ESD Protection

The negative holding voltage of high-voltage (HV) dual-directional silicon-controlled rectifier (DDSCR) is usually attenuated to a very low level due to the grounded guard ring, which has been ignored by many researchers nowadays. In this brief, a novel symmetrical DDSCR (SDDSCR) is proposed to suppress the deterioration of DDSCR's negative holding voltage. By introducing a diffusion resistor into the p-type guard ring (PGR), experimental results indicated that the reverse parasitic SCR path associated with PGR is suppressed effectively. Thus, a symmetric high holding voltage characteristic is implemented for SDDSCR without increasing any silicon footprint. Moreover, the PGR resistor technology presented in this brief can be extended to various existing HV DDSCRs, which could improve their negative holding voltage deteriorated by guard ring.