NLDD/PHALO-Assisted Low-Trigger SCR for High-Voltage-Tolerant ESD Protection Without Using Extra Masks

A new silicon-controlled rectifier (SCR) is proposed and realized in the foundry's 0.18-mum CMOS process for electrostatic discharge (ESD) protection. Without using an extra mask or trigger circuits, the new n-type lightly doped drain and p-type halo-assisted SCR has a trigger voltage V
_t1
as low as 7 V and an ESD robustness exceeding 50 mA/mum, which enables effective ESD protection. Compared with the traditional low-voltage-triggered SCR, the new structure not only has a lower trigger voltage but also is more suitable for high-voltage-tolerant applications avoiding any gate-oxide reliability issue.