Low-Capacitance SCR With Waffle Layout Structure for On-Chip ESD Protection in RF ICs

The silicon-controlled rectifier (SCR) has been used as an effective on-chip electrostatic discharge (ESD) protection device in CMOS technology due to the highest ESD robustness in nanoscale integrated circuits (ICs). In this study, the SCR realized in a waffle layout structure is proposed to improve ESD current distribution efficiency for ESD protection and to reduce the parasitic capacitance. The waffle layout structure of the SCR can achieve smaller parasitic capacitance under the same ESD robustness. With smaller parasitic capacitance, the degradation on RF circuit performance due to ESD protection devices can be reduced. The proposed waffle SCR with low parasitic capacitance is suitable for on-chip ESD protection in RF ICs. Besides, the desired current to trigger on the SCR device with a waffle layout structure and its turn-on time has also been investigated in a silicon chip.