A Novel and Robust Un-Assisted, Low-Trigger and High-Holding Voltage SCR (uSCR) for Area-Efficient On-Chip ESD Protection

A novel and robust un-assisted low-trigger and high-holding voltage silicon controlled rectifier (uSCR) is proposed and realized in a 0.35-mum fully-salicided BiCMOS process. Without using any external trigger circuitry, the uSCR has a trigger voltage as low as 7 V to effectively protect deep submicron MOS circuits and a holding voltage higher than the supply voltage to minimize transient influence and avoid latch-up issue. Moreover, the electrostatic discharge (ESD) protection robustness of the uSCR in both positive and negative operations exceeds 60 mA/mum, which enables ESD protection levels of 8 kV human body model (HBM) and 2 kV charged device model (CDM) for a low voltage ICs, while each uSCR cell only consumes an area of about 2400 mum².