Comparison Between High-Holding-Voltage SCR and Stacked Low-Voltage Devices for ESD Protection in High-Voltage Applications

The modified silicon-controlled rectifier (SCR) fabricated in a 0.25-mu m high-voltage (HV) bipolar-CMOS-DMOS (BCD) technology has been proposed to seek for both effective electrostatic discharge (ESD) protection and latchup immunity. Experimental results show that one of the proposed SCRs has a high holding voltage of up to similar to 30 V in the 100-ns transmission line pulsing measurement results. However, through the experimental verification by using the transient latchup test, the holding voltage of such proposed device decreases to similar to 20 V. It is due to the increased bipolar junction transistor current gains of the SCR path induced by the Joule-heating effect in the long-term measurement. For 20-V circuit applications, the ESD robustness of the proposed SCR with a holding voltage of similar to 20 V is lower than that of stacked low-voltage p-type MOS in the previous studies. Developing special modification of such HV devices is inefficient to achieve both effective ESD protection and latchup-free design in this 0.25-mu m HV BCD technology.