Ultra-low-voltage-triggered Silicon Controlled Rectifier (ULVTSCR) ESD Protection Device for 1.2V/1.8V Application

Abstract High trigger voltage (Vt1) characteristic of silicon-controlled rectifier (SCR) device has limited its application in electrostatic discharge (ESD) protection of low voltage circuit, especially in advanced CMOS technologies. In this letter, an ultra-low-voltage-triggered SCR (ULVTSCR) is proposed to decrease the trigger voltage of the conventional SCR. The proposed device consists of an external NMOSs-string (ENMOSs-string), an internal NMOS (INMOS) with its gate controlled by the ENMOSs-string, and a main SCR triggered with the INMOS assistance. The ESD current-voltage characteristics of ULVTSCR has been measured with the transmission line pulsing (TLP) tester. The test results indicate that the proposed ULVTSCR possesses much lower Vt1 of ~ 5.03V as well as reduced area consumption compared to the existing optimization methods, making it highly suitable for the ESD protection for 1.2V/1.8V IO ports in CMOS technology. In addition, the impact of various critical dimensions of ULVTSCR have also been evaluated to further improve the ESD characteristics.