Design and analysis of a multi-finger dual-direction SCR discharging electro-static current in a gradual transition manner

Abstract

In order to seek an electro-static discharge with higher failure current per unit area and latch-up immunity, a novel multi-finger dual-direction silicon controlled rectifier (DDSCR) using the 0.5 μm complementary and double-diffusion metal-oxide-semiconductor technology was proposed. The working principle of the device is analyzed by using equivalent circuit and technology computer aided design simulation. From the test result of the transmission line pulse testing system we can see that the holding voltages for the traditional dual-direction silicon controlled rectifiers with a single-finger and two-fingers are 11.34 V and 7.63 V, respectively, which is decreased as the number of fingers increases. The holding voltage of the proposed device is 12.2 V, which is higher than that of the traditional 2-finger DDSCR and suitable for communication interface high voltage electrostatic discharge (ESD) protection. Furthermore, the influence of some dimensions, fingers and total finger width on the device is discussed. The proposed device not only solves the problem of decreasing the holding voltage caused by increasing the number of fingers, but also has a slight effect on the failure current. The root cause for such holding voltage trend is their different working mechanisms. The proposed device is turning on one finger by another instead of simultaneously turning on in the multi-finger traditional devices. Therefore, the proposed ESD device owns a holding voltage similar to that of the 1-finger device.