Analysis of Turn-on Uniformity of Multi-finger DDSCR Devices under ESD Stress

This paper presents a detailed study of turn-on uniformity under electrostatic discharge events in single-finger and multi-finger traditional DDSCR devices. Since the structure of the multi-finger DDSCR device is not completely symmetrical, the electric field strength of each finger breakdown junction is different, resulting in different impact ionization rates. Therefore, each finger of device cannot be turned on at the same time, and the turned-on finger enters the snap back region and pull down the voltage of the device. If the ESD failure voltage Vt2 of the multi-finger device is less than the trigger voltage Vt1, then other fingers will not turn on until the device fails, and the ESD current can be only discharged through the partial area. The transmission line pulse (TLP) test results show that the failure currents It2 of the single-finger, 2-finger and 4-finger DDSCR devices are 6.22A, 11.83A and 13.33A, respectively, and the 4-finger device cannot be uniformly turned on.