Study On High Voltage Bidirectional Silicon Control Electrostatic Protection Devices

Electrostatic Discharge(ESD)is a common natural phenomenon.Electrostatic discharge has caused great harm to the modern integrated circuit industry because of its high voltage,large current,energy concentration,and short discharge time.The manufacturing process of the integrated circuit has become smaller,more advanced,and thinner,so that the integrated circuit has faster and faster processing capacity and lower and lower energy consumption,but its robustness to ESD becomes weaker.Therefore,the research on ESD protection devices is an important guarantee for the safe and stable development of the integrated circuit industry.The goal of this study is to provide efficient,stable,high-performance bidirectional ESD protection devices for high-voltage multi-supply-powered integrated circuits.Based on the working principle and performance analysis of the traditional DDSCR structure,some new device structures have been proposed for improving the defects of high trigger voltage and low holding voltage in the traditional devices.These new devices are realized,tested and analyzed in a 0.5 ?m BCD process.The content is as follows:(1)The device structure and working principle of traditional DDSCR arediscussed,and by using the IBDSCR structure,the I/O port of an operational amplifier is successfully provided with effective ESD protection.The IBDSCR structure reduces the trigger voltage by increasing the heavily doped diffusion region across the well,and increases the device holding voltage by increasing the distance between the anode and the cathode,thereby improving the defect that the traditional DDSCR has.(2)A novel embedded multi-fingered DDSCR structure was proposed and its equivalent ladder network resistance model was constructed.The study explains the reason why the new device's holding voltage is irrelevant to the number of fingers and the key factors that determine the performance of this new structure.The traditional 6-finger device and 6-finger embedded device were realized in the same process and tested under the Hanwa transmission line pulse(TLP)system.The results showed that the new structure increased the holding voltage of the 6-finger DDSCR device from 5.44V to 21.24V overcomes the shortcomings of the traditional DDSCR that the holding voltage decreases with the number of fingers increases.(3)Researching the working principle of diode-triggered ESD devices,analysissing the working mechanism of the forward-biased-diode-arrays-triggered DDSCR which is used in low-voltage circuits and proposing a reverse-biased-diode arrays-triggered DDSCR which can be used in high-voltage circuits.The TLP test results show that the new device reduces the trigger voltage from 76V to 30.31V,which is basically the same as the 26.2V predicted by the theoretical calculation,and the design principle that the new device trigger voltage controlled by diode array is confirmed.In addition,an optimized layout has been proposed for the reverse-biased diode arrays trigger DDSCR,which slightly improves the uniform conduction of multi-finger DDSCR devices.