Research Of New ESD Protection Devices Based On High Voltage Bipolar Process

High-voltage(HV)IC integrated circuits occupy an important position in the semiconductor industry and are widely used in industrial motors,automotive electronics,and display drivers.In high-voltage IC products,Electro-Static Discharge(ESD)has become an important factor affecting product reliability.The ESD phenomenon is a process in which static electricity is transferred in different electrostatic potential objects,accompanied by strong electric field,high voltage,and instantaneous large current.At the same time,the discharge time of ESD is very short,ranging from tens of nanoseconds to several hundred nanoseconds.It is easy for the gate oxide layer of the chip to break down and the metal wire to be blown,which affects the normal function of the chip.This paper firstly gives a brief overview of the research background,development trend,physical model and test model of ESD protection,and elaborates the working mechanism and physical mechanism of four traditional ESD protection devices in combination with the 55 nm flow film results.Then,this paper mainly introduces the ESD protection design of 40 V high voltage Bipolar process IC circuit,including the design of single ESD protection device and port network ESD protection design.In the design of single-body ESD protection devices,this paper mainly uses the hysteresis characteristics of SCR.A novel vertical structure SCR device is designed.Unlike traditional lateral devices,the current of the device is mostly turned on from the chip body,which can effectively avoid device damage caused by excessive current on the surface of the chip.Its protection ability can reach 17 KV and solved the problem of low protection of the high voltage process.In addition,through the analysis of the test results of the structure and the auxiliary simulation analysis,two different improved structures are proposed in this paper to better solve the problem of high power consumption and slow triggering of the device under high voltage process.In this paper,the breakdown characteristics of the reverse diode are used to design a MLSCR device for stacking and a diode-triggered SCR device with more area saving.The working mechanism and physics of this device are explained in detail through device simulation.The mechanism can increase the trigger voltage and the sustain voltage of the device by increasing the number of stacked cells and the number of diode strings,and solve the problem that the traditional ESD protection device is prone to latch-up in the high-voltage process,and has the protection capability of 10 KV.For the ESD protection of bidirectional ports,this paper proposes a new diode-assisted trigger bidirectional SCR device,which increases the device's leakage path to make the device have a higher sustain voltage and uses a symmetrical structure to efficiently Protects ESD in both directions.Finally,in the port network ESD protection design,this paper introduces the fullchip ESD protection strategy of the high-voltage process,introduces the concept of ESD bus,designs a special ESD protection network for four different ports,and provides BJT protection and SCR protection.A total of two protection schemes achieve ESD protection between any two ports,and both solutions can meet the protection requirements of 4KV.