Research Of High-performance TVS Device Based On SCR

In recently years,with the upgrading of global semiconductor manufacturing technology,the realization of high-performance integrated circuits has led to the rapid development of various consumer electronics products.In order to ensure the reliability and quality of these consumer electronic products,ESD(Electronic Discharge)protection design for various situations is indispensable.The application of TVS(Transient Voltage Suppressor)devices is a common system-level ESD protection method.In various system level ESD protection designs such as communication interface circuits and electromagnetic protection networks,low capacitance TVS devices are widely used to ensure the integrity of data signals.With the development of integrated circuits towards high-speed and high-precision,the capacitance parameters of TVS devices need to be lower and lower.This thesis focuses on the low capacitance TVS device used for the protection of data communication transmission interface circuit.Based on the SCR(Silicon Controlled Rectifier)device with high robustness,the device mechanism and operation mode of SCR device are introduced,and the problem of the modified lateral silicon controlled rectifier(MLSCR)device in the low capacitance direction is discussed.Based on this,the main research content of this article is as follows:(1)Firstly,a P+Trigger Silicon Controlled Rectifier(PTSCR)was studied and analyzed.Based on the MLSCR device,this structure changes the PN junction capacitance formed by two highly doped regions into a PN junction capacitance formed between a highly doped well region and a very low doped substrate region by adjusting the distance between the well regions,The length and width of the PT layer across the two well regions are controlled to reduce the PN junction capacitance between a highly doped well region and a highly doped PT layer without affecting the performance of SCR devices.At the same time,in order to discuss the impact of the structural parameters of TVS devices as discrete devices on their various performances,software simulations are conducted for the devices.Through the analysis of the simulation results,it can be seen that the capacitance of the PTSCR device is lower than that of the MLSCR device when the opening characteristics meet the requirements of the TVS device.Without reducing the width of the PT layer,by adjusting the well spacing,the capacitance value of the PTSCR device is 65.19% of the MLSCR device with the same parameters.If the width of the PT layer is reduced to 10% of the overall width of the device,the overall capacitance value of the device becomes the original43.77%.(2)Then,based on the PTSCR device,a new double-punch through trigger silicon controlled rectifier(DPTTSCR)is proposed.This structure removes the original PT layer and the N+ region in the N-well,reduces the size of the device,and changes the device trigger mechanism from the original avalanche breakdown to the punch through-trigger,which can reduce the trigger voltage of the device while reducing the capacitance characteristics of the device.The simulation results show that the capacitance of DPTTSCR device is 15% of that of PTSCR device.