Design Of Silicon Based High Voltage Power VDMOSFET Device

Power VDMOSFET is widely used in switching power supply,automotive electronics,rectifier and other applications due to its advantages of fast switching speed,high input impedance and low driving power,and plays an important role in electronic power systems.At this stage,in the field of high-voltage VDMOS,there are already large-scale production lines abroad,while my country is in its infancy.The demand in this area mainly depends on imports,and there is a long procurement cycle,high prices,and the risk of being embargoed at any time.Therefore,it is of great significance for my country to independently develop high-voltage power VDMOS devices designed and produced based on domestic process production lines.The goal of this paper is to design a high-voltage power VDMOS device with a drain-source breakdown voltage of 2500V,a drain-source current of 200 m A,an on-resistance less than 450Ω,and a threshold voltage between 2.5 and 4.5 based on the domestic process production line.The main work of the paper is as follows:1.In order to achieve the design goal,two design schemes are proposed:(1)two 1250V single vdmos are connected in series;(2)one 2500 V single vdmos is realized.In this paper,the basic principle of VDMOS device is firstly analyzed,and a suitable high-voltage process is designed.On the basis of this process,SILVACO simulation software is used,and two schemes are used to influence the breakdown voltage and on-resistance of the cell structure,the parameters of the threshold voltage are simulated and optimized,and the appropriate structural parameters are selected.The advantages and disadvantages of the two schemes are compared,and the final choice is scheme one,which is realized by using two1250 V single vdmos in series.At the same time,considering that the withstand voltage of the terminal region can only reach about 80%of the cell structure,the breakdown voltage of the cell region should reach more than 1500 V.Finally,the single-tube withstand voltage reaches 1631 V,the threshold voltage is 3.3 V,and the characteristic on-resistance is 76.62Ω·mm~2.2.The traditional uniform spacing field limit ring terminal,the linear gradient spacing field limit ring terminal,the linear gradient spacing field limit ring field plate composite terminal,and the nonlinear gradient spacing field limit ring field plate composite terminal are respectively studied.The influence of parameters such as number,ring width,ring spacing,and ring spacing increment on the withstand voltage of the terminal structure.In addition,the effect of field plate and channel stopper on the withstand voltage of the device termination structure is also studied.Finally,a field-limited ring-field plate composite terminal structure with nonlinear gradient spacing design is designed,which achieves a terminal structure breakdown voltage of 1510 V,a terminal length of 354μm,a terminal efficiency of about 93%,and relatively high stability and reliability.Under the premise of meeting the terminal breakdown voltage of 1500 V,the terminal length is reduced by 46.7%compared with the traditional uniform spacing field limiting ring structure;compared with the linear gradient spacing field limiting ring structure,the terminal length is reduced by23%.On the premise of satisfying the design requirements,the chip manufacturing cost is reduced.