Modeling And Verification Of Superjunction Mosfet Based On The Bsim4 Model

Power MOSFETs are the cornerstone of electronic power technology.They are majority carrier devices and have the advantages of high input impedance,high breakdown voltage,and low loss during switching.While superjunction MOSFETs break the "Silicon Limit" of traditional power MOSFETs.The characteristic of lower onresistance under the same breakdown voltage makes them widely used in switching power supplies,energy-saving equipment,automotive electronics and other equipment.The SPICE(Simulation Program with Integrated Circuit Emphasis)model is a bridge between the device process and circuit design,and it can be used to simulate the electrical behavior of devices in circuits.However,the SPICE models of MOSFETs commonly used in the industry are only suitable for small-sized and low-power devices.There are few studies on high-power superjunction MOSFETs models,and there is no commonly used model for superjunction MOSFETs.Therefore,in-depth study on the SPICE model of superjunction MOSFETs is of great significance to improve device design efficiency and save device development costs.In this thesis,a complete SPICE model of superjunction MOSFETs is developed including DC macro model and dynamic model.When establishing the DC macro model,the channel region model adopts the BSIM4 core model,and the drift region adopting two ideas establishes a JFET model considering the quasi-saturation effect of the superjunction MOSFETs and a variable resistance model,respectively.The variable resistance model includes linear model and parabolic model according to the contour of resistance on both sides of the drift region.And a thermal resistance model and a voltagecontrolled resistance model are established respectively for the self-heating effect of the device during high-power operation.Then a body diode model including the static DC characteristics of source-drain forward bias and the temperature characteristics of breakdown voltage is established.When establishing the dynamic model,the body diode reverse recovery model is first established,and then the method for establishing the capacitor empirical model of superjunction MOSEFTs is introduced,and then the capacitor physical model is established according to the unique structure of superjunction MOSEFTs,and finally the capacitor physical model is revised in order to apply to the situation of Miller spikes under the unbalanced charge doping of P and N columns.After the model is established,the model is verified for a superjunction MOSFET device.Firstly,the electrical characteristics of the device are measured,and then the parameters of the superjunction MOSFETs model established for the device are extracted.After the model is written in Verilog-A language,the SPICE simulator is used to simulate the DC characteristics and dynamic characteristics.The results show that the mean square errors between the optimal simulation results and the measured results of the DC macro model are both within 1%;while the mean square errors between the optimal simulation results and the measured results of the reverse recovery model and the capacitor model are controlled within 3%.The established SPICE model of the superjunction MOSFETs device not only has fast simulation speed and good convergence,but also has a high degree of fit between the simulation results of the model and the measured results.Therefore,the established SPICE model of the superjunction MOSFETs has great guiding significance for predicting the performance of the device in the circuit,which has reached the expected goal of this thesis.