Study On SPICE Model Of 4H-SiC LJFET And Design Of Wide Temperature Inverter

As a new generation of wide band gap semiconductor material,silicon carbide(SiC)has the advantages of high temperature resistance,high voltage resistance,high critical electric field,high saturation velocity and high thermal conductivity.SiC junction field effect transistor(JFET)structure can avoid the defects of SiC/Si O₂ interface because it does not contain gate oxide layer structure.Because of this structural characteristic,SiC JFETs are more suitable for high temperature and high frequency environments than SiC metal field effect transistors(MOSFET).At present,the main jfets structure has a Vertical channel jfets,Trenched and Implanted vertical JFETs(TIJFET)and Lateral channel JFETs(LJFET).Because of the limit of the preparation of silicon carbide device technology,LJFET is more suitable for integrated circuits and SPICE model is an important part of device application in circuit design.However,there is not much research on SPICE model of SiC LJFET and related circuit design.In this paper,a new kind of compact model is developed,which is half physical and half empirical.The convergence and accuracy of the model are considered.The SPICE model of the device and circuit is verified by co-simulation.At the same time,a new integrated LFET inverter structure is designed and the process and layout are designed.In this paper,the application level of SiC LJFET device model is developed.--First,the structure and operating principle of SiC LJFET devices are combined with sentaurus TCAD simulation to analyze the effect of device structure on electrical characteristics.Then,on the basis of Shockley model,4H-SiC material model was added to optimize the model in a wide temperature range.Considering the secondary physical effects of devices,optimization models of channel length modulation effect and velocity saturation effect were added.In the development of the AC model of the device,the capacitance model is simplified to some extent based on the distribution state of space charge region of the channel in the actual operation of the device,and the semi-empirical model of the device capacitance is obtained.The sentaurus TCAD was co-simulated with the SPICE model by LTspcie,which validated the model at 25?to 400?.The results show that the RMS of the static output and transfer characteristics of the SPICE model with wide temperature is less than 5%on average,and the RMS of the transient characteristics is about 10%on average.Under the premise of ensuring the convergence of the SPICE model,the precision requirements of the circuit design are basically met.Then,based on the SPICE wide temperature model,a wide temperature LJFET integrated circuit inverter(CLJFET)is designed,and the process preparation and layout are also designed.First,the structure parameters and doping concentrations of n-type and p-type LJFETs were designed based on the sentaurus TCAD simulation platform to match the threshold voltages of the two transistors over a wide temperature range.The accuracy of the models was verified by SPICE modeling of the two transistors,and a phase inverter circuit was built for co-simulation with the sentaurus TCAD.Finally,the preparation process of the SiC CLJFET inverter is designed,and the circuit layout of the inverter is drawn using L-edit.The results of co-simulation show that the wide temperature inverter circuit designed in this paper can work normally at the temperature from 350K to 600K.The co-simulation error of the static transmission characteristics of the inverter is less than 10%,the average co-simulation error of the transient characteristics is less than 5%according to the temperature,and the co-simulation error of the transient characteristics is less than 15%,which basically proves the convergence and effectiveness of the model for the circuit system design.