Study And Design Of Novel IGBT Structure Based On Si/SiC

IGBT(Insulated Gate Bipolar Transistor)devices are widely used in high-voltage power transmission,transportation,household appliances,military equipment,aerospace and other fields due to their high current,high power and easy driving characteristics.The conductance modulation effect in the drift region of IGBT device makes the device have a low on-state voltage drop(V_on)when it is turn on;when the device is turn off,a large number of unbalanced carriers in the drift region will make the device turn off current tailing,resulting in excessive turn off loss(E_off).At present,IGBT devices focus on turn off loss(E_off)and on-state voltage drop(V_on).With the rise of the third generation wide band gap semiconductor materials,SiC materials have attracted the attention of researchers because of their wide band gap,high breakdown electric field,high electron drift rate and strong heat dissipation.With the advancement of the integrated circuit industry and semiconductor technology,SiC and SiGe are widely used in CMOS technology.The Si/SiC heterojunction provides new ideas for improving the contradictory relationship between IGBTs.This article proposes a new structure to improve the performance of IGBT devices:(1)A SiC IGBT structure with Si/SiC heterojunction with NPN in the anode is proposed.Siis introduced at the anode and the NPN structure is doped.When the device is turned off,compared with the conventional NPN device,the barrier of the valence band of the heterojunction makes the NPN draw holes near the anode,draw out the drift region,and reduce the turn-off time.The simulation results show that under resistive load,compared with the conventional SiC IGBT,the turn-off time of the device is reduced by 39%,respectively.Under inductive load,the turn-off loss(E_off)is reduced by 79%.(2)A Si/SiGe and Si/SiC two heterojunction SiIGBT structure with improved conductivity modulation effect is proposed,and P-type doped SiC is introduced at the anode.When the device is turned on,the high potential barrier of the heterojunction conduction band blocks electrons from flowing to the anode,causing a large number of carriers to accumulate inside the device,enhancing the conductance modulation effect of the device,and increasing the output current,but the device turn-off current is severely tailed.The Si/SiGe heterojunction introduced at the anode side sweeps the drift region holes out of the drift region when the device is turned off,reducing the turn-off time.Through optimization,the double heterojunction is designed and the device performance is improved at the same time.The simulation results show that compared with the conventional Con-IGBT,the output characteristics are improved by 35%,the on-state voltage drop(V_on)is reduced by14%,and the turn off loss(E_off)is reduced by 41%,achieving a trade-off relationship between the turn-off loss(E_off)and the on-state voltage drop(V_on).(3)A reverse-conducting SiIGBT structure with Si/SiC heterojunction is proposed,and N-type doped SiC is introduced at the anode.In the initial stage of device turn-on,the Si/SiC heterojunction will not cause electrons to be injected into the anode,eliminating the Snap Back phenomenon;when the device is turned off,it provides an electron extraction channel to speed up the discharge of carriers from the drift region and reduce the turn-off time.The simulation results show that compared with the conventional Con-IGBT structure,the turn-off loss(E_off)is reduced by 18%,and the on-state voltage drop(V_on)remains unchanged.The introduction of SiGe at the anode side further reduces the turn-off time.Compared with the conventional Con-IGBT structure,the turn-off loss(E_off)is reduced by58%.A better compromise relationship between the on-state voltage drop(V_on)and the turn-off loss(E_off)is obtained.