Design And Research On Novel Reverse-Conducting IGBT

Insulated Gate Bipolar Transistor(IGBT)has the advantages of high input impedance,low control power,simple drive circuit,fast switching speed,low on-voltage drop,large on-state current,and low loss.IGBT is One of the core components of electronic technology which is widely used in various types of power electronics.However,in most IGBT application circuits,a diode is needed to be antiparallel with the IGBT to conduct the reverse current.This is because the IGBT does not have a body diode like Metal Oxide Semiconductor Field Effect Transistor(MOSFET).In reverse operation,it can only be equivalent to an open-base PNP transistor that cannot be turned on.In order to reduce manufacturing costs and reduce parasitic inductance,the idea of integrating a diode into an IGBT device has been proposed.The new IGBT concept having a reverse conducting capability is called as RC-IGBT.However,there are still many problems that need to be solved in the RC-IGBT,such as the snapback phenomenon that usually occurs during the forward conduction process,and the difficulty of back-side process,etc..Therefor,RC-IGBT cannot directly replace the module of IGBT with the antiparallel diode.A novel RC-IGBT device proposed in this paper can effectively solve the snapback phenomenon in the conduction process.The main contents of this paper are as follows:1.The structure and working principle of the IGBT device are analyzed in detail,and the main characteristics are analyzed theoretically,including static characteristics which include threshold voltage,forward conducting characteristics and blocking characteristics,and the dynamics characteristics which include the turn-on process and the turn-off process.2.The principle of snapback phenomenon in the forward conduction of conventional RC-IGBT devices is analyzed.The theory of conducting characteristics and blocking characteristics of thyristor is analyzed.Based on these,Shockley diode is proposed to realize the reverse conducting characteristic and is verified by simulation.It is found that when the thickness of the P-base region and doping concentration are appropriate,the thyristor can realize forward conduction without snapback phenomenon and the reverse blocking voltage will increase.3.A novel RC-IGBT device is proposed,which is realized by integrating theshockley diode into the junction termination region of IGBT.Then TCAD simulation is carried out to prove verify the characteristics of the proposed RC-IGBT.Compared with the conventional RC-IGBT,the proposed device has different forward conduction,blocking and switching characteristics,and its characteristics are more similar to the FS IGBT.Specifically,the N+ collector region of the proposed RC-IGBT does not affect its characteristics as it does in conventional one.The proposed device has breakdown voltage,threshold voltage,forward and reverse conduction voltage drops of 670 V and 5.3 V,1.5 V and 1.1 V,respectively.