Simulation Study Of Low Power 4H-SiC Trench IGBT

Silicon carbide material is a kind of semiconductor material with high thermal conductivity,wide forbidden band,high temperature resistance and strong radiation resistance.In recent years,due to its excellent characteristics,it has received extensive attention from the international community.It has great application prospects in modern military electronic communication systems,aerospace systems,electromagnetic weapons systems,high-performance radar systems,high-speed railway traction equipment and other national defense and civil fields.Insulated gate bipolar transistor(IGBT)has the characteristics of high saturation current density of metal oxide semiconductor field effect transistor(MOSFET)voltage control and bipolar transistor(BJT)at the same time and has developed into the most competitive electronic device at present.It can realize lower conduction voltage drop.At the same time,for SiC IGBT devices,their turn-off loss accounts for most of the power loss.The compromise between on-state characteristics and turn-off characteristics has always been a key issue to be considered in device design.To solve this problem,based on the traditional trench SiC IGBT structure,the following work has been done in this paper:1.A stepped collector heterojunction IGBT structure(SCH-IGBT)is proposed,which is characterized by penetrating the P+ collector region into the N-drift region and introducing the p-poly/p-SiC heterojunction,so that when the device is normally conducting,the P+ region penetrating into the N-drift region can maintain the conducting characteristics of the device,and the existence of the heterojunction also provides an additional low resistance path for electron discharge.The simulation results show that under the premise of the same breakdown voltage,the turn-off loss of the improved structure is increased by 60.6%,while the turn-on voltage drop is increased by 11.1%.2.A trench type heterojunction IGBT structure(TH-IGBT)is proposed,which is characterized in that a trench type p-poly/p-SiC heterojunction is introduced at the collector side of the device.By controlling the doping concentration on both sides of the heterojunction,when the device is conducting in the forward direction,holes can be injected into the drift region at the common PN junction part and the heterojunction part.At the same time,when the device is turned off,the heterojunction part provides a low-resistance path for electron discharge,thus reducing the turn-off loss of the device.The simulation results show that under the premise of the same breakdown voltage,the turn-off loss of the improved structure is increased by 91.24%,while the on-state voltage drop is increased by 10.7%.