Design Optimization And Experimental Verification Of High Voltage 4H-SiC JBS Power Rectifier

As the application environment changes so fast,the application of traditional Si-based devices is nearly to its limitation and cannot meet the increasing application requirements.Therefore,new semiconductor materials must be studied.The third-generation semiconductor material 4H-SiC has very good characteristics,its high critical breakdown electric field strength is 10 times that of silicon material,the wide band gap and thermal conductivity are three times that of silicon material,and high electron saturation velocity speed is silicon material.These excellent properties of 4H-SiC materials are particularly suitable for use in the field of power electronics.In the power diode structure,junction barrier controlled Schottkey(JBS)is a particularly important structure.Its structural characteristics determine that when the JBS forward bias voltage,the Schottky junction in JBS will enter the conduction state before the PN junction due to the lower barrier;when the JBS is reverse biased voltage,due to JBS The depletion region of the middle PN junction will expand toward the channel region,thereby effectively increasing the breakdown voltage of the device.Due to the high blocking characteristics,fast switching characteristics and high current characteristics of JBS power diodes,it becomes a mainstream diode structure.Therefore,the device structure mainly discussed in this paper is 4H-SiC JBS power rectifier.The main contents of this paper are as follows:1.Through continuous investigation and study of various materials,the simulation model needed to establish 4kV 4H-SiC JBS diodes is clearly defined.,Select the appropriate physical model.The parameters of the physical model required for 4H-SiC JBS diode simulation.are modified to establish the physical models.These models include mobility model,field correlation model(fldmob),Auger composite model(auger),impact ionization model(selb),incomplete ionization model(incomp),energy band narrowing model(bgn).2.Design 4000 V 4H-SiC JBS diode cell structure.Inorder to obtain the best structures of 4H-SiC JBS power diodes.The main parameters include: thickness and doping concentration of the drift region,the length of the p+ region and the width the p+ region.Finally,the basic structural parameters of the diode cell are determined,and the cell structure with a breakdown voltage of about 5200 V is obtained.3.4000 V 4H-SiC JBS diode junction termination techniques were studied.The main terminal technologies involved include field plate technology(FP),field limiting ring(FLR)technology,and etched junction terminal extension(JTE)technology.Based on the optimized cell structure,breakdown voltages of 5500 V are achieved by the design of etching of multi-zone JTE?A new etching multi-step JTE junction termination structure which can reduce process difficulties is proposed in this paper.4.Use the Tanner Tools software to draw 4H-SiC JBS power diode layouts.Finally,the ideal terminal structure in the simulation design was selected for the conduct experiment,and experiment results were tested and analyzed.