Analysis And Design Of 10KV 4H-SiC IGBT

As the most typical representative of the third generation wide bandgap materials,Silicon carbide(SiC)has a series of merits like broad band gap,high critical breakdown electric field,high thermal conductivity and high carrier saturation velocity,and it becomes a hotspot in the field of power semiconductors.Silicon carbide insulated gate bipolar transistor(SiC IGBT)not only has the characteristics of SiC materials,such as high blocking voltage,high-temperature,anti-radiation and high working frequency,but it also has the advantages of IGBT,including easy to drive,simple control,low on-state voltage drop,high on-state current and low power loss.Therefore,SiC IGBT has become one of the ideal power switching devices in high voltage(more than 10kV)and high power applications,such as solid-state transformer,high pulsed power supply,high-voltage inverter,flexible AC/DC transmission system,HVDC transmission system and static var compensator,thus having broad development prospect.In this thesis,the analysis and design of high voltage 4H-SiC IGBT including cells and terminations are carried out:(1)Against the shortage of parameters and models of SiC materials in Silvaco simulation software,the SiC IGBT simulation platform is set up through the selection of parameters and models,and the simulation results agree well with the experimental results.And on this basis,the comparison analysis between the N type and P type 4H-SiC current enhanced IGBT(CEL-IGBT)with the similar structural parameters is carried out.Because holes have higher impact ionization coefficient and lower mobility values than electrons in SiC materials,the simulation results show that the N type SiC CEL-IGBT has higher breakdown voltage,lower on-state voltage drop and better trade-off between on-state voltage drop and turn-off loss than the P type structure.(2)For overcoming the deficiency of 4H-SiC CEL-IGBT structure,a new 4H-SiC CEL-IGBT structure with buried island(BICEL-IGBT)is proposed.And the comparison analysis between the two structures is carried out.The 15000 V BICEL-IGBT and CEL-IGBT devices are obtained by optimizing device parameters through simulation.With the forward on-state voltage drop of 5.53 V,the turn off loss of BICEL-IGBT structure is 2.79 mJ,which is reduced by 31% compared to 4.01 mJ for the CEL-IGBT structure.(3)The design of field limiting ring and groove composite terminal structure is carried out.The 16900 V withstand voltage is obtained when the 50 rings is used and the terminal width is 1.2mm.Furthermore,the process and layout of the 4H-SiC IGBT structure are designed.