Research On New Structure Of High Voltage And Low Loss Trench SiC IGBT

Silicon carbide insulated gate bipolar transistor(SiC IGBT),as a wide bandgap power semiconductor device,not only has the advantages of high critical breakdown electric field,high breakdown voltage,high temperature resistance and high operating frequency of SiC material,but also has the advantages of high conduction current density,low forward voltage drop,simple driving and low loss of IGBT devices.And it has become the core switching power device in the fields of power grid,high voltage inverters,and high voltage DC power transmission.In this thesis,three new structures of high-voltage and low-loss trench SiC IGBTs are proposed,which can not only reduce the on-state voltage drop(V_ceon),but also improve the trade-off relationship between the on-state voltage drop(V_ceon)and turn-off loss(E_off)of the device.The main contents are as follows:1.An injection-enhanced SiC IGBT with surface contact barrier is proposed,including a surface heterojunction contact barrier SiC IGBT(HJB-IGBT)structure and a surface Schottky contact barrier SiC IGBT(SCB-IGBT)structure.The heterojunction contact barrier formed by the P-type polysilicon on the surface of the HJB-IGBT device and the P-body region raises the potential of the P-body region by 0.77 V.Similarly,the SCB-IGBT passes through the integrated Schottky diode(p-SD)in the forward conduction state,the potential of the P-type base region is increased by 1.46 V,forms a potential barrier to prevent the flow of holes into the emitter,thereby enhancing conductivity modulation and optimizing carrier distribution in the conduction state drift region.Finally,the on-state voltage drop of HJB-IGBT and SCB-IGBT are 4.75 V and4.64 V,respectively,which are 17.4%and 19.3%lower than the 5.75 V of Con-IGBT.At the same time,the turn-off loss E_off of HJB-IGBT and SCB-IGBT are 10.05m J/cm~2 and9.45 m J/cm~2,respectively,which are 58.9%and 61.4%lower than the Con-IGBT under the same V_ceon.2.A SiC IGBT device with integrated PMOS and surface Schottky contact(PGS-IGBT)is proposed.When the PGS-IGBT is in the on-state,the hole path formed in the PMOS is closed,and the p-type schottky diode(p-SD)forms a potential barrier to prevent the flow of holes into the emitter,thereby enhancing conductivity modulation and optimizing carrier distribution in the conduction state drift region,When the PGS-IGBT is in the off-state,the PMOS is turned on to form a hole path.The formation of the hole path can speed up the extraction of holes,which has a faster turn-off speed.Finally,the on-state voltage drop of PGS-IGBT is 27.5%lower than that of the floating P-type IGBT(FP-IGBT);At the same time,the turn-off loss E_off of PGS-IGBT is E_offis 15.75 m J/cm~2,which is 35.7%lower than the Con-IGBT under the same V_ceon.Under the same V_ceon of7.16 V,the turn-off loss E_off of PGS-IGBT is 7.25 mJ/cm~2,which is 64.3%lower than that of FP-IGBT.