Design And Optimization Of Low Loss Split Gate IGBT Devices

The power semiconductor devices play an important role in the power control,transformation and regulation.Insulated Gate Bipolar Transistor（IGBT）has been widely used as one of the core switching devices in the field of medium and high power because of its excellent performance.To solve the problem of large gate capacitance in IGBT,a solution for Split Gate IGBT（SG-IGBT）has been proposed.However,the conventional split gate structure can weaken the conductivity modulation effect in the drift region and degrade the device performance.In this thesis,based on traditional SG-IGBT,a trench IGBT with Self-Biased Split Gate structure（SBSG）is proposed and its characteristics are verified by simulation.The main content of this thesis is as follows:1.In this thesis,a trench IGBT with Self-Biased Split Gate（SBSG-IGBT）is proposed.The structure consists of a polycrystalline silicon diode introduced on the surface of the device,whose cathode is connected to the split gate electrode and connected in series with an external capacitor to form a self-biased circuit.The charging energy of the circuit comes from the voltage in the floating P region when the device is turned off.To prevent the circuit voltage from boosting too high,the floating P region is clamped by an extra hole path.After IGBT is powered on and several cycle cycles are passed,the split gate potential is stable,the self-bias of the circuit is completed,and the self-bias voltage of the split gate is V_SG=10 V.The conductance modulation effect at the bottom of the trench is improved by stably split gate self-bias power supply,which improves the carrier distribution in the drift region of the device.The simulation results show that compared with SG-IGBT,for SBSG-IGBT,the carrier concentration at the bottom of trench is increased by 90%,the conduction voltage drop(V_ceon)is decreased by 12.8%.At the same time,its gate capacitance is reduced by 64%compared with traditional IGBT,and the Miller platform is reduced by 70.6%.Under the sameV_ceon,SBSG-IGBT is 11.2%lower than traditional trench IGBT and 26.6%lower than SG-IGBT.2.Based on the principle of self-biased split gate,the self-biased structure HBSG-IGBT with Hole Barrier layer and the self-biased structure FPCSG-IGBT with Floating P region Clamp are also proposed.Through additional hole barrier layer and floating P region clamp,the carrier concentration under the trench of these two structures is increased by 150%and 100%,respectively,compared with the conventional SG-IGBT.TheV_ceon is significantly improved compared with the conventional SG-IGBT.Compared with SG-IGBT,the E_off of HBSG-IGBT is reduced by 46.6%,the E_off of FPCSG-IGBT is reduced by 71.5%,and the device performance is greatly improved.