Investigation On Energy Optimization And Turn-on Characteristic Of IGBT

Power electronics technology is a crucial supporting technology in the national security field and the national economy.It efficiently converts one form of electrical energy into another form of electrical energy to meet a variety of applications.Simultaneously,it is still an important technical means to achieve energy conservation and environmental protection,as well as to improve the living standards of the human beings.It plays a decisive role in implementing the current national policy of energy conservation,emission reduction,development of new energy,and realization of a low carbon economy.The core component in power electronics technology is power semiconductor devices.The insulated gate bipolar transistor?IGBT?is one of the most important power semiconductor devices,which combines the advantages of high operating frequency and low on-state voltage(V_on).With the diversification of the application forms of electrical energy,people have progressive requirements for power devices,mainly in terms of power consumption and reliability.For minority-carrier devices such as IGBT,due to the tradeoff between the dynamic power and the static power,the mainstream technology generally revolves the optimization of the tradeoff between V_on and turn-off energy loss(E_off).In addition,the turn-on energy loss(E_on)can be reduced by speeduping the turn-on process,but with significant electromagnetic interference?EMI?noise.Consequently,a tradeoff between E_on and the EMI noise is also considered by changing the gate resistance.The main works of this dissertation are to improve the performance of IGBT,mainly focusing on optimizing the tradeoff between V_on and E_off,as well as its turn-on characteristics.The main innovations of this thesis are included as follows:1.A novel mental-oxide-semiconductor?MOS?controlled thyristor is proposed,where the P-well region is connected to the Emitter electrode through two series polysilicon diodes.The proposed device completely eliminates the contradiction between V_on and breakdown voltage?BV?appearing in the conventional carrier stored trench-gate bipolar transistor?CSTBT?,and thereby an ultra-low V_on can be achieved by increasing the dose of the carrier stored layer?N-layer?.In addition,the electron quasi-Fermi potential of the intrinsic drain of the trench NMOS is clamped at 0.7 V by two series diodes,which contributes to an ultra-low saturation current.The simulation results demonstrate that the V_onn and saturation current density are reduced by 33.6%and 66.6%,respectively.Finally,due to the increased process steps and process difficulties of two polysilicon diodes,replacing two polysilicon diodes with a gate-drain shorted PMOS is proposed to simplify the processes,which also exhibits significant improvements in V_onn and saturation current.2.The turn-on characteristics of floating dummy-cell?FD?IGBT with floating p-base region are investigated,and a novel FD-IGBT is proposed.In the proposed device,the potential of the floating p-base region is clamped by the open base P-N-P transistor,so that the effect of floating p-base region on the gate voltage is reduced,which means that the controllability of gate resistance on dI/dt and dV/dt is enhanced.Moreover,another advantage of the proposed structure is that it can significantly reduce the Miller capacitance by clamping the potential of the floating p-base region,consequently,reducing the E_on.The simulation results show that,for the same E_on+E_off of 90.8 mJ/cm²,the dI_CE/dt of the proposed IGBT and the reverse-recovery dV_KA/dt of the free-wheeling diode?FWD?are decreased by 87.7%and 58.2%,respectively.3.A novel low V_on and E_off superjunction?SJ?-IGBT is proposed,where the P-pillar is connected to the Emitter electrode through a gate-drain shorted PMOS.In the on-state,the hole quasi-Fermi potential of the P-pillar can be raised by the PMOS which is in off-mode,with the enhanced conduction modulation effect and a lower V_on.In the turn-off transient,because the PMOS can be automatically turned on,the proposed SJ-IGBT can be rapidly turned off,which leads to a lower E_off.The simulation results indicate that the V_onn and E_off are reduced by 46.7%and 20%,respectively.4.A novel fast-switching lateral IGBT?LIGBT?is proposed,where the collector junction?P-collector/N-buffer?is paralleled with a polysilicon P⁺/N⁺diode.In the blocking state,all electrons generated by the voltage-sustaining layer can entirely flow to the collector electrode through the diode without hole injection,which implies that the BV is independent on the function of the open-base P-N-P transistor.In the turn-off transient,the electron in the drift region can be extracted by the diode without hole injection,contributing to a fast-switching characteristic.The simulation results show that the current fall time is reduced by 65.9%.