Research On Structure Design And Simulation Of Reverse Conducting IGBT

Power semiconductor devices play a vital role in the conversion of electrical energy,especially IGBT(Insulated Gate Bipolar Transistor),which is used in many fields and is one of the indispensable power semiconductor devices.However,conventional IGBT does not have reverse conduction capability.When driving inductive loads,they need to be used in parallel with Freewheeling Diode(FWD).At present,integrating FWD into IGBT is a research hotspot of IGBT.This kind of device is called RC-IGBT(Reverse Conducting IGBT).RC-IGBT has the characteristics of miniaturization,low power consumption,low cost and high stability,but there are problems of Snapback phenomenon and current unevenness.To solve these two problems is the focus of many research works of RC-IGBT.Based on the research of the static and dynamic characteristics of conventional RC-IGBT,a fast recovery RC-IGBT with partial schottky emitter and collector P-type buried layer(FSP-RC-IGBT)is proposed and its electrical characteristics is analyzed through numerical simulation in this thesis.The simulation results show that the P-type buried layer in FSP-RC-IGBT can effectively suppress the forward Snapback phenomenon of the device and reduce its On-state Voltage(V_on).The partial schottky emitter in the FSP-RC-IGBT can reduce the stored charge in the drift region of the device during reverse conduction,so that the reverse recovery charge of FSP-RC-IGBT is reduced by 23%compared with the conventional RC-IGBT,and 35%compared with the IGBT+FWD parallel structure,the reverse recovery speed of FSP-RC-IGBT is improved.In addition,the reverse recovery failure of FSP-RC-IGBT is also improved.Through preliminary process research,it is found that the novel structure has high process feasibility,and its process schemes under plane gate and trench gate is given.In order to obtain more superior device performance,a Superjunction RC-IGBT(SJ-RC-IGBT)with high voltage and low power consumption is also proposed in this thesis.SJ-RC-IGBT takes the Superjunction thyristor as the reverse conduction structure,which completely eliminates the reverse Snapback phenomenon of conventional thyristor RC-IGBT,and several types of key electrical characteristics of SJ-RC-IGBT are improved greatly.In particular,the Breakdown Voltage(BV)and the tradeoff relationship between V_on and Turn-off Loss(E_off)is improved significantly in SJ-RC-IGBT.When BV>1200 V and V_on=1.1V,the SJ-RC-IGBT can obtain an E_off as low as 6.04 m J/cm²,which reflects the characteristics of high voltage and low power consumption.Due to the shunting effect of the Superjunction,the SJ-RC-IGBT also has the potential to prevent turn-off latch up and reverse recovery latch up,and has excellent short-circuit capability.