Design And Optimization Of IGBT With Gate ESD Protection Function

IGBT(Insulated Gate Bipolar Transistor)is a composite device that uses MOSFET(Metal Oxide Semiconductor Field Effect Transistor)to drive BJT(Bipolar Junction Transistor)to achieve conduction.It has the advantages of both MOSFET and BJT and has been widely used since its inception.Research and Application.ESD(Electro-Static discharge)refers to"electrostatic discharge".For IGBT devices,the high electric field caused by ESD will increase the potential difference across the gate capacitor.When the potential difference across the gate capacitor exceeds the gate oxide breakdown voltage(V_OX),the device will fail.In order to improve the gate ESD protection capability of IGBT devices,this thesis mainly studies the following contents:(1)Firstly,the reasons for the damage of IGBT gate oxide layer caused by ESD are analyzed,and the method of voltage clamping between IGBT gate and emitter is proposed,which provides a theoretical basis for realizing the gate ESD protection function of the device.(2)A gate voltage self-clamp IGBT(Gate Voltage Self-Clamp IGBT,GVC-IGBT)with gate ESD protection function is proposed.GVC-IGBT integrates a clamping diode between the gate and emitter of some IGBT cells,and clamps the gate transient voltage from 21 V to-0.7 V through the reverse avalanche breakdown and forward conduction of the clamping diode.The maximum gate-emitter ESD voltage V_ESD of GVC-IGBT can withstand reaches 5.149 k V,which is 5.86 times higher than that of conventional IGBT(Conventional IGBT,Con-IGBT),and the emitter-gate V_ESD reaches 13.434 k V.The Con-IGBT is increased by 15.3 times,and the V_CE(ON)is increased by 5.8%,which realizes the gate ESD protection function and meets the design requirements.However,the turn-on voltage drop of GVC-IGBT has a large increase,and the emitter-gate clamping voltage is too small.(3)Aiming at the application of gate-emitter negative power turn-off,this thesis proposes a polysilicon gate voltage self-clamp IGBT(PGVC-IGBT)with gate ESD protection function.The gate transient voltage is clamped between 21 V and-21 V by fabricating two back-to-back clamping diodes of polysilicon material on the device gate.The gate-emitter V_ESD of PGVC-IGBT reaches 5.984 k V,which is 6.81 times higher than that of Con-IGBT,and the emitter-gate V_ESD reaches 5.934 k V,which is 7.19 times higher than that of Con-IGBT,while V_CE(ON)only increased by 3.7%,realizing the gate ESD protection function and meeting the design requirements.PGVC-IGBT has lower on-voltage drop than GVC-IGBT,and the emitter-gate clamping voltage is significantly improved.Although the process of the device is more complicated and the cost is higher,it has certain practical value in the application of negative voltage turn-off.