Research On New Structures Of IGBT With Dual-Trench

Insulated gate bipolar transistor(IGBT)is the mainstream power switching device in medium and high power power electronic circuits due to the combination of the advantages of easy driving,simple control,large conduction current and low loss.With the improvement of the efficiency and the development trend of miniaturization of power electronic systems,higher requirements are placed on the loss characteristics and power density of IGBTs.Therefore,in order to improve the trade-off relationship between the on-state voltage drop(Vceon)and the turn-off loss(Eoff)and further improve the performance of IGBT,two types of new structures of IGBT with dual-trench structure are proposed in this thesis.The main contents are as follows:1.The first proposed new structure type is the dual-trench IGBT structure with shield emitter trench(SET-DTIGBT),which includes SET-DTIGBT with thick oxide layer(TOSET-DTIGBT)and SET-DTIGBT with mutually perpendicular dual-trench structure(3DSET-DTIGBT).By introducing the shield emitter trench,devices can obtain a higher breakdown voltage(BV)and a smaller Vceon at the same time.In addition,TOSETDTIGBT has shallow gate electrode and thick gate trench bottom oxide.Therefore,compared with the conventional CS-TIGBT,the gate charge(Qg),Miller charge(Qgc)and Miller capacitance(CGC)of the TOSET-DTIGBT are reduced by 42.4%,74.3%and 79.4%,respectively.At the same Vceon=1.55V,the Eoff of the TOSET-DTIGBT with the thickness of oxide layer at the bottom of the gate trench Tog2=1?m is 49.7%lower than that of the CS-TIGBT,thus TOSET-DTIGBT greatly improving the trade-off relationship between Vceon and Eoff.The 3DSET-DTIGBT structure introduces the shield emitter trench on the surface of the device to form the mutually perpendicular dual-trench structure.Due to the shallow gate electrode depth,the Qg,Qgc,and CGC of the 3DSET-DTIGBT are reduced by 50.1%,80.9%,and 96.1%,respectively,compared to the CS-TIGBT.At the same Vceon=1.3V,the Eoff of 3DSET-DTIGBT is reduced by 41.1%compared with CSTIGBT.Moreover,compared with CS-TIGBT,the saturation current density of 3DSETDTIGBT at Vce=50V is reduced by 33.6%.Therefore,when 3DSET-DTIGBT is shortcircuited,the short-circuit withstand time is increased from 3.3?s of CS-TIGBT to 5.1?s.So 3DSET-DTIGBT improves the short-circuit safe operation area of the device.2.The second proposed new structure type is the three-dimensional dual-trench IGBT structure with adapting hole path(3DAHP-DTIGBT).The adaptive hole path is turn-on when the 3DAHP-DTIGBT is in the off-state,and the hole path is turn-off when the 3DAHP-DTIGBT is in the on-state.On the one hand,the opening of the hole path can reduce the electric field peak at the bottom of the gate trench and reduce the adverse effect of the CS layer on the breakdown characteristics.So that the 3DAHP-DTIGBT can obtain a smaller Vceon by increasing the NCS while obtaining a sufficiently high BV.On the other hand,the opening of the hole path can also reduce the CGC and the Qgc of the device,and accelerate the hole extraction during the turn-off process,thus reducing Eoff.Compared with the CS-TIGBT,the CGC and Qgc of the 3DAHP-DTIGBT are reduced by 28.2%and 47.3%,respectively.At the same Vceon=1.3V,the Eoff of 3DAHP-DTIGBT is 41.9%lower than that of CS-TIGBT.Therefore,the 3DAHP-DTIGBT greatly optimizes the trade-off relationship between Vceon and Eoff.