Research On Novel High Speed SOI-LIGBT

As the core of power electronics technology,power semiconductor devices play an impartant role in the control,conversion,and regulation of electrical energy.Lateral Insulated Gate Bipolar Transistor?LIGBT?is one of the most important power devices,which has the advantages of high input impedance,low on-state voltage,high current density,simple driving circuit,and etc.Meanwhile,the carrier-storied layer?CSL?is introduced on the IGBT emitter side,which can prevent the hole carriers in the N-drift flowing into emitter,further enhancing conductivity modulation effect and optimizing the trade-off relationship between on-state voltage(V_on)and turn-off loss(E_off).However,the excessive CSL doping concentration(N_CS)leads to breakdown of P-base/CSL prematurely.On the other hand,Reverse-Conducting LIGBT?RC-LIGBT?integrates a freewheeling diode inside the device,contributing to the reverse conduction capability.However,the traditional RC-LIGBT usually occurs snapback phenomenon in forward state.In order to solve the above issues,the author carried out a series of research work under the guidance of Professor Xingbi Chen,Associate Professor Moufu Kong and Dr.Bo Yi.The main content is divided into the following aspects:1.A novel thin layer silicon-on-insulator carrier-stored LIGBT?CSL-SOI-LIGBT?with diode-clamped P-shield layer is proposed.The potential of the P-shield layer and CSL is clamped at lower value by the two series-connected diodes.Thus,the reverse voltage is sustained by the P-shield/N-drift junction rather than the P-base/CSL junction in traditional device during the off-state.Therefore,N_cs can be improved by several orders of magnitude without compromising the breakdown voltage?BV?.On the other hand,the lower drain-to-source voltage of the intrinsic channel n-MOS contributes to an ultra-low saturation current.After being verified by simulation,the saturation current of proposed structure is reduced by more than 53.3%than that of the traditional LIGBTs,E_off is reduced by 28.8%and 21%compared with those of the conventional LIGBT-A and LIGBT-B when V_on is about 1.37 V.2.Based on the previous reasarch,a novel thin layer trench LIGBT?TLIGBT?with P-shield layer and self-biased pMOS is also studied.The self-biased pMOS provides a hole current path between P-shield and emitter,and clamps the potential of P-shield layer and CSL.Compared with the diode-clamped structure,the self-biased pMOS can improve the electrical performance of the device by adjusting the doping concentration of the body region.The simulation results reveal that E_off of the proposed TLIGBT is reduced by 41.9%and 25.4%compared with conventional TLIGBT-A and TLIGBT-B when V_on?1.35,respectively.And the saturation current density decreased by more than 44%.Consequently,the short-circuit withstand time is improved by over 164%.3.A novel RC-LIGBT with an embedded p-type Schottky Barrier Diode?p-SBD?is proposed.In reverse-conducting state,the p-SBD and body PiN diode are connected in series through a floating electrode,which provides a current path for carriers.In forward-conducting state,the p-SBD is reversed-biased so that the N-buffer region and P⁺-collector are not shorted,which eliminates the voltage folding effect.At the same time,the leakage current increases dramatically when temperature is high or the p-type schottky barrier height is low?that is work function of metal is high?,so the p-SBD is equal to turn-on and the N-buffer and P⁺-collector are shorted,which contributes to the reduction of hole injection efficiency and the improvement of the forward biased safe operating area and the short circuit safe operation area.The reverse recovery charge of the proposed RC-LIGBT shows 43.9%and 63.2%reduction compared with those of the SSA-RC-LIGBT with L_B?the distance between the P⁺-collector and the shorted N⁺-collector?being 34?m and 64?m,respectively.And the turn-off loss of is reduced by 68.2%and 87.1%at V_on=2.6 V,respectively.