A Research On Novel IGBT With Cathode Injection Enhancement

With the development of power electronics technology,people require to improve the conversion efficiency of electric energy.As a key component of semiconductor power devices,it is necessary to compromise the key electrical performance parameters of Insulated Gate Bipolar Transistor(IGBT),such as breakdown voltage(BV),on-state voltage(V_on),turn-off loss(E_off),the controlling of the d V/dt,turn-on loss(E_on),short-circuit withstand time(t _SC)and so on.These key electrical performance parameters often need to compromise to realize the great design.In order to optimize the relationship between the V_on and the E_off,a more ideal carrier distribution is expected for the devices.To solve this problem,the introduction of a carrier-stored Layer(CSL)on the emitter side of an IGBT device has been widely studied.The introduction of the CSL makes holes accumulate below it,which can enhance the conductivity modulation effect and further reduce the V_on.However,this design method also has problems:excessively high doping concentration of CSL(N_CS)will lead to the drop of the breakdown voltage.In view of the above problems,the author takes IGBT as the research subject,carries out a series of analysis and research,and puts forward the specific improvement measures.The specific research work is summarized as follows:1.A novel superjunction insulated gate bipolar transistor(Pro-SJ-IGBT)with heavily doped CSL and an integrated self-biased pMOS is proposed and investigated in this paper.An extra P-buried layer is introduced on the top of the drift region to form the self-biased pMOS.During the off-state,the self-biased pMOS is auto-turned on and the potential of the P-buried layer as well as the CSL is clamped by the p-channel.As a result,the doping concentration of the CSL can be significantly increased without jeopardizing the breakdown voltage.In the on-state,the heavily doped CSL enhances the conductivity modulation effect and hence reduces the V_on.Furthermore,the self-biased pMOS diverts most of the hole current in the saturation region,contributing to a smaller drain-to-source voltage of the intrinsic n MOS.Thus,a low saturation current and a larger short circuit safe operating area(SCSOA)are achieved.Consequently,Simulation results show that the t _SC is improved by 52.7%and 86.7%compared with those of the conventional SJ-IGBT-A(Con-A)and conventional SJ-IGBT-B(Con-B),respectively.Besides,the E_off of the proposed SJ-IGBT is significantly reduced by 66.9%and 49.1%.2.A novel Carrier-Stored Trench Bipolar Transistor(CSTBT)with heavily doped CSL and a p-type Schottky Barrier diode(p SBD)is proposed and investigated by TCAD tool.The voltage of the CSL is shielded by a buried P-type layer,whose potential is clamped by p SBD in series-connection with a PN diode.Hence,the CSL can be heavily doped resulting in a significant improvement in the trade-off between V_on and E_off.Compared with a conventional CSTBT with floating P-base(FP-CSTBT),E_off of the proposed CSTBT is reduced by 27.9%at V_on is 1.1 V.Moreover,owing to the shielding effect of the P-bury layer,the saturation current density of the proposed CSTBT is reduced by 52%compared with that of the FP-CSTBT.Consequently,significantly enlarged SCSOA is obtained and the t _SC is increased greatly at ultra-low V_on(?1.1 V).Based on the theory and simulation analysis,this paper conducts in-depth research on the two novel IGBTs,and obtains some effective conclusions,which has important reference significance for experimental research and application research in the future.