| With the continuous development of power semiconductor devices,insulated gate bipolar transistor(IGBT)has become one of the most widely used power devices.The application of reverse-conducting lateral insulated gate bipolar transistor(RC-LIGBT)based on silicon-on-insulator(SOI)technology in the power ntergrated circuit field is becoming more and more extensive due to its capability of forward and reverse conducting,low on-state voltage,high input impedance,and low packaging cost.In the traditional RC-LIGBT device,the freewheeling diode and the LIGBT device is integrated together on a cell through an N~+region shorted with the P~+anode,which results the reverse conducting capability.However,this device will suffer from the snapback phenomenon in the forward conducting state,which increases the on-state voltage drop of the device and may also cause unexpected state in the device.It's one of the hot research topics of RC-LIGBT to solve the impact of snapback phenomenon.In this thesis,the operating principle of the RC-LIGBT is analyzed,and the generation mechanism and the solution of the snapback phenomenon are also investigated.In addition,some new RC-LIGBT structures are proposed which can effectively eliminate the effect of the snapback phenomenon.The main points of this thesis are as follows:1.The development and transformation of power devices and IGBTs are presented,and the development status of RC-LIGBT devices are also expounded.2.Theories and technologies that commonly used in lateral power devices are introduced.The device structure and operating principle of RC-LIGBT are expounded,and its breakdown characteristics,forward and reverse conducting characteristics,the trade-off relationship between the turn-off loss and the on-state voltage drop,and reverse recovery characteristics are all analyzed in detail.The mechanism of the snapback phenomenon is also investigated.3.A traditional SSA-LIGBT device with a breakdown voltage of 600 V is designed and simulated.Its electrical characteristics are simulated through simulation software Sentaurus TCAD,its working principle and the principle of suppressing the snapback phenomenon are both analyzed.Moreover,based on the simulation results,the advantages and disadvantages of SSA-LIGBT are analyzed and these results are also used to find an effective way to completely eliminate the snapback phenomenon.4.A novel 600 V RC-LIGBT device with anti-parallel IGBT is proposed and studied in this thesis.In the proposed device,an NMOS are employed in the anode region to perform as an anti-parallel IGBT.In the forward state,because the NMOS is turned off,the effect of the snapback phenomenon is completely eliminated;while in the reverse state,the anti-parallel IGBT automatically turns on and generates a reverse current to realize reverse conducting.Due to the smaller device size,the device achieves a lower on-state voltage drop and a better tradeoff between the on-state voltage drop and the turn-off losses than the SSA-LIGBT,respectively.The turn-off loss of the proposed device is reduced by 81.8%compared with the traditional SSA-LIGBT device.Furthurmore,in comparison with the traditional SSA-LIGBT,the reverse recovery charge of the proposed device is reduced by 16.9%.Although its reverse on-state voltage drop is higher than that of SSA-LIGBT,it can be significantly improved by reasonable parameter optimization.5.A novel 550 V RC-LIGBT device based on buried oxide layer isolation is proposed and investigated.A free-wheeling diode under the buried oxide layer is integrated in the device.And the isolation of the buried oxide layer completely eliminates the snapback phenomenon.Compared with the SSA-LIGBT,a smaller device size,a higher forward current density and a better trade-off relationship between the on-state voltage drop and the turn-off loss are all obtained.The turn-off loss is reduced by 62.2%compared with the traditional SSA-LIGBT. |
