Research On The Improvement Of Electrical Performance For Lateral IGBT

As a core technology for electric energy applications,the power electronics promote the development of electric vehicles,high-speed rail and other green industries.The insulated gate bipolar transistors(IGBTs)have become the core power devices in power electronics due to its high input impedance and low turn-on voltage.With the continuous demand for energy saving,emissions reduction,low carbon and environmental protection,IGBT has become one of the most important device.To realize the intelligence,integration and miniaturization of power electronic systems,researchers have proposed the smart power intergrated circuit(SPIC)module,which integrates the control circuits,protection circuits and driver on a single chip,and greatly reduces the parasitic effects.The development of semiconductor process has made lateral power semiconductor devices an attractive choice in SPIC.However,the lateral power device with the larger area has a lower current density and a higher turn-on voltage drop than the vertical device.In order to achieve higher current density and lower conduction loss of lateral power devices,this dissertation puts forward guiding directions and ideas for the optimization of lateral power devices,and gives the actual structural design based on Professor Xingbi Chen’s theoretical research on power devices.The simulation research is carried out using technical computer-aided design(TCAD)simulation software.This dissertation mainly studies the lateral insulated gate bipolar transistor(LIGBT),which is described as follows:1.An adjustable low positive voltage power supply at the high voltage side of vertical or horizontal devices is proposed.This structure uses the junction termination of vertical or horizontal devices to realize the low-voltage power supply with different values from 4 V to 13 V based on the Professor Xingbi Chen’s patent.In order to drive the low-voltage circuit at the anode side and realize the integration of the low-voltage power supply in the intelligent power module,this dissertation adopts a simple structure to provide a stable low-voltage power with adjustable voltages value.2.A new LIGBT with high electron injection at the cathode is proposed.This structure enhances the conductance modulation effect of the drift region by using the large current capability of the thyristor;Meanwhile,a bipolar transistor is intergrated at the cathode side to provide electron current for the device,which realises high electron injection at the cathode;In addition,the collector of the cathode-side bipolar transistor is clamped by a diode to ensure the current saturation capability of the device.The simulation results show that the turn-off loss of the proposed structure is reduced by87.5% with the same turn-on voltage of 1.42 V as the conventional LIGBT;and the turn-off loss is also reduced by 34% compared with the SCM-LIGBT when the turn-on voltage is designed as 1.25 V.3.A new LIGBT structure without Miller platform is proposed.This structure reduces the Miller capacitance by increasing the thickness of the gate oxide of the MOS transistor.Besides,the thyristor is employed to reduce the Early voltage of the device.Then the Miller platform in the switching process is completely eliminated and the control capability of the gate resistance on the di/dt during the turning-on process is improved.Compared with the SCM-LIGBT,the control ability of the gate resistor on the di/dt is improved by 49%.In addition,the saturation current density of this structure is reduced by 55% compared with the SCM-LIGBT,and the short-circuit safe operating time is increased by 374%.Moreover,the trench gate MOS applied in the design is only used to provide the turn-on current of the device,so the process deviation of the trench gate will not affect the performance of the device.4.A new RC-LIGBT with adjustable resistor at the anode region is proposed.Firstly,the design routes for realizing RC-LIGBT and the influence of the variable resistor on the performance of RC-LIGBT are analyzed.Then,a new design to realize the adjustable resistor is given.When the proposed RC-LIGBT is in the forward conduction state,the variable resistor has a large value at low anode voltage to eliminate the snap-back phenomenon;when the anode voltage is high enough,the resistance of the variable resistor is reduced,and the device is converted to the LDMOS mode.Thus,the current capability of the proposed device is decreased,which realizes the better short-circuit performance.The simulation results show that the snap-back phenomenon of the RC-LIGBT is completely eliminated.And compared with SSA-LIGBT,the short-circuit operating time of the proposed one is increased by 158.8%.And the turn-off loss and turn-off time are reduced by 53% and 53.5%,respectively.