Research Of High Power Integrated Devices With High-K Material

Intelligent Power Integrated Circuits(SPIC)require that power semiconductor devices and low-voltage control circuits can be integrated on the same chip.At the same time,it is hoped that the power density of power semiconductor devices can be increased as much as possible.Therefore,new devices with high-power integrated characteristics are an important development direction.For Insulated Gate Bipolar Transistors(IGBT)and Metal-Oxide-Semiconductor Field Effect Transistors(MOSFET),the vertical structure generally has a large power density,but cannot be integrated;the lateral structure can be integrated because the high potential electrodes are distributed on the same side of the device,but the power density is often reduced because of the larger surface area.Moreover,the tail current of IGBT device makes the power consumption of turn-off increase sharply,and there is a trade-off between turn-on current and turn-off time,which cannot be improved at the same time.Besides,the specific on-resistance and breakdown voltage of MOSFET devices also restrict each other,which limits their application in high voltage field.In order to solve the above problems,this thesis proposes two devices with high power and integration characteristics by introducing high permittivity(HK)material based on Lateral Insulated Gate Bipolar Transistor(LIGBT)and Vertical Double-diffused MOSFET(VDMOS).For LIGBT device,the power density can be increased on the basis of integration,and the tail current at turn-off is eliminated.For VDMOS device,integration is realized on the basis of high power,and the restriction relationship between specific on resistance and breakdown voltage can be improved.The main research work and simulation contents of this paper are as follows:A LIGBT device with HK material is proposed.By depositing HK material and polysilicon layer on the surface of the device,the flow of holes is controlled,and the tail current is eliminated at the time of turn-off.The device with different thickness and dielectric constant of HK dielectric layer is simulated and compared with the conventional LIGBT.It is found that the new LIGBT can not only increase the breakdown voltage of the device in turn-off state,but also increase the on-current density and turn-off speed of the device in turn-on and switching state,breaking the restriction relationship between on-off current and turn-off time of the conventional LIGBT.The simulation results show that the on-characteristic and switching characteristics of the device are always better than those of the conventional LIGBT when the parameters of some key areas of the device and the conventional LIGBT change.An integrated VDMOS device with HK material is proposed.The high level electrodes of the device are located on the same side and can be monolithically integrated with other circuits.Meanwhile,the introduction of HK material can optimize the electric field distribution in the drift region and improve the performance parameters of the device.The device with different HK dielectric constant is simulated and compared with the integrated VDMOS.It is found that the threshold voltage of the new VDMOS device is significantly reduced,the switching speed is as fast as that of the integrated VDMOS device,the breakdown voltage is significantly increased,the specific on-resistance is greatly reduced,and the restriction relationship between the on-resistance and the breakdown voltage is obviously improved.When the key parameters of the device change,the device characteristics are simulated and the figure of merit is calculated,which provides a basis for optimizing the device structure.