A SIC Mosfet Merged SBD

With the rapid development of the semiconductor industry in today's society,the conventional silicon devices are limited by the properties of their materials,and to a certain extent it is difficult to meet the high-frequency,high-power,and low-loss performance requirements in the power electronics field.Silicon carbide Metal-OxideSemiconductor Field-Effect Transistor devices are an important branch of the vigorous development of wide bandgap semiconductor devices.Compared with the conventional silicon materials,SiC materials have the characteristics of much higher critical breakdown electric field,wider bandgap,and higher thermal conductivity.Due to the excellent performance,the SiC power MOSFET device is widely used in new energy vehicles,high-power power supplies,aerospace and other fields.It has become one of the most widely used new power devices with one of the best market prospects.Due to the problem of non-equilibrium carrier extraction during the reverse recovery process of the body diode of the SiC MOSFET device,the operating frequency of the device is restricted to a certain extent,and the switching power loss is also increased.Based on the analysis and discussion of those shortcomings,this thesis proposes a new SiC MOSFET power device with much better reverse recovery characteristics.In addition,in order to give full play to the superior performance of silicon carbide MOSFET devices,this thesis also tries to combine the superjunction structure with the new SiC MOSFET device,and simulations and discussion are carried out.The main work of this thesis is as follows:First,a new device structure is proposed to improve the reverse recovery performance of the SiC trench MOSFET device.Compared with the conventional SiC trench MOSFET devices,the reverse turn-on voltage of the proposed MOSFET device with integrated Schottky Barrier Diode structure is only 25% of that of the conventional SiC MOSFET body diode.At the same time,the reverse recovery time of the new MOSFET device is reduced by 86% compared with the conventional structure,and the reverse recovery charge is reduced by 78%.It can be known from the simulation results that the new device effectively improves the reverse recovery characteristics of the device and reduces the power loss of the device.Subsequently,a superjunction SiC trench MOSFET device structure is designed,which effectively improves the overall performance of the SiC MOSFET device.Compared with the conventional superjunction MOSFET device,the reverse recovery peak current of the new superjunction MOSFET device is reduced by 66%,and the reverse recovery charge is reduced by 79%.At the same time,compared to the previous structure proposed in this thesis,the specific on-resistance is reduced by 86%.The new device not only effectively improves the reverse recovery characteristics by introducing the superjunction structure,but also reduce the switching loss of the device.This thesis discusses the design and performance of new SiC trench MOSFET devices,provides certain models and data for the design and optimization of silicon carbide trench devices,and provides a design innovation for the design of domestic silicon carbide MOSFET devices.