Design Of A 4H-SiC GTO Thyristor Used In Pulse Power Field

The requirement of pulse power system for pulse power switch is higher and higher,due to pulse power technology's continuous progress and the expansion of its application field.Silicon carbide Gate turn-off(SiC GTO)thyristor is an important power device applied in pulse power area.It not only has high current processing ability and high blocking voltage,but also has lower leakage current,on-resistance and higher working temperature than Si-based power devices of the same voltage level.Because of these advantages,it is very suitable for high voltage and high current pulse power applications.In this paper,the material properties of 4H-SiC,the working principle of GTO thyristor and the pulse power system are introduced and analyzed.A 4H-SiC GTO thyristor with a blocking voltage of 6000V is designed to meet the application requirements in the field of pulse power.By optimizing the device structure,the device has good pulse discharge performance.Finally,the process flow design and layout drawing are carried out.The main contents of this paper are as follows:1.The development history of pulse power technology is introduced.The working mechanism of capacitive energy storage pulse discharge circuit is theoretically analyzed.The performance requirements of pulse power switch are obtained.The design and optimization direction of 4H-SiC GTO thyristor in this paper is determined to be low on resistance and low turn-on delay time.The material characteristics of 4H-SiC and related device simulation models are analyzed.The device structure and working mechanism of4H-SiC GTO thyristor are studied.The comparison and analysis of various GTO thyristors are made,which provides theoretical support and guidance for subsequent device design and optimization.2.The relationship between the structure parameters and the performance of the 4H-SiC GTO thyristor is simulated and analyzed.After optimization,the structure parameters of the cell and the junction termination are determined.The blocking voltages of the cell and the junction termination both exceed 6000V with sufficient margin.For devices with an active area of 0.5 cm~2,in the simulation of pulse discharge with a power supply voltage of 4000V and a capacitance of 1.1μF,the corresponding device conduction voltage drop is only 35.3 V at the peak current of 14 kA.The design of process flow and the layout drawing of the device are completed with considering the process capability of the foundry.3.By further studying the working mechanism of 4H-SiC GTO thyristor,a new type structure of 4H-SiC GTO thyristor with high cathode injection efficiency is proposed,which has better conduction capability.In the static conduction performance simulation,when the conduction current density is 1000A/cm~2,the specific conduction resistance of the device decreases by about 22.7%compared with the conventional device.In the simulation of pulse discharge with a peak current of 14 kA and a half sinusoidal of 1μs,the conduction voltage drop corresponding to the peak current of the device is about 54.4%lower than that of the conventional device.