Design And Optimization Of JTE Termination For 4H-SiC High Voltage Power Devices

In the actual fabrication process of the power devices,the junction bending generated at the edge of the PN junction due to the diffusion,the actual withstand voltage of the power devices is much smaller than the ideal voltage value of the design,so junction termination technology is needed to reduce the effect of the junction bending(curvature effect).This paper mainly analyzes and studies the conventional terminal technology.In view of the sensitivity of the device breakdown to JTE dose and interface charge in the conventional JTE,the terminal structure is proposed to improve their influence on the device.The main research contents are as follows:1.In this paper,we introduce the origin of device junction termination technology,the current status of foreign and domestic junction termination technology development,and analyze the factors affecting the breakdown voltage of the devices.In addition,the working principle of conventional termination structure and their influence on the devices are also analyzed Finally,the important physical models in the simulation and simulation software are introduced.2.In this paper,a stepped double-zone junction termination extension(Step-DZ-JTE)is studied,which changes the terminal region formed by ion implantation through the specific mask without increasing the number of P-type impurity ion implantation,so that the double-zone JTE(DZ-JTE)has a stepped shape.The stepped DZ-JTE gradates the charge distribution in the termination region,thereby rendering the structure exhibit a multi-zone JTE effect.The proposed structure is optimized by the device simulation tool(Atlas),and the relationship between the device performance and the structure parameters is analyzed through simulation.As the same time,it is compared with the performance of the conventional single-zone and double-zone junction termination extension.The simulation results show that in the optimized Step-DZ-JTE structure,stepped region can share the electric field(EF)in the first JTE region of the conventional DZ-JTE at a higher JTE dose,thereby effectively alleviating the excessive concentration of the EF in the first JTE region of the conventional DZ-JTE.This also indicates that Step-DZ-JTE structure broadens the window of the JTE implant dose.Meantime,it is further improved in allowing the maximum positive interface charge density.3.Based on the Step-DZ-JTE,it is further studied that the field plate and the floating field limiting rings respectively combine the structures.Since the Step-DZ-JTE structure has its own advantages at high dose,a field limiting rings(FLRs)or field plate(FP)is added to share the EF at the main junction and reduce the EF at the edge of the main junction at low doses.Moreover,the FLRs or FP can be completed simultaneously with the cell region process,without adding additional processes.Through the simulation optimization,the results show that these two hybrid structures further broaden the window of the JTE dose.Since the field plate is not sensitive to the interface charge,the field rings assisted the Step-DZ-JTE further improves the influence of the interface charge on the device.