Simulation Study On Junction Termination Structure Of Thyristor

Power semiconductor devices are the foundation and core of power electronics technology,which is characterized by high voltage resistance and large current,and to improve the voltage level of power semiconductor devices is an important task.The junction termination structure of a power semiconductor device is an important part of the device that requires a reasonable design,which can improve the performance of the power semiconductor device.Thyristor is a kind of power semiconductor devices,and its high voltage resistance and large current passing capability are the necessary factors in the development of electrical systems in the industry,and of some power electronic devices.The technical requirements for the thyristor are still improved,and suitable devices for the development of the industry have been found from the derived thyristors,such as IGCT（integrated gate commutator thyristors）.Based on the study of the general working principle of the common thyristor,this thesis analyses the mechanism of the junction termination structure of the thyristor.The breakdown voltage of the thyristor determines the voltage resistance level of the device.The thyristor which is not made with junction termination structure will break down at very low voltage,making the whole device unable to satisfy the design requirements of blocking voltage.Therefore,in the design of the thyristor,it is necessary to attach great importance to this part of junction termination structure.Among various kinds of junction termination structure,there are structures suitable for the thyristor,and those not suitable for the thyristor.However,junction termination structure is not a fixed structure,and needs to be improved according to the actual situation.For example,we need to select the proper angle of the bevel termination,and the exact position of the bevel termination will have an effect on the function of the thyristor.The improvement of the thyristor's junction termination structure must be considered whether meets the requirement,and whether the process conditions are allowed.It is necessary to consider all aspects of the process,so that the structure of the junction termination can be better designed.This thesis discusses several kinds of junction termination structures of thyristor,mainly the bevel termination structure,including positive and negative bevel termination structure,area-reduced junction termination structure,double positive bevel termination structure,double negative bevel termination structure and so on,which are suitable for different thyristors.Then the simulation tools are introduced,and the Silvaco TCAD is described in detail.Then some basic parameters of a thyristor are designed.These parameters can be designed according to the specific structure during the simulation,and the parameters of the thickness and the doping concentration of the four-layer structure P₁,N₁,P₂,N₂ are determined to improve the contrast ability and feasibility of the simulation.And various bevel termination structures are applied to the designed four-layer structure for simulation,and the verification that the surface electric field intensity is lower than the internal electric field intensity is obtained.Moreover,the advantages and disadvantages of various bevel termination structures are briefly compared for reference of manufacturing process.Based on the structure of FLR-negative bevel termination structure,the structure of FLR-area-reduced junction termination structure is designed and simulated.At the same time,it is compared with the structure of FLR-negative bevel termination structure and analyzed.The above work basically covers the junction termination structure that can be applied to the thyristor,as well as a brief description of the process characteristics of the thyristor's junction termination structure,and it summarizes the work of the research,and describes the future research work,and it makes a small contribution to improve the performance of thyristors.