Design Of An IGBT With Sandwich Structure Termination

IGBT is a core power semiconductor device that can realize high-speed rail,automotive power systems and home appliances and other fields of our contury to be self-controllable.Domestic IGBT has made a great progress in the past 10 years,through unremitting efforts in process technology and design.However,compared with the international advanced IGBT manufacturers,domestic IGBT design and manufacturing capabilities still have a large gap,including IGBT structure?cell,terminal?thining technology.In the junction termiantion technology of IGBTs,the composite structure with field plates and field limiting rings is domiant in current domestic IGBT technology,which occupies a large area of the chips.Thus,this thesis aims to design a 650V IGBT with sandwich structure termination based on the existing domestic technology platform.This thesis first explains junction termination principle and briefly analyzes several types of junction termination.Combined with the RESURF concept and previous design experience,a sandwich structure termination is proposed,and the termination structural parameters including the length,depth,width,doping concentration of the buried layer,and the interface charge effect on the termiantion electrical characteristics are analyzed by the numerical simulation software MEDICI.Then based on the domestic IGBT process manufacturing platform,taking account of the device structure,the compatibility of termination and cell process,design a set of process flow,and use the process simulation software TSUPREM4 to verify the feasibility of the process flow,explore the influence of the process parameters on the structure of the IGBT cell and sandwich termination.According to MEDICI's electrical simulation results of the 2D cell and termination strucure generated by TSUPREM4,analyze the relationships between the electrical characteristics of the cell and the process parameters of the Pbody region,the epitaxy,the trench gate,and the backside parameters,determine a feasible process parameters.The process tolerance of the termination injection dose is explored.Finally,the layout of the sandwich structure termination and cell of the IGBT is drawed on L-edit software.The optimized IGBT cell has a breakdown voltage of 732V,a threshold of 4.4 V,and a turn-on voltage drop of 1.54 V.The optimal sustaining voltage of the sandwich structure termination is 789 V,which is 13 V higher than that of the conventional field limit ring,and its length is 160?m,which is 100?m shorter than that of the conventional field limiting ring;when the interface charge surface density is 5×10¹11 cm^-2,the sustaining voltage of the sandwich structure termination is 96.7%of its initial sustaining voltage,whereas the sustaining voltage of the conventional field limit ring is only 89.9%of its initial one.Therefore,the sandwich structure termination has a high tolerance to the interface charges than the conventional field limiting ring termination.