Design Of Reverse Conducting 1700V CSTBT

CSTBT?Carrier Stored Trench-Gate Bipolar Transistor?is a new type device of IGBT based on the structure of Trench IGBT?TIGBT?.By introducing slightly high doped n-type regions above the n-type drift area,this structure forms Carrier Stored Layer?CS Layer?and reduces the pressure drop in the on-state of the device.RC-CSTBT?Reverse Conducting Carrier Stored Trench-Gate Bipolar Transistor?,by introducing N type doping area in the part of the back of CSTBT,integrate the Fast Recovery Diodes?FRD?needed to be reverse paralleled in application within the CSTBT.And this kind of structure of IGBT can effectively improve the integration of power devices,and reduce the packaging cost.The key to the design of RC-CSTBT is to optimize the tradeoff between CSTBT's and FRD's performance and to eliminate snapback phenomena in the on-state of RC-CSTBT.In this paper,a 1700V RC-CSTBT is designed according to the actual conditions of the foundry.Work of the research is as follows:1.Establish the overall technological process of the structure.The whole process not only includes the production of the front emitter,the gate and the terminal,but also includes the production of the back FS Layer?Field Stop Layer?,P type collector area and N⁺short circuit area.The back FS layer is formed by high energy ion implantation,which reduces the thickness of the device and the injection efficiency of the back.2.Design and optimize the structure of CSTBT based on the required parameters of the device,includes CSTBT's forward blocking voltage BV,threshold voltage V_TH,saturation conduction pressure drop V_CE,sat and parasitic capacitance,etc.In the whole optimization process,the tradeoff between the process parameters and the performance of the device will all be considered,the optimized device performance conforms to all the design expectations.3.The design of 1700V RC-CSTBT is carried out on the basis of CSTBT optimized cell.It contains the optimization of the number of CSTBT cell and FRD cells to eliminate snapback phenomenon,the simulation of turn-off characteristic,the design of three terminal structures and the design of the layout.Through the simulation optimization of the design of 1700V RC-CSTBT,all the parameters are as follows:forward blocking voltage BV is 2270 V,the threshold voltage V_TH 5.1 V,the forward on-state saturation voltage drop V_CE,sat is 2.46 V,the fall time T_f under the IGBT mode is 178 ns.The layout of 1700V RC-CSTBT with current density of 100A/cm² is drawn.The area of active area is 45mm²,while the whole device area is 54.76mm².