Improvements on Breakdown Characteristics of FS- IGBT with Multi-Field Limited Ring Terminal Structure

The proper termination structure of the device can effectively improve the voltage capacity of IGBT. The phenomenon of electric field concentration can be reduced, and the breakdown voltage be increased, by using field limit multi-ring terminal structure. A physical model for silicon-based field cut-off IGBT with the field limited multi-ring structure was established. The dependence of the breakdown voltage on the structural geometric dimensions and the drift region doping concentration were simulated based on numerical simulation software in this paper. The surface electric field intensity and distribution when breakdown occurs was extracted by adjusting the ring spacing, and the breakdown mechanism was analyzed in depth. The breakdown voltage increases with the increase in number of field-limited rings and its doping concentration. It firstly increases and then decreases with the increase in junction depth of the field limited ring. The optimum technological parameters were obtained by comparing and analyzing, the number of field-limited rings N = 110, the doping concentration of field limited rings N _Pj =6×10 ¹⁷ cm ^-3 , its junction depth H _n =2 µm, the doping concentration of drift region N _d =1.6×10 ¹³ cm ^-3 , for which the maximum breakdown voltage of V _B =4518 V, and the stability and reliability of the devices are improved.