一种低功耗4H-SiC IGBT的仿真研究

针对传统沟槽栅4H-SiC IGBT关断时间长且关断能量损耗高的问题,文中利用Silvaco TCAD设计并仿真了一种新型沟槽栅4H-SiC IGBT结构。通过在传统沟槽栅4H-SiC IGBT结构基础上进行改进,在N ⁺缓冲层中引入两组高掺杂浓度P区和N区,提高了N ⁺缓冲层施主浓度,折中了器件正向压降与关断能量损耗。在器件关断过程中,N ⁺缓冲层中处于反向偏置状态的PN结对N ^-漂移区中电场分布起到优化作用,加速了N ^-漂移区中电子抽取,在缩短器件关断时间和降低关断能量损耗的同时提升了击穿电压。Silvaco TCAD仿真结果显示,新型沟槽栅4H-SiC IGBT击穿电压为16 kV,在15 kV的耐压设计指标下,关断能量损耗低至4.63 mJ,相比传统结构降低了40.41%。

Simulation Study of a Low Power 4H-SiC IGBT

In this paper, a new trench gate 4H-SiC IGBT structure is designed and simulated by Silvaco TCAD for the problem that the traditional trench gate 4H-SiC IGBT has long turn-off time and high turn-off energy loss. By improving the structure of the conventional trench gate 4H-SiC IGBT, two sets of high doping P and N layers are introduced in the N ⁺ buffer layer to increase the donor concentration of the N ⁺ buffer layer, which compromises the forward voltage drop of the device and turn off the energy loss. The PN junction in the reverse bias state in the N ⁺ buffer layer optimizes the electric field distribution in the N ^-drift region when the device is in the turn-off process, which accelerates the electron extraction in the N ^-drift region and shortenes the turn-off time of the device. This ultimately reduces the turn-off energy loss of the device and increases the breakdown voltage of the device. Silvaco TCAD simulation results show that the new trench gate 4H-SiC IGBT has a breakdown voltage of 16 kV. Compared with the conventional structure with a breakdown voltage of 15 kV, the turn-off energy loss is as low as 4.63 mJ, which is 40.41% lower than the conventional structure.