p型突出屏蔽区4H-SiC UMOSFET结构仿真研究

Simulation study of 4H-SiC UMOSFET structure with p type prominent shielded region

研究了一种新型4H-Si C U型槽栅金属氧化物半导体场效应晶体管(UMOSFETs)结构.该结构中的p-body区下方有一p型突出屏蔽区.在关态下,该p型突出屏蔽区能够有效的保护栅氧化层,降低栅氧电场,提高击穿电压.在开态下,该p型屏蔽区并没有对器件的电流产生阻碍作用,并没有带来JFET电阻效应,能够有效的降低器件导通电阻.此外,该结构表面还集成了poly Si/Si C异质结二极管,降低了器件的反向恢复电荷,从而改善器件的反向恢复特性.仿真结果显示,与p+-Si C屏蔽区UMOSFET结构比较,该新结构的特征导通电阻降低了53. 8%,反向恢复电荷减小了57. 1%.

A new type of 4H -SiC U-shape gate metal oxide semiconductor field effect tran-sistor （UMOSFETs） structure was studied in this paper. There was a p type prominent shiel-ding region under the p - body region in the structure. Under the off - state, the p - typeprominent shielded region can effectively protect the gate oxide layer, reduce the gate oxideelectric field and improve the breakdown voltage. Under on - state, the p shielded region didnot impede the current of the device, and also did not bring JFET resistance effect. It can ef-fectively reduce the on -resistance of the device. In addition, the polySi/SiC heterojunctiondiode was also integrated on the surface of the structure, which reduced the reverse charge ofthe device and improved the reverse recovery characteristic of the device. The simulation re-suits showed that the on - resistance of the new structure was reduced by 53.8 % and the re-verse recovery charge was reduced by 57.1% compared with the p ＋ - SiC shielded UMOS-FET structure.