Numerical Simulation Analysis of Switching Characteristics in the Source-Trench MOSFET’s

Jinhee Cheon,Kwangsoo Kim

doi:10.3390/electronics9111895

Abstract

In this paper, we compare the static and switching characteristics of the 4H-SiC conventional UMOSFET (C-UMOSFET), double trench MOSFET (DT-MOSFET) and source trench MOSFET (ST-MOSFET) through TCAD simulation. In particular, the effect of the trenched source region and the gate trench bottom P+ shielding region on the capacitance is analyzed, and the dynamic characteristics of the three structures are compared. The input capacitance is almost identical in all three structures. On the other hand, the reverse transfer capacitance of DT-MOSFET and ST-MOSFET is reduced by 44% and 24%, respectively, compared to C-UMOSFET. Since the reverse transfer capacitance of DT-MOSFET and ST-MOSFET is superior to that of C-UMOSFET, it improves high frequency figure of merit (HF-FOM: RON-SP × QGD). The HF-FOM of DT-MOSFET and ST-MOSFET is 289 mΩ∙nC, 224 mΩ∙nC, respectively, which is improved by 26% and 42% compared to C-UMOSFET. The switching speed of DT-MOSFET and ST-MOSFET are maintained at the same level as the C-UMOSFET. The switching energy loss and power loss of the DT-MOSFET and ST-MOSFET are slightly improved compared to C-UMOSFET.

Highlights

4H-SiC MOSFETs are widely considered to be the leading next-generation power semiconductor devices due to their superior material properties, such as high critical electric field, high thermal conductivity, and ability to operate at high temperatures [1,2]
The high frequency figure of merit (HF-FOM) of DT-MOSFET and ST-MOSFET is 289 mΩ·nC, 224 mΩ·nC, respectively, which is improved by 26% and 42% compared to C-UMOSFET
The switching energy loss and power loss of the DT-MOSFET and ST-MOSFET are slightly improved compared to C-UMOSFET

Summary

Introduction

4H-SiC MOSFETs are widely considered to be the leading next-generation power semiconductor devices due to their superior material properties, such as high critical electric field, high thermal conductivity, and ability to operate at high temperatures [1,2]. In the case of SiC UMOSFETs, it is very important to suppress electric field crowding at the gate oxide edge To address this problem, a structure which includes a gate trench bottom P+ shielding region (BPR) has been proposed [12,13,14,15]. As a variant of the double trench, a source trench structure for the double trench structures have been most actively studied in recent years with regard to their distributing the electric field through thermally grown oxide has been proposed [26]. In the case of the double trench structure, the source region dynamic characteristics of the 1700 V source trench MOSFET structure have not been actively and gate are both trenched. Dynamic characteristics of the 1700 V source trench MOSFET structure have not been actively discussed.

Device

Static Characteristics

Terminal Capacitance Characteristics

Dynamic Charateristics

Conclusions

Results