High-Frequency Switching Properties and Low Oxide Electric Field and Energy Loss in a Reverse-Channel 4H-SiC UMOSFET
Zhanwei Shen, Feng Zhang, Guoguo Yan, Zhengxin Wen, Wanshun Zhao, Lei Wang, Xingfang Liu, Guosheng Sun, Yiping Zeng
Abstract
A reverse-channel 4H-SiC trench gate metaloxide-semiconductor field-effect transistor (UMOSFET) (RC-MOS) is proposed in this article. The RC-MOS is demonstrated to have low specific ON-resistance (RON,sp) by numerical simulation. The trench oxide in the RC-MOS is fully protected by the n+ source, the p-shield, and the p-base regions. Thus, a reduced trench corner field far below 3 MV/cm can be achieved in both the OFFand ON-state. Furthermore, the gate-to-drain charge (QGD) of the RC-MOS is 33 nC/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , which is much lower than that of the dual buffer layer MOSFET (DB-MOS), owing to little overlap between the gate and drain electrodes. Consequently, the RC-MOS exhibits the superior figures of merit QGD x RON,sp = 82 mΩ·nC. Due to the low reverse transfer capacitance and gate charges in the RC-MOS, the total switching loss of 570 μJ/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> is decreased by 64.5% in comparison to that of the DB-MOS. These superior properties show that the proposed UMOSFET can be a good candidate for further improvements in the gate oxide reliability and high-frequency performance of SiC MOSFETs.