A New SiC Quasi MOSFET for Ultra-Low Specific On-Resistance and Improved Reliability

Abstract

In this paper, a new ultra-low specific on-resistance quasi SiC MOSFET is proposed. Compared with the conventional SiC MOSFET, the proposed quasi SiC MOSFET has no problems caused by low channel mobility and gate oxide reliability. And compared with the conventional SiC JFET, the proposed quasi SiC MOSFET is a normally-off device without the controllability issue of the normally-on device. Through simulation, it is found that the specific on-resistance $(R_{\mathrm{ on,sp}})$ of the proposed quasi SiC MOSFET is 2.46m $\Omega \cdot $ cm 2, while the $R_{\mathrm{ on,sp}}$ of the conventional SiC MOSFET is 3.29 $\text{m}\Omega \cdot $ cm 2, with a reduction of more than 25% at almost the same breakdown voltage. In the forward conduction state, the saturation current of the proposed quasi SiC MOSFET is smaller than that of the conventional SiC MOSFET at $V_{\mathrm{ GS}}\,\,=$ 15V and 20V, which shows that the proposed quasi SiC MOSFET has a better safe operating area (SOA) and better short-circuit capability. Compared with the conventional SiC MOSFET, the Figure-of-Merit (FOM) of the proposed device is improved by 38%. In addition, since the proposed structure is sustaining voltage by the high voltage JFET cell without a gate oxide layer, it is suggested that the proposed device does not have gate oxide reliability problems.