690V, 1.00 mΩcm<sup>2</sup> 4H-SiC Double-Trench MOSFETs

The trench gate structure MOSFET, with its lack of JFET resistance, is one of the structures able to achieve low on-state resistance [1,2]. In 2008, this group succeeded in fabricating 790V SiC trench MOSFETs with the lowest R on,sp (1.7 mΩcm 2 ) at room temperature. However these devices had issues regarding oxide destruction at the trench bottom during high drain-source voltage application. In order to improve this problem, this group developed the double-trench MOSFET structure. This structure has both source trenches and gate trenches. This paper compares two kinds of trench MOSFETs: the conventional, single trench structure and a double-trench structure. Also, the latest characteristics are presented.