Improved On-Current of 4H-SiC MOSFETs with a Three-Dimensional Gate Structure

Abstract

4H-SiC (0001) MOSFETs with a three-dimensional gate structure, which has a top channel on the (0001) face and side-wall channels on the {11-20} face have been fabricated. The three-dimensional gate structures with a 1-5 m width and 0.8 m height have been formed by reactive ion etching, and the gate oxide has been deposited by plasma-enhanced chemical vapor deposition and then annealed in N2O ambient at 1300°C. The fabricated MOSFETs have exhibited superior characteristics: ION / IOFF, the subthreshold swing and VTH are 1010, 250 mV/decade and 3.5 V, respectively. The drain current normalized by the gate width is increasing with decreasing the gate width. The normalized drain current of a 1 m-wide MOSFET is ten times higher than that of a conventional planar MOSFET.