Novel 1.2kV 4H-SiC Deep P-Well One-Channel MOSFET with Asymmetric Channel Design

This paper introduces a novel 1.2kV deep p-well 4H-SiC MOSFET with a one-channel layout, featuring a single active channel per unit cell to enhance the electrical characteristics. It was experimentally validated that the one-channel deep p-well MOSFET achieves a 65% reduction in input capacitance $(\mathbf{C}_{\mathbf{i}\mathbf{s}\mathbf{s}})$ and an average 13% decrease in specific on-resistance $(\mathbf{R}_{\mathbf{o}\mathbf{n},\mathbf{s}\mathbf{p}})$ despite there only being one active channel per unit cell. The one-channel deep p-well MOSFET achieves a lower $\mathbf{R}_{\mathbf{o}\mathbf{n},\mathbf{s}\mathbf{p}}$, not only due to its smaller cell pitch, but because of its asymmetric channel design. This asymmetry was introduced by aligning the p-well mask perpendicular to the $[11 \overline{2} 0]$ direction of the wafer during p-well implantation, leading to the active channel of the one-channel MOSFET being more accumulation mode and the inactive channel being more inversion mode. TCAD simulations were employed to support that the asymmetric channel design enhances the static electrical characteristics, while scanning electron microscopy (SEM) was utilized to verify that the fabricated devices align with the intended design.