Analysis of high-voltage metal–oxide–semiconductor transistors with gradual junction in the drift region

Abstract

The device characteristics and hot-carrier-induced degradation of high-voltage n-type metal–oxide–semiconductor transistors with traditional and gradual junctions in the drift region are studied in this work. The gradual junction used in this study is realized by self-aligned N− implantation through dual thicknesses of screen oxide during N− drift implantation. Compared with traditional devices, devices with gradual junctions have improved off-state breakdown voltage (VBD) without sacrificing on-state driving current and hot-carrier-induced degradation. More improvement in VBD is observed if the dimensions of the device are larger. The mechanism responsible for VBD improvement in devices with gradual junctions is also investigated by using technology computer-aided-design simulations.