Drain-extended MOS design using High-k dielectric to control off-state BTBT with enhanced switching performance

Abstract

This work explores the application of high-k dielectric to suppress off-state band-to-band tunneling (BTBT) and enhance the switching performance of conventional Drain-extended NMOS (C_DeNMOS). C_DeNMOS switching performance is limited by extended gate over the drift region, while the high field effects near the gate edge are responsible for BTBT below the gate-to-drain overlap region. We investigate two improved configurations of DeNMOS (1) Planar and (2) Trench structures incorporating a floating plate (FP). In comparison to C_DeNMOS, it is demonstrated that employing high-k dielectric HfO2 with appropriately doped FP in the Planar and Trench structures can efficiently modulate the surface field while also reducing surface charge accumulation. As a result, BTBT is suppressed in Planar and Trench structures when HfO2 is used as dielectric, in addition to improvement in switching delay, reverse recovery behavior, and switching energy performance at higher operating frequencies.