Modeling and Simulation of Dual Metal Quadruple Gate (DMQG) MOSFETs

Abstract

In an ever-increasing need for higher current drive and better short-channel characteristics, Silicon-On-Insulator (SOI) Metal-Oxide-Semiconductor (MOS) transistors are evolving from classical, planar, single-gate devices into three-dimensional devices with multiple gates. Multiple-gate (MuG) MOSFET structures can achieve superior electrostatic integrity than the conventional bulk MOSFET structure and hence offer a pathway to lower drain voltage, reduced threshold voltage,and extended transistor scaling.Among the MuG MOSFETs, quadruple gate (QG) MOSFETis the most promising structure as the channel remains surrounded by four gates, which provide ultimate control over the charge carrier in the channel region. In this thesis, we are intended to analytically analyze the subthreshold characteristics of dual-metal quadruple gate (DMQG) MOSFETs. In brief, attempts have been made to present analytical models for threshold voltage,drain-induced barrier lowering (DIBL), subthreshold current, and subthreshold swing parameters for DMQG MOSFETs in nanometer regime.Moreover, attempts have also been made to presentthe analytical models of subthreshold characteristics of ultra-thin DMQG MOSFETsby considering the quantum confinement effects.The model results are analyzed with wide variations in the device parameters like gate metal work functions, channel cross-section (width × height), channel length, oxide thickness, and gate length ratios.Further, the analytical modeling of drain current, transconductance, and drain conductance characteristics have been presented forDMQG MOSFETs.Finally, The cut-off frequency (𝑓𝑇) and the maximum frequency of oscillation (𝑓𝑚𝑎𝑥) of the proposed structure are analyzed in detailfor RFcircuitsandsystems.The validity of the analytical models is verified by comparing model results with the numerical simulation results obtained from ATLAS™, a device simulator from SILVACO Inc.