An iterative technique based on device transport and continuity equations is used to formulate a unified nonquasi-static model for the long-channel four-terminal MOSFET for both transient and small-signal analyses in all regions of operation (weak, moderate, and strong inversion). The model is physically derived without resorting to the concept of channel charge partitioning or the use of a priori assumptions about the functional form of the channel charge density. It is shown that the Ward charge-based model is only a 0th-order solution of this formulation. The first-order solution presented here holds for arbitrary time-varying input voltages and can be reduced exactly to a recently proposed small-signal nonquasi-static admittance model. Relaxation due to the channel resistance is included to account for the device nonquasi-static transient behavior. The first-order model consists of simple ordinary differential equations, which can be easily discretized for solution. Results from the proposed model are examined and compared with numerical simulation results and experimental data. Good agreement has been obtained. I. INTRODUCTIONYNAMIC modeling of the long-channel four-termi-D nal MOSFET for large-and small-signal analyses of MOS integrated circuits has always been undertaken as two separate tasks. This is due to the fact that the coupled device current transport and continuity equations are extremely difficult to solve under arbitrary time-varying input voltages. Only under the simplified case of a threeterminal MOSFET with the bulk effect neglected and with small sinusoidal signals superimposed on the terminal bias voltages can the coupled equations be solved [1]- [3]. In order to include the bulk effect, a linearized bulk-charge density was recently used by Bagheri and Tsividis [4] to formulate, for the first time, a small-signal nonquasi-static admittance model for the four-terminal MOSFET that is valid in all regions of operation (weak, moderate, and strong inversion). The formulation of large-signal models for transient analysis under arbitrary time-varying input voltages is therefore a formidable task, and existing ,
SUMMARYThis paper reviews the state of the art in hydrodynamic simulation of hot-carrier transport in semiconductor devices with application to MOSFET substrate current calculation. Hydrodynamic equations for semiconductors and derived and discretized expressions of these equations for device simulation are presented. Special attention has been given to the discretization of the input power term that appears in the energy conservation equation. A new discretization method for the input power term, based on power generation consideration, is proposed. Energy-based physical models for mobility and impact ionization are described for use in hydrodynamic simulation. Simulation results for both conventional and lightly-doped-drain MOSFETs are presented.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.