An Inversion-Charge Analytical Model for Square Gate-All-Around MOSFETs (original) (raw)
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Inversion Charge Quantization Model for Double Gate MOSFETs
Nanoscience &Nanotechnology-Asia, 2018
In this article we have developed an analytical model for Double gate Metal Oxide Semiconductor Field Effect Transistor (DG MOSFET) including Quantum effects. The Schrodinger-Poisson's equation is used to develop the analytical Quantum model using Variational method. A mathematical expression for charge centroid is obtained and then an inversion charge model was developed with quantum mechanical effects by means of oxide capacitance for different channel thickness and gate oxide thickness.
A new explicit and analytical model for square Gate-All-Around MOSFETs with rounded corners
Solid-State Electronics, 2015
The scaling of MOSFET transistors makes the use of new device geometries, such as multigate FETs, a need to solve the limitations of the conventional bulk technology. In this context we introduce an analytical model for square Gate All Around (GAA) MOSFETs with rounded corners including quantum effects. The modeling of rounded corners in GAA and FinFET devices is imperative because there are no perfectly square corners in the cross-section of real devices. In this model the 2D inversion charge distribution function (ICDF) is described analytically for devices of different sizes and for different operation regimes. The model reproduces accurately simulated data obtained with a state-of-the-art simulator that solves self-consistently the Poisson and Schrödinger equations in the devices under consideration. The analytical ICDF is used to better understand the device physics and to calculate the inversion charge centroid and the gate-to-channel capacitance for different device geometries and biases for modeling purposes.
An analytical model for square GAA MOSFETs including quantum effects
Solid-State Electronics, 2010
In this paper we introduce an analytical model for square Gate-All-Around (GAA) MOSFETs including quantum effects. With the model developed, it is possible to provide an analytical description of the 2D inversion charge distribution function (ICDF) in square GAA MOSFETs of different sizes and for all the operational regimes. The accuracy of the model is verified by comparing the data with that obtained by means of a 2D numerical simulator that self-consistently solves the Poisson and Schrödinger equations. The expressions presented here are useful to achieve a good description of the physics of these transistors; in particular, of the quantization effects on the inversion charge. The analytical ICDF obtained is used to calculate important parameters from the device compact modeling viewpoint, such as the inversion charge centroid and the gate-to-channel capacitance, which are modeled for different device geometries and biases. The model presented accurately reproduces the simulation results for the devices under study and for different operational regimes.
An explicit analytical charge-based model of undoped independent double gate MOSFET
Solid-state Electronics, 2006
This paper describes an explicit analytical charge-based model of an undoped independent double gate (DG) MOSFET. This model is based on Poisson equation resolution and field continuity equations. Without any fitting parameter or charge sheet approximation, it provides explicit analytical expressions of both inversion charge and drain current considering long undoped transistor. Consequently, this is a fully analytical and predictive model allowing describing planar DG MOSFET as well as FinFET structures. The validity of this model is demonstrated by comparison with Atlas simulations.
IEEE Transactions on Electron Devices, 2008
A semiempirical model was developed for calculating the inversion charge of cylindrical surrounding gate transistors (SGTs), including quantum effects. To achieve this goal, we used a simulator that self-consistently solves the 2-D Poisson and Schrödinger equations in a cross section of the SGT. By means of the proposed models, we correctly reproduced the simulation data for a wide range of the device radius and gate voltage values. Both the inversion charge and the centroid models consist of simple mathematical equations within an explicit calculation scheme suitable for use in circuit simulators.
Semi-analytical non-charge-sheet and non-depletion MOS model, for inversion charge calculation
International Journal of Numerical Modelling: Electronic Networks, Devices and Fields, 2013
A new computationally implemented semi-analytic mathematical model is presented to obtain a more accurate estimation of the inversion charge in a MOS structure than standard models. The values of the error of the inversion charge obtained are compared with the assumed 'exact' numerical calculated values. These errors are appreciably smaller than the estimation coming from the classical charge-sheet and depletion approximations. Also the calculation time to obtain the inversion charge is shown to be significantly lower than the numerical one. Because of its accuracy and its relatively low computational speed, the proposed model is a good alternative methodology for the calculation of the inversion charge of MOSFET transistors as a function of their physical features and gate bias voltage. In this sense it should be very useful to be implemented by computer-aided design integrated circuit simulation software.
Effects of the inversion-layer centroid on the performance of double-gate MOSFETs
IEEE Transactions on Electron Devices, 2000
The role of the inversion-layer centroid in a double-gate metal-oxide-semiconductor field-effect-transistor (DGMOSFET) has been investigated. The expression obtained for the inversion charge is similar to that found in conventional MOSFET's, with the inversion-charge centroid playing an identical role. The quantitative value of this magnitude has been analyzed in volume-inversion transistors and compared with the value obtained in conventional MOSFETs. The minority-carrier distribution has been found to be even closer to the interfaces in volume-inversion transistors with very thin films, and therefore, some of the advantages assumed for these devices are ungrounded. Finally, the overall advantages and disadvantages of double-gate MOSFET's over their conventional counterparts are discussed.
Solid-State Electronics, 2007
An explicit current-voltage model for undoped double-gate MOSFETs based on an accurate analytic approximation to the carrier concentration is presented in this paper. An analytic approximation solution to the carrier (electron) concentration is derived from the Taylor expansion of the exact solution of the Poisson equation. This analytic approximation gives a highly accurate result of the electron concentration when compared with that evaluated by Newton-Raphson iterative. The resulting electron concentration is then coupled to the Pao-Sah current equation to produce an explicit current-voltage model for symmetric undoped double-gate MOSFETs. The model predictions have been extensively validated by numerical simulations.
IEEE Transactions on Electron Devices, 2008
This paper presents a rigorously-derived analytical solution of the Poisson equation with both electrons and holes in pure silicon, which is applied to the analysis of undoped symmetric double-gate transistors. An implicit surface-potential equation is obtained that can be solved by a second-order Newton-Raphson technique along with an appropriate initial guess. Within the assumption of holes at equilibrium that is being used in the existing literature, the new results, when compared with the models based on one carrier, reveal that missing the other carrier in the formulation results in a singularity in the gate capacitance exactly at flatband, which may give trouble for high-frequency analysis, although the errors in surface potentials are below the nano-volt range for all gate voltages. However, the solution without assuming constant hole imref, as presented in this paper for the first time, further pinpoints the inadequacy in existing theories of surfacepotential solutions in double-gate MOSFETs with undoped thin bodies, although its application to transport solutions of terminal current/charge models depends highly on the type of source/drain structures and contacts.
IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, 1989
A mobility curve for electrons in MOSFET's inversion charge layer is determined from measured drain current of transistors produced by a wide range of MOS technologies. A comparison between this mobility curve and previously published results shows that a truly universal mobility curve does not exist and only "local" universal mobility curves can be expected, i.e., unique mobility curves which are valid over a finite range of MOS technologies and/or over a particular set of fabrication facilities. However, its basic characteristics of being technology independent over a wide range of process variation point out the potential of using such a local universal mobility curve as a powerful basis for developing predictive device modeling tools. This potential is demonstrated for an analytical MOSFET model and a twodimensional device simulator where the mobility models have the general characteristics of experiment based local universal mobility curves.