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A simple analytical expression of the 3-D potential distribution along the channel of lightly doped silicon trigate MOSFETs in weak inversion is derived, based on a perimeter-weighted approach of symmetric and asymmetric double-gate MOSFETs. The analytical solution is compared with the numerical solution of the 3-D Poisson's equation in the cases where the ratios of channel length/silicon thickness and channel length/channel width are ≥ 2. Good agreement is achieved at different positions within the channel. The perimeter-weighted approach fails at the corner regions of the silicon body; however, by using corner rounding and undoped channel to avoid corner effects in simulations, the agreement between model and simulation results is improved. By using the extra potential induced in the silicon film due to short-channel effects, the subthreshold drain current is determined in a semianalytical way, from which the subthreshold slope, the drain-induced barrier lowering, and the threshold voltage are extracted. [ABSTRACT FROM AUTHOR]

A simple threshold voltage model of an undoped symmetrical double-gate MOSFET has been developed, based on an analytical solution of Poisson's equation for the potential distribution. The model has been verified by comparing the threshold voltage roll-off with the channel length with simulation results for different silicon thicknesses, gate oxide thicknesses, and drain voltage values. Good agreement between model and simulation results is obtained by calibrating the minimum carrier charge sheet density adequate to achieve the turn-on condition. [ABSTRACT FROM AUTHOR]

A simple analytical expression of the 2-D potential distribution along the channel of silicon symmetrical double-gate (DG) MOSFETs in weak inversion is derived. The analytical solution of the potential distribution is compared with the numerical solution of the 2-D Poisson's equation in terms of the channel length L, the silicon thickness tox, and the gate oxide thickness sSi. The obtained results show that the analytical solution describes, with good accuracy, the potential distribution along the channel at different positions from the gate interfaces for well-designed devices when the ratio of L/tSi is ≥ 2-3. Based on the 2-D extra potential induced in the silicon film due to short-channel effects (SCEs), a semi-analytical expression for the subthreshold drain current of short-channel devices is derived. From the obtained subthreshold characteristics, the extracted device parameters of the subthreshold slope, drain-induced barrier lowering, and threshold voltage are discussed. Application of the proposed model to devices with silicon replaced by germanium demonstrates that the germanium DG MOSFETs are more prone to SCEs. [ABSTRACT FROM AUTHOR]

Abstract: Integrated circuits for analog and telecom applications require metal insulator metal (MIM) capacitors with not only a high capacitance value (typically 5nF/mm2), but also a low series resistance R s. The optimization of this latter parameter is investigated in this paper, by means of a simple analytical model, taking into account both the impact of material parameters and device architectures, suggesting possible strategies for R s minimization. Such a model is also suitable for MIM circuit simulation, and can be also extended to other devices, such as to the gate series resistance modeling of RF MOSFET. Results are in good agreement with numerical simulations and HF measurements, performed on state of the art planar MIM devices. Moreover, discussion on via placement to access the top electrode has been held, in order to optimize the series resistance of the capacitor. [Copyright &y& Elsevier]

Highlights: [•] DIBL and SS are not affected by quantum confinement effects in subthreshold regime. [•] Higher dielectric constant of III–V materials is the dominant cause of SCE increase. [•] In the strong-inversion regime, quantum effects cause DIBL increase in III–V MOSFETs. [ABSTRACT FROM AUTHOR]

Abstract: A simple analytical threshold voltage model for lightly doped tri-gate MOSFETs has been developed, using the superposition of the threshold voltages of a symmetric and an asymmetric double-gate MOSFET. The model has been verified by comparison with experimental and simulation results of tri-gate FinFETs with various fin widths and channel lengths. Excellent agreement between model, experimental and simulation results is obtained, demonstrating the validity of the proposed threshold voltage model. [Copyright &y& Elsevier]

Abstract: The impact of the spacer length at the source (L s) and drain (L d) on the performance of symmetrical lightly-doped double-gate (DG) MOSFET with gate length L =20nm is analyzed, with the type and doping concentration of the spacers kept the same as in the channel material. Using the transport parameters extracted from experimental data of a double-gate FinFET, simulations were performed for optimization of the underlapped gate-source/drain structure. The simulation results show that the subthreshold leakage current is significantly suppressed without sacrificing the on-state current for devices designed with asymmetrical source/drain extension regions, satisfying the relations L s = L/2 and L d = L. In independent drive configuration, the top-gate response can be altered by application of a control voltage on the bottom-gate. In devices with asymmetrical source/drain extension regions, simulations demonstrate that the threshold voltage controllability is improved when the drain extension region length is increased. [ABSTRACT FROM AUTHOR]

Abstract: An analytical drain current model for undoped (or lightly-doped) symmetric double-gate (DG) MOSFETs is presented. This model is based on the subthreshold leakage current in weak inversion due to diffusion of carriers from source to drain and an analytical expression for the drain current in strong inversion of long-channel DG MOSFETs, both including the short-channel effects. In the saturation region, the series resistance, the channel length modulation, the surface-roughness scattering and the saturation velocity effects were also considered. The proposed model has been validated by comparing the transfer and output characteristics with simulation and experimental results. [Copyright &y& Elsevier]