Browsing by Author "Tang, TW"

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A SPICE-compatible model for nanoscale MOSFET capacitor simulation under the inversion condition
(2002-12-01)
Tang, TW
;
Li, YM
;
友訊交大聯合研發中心
;
D Link NCTU Joint Res Ctr
A SPICE-compatible charge model for nanoscale MOSFETs is proposed. Based on the solution of Schrodinger-Poisson (S-P) equations, the developed compact charge model is optimized with respect to: 1) the position of the charge concentration peak; 2) the maximum of the charge concentration; 3) the total inversion charge sheet density; and 4) the average inversion charge depth, respectively. This model can predict inversion layer electron density for various oxide thicknesses and applied voltages. Compared to the S-P results, our model prediction is within 5% of accuracy. Application of this charge quantization model to the C-V measurement produces an excellent agreement., This compact model has continuous derivatives and is therefore amenable,to a device simulator. It can also be easily incorporated into circuit simulator for modeling ultrathin oxide MOSFET C-V characteristics.
Modeling of quantum effects for ultrathin oxide MOS structures with an effective potential
(2002-12-01)
Li, YM
;
Tang, TW
;
Wang, XL
;
友訊交大聯合研發中心
;
D Link NCTU Joint Res Ctr
In this paper, the effectiveness of the effective potential (EP) method for modeling quantum effects in ultrathin oxide MOS structures is investigated. The inversion-layer charge density and MOS capacitance in one-dimensional MOS structures are simulated with various substrate doping profiles and gate bias voltages. The effective mass is used as an adjusting parameter to compare results of the EP model with that of the Schrodinger-Poisson solution. The variation of this optimum parameter for various doping profiles at different gate voltages is investigated. The overestimated average inverse charge depth by the EP method is quantified and its reason explained. The EP model is a good practical simulation tool for modeling quantum effects but more work needs to be done to improve its accuracy near the interface.
Numerical simulation of quantum effects in high-k gate dielectric MOS structures using quantum mechanical models
(2002-08-01)
Li, YM
;
Lee, JW
;
Tang, TW
;
Chao, TS
;
Lei, TF
In this paper the electrical characteristics of metal oxide semiconductor (MOS) capacitors with high-k gate dielectric are investigated with quantum mechanical models. Both the self-consistent Schrodinger-Poisson (SP) model and the density gradient (DG) model are solved simultaneously to study quantum confinement effects (QCEs) for MOS capacitors. A computationally efficient parallel eigenvalue solution algorithm and a robust monotone iterative (MI) finite volume (FV) scheme for the SP and DG models are systematically proposed and successfully implemented on a Linux cluster, respectively. With the developed simulator, we can extract the effective gate oxide thickness from capacitance voltage (C-V) measurements for TaN and Al gate NMOS capacitors with ZrO2 and SiO2 gate dielectric materials. We found that quantization effects of 5.0 nut Z(r)O(2) MOS samples cannot be directly equivalent to commonly quoted effects of 1.5 nm SiO2 MOS samples. Achieved benchmarks are also included to demonstrate excellent performances of the proposed computational techniques. (C) 2002 Elsevier Science B.V. All rights reserved.