Electron Mobility In MOSFETs Research Articles

Impact of the Back-Gate Biasing on Trigate MOSFET Electron Mobility

In this brief, the influence of the back-gate biasing, V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">bg</sub> , on the electron mobility of Si trigates on ultrathin buried oxide is studied, using state of the art scattering models for 2-D confined devices. The variation of the back-gate influence with the device size is analyzed and explained addressing to the charge redistribution in the channel. The lower confinement of larger devices results in strong changes in the electron mobility as V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">bg</sub> is modified, contrary to what is observed in smaller devices. The charge redistribution due to V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">bg</sub> also affects the relative influence of the interface walls, which is analyzed in depth. The impact on the mobility of the main scattering mechanisms as a function of V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">bg</sub> is also discussed.

(Invited) Electrical Characterization and Reliability Assessment of Double-Gate FinFETs

The performance and reliability of doped and undoped (100)<100> and (110)<110> sidewall silicon-on-insulator (SOI) FinFETs with an Hf-based gate dielectric were evaluated. The electron mobility of the (110) FinFET sidewall is comparable to the (100) FinFET sidewall devices, which is opposite of the typical planar MOSFET electron mobility dependence on orientation, wherein (110) degrades significantly. In addition, TiN metal gate-induced strain cannot completely explain the similarity in (110) and (100) electron mobility because, although lower in magnitude, the two orientations with polysilicon electrodes resulted in similar mobility values. When investigating the orientation dependence of negative bias temperature instability (NBTI), (110) was found to cause more degradation than (100), and FinFETs with higher fin body doping demonstrated even more degradation.

Effect of Remote-Surface-Roughness Scattering on Electron Mobility in MOSFETs with High-k Dielectrics

In this paper, we developed a model for remote surface roughness scattering (RSR)-limited electron mobility in the inversion layer of nMOSFETs with high-k dielectrics. A Numerical method is applied to calculate RSR-limited electron mobility. It has been demonstrated that the RSR-limited electron mobility is highly degraded in the high electric field region.

Effect of Remote Surface Roughness Scattering on Electron Mobility in MOSFETs with High-k Dielectrics

not Available.

Effects of Channel and Crystalline Orientations on the Electron Mobility in MOSFETs Fabricated on (114) and (5 5 12)-Silicon Substrates

This work reports the measurement of the electron mobility in the inversion layer of MOSFETs fabricated on Si(114) and Si(5 5 12), for medium and high effective transverse electric fields, Eeff. We studied the channel mobility in these surfaces as a function of the channel direction [1-4]. Results reveal the strong influence on electron mobility of the channel direction on high-index surfaces. It was noted that mobility on high index-surfaces is degraded when the channel direction goes far away from , but it is less affected when the channel runs parallel to this direction. Even though Si(0 0 1) has been the surface with the highest electron mobility reported, we found that mobility on Si(1 1 4) is higher than that on Si(0 0 1) when Eeff {greater than or equal to} 0.4 MV/cm.

Modeling of remote Coulomb scattering limited mobility in MOSFET with HfO 2/SiO 2 gate stacks

The reduction of electron mobility in MOSFET with HfO 2/SiO 2 gate stack is analyzed using a model for remote Coulomb scattering (RCS) due to charges fixed at HfO 2/SiO 2 interface. The RCS limited mobility is calculated using the Kubo-Greenwood approach from 300K down to 100K. Our results show that a single value of charge density perfectly reproduce the degradation of mobility with an interfacial layer varying from 2nm down to 1nm in all the range of temperature. It means that soft optical phonon is not the limiting factor for the mobility and is probably masked by the large amount of charges.

Effects of Channel and Crystalline Orientations on the Electron Mobility in MOSFETs Fabricated on (114) and (5 5 12)-Silicon Substrates

not Available.

A MOSFET electron mobility model of wide temperature range (77 - 400 K) for IC simulation

Based on the physics of scattering mechanisms of MOSFET inversion layer carriers at different temperatures and vertical electric fields, a new unified mobility model of wide temperature (77 - 400 K) and range is proposed for IC simulation. Measurement data taken in a wide range of temperatures and electric fields are compared with the simulation results of a MOSFET current model implementing this new mobility equation. Excellent agreement between the simulation and measurement data is found.

Influence of the doping profile on electron mobility in a MOSFET

In this work, the actual effect of the doping profile on electron mobility in MOSFET channels has been studied. For this purpose, a one-electron Monte Carlo simulation has been used to calculate the electron mobility. The influence on the mobility of several ion-implanted profiles typical of present technology and of diffused profiles have been compared.

Semi-empirical model of electron mobility in MOSFETs in strong inversion regime

The authors present a semi-empirical model for the electron mobility in a MOSFET in the strong inversion region. The model includes the contribution of the coulomb, phonon and surface-roughness scattering, and reproduces experimental results with high accuracy in the 77–300 K temperature range. The authors analyse the influence of coulomb scattering on the different terms of the model after stressing the samples with successive Fowler-Nordheim tunnelling-injection series. In addition, it is shown that the terms a priori attributed to coulomb and phonon scattering receive the contribution of both mechanisms and thus cannot be separately attributed to each of them.

Influence of the oxide-charge distribution profile on electron mobility in MOSFET's

To characterize the effect of oxide-charge distribution on electron mobility in a MOSFET channel, a more precise method for obtaining the oxide-charge profile than CV measurement is needed. We have shown by Monte Carlo simulation that the effective interface-charge concentration obtained from threshold voltage measurements does not reproduce the actual effect that the oxide charge has on electron mobility. It is therefore absolutely necessary to know the real profile of the charge distribution. An analytical expression to obtain the interface-charge concentration which correctly models the effect of the actual oxide-charge distribution is calculated from Monte Carlo results.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Effects of bulk-impurity and interface-charge on the electron mobility in MOSFETs

The effects of interface and bulk-impurity charges on electron mobility in a MOSFET are compared by using Monte Carlo simulation. It has been shown that the increase in bulk-impurity concentration causes a reduction of mobility at low electric fields, in two ways: (i) an increase of Coulomb interaction produced by an increase of charges in the bulk; and (ii) the reduction of screening caused by the loss of charge in inversion layer. Except for high-doping levels, the latter is the most significant cause of mobility degradation.

Improved universal MOSFET electron mobility degradation models for circuit simulation

Based on the physical insights provided by the universal mobility curve, an improved comprehensive universal model for effective electron mobility in inversion layers of n-channel MOSFETs is developed for circuit simulation. This model expresses the effective electron mobility at room temperature as a function of effective vertical field. It exhibits a high degree of accuracy for a wide range of different device characteristics, such as channel doping levels, gate oxide thicknesses, and channel dimensions. In addition, it predicts very well the effective mobility under the effects of substrate biases for gate voltages well above threshold, which is an improvement over earlier models. Moreover, this model has been developed with an emphasis on the functional dependence of mobility on high effective field, and is thus particularly accurate in that range of effective field. This is a significant advantage of the model since today's submicrometer MOSFETs typically operate at high effective fields. >

Effect of rapid thermal reoxidation on the electrical properties of rapid thermally nitrided thin-gate oxides

The authors report a systematic study of the impact of post-nitridation rapid thermal anneals in oxygen and nitrogen on the electrical properties of MOS devices with thin gate oxides. A comparative study of the two annealing ambients has led to the formulation of qualitative models to describe the charge trapping properties of the respective gate dielectrics. Roles of the post-nitridation anneals in altering the radiation and hot-electron sensitivity of the MOS devices are investigated and explained on the basis of structural changes in the gate oxides during nitridation and subsequent annealing. The performance and reliability of MOSFETs with reoxidized nitrided gate oxides are investigated. Overall, the results indicate that reoxidized nitrided oxides show improved charge trapping properties, better resistance to radiation and hot-carrier stress, and improved high-field electron mobility in MOSFETs. >