Ultra-scaled Devices Research Articles

Single-electron phenomena in ultra-scaled floating-gate devices and their impact on electrical characteristics

In this paper, single-electron effects are firstly evidenced on nanoscale floating-gate memory devices and their impact on some electrical characteristics is studied. During this work, these phenomena have been put in evidence as well as on transfer characteristics than on I D-time measurements for a wide range of device area. After showing that the amplitude of discrete threshold voltage shifts due to single-electron transfer (δ V TH) is inversely proportional to the device area, the impact of these phenomena on retention characteristics has been quantified and discussed for ultra-scaled memory devices, with dimensions reduced to 40 × 30 nm 2. It is shown that the intrinsic reliability of these devices is affected by the stochastic nature of single-electron transfer.

An improved semi-classical Monte-Carlo approach for nano-scale MOSFET simulation

A conventional Monte-Carlo simulator has been extended to include electrostatic and transport effects that are most relevant for the analysis of nano-scale MOSFETs with either bulk or single and double gate silicon-on-insulator (SOI) architectures and silicon film thickness down to approximately 10 nm. Corrections to the self-consistent electrostatic potential and a new model for the surface roughness scattering have been included. The effectiveness of the approach has been tested simulating carrier transport in a 25 nm double gate SOI MOSFET. The simulation results point out the strong influence of the scattering on the ON current even in these ultra-scaled devices.

Modeling of the programming window distribution in multinanocrystals memories

In this paper, the impact of the Si nanocrystals technological fluctuations on the programming window dispersion of multi nanocrystals memory is thoroughly investigated. Technological dispersions of different nanocrystals populations, directly measured by high-resolution transmission electron microscopy, are used as starting points for the modeling of the device characteristics. Numerical Monte Carlo simulations as well as an original compact modeling, based on the compound distributions (CD) statistics, are here presented. Exact analytical results (CD model), approximated analytical results (CD+Central Limit Theorem model) and numerical results (numerical convolution) are deeply discussed. Finally, the good agreement between our simulations and experimental data of ultrascaled nanocrystal devices, made by conventional UV lithography or by e-beam lithography, definitively confirms the validity of our theoretical approach.