Numerical simulation of advanced CMOS and beyond CMOS devices

Co-supervisore: Marco PalaopenLo scaling dei dispositivi elettronici e l'introduzione di nuove opzioni tecnologiche per l'aumento delle prestazioni richiede un costante supporto dal punto di vista della simulazione numerica. Questa tesi si inquadra in tale ambito ed in particolare si prefigge lo scopo di sviluppare due tool software completi basati su tecniche avanzate al fine di predire le prestazioni di dipositivi nano-elettronici progettati per i futuri nodi tecnologiciDottorato di ricerca in Ingegneria industriale e dell'informazioneembargoed_20131103Conzatti, Francesc

Study of the compounding process parameters for morphology control of LDPE/layered silicate nanocomposites

AbstractA careful insight into melt compounding procedure is proposed in order to achieve a better understanding and control of the dispersion and orientation mechanisms of organo-clay platelets into LDPE nanocomposites. The method involved is the preparation of a maleic anhydride grafted polyethylene masterbatch containing 10 wt% organo-clay via twin-screw extrusion. A substantial nanodispersion and orientation of clay platelets was obtained as observed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses. Moreover, the nanocomposites prepared by diluting the master-batch through the blend mixing with additional LDPE preserved or improved the exfoliation and lamellae orientation. Finally, the thermo-gravimetric analysis (TGA) showed a significant improvement of the thermal stability while both differential scanning calorimetry (DSC) and XRD evidenced a slight increase of the LDPE crystallinity degree with respect to neat polymer matrices thus suggesting the occurrence of orientation also for the polymer

Modeling of Field-Effect-Transistors with Strained and Alternative Channel Materials

In this paper we present a review of the modeling of strain effects in nano-scale transistors and we describe different approaches that can be followed in order to include the effect of strain in both conventional and innovative devices. We first describe the mathematical framework for the modeling of strain and then we present two important case-studies where we have successfully emploied advanced modeling techniques in order to investigate the effect of strain in germanium-based MOSFETs and in InAs Tunnel-FETs

Drain Current Improvements in Uniaxially Strained p-MOSFETs: a Multi-Subband Monte Carlo Study

This paper presents a Multi-Subband Monte Carlo study of the drain current improvements in uniaxially, compressively strained (0 0 1)/[1 1 0] p-MOSFETs and analyzes the ingredients through which the strain improves the long channel mobility as well as the I(ON) of nanoscale transistors. We first discuss the strain induced mobility enhancement and then address the effects of the strain on the I(ON). In particular, our results show that compressive stress in (0 0 1)/[1 1 0] p-MOS transistors increases the I(ON) by improving both the injection velocity and the back-scattering coefficient and that, furthermore, the back-scattering coefficients of the p-MOS transistors have values comparable to those of n-MOS devices with similar channel length

Alternative synthetic routes for the preparation of PLA∕montmorillonite nanocomposites

Although the improvement of tensile Modulus and thermal stability due to the addition of innovative organoclays to PLA were negligible, our investigation allowed to evidence that the preliminary preparation of an inorganic rich composite through in situ polymerization of lactyde gave a final morphology improved with respect to that achieved by simply melt dispersing organoclay powder. Anyway the former preparation method should be further investigated in order to control PLA structural features resulting from the ring opening polymerization synthesis

Investigation of strain engineering in FinFETs comprising experimental analysis and numerical simulations

his study combines direct measurements of strain, electrical mobility measurements, and a rigorous modeling approach to provide insights about strain-induced mobility enhancement in FinFETs and guidelines for device optimization. Good agreement between simulated and measured mobility is obtained using strain components measured directly at device level by a novel holographic technique. A large vertical compressive strain is observed in metal gate FinFETs, and the simulations show that this helps recover the electron mobility disadvantage of the (110) FinFET lateral interfaces with respect to (100) interfaces, with no degradation of the hole mobility. The model is then used to systematically explore the impact of stress components in the fin width, height, and length directions on the mobility of both n- and p-type FinFETs and to identify optimal stress configurations. Finally, self-consistent Monte Carlo simulations are used to investigate how the most favorable stress configurations can improve the on current of nanoscale MOSFETs