Fabien Rozé

Bio: Fabien Rozé is an academic researcher. The author has an hindex of 1, co-authored 1 publications receiving 3 citations.

Study of Thermal Oxidation of SiGe for Advanced CMOS FD-SOI Technologies

Abstract: La reduction continue des dimensions des transistors depuis les annees 60 est a l’origine de l’explosion des usages de l’electronique. Toutefois, la reduction des dimensions a l’echelle nanometrique s’accompagne de nouvelles difficultes qui tendent a limiter les gains des transistors en termes de performances et de consommation.Afin de surmonter ces obstacles et maintenir cette dynamique, des canaux a base de nouveaux materiaux a forte mobilite et de nouvelles architectures de transistors sont desormais utilisees ou a l’etude. L’interet de films SiGe contraint en compression sur isolant (SGOI: SiGe-On-Insulator) ultra-minces est double : ils beneficient de la forte mobilite des trous du SiGe contraint en compression ainsi que du meilleur controle electrostatique des structures dites « sur isolant ». Des films SGOI presentant une forte concentration en Ge et une importante contrainte peuvent etre fabriques par une technique industrielle appelee condensation. Cette technique repose sur deux processus simultanes : l’oxydation thermique et selective du SiGe (seul le Si est oxyde) et l’inter-diffusion du SiGe entre l’oxyde thermique et l’oxyde enterre qui se comporte comme une barriere a la diffusion.L’utilisation de cette technique dans un environnement industriel necessite de relever deux defis : maitriser les mecanismes et la cinetique d’oxydation, et atteindre les plus fortes contraintes et qualites cristallines pour lesfilms SGOI.La cinetique de plusieurs procedes d’oxydation industriels et pertinents au regard des besoins technologiques actuels est etudiee a l’aide d’une nouvelle methodologie d’analyse quantitative. Nous etablissons une correlationentre le coefficient de diffusion de l’espece oxydante, qui determine la cinetique d’oxydation, la concentration en Ge a l’interface d’oxydation, et la densite de l’oxyde mesuree par reflectivite de rayons X sur une ligne desynchrotron.Puis, nous avons fabrique des films SGOI presentant des concentrations en Ge jusqu’a 80%. Nous discutons l’evolution de la contrainte de ces films en fonction des parametres du procede et des niveaux de contrainte. Enfin,nous mettons en evidence les effets du procede de condensation sur la qualite cristalline du film SiGe aux interfaces avec les oxydes grâce a l’effet de canalisation d’une technique de retrodiffusion d’ions a moyenne energie (MEIS : Medium Energy Ion Scattering)

A novel dual isolation scheme for stress and back-bias maximum efficiency in FDSOI Technology

Abstract: A novel dual isolation scheme with both Shallow Trench Isolation (STI) and local oxidation, so called Dual Isolation by Trenches and Oxidation (DITO), is presented to maximize the stress induced by SiGe channel and the back-biasing efficiency at the same time in FDSOI technology. DITO integration experimentally demonstrates +36% pMOSFET drive current at same leakage, which is translated into −23% ring-oscillator delay reduction at a supply voltage of V dd =0.8V. It is found that this gain is attributed to 0.45GPa saved compressive stress in the longitudinal direction, compared to the standard STI isolation. On top of that, DITO enables the Vt tuning in an extended range for both nMOS and pMOS independently through back-bias application in both reverse and forward modes. +29% and 1 decade leakage extensions are provided by this full range Vt tuning compared to the standard single STI and well FDSOI architecture where only one back-bias mode is allowed. DITO thus leverages highly-stressed and highly-tunable devices for both high performance and low power applications.

Reduced oxygen partial pressure SiGe condensation for the fabrication of compressively strained SGOI substrates

Abstract: We report the use of a low oxygen partial pressure dry furnace oxidation process for the fabrication of ultra-thin compressively strained SGOI layers. The effect of a reduced oxygen partial pressure on oxidation kinetics and Ge depth profile evolution is shown. Resulting strain, SiGe surface and roughness evaluation are carried out to compare the residual strain values and the crystal defects generation to results obtained with a conventional pure oxygen process.

Effect of Deposition Conditions on Oxide Parameters of Silicon

Abstract: In this study, the effect of deposition conditions and the temperature thermal treatment on the oxide parameters of two structures of silicon layers were investigated. The study present the evolution of in situ boron profiles following a dry thermal oxidation in poly-Si/SiO2 /c-Si films deposited at 520°C and 605°C temperatures and thermally oxidized in dry oxygen at respectively temperature 840°C, 945°C and 1050°C for duration tr=1h33’. The results show that the deposition conditions and the temperature treatment make a very important impact on the obtained films, which affect the redistribution and localization of dopants. It has been observed that the obtained value of the linear and the parabolic rate constant, the diffusion coefficient and the oxidation thickness are higher in the films deposited at Td = 520°C than those deposited at Td = 605°C. Also, the X-ray diffraction is strongly affected by the oxide thickness deposited between poly-silicon layers and crystalline substrates.