Multiscale modelling of low-pressure CVD of Silicon based materials in deep submicronic trenches: a continuum feature scale model

The ability to predict feature profile evolution across wafers during filling from equipment scale operating conditions is one important goal of process engineers for power component fabrication. We develop an integrated approach for simulating the multiple length scales needed to address this problem for Low Pressure CVD processes of silicon based materials in deep submicronic trenches (aspect ratio can exceed 50). In this approach, continuum models at the reactor (100m) and feature (10-7m) scales are tightly coupled in order to predict micro- and macro- loading effects in a transient environment. First, the main principles and assumptions of the reactor and trench scale models are presented. Then, some characteristic examples of numerical results at the trench scale are analysed and compared with the predictions of the deterministic Ballistic Transport-Reaction Model (BTRM) EVOLVE. This comparison shows that our continuum approach gives results as accurate as those of the BTRM one even for highly non conformable layers, for computations times up to 3 times lower

Modélisation multi-échelle du comblement par LPCVD de tranchées profondes pour la fabrication de nouveaux composants de puissance

Plus que jamais, accroître simultanément le niveau d'intégration et les performances des composants microélectroniques présente un enjeu majeur pour les praticiens du domaine. Dans le cas des capacités, une solution efficace pour réduire l'aire d'occupation en surface du substrat tout en conservant de fortes capacitances est de fabriquer des structures à trois dimensions, impliquant la gravure puis le comblement de tranchées profondes dans le volume des plaquettes de silicium. La fabrication de ces capacités 3D implique en particulier le dépôt par LPCVD (Low Pressure Chemical Vapor Deposition) de silicium polycristallin, de nitrure de silicium, de silicium dopé in situ au bore et au phosphore, dans des tranchées de largeur micronique à très fort rapport de forme (le rapport de la largeur sur la profondeur des gravures peut excéder 50). Les procédés de LPCVD industriels permettent actuellement de traiter simultanément jusqu'à 200 plaquettes pré-gravées de 20 voire 30 cm de diamètre. Parvenir à combler de façon conforme, c'est-à-dire sans laisser de vide, et avec une bonne uniformité en termes d'épaisseur déposée, de composition chimique et de structure cristalline, de telles microstructures, à la fois suivant leur profondeur et en tout point de la charge de plaquettes, présente un enjeu technologique important. C'est dans le but d'accélérer la phase de mise au point et d'industrialisation de ces procédés LPCVD pour le comblement de tranchées profondes qu'une étude de modélisation multi-échelles a été engagée. Cette étude vise à développer un ensemble auto-cohérent de modèles permettant de représenter localement les phénomènes physico-chimiques en jeu, de l'échelle du réacteur jusqu'à celle de la tranchée, en vue de disposer d’outils performants de simulation et d’optimisation du comportement du procédé. Dans un premier temps, un modèle de simulation du réacteur a été mis au point sur la base du code de CFD Fluent, qui permet d’accéder aux cartes de vitesses d’écoulement, de température, de composition du gaz et de vitesses de dépôt en tout point de l’équipement. Un modèle 2D à l’échelle des tranchées a ensuite été développé, toujours sur la base du code Fluent, qui permet de suivre l’évolution du profil en épaisseur du dépôt avec le temps. Les premiers résultats obtenus pour le dépôt de silicium pur à partir de silane seront présentés et commentés, pour divers rapports de forme et géométries de tranchées. En particulier, le phénomène rémanent de « bowing » sera simulé. La nécessité d’interconnecter ces deux échelles de modélisation par une procédure auto-cohérente sera illustrée, en particulier pour les cas de fortes surfaces spécifiques initiales des plaquettes. De premières pistes de progrès seront finalement proposées

Synthesis and biological evaluation of novel ferrocenyl curcuminoid derivatives

International audienceWith the purpose to improve the biological activities of curcumin, eight novel ferrocenyl curcuminoids were synthesized by covalent anchorage of three different ferrocenyl ligands. We evaluated their cytotoxicity on B16 melanoma cells and normal NIH 3T3 cells, their inhibition of tubulin polymerization and their effect on the morphology of endothelial cells. The presence of a ferrocenyl side chain was clearly shown to improve the biological activity of most of their corresponding organic curcuminoid analogues

Modeling of carrier lifetime based on Deep-Level Transient Spectroscopy for power PIN diodes

International audienceThe dynamic performances of PIN diodes are very difficult to predict with Technology Computer-Aided Design (TCAD) simulation tools, especially when the carrier lifetime is adjusted. The standard simulation model used in TCAD tools for carrier lifetime is based on Shockley-Read-Hall (SRH) recombination theory. This model is not sufficient as it considers the presence of only one deep energy level located at the material mid-gap. Used as a lifetime killer, Platinum doping introduces several deep energy levels facilitating the minority carrier recombination. Thus, a new approach based on trap physical description is performed using Deep Level Transient Spectroscopy (DLTS) measurement technique. This approach has significantly reduced the big mismatch observed between the PIN diode turn-off measurements and the standard simulation model results

Ferrocenyl flavonoid-induced morphological modifications of endothelial cells and cytotoxicity against B16 murine melanoma cells

International audienceWith the aim of improving the cytotoxic and vascular disrupting activities of flavonoids, several classes of ferrocenyl-modified flavonoids were prepared and tested on cancer and endothelial cells. Three tenmember series of ferrocenyl flavonoids: chalcones ((E)-1-(R-2'-hydroxypheny1)-3-ferrocenylprop-2-en-1-ones), aurones ((Z)-R-2-(ferrocenylidene)benzofuran-3-ones) and flavones (R-2-ferrocenyl-chromen-4-ones) were synthesized by recently reported methods. Three ferrocenyl flavonols (R-3-hydroxy2-ferrocenyl-chromen-4-ones) and four ferrocenyl flavanones (3-ferrocenylmethylidenyl-R-2-phenyl-chroman-4-ones) were also obtained. All compounds were evaluated for their cytotoxic effects on a cancer cell line (B16 murine melanoma) and for their morphological effects on endothelial cells (EAhy 926). Some interesting structure-activity relationships were disclosed: of all the compounds, the halogen-substituted aurones showed the best cytotoxic activity, with IC50 values ranging between 12 and 18 mu M. Ferrocenyl flavonols and ferrocenyl flavanones with substitution in the 3-position (-OH and =C-Fc respectively) were not active against cancer or endothelial cells. Some of the ferrocenyl flavones caused the endothelial cells to adopt a round shape (''rounding up'') at submicromolar concentrations, which can be predictive of vascular disrupting activity. The most morphologically active flavones showed only moderate cytotoxicity against cancer cells, indicating that they may primarily act as antivascular agents. (C) 2013 Elsevier B.V. All rights reserved

New triggering-speed-characterization method for diode-triggered SCR using TLP

International audienceThe key parameters in the optimization of the Diode Triggered Silicon-Controlled Rectifier (DTSCR) as a RF ESD protection, are the turn-on time and the trigger-voltage overshoots seen before the SCR turns on, during very fast ESD transients [1]. But at this time, there is no normalized method to evaluate and report the ESD device turn-on speed [2]. Such a method would be required to effectively compare device performance. In this work a new method , based on stored-charge, is investigated to characterize the triggering speed of DTSCR using Transmission Line Pulsing (TLP) measurements

Performance of a Region of Interest–based Algorithm in Diagnosing International Society of Urological Pathology Grade Group ≥2 Prostate Cancer on the MRI-FIRST Database—CAD-FIRST Study

International audienceBackground and objective: Prostate multiparametric magnetic resonance imaging (MRI) shows high sensitivity for International Society of Urological Pathology grade group (GG) ≥2 cancers. Many artificial intelligence algorithms have shown promising results in diagnosing clinically significant prostate cancer on MRI. To assess a region-of-interest-based machine-learning algorithm aimed at characterising GG ≥2 prostate cancer on multiparametric MRI.Methods: The lesions targeted at biopsy in the MRI-FIRST dataset were retrospectively delineated and assessed using a previously developed algorithm. The Prostate Imaging-Reporting and Data System version 2 (PI-RADSv2) score assigned prospectively before biopsy and the algorithm score calculated retrospectively in the regions of interest were compared for diagnosing GG ≥2 cancer, using the areas under the curve (AUCs), and sensitivities and specificities calculated with predefined thresholds (PIRADSv2 scores ≥3 and ≥4; algorithm scores yielding 90% sensitivity in the training database). Ten predefined biopsy strategies were assessed retrospectively.Key findings and limitations: After excluding 19 patients, we analysed 232 patients imaged on 16 different scanners; 85 had GG ≥2 cancer at biopsy. At patient level, AUCs of the algorithm and PI-RADSv2 were 77% (95% confidence interval [CI]: 70-82) and 80% (CI: 74-85; p = 0.36), respectively. The algorithm's sensitivity and specificity were 86% (CI: 76-93) and 65% (CI: 54-73), respectively. PI-RADSv2 sensitivities and specificities were 95% (CI: 89-100) and 38% (CI: 26-47), and 89% (CI: 79-96) and 47% (CI: 35-57) for thresholds of ≥3 and ≥4, respectively. Using the PI-RADSv2 score to trigger a biopsy would have avoided 26-34% of biopsies while missing 5-11% of GG ≥2 cancers. Combining prostate-specific antigen density, the PI-RADSv2 and algorithm's scores would have avoided 44-47% of biopsies while missing 6-9% of GG ≥2 cancers. Limitations include the retrospective nature of the study and a lack of PI-RADS version 2.1 assessment.Conclusions and clinical implications: The algorithm provided robust results in the multicentre multiscanner MRI-FIRST database and could help select patients for biopsy.Patient summary: An artificial intelligence-based algorithm aimed at diagnosing aggressive cancers on prostate magnetic resonance imaging showed results similar to expert human assessment in a prospectively acquired multicentre test database

Bulletin Bibliographique

Ce bulletin bibliographique réunit plus d’une centaine de recensions d’ouvrages pour l’année 2011. Il fait appel aux principales disciplines de connaissance des faits religieux, telles que la sociologie, l’histoire, l’ethnologie ou la philosophie. Les multiples religions du monde sont appréhendées dans divers moments et contextes en même temps que les systèmes d’idées et d’usages avec lesquelles elles composent ou s’affrontent dans l’espace public. Outre les comptes rendus, plusieurs notes critiques reviennent sur la production du savoir : le sens des mots-clés d’hier et d’aujourd’hui dans les dictionnaires savants sur les phénomènes religieux ; les anthropologues et la religion en France et dans le monde ; l’histoire et la sociologie des mouvements messianiques et millénaristes ; les raisons de l’effervescence pentecôtiste au Nigeria ; les enjeux de l’engagement congréganiste dans l’éducation italienne du XIXe siècle