Microscopic Analysis of Erase-Induced Degradation in 40 nm NOR Flash Technology

International audienceAn in-depth investigation of NOR flash degradation occurring during Fowler-Nordheim (FN) erase operation is provided. After showing how to properly reproduce the flash equivalent stress on transistors, a complete set of delay-free experiments is performed on MOSFET devices. This paper explores FN-induced SiO2 damage from the two oxide interfaces, capturing both electrostatic aging, by reading the drifts of linear characteristics on single MOSFET, and erase efficiency degradation of the memory cell, by measuring the gate current evolution directly on array structures. After showing how to read the signatures of different defects, important insights are given on physical degradation mechanisms and significant guidelines are provided for the extraction of relevant physical-based parameters for modeling and optimization of flash cell endurance. In particular, the power law correlation between injected and trapped charges has been observed for both types of carriers, highlighting the difference in the power exponent which leads to a turnaround of Vth at erase state during flash endurance. It has been underlined how the holes are mainly trapped close to Si/SiO2 interface, essentially influencing the electrostatics, whereas the electrons are mainly located close to poly/SiO2 interface, mostly impacting the gate current. In addition, an accurate noise-free extraction of electrostatic parameters related to holes and amphoteric defects has been performed highlighting the negligible shift of the total threshold voltage. Finally, the interface trap aging kinetics has been experimentally addressed, emphasizing the weak electron-energy dependence

Physically-based evaluation of aging contributions in HC/FN-programmed 40 nm NOR Flash technology

International audienceIn this paper, an in-depth aging assessment for 40 nm NOR Flash cells, programmed by Hot Carrier (HC) and erased by Fowler-Nordheim (FN) mechanisms, is performed during Program/Erase (P/E) cycling. Firstly, the difficulty of properly analyzing the overall HC + FN wear out and the importance of evaluating the different cell characteristic drifts are pointed out. Thus, in order to thoroughly explore the cell degradation, ad-hoc experimental setup and test structures are considered. In particular, using customizable gate patterns during P/E operations, the cell endurance is successfully reproduced on equivalent Flash transistors. Taking advantage of these results and of cell dynamics computation within P/E phases, a fine extraction and separation of electrostatic and cell performance decays within the Programming Window (PW) evolution is presented. Then, using this technique, an accurate physical assessment of cell aging characteristic evolutions under different gate ramp patterns is provided. This attitude is shown to give important guidelines for the optimization of Flash cell endurance performance for a certain initial PW. In particular, the erase pattern is demonstrated not to significantly influence the PW drift, whereas, lowering the ramp speed during the program operation, an important increase of Vth in both states is observed and physically explained

Morphodynamic incidences of the trepanning of the endokarst by solution pipes. Examples of chalk caves in Western Europe (France and Belgium)

peer reviewe

Effects of Lightly Doped Drain and Channel Doping Variations on Flash Memory Performances and Reliability

International audienc

Energy consumption optimization in nonvolatile silicon nanocrystal memories

International audienc

Soft Errors Induced by Natural Radiation at Ground Level in Floating Gate Flash Memories

IEEE International Reliability Physics Symposium (IRPS), Anaheim, CA, APR 14-18, 2013International audienceThis work reports the combined characterization at mountain altitude (on the ASTEP Platform at 2552 m) and at sea-level of more than similar to 50 Gbit of 90 nm NOR flash memories subjected to natural radiation (atmospheric neutrons). This wafer-level experiment evidences a limited impact of the terrestrial radiation at ground level on the memory SER evaluated without ECC. Experimental values are compared to estimations obtained from Monte Carlo simulation using the TIARA-G4 code combined with a physical model for charge loss in such floating-gate devices

Liens entre cancer de l’œsophage et exposition professionnelle à l’amiante : étude au sein de la cohorte ARDCo

International audienc

Cancer of the esophagus and asbestos exposure

International audienceBACKGROUND:Our study aimed at analyzing incidence and mortality from esophageal cancer within a cohort of workers with previous occupational asbestos exposure (ARDCo Program).METHODS:A 10-year follow-up study was conducted in the 14 515 male subjects included in this program between October 2003 and December 2005. Follow-up began when exposure stopped. Asbestos exposure was analyzed by industrial hygienists using data from a standardized questionnaire. The Cox model was used, with age as the time axis variable adjusted for smoking, time since first exposure (TSFE) and cumulative exposure index (CEI) of exposure to asbestos.RESULTS:We reported a significant dose-response relationship between CEI of exposure to asbestos and esophageal cancer, in both incidence (hazard ratio [HR] 1.26, 95% confidence interval [CI] 1.00-1.58), and mortality (HR 1.40, [95%CI 1.12-1.75]).CONCLUSIONS:This large-scale study suggests the existence of a relationship between asbestos exposure and cancer of the esophagus

Maladies parodontales : thérapeutiques et prévention

Les dents, comparables à la partie visible de l'iceberg, sont l'objet de multiples soins etattentions, mais malheureusement il n'en va pas de même du parodonte, leur point d'ancrage etsoutien indispensable. Quoi de plus banal en effet qu'un saignement survenant lors dubrossage quotidien ? Il ne déclenche bien souvent aucune inquiétude ni demande deconsultation. Il s'agit pourtant là d'un des signes cliniques les plus évidents de la « maladieparodontale » (recouvrant en réalité un ensemble de pathologies complexe et multiformedésigné par le terme de « parodontopathies ») qui affecte, à des degrés divers, pratiquement90 % de la population en France dans toutes les tranches d'âge et cause la perte de 30 à 40 %des dents.Si l'étiologie infectieuse des parodontopathies ne fait aucun doute, il est encore difficileaujourd'hui d'attribuer un rôle déterminant à un germe précis en raison de la richesse de laflore buccale et de la complexité des réponses inflammatoires face à l'agression.L'antibiothérapie simple ou composée est donc d'une efficacité limitée elles perspectives d'uneprotection par voie vaccinale classique, encore lointaines. Quels sont actuellement le ou leschoix thérapeutiques et leur prise en charge ?Afin de faire le point sur les modalités de traitements et leur suivi, sur les stratégies deprévention et de prise en charge des maladies parodontales, la Mutuelle générale del'éducation nationale a demandé à l'INSERM de mener une expertise collective. Un groupeinternational pluridisciplinaire, composé d'une vingtaine d'experts, cliniciens, universitaires etchercheurs spécialisés dans les domaines allant de l'immunologie la plus fondamentale àl'économie de la santé, a analysé plus de 2 000 publications de la littérature internationalepertinente des cinq dernières années.Face à ce véritable problème de santé publique deux types de réponse sont possibles: enpriorité, la prévention sous toutes ses formes puis, lorsque la maladie est déclarée, le recours àl'arsenal des thérapeutiques les mieux adaptées aux différentes formes de parodontites et auniveau de destruction du parodonte. Mais il faut souligner que la protection des résultatsacquis au prix des techniques les plus performantes est complètement dépendante d'un étroitpartenariat entre la patient et le spécialiste dans le cadre d'un protocole très élaboré demaintenance, déjà fonctionnel dans certains pays européens. Voici donc les trois maître-motsde la lutte contre ces maladies