Stress transfer in ultimate transistors through SiN deposits: study by electron holography and finite element modelling

Longtemps considérées comme pénalisantes, les contraintes sont aujourd'hui utilisées sciemment pour fabriquer des transistors CMOS de dernière génération car elles permettent d'augmenter très sensiblement la mobilité des porteurs dans le silicium et donc la vitesse des dispositifs type MOS. L'utilisation de couches fortement contraintes qui, déposées sur un transistor, introduisent une déformation élastique dans la région électriquement active du dispositif, est une solution très prometteuse. A cette fin, les couches amorphes de Nitrure de Silicium (SiN) sont particulièrement intéressantes car elles sont peu couteuses à fabriquer et compatibles avec les technologies MOS. Cependant, l'optimisation de ce procédé de mise sous contrainte impose de connaître précisément les propriétés mécaniques de ces couches. Celles-ci étant très dépendantes des conditions d'élaboration et donc des lieux de production, ces propriétés sont en général pas connues. La récente invention de l'Holographie Electronique en Champ Sombre (Dark Field Electron Holography, DFEH), qui permet de mesurer des distributions de déformations avec un champ de vue de l'ordre du micromètre, une résolution spatiale nanométrique et une très bonne précision (10-4), ouvre de nouvelles perspectives dans ce domaine. Le but de ce travail de thèse était d'étudier, en couplant des mesures DFEH à des Modélisations par Eléments Finis (FEM), les déformations transférés par des couches de SiN amorphe déposées sous des conditions communément utilisées dans l'industrie microélectronique. Dans un premier temps, j'ai étudié les déformations introduites dans des structures modèles composées de motifs de Silicium recouvert par un dépôt de SiN. Ce faisant, j'ai pu développer le concept générique de "capteur de déformation". L'idée est d'utiliser un matériau cristallin bien connu comme un "capteur" pour étudier les déformations cristallines introduites en son sein par une couche déposée. La confrontation avec des simulations par éléments finis (FEM) permet ensuite de déterminer les caractéristiques mécaniques (contrainte interne et module de Young) de ces couches déposées. Pour me rapprocher de la structure réelle de dispositifs MOS, j'ai ensuite étudié puis expliqué les déformations introduites par un réseau de lignes de poly-Si déposé sur un substrat de silicium, lui-même recouvert par une couche de SiN contraint. Doté de cette méthodologie, j'ai finalement étudié la distribution des déformations dans de " vrais " dispositifs MOSFETs (type "n" et "p") réalisés en technologie "28 nm". Plus précisément, je me suis attaché à comprendre l'effet des différentes étapes technologiques sur la distribution des déformations dans des dispositifs " complets ". J'ai ainsi pu mettre en évidence que l'introduction de certains " éléments " (spacers, contacts) ou la réduction de "taille" peuvent sensiblement affecter/réduire les effets bénéfiques espérés grâce à cette approche technologique.For long time considered as detrimental, stress is now an integral feature of ultimate MOS technology because it considerably increases the carrier mobility in silicon, hence it can be used to boost device performances. The use of highly stressed layers deposited over the transistor for introducing an elastic deformation in the electrically active region of the device is a very promising solution. For that, silicon nitride (SiN) amorphous layers are particularly interesting because they are cheap and compatible with MOS technology. However, the optimization of this method for stress transmission requires the precise knowledge of the mechanical properties of these layers. Being highly dependent on the fabrication parameters and thus on the production sites, these properties are generally unknown. The recent invention of Dark Field Electron Holography (DFEH), which allows strain fields to be mapped over micro-scale fields of view, with nanometric spatial resolution and high precision (10-4), opens new perspectives in this field. The aim of this thesis was to investigate, by combining DFEH measurements and Finite Element Modelling (FEM), the strain transferred by amorphous SiN layers deposited under conditions commonly used in the microelectronics industry. At first, I studied the strain introduced in model structures composed of silicon patterns covered by a SiN deposit. While doing this, I have developed the generic concept of "strain sensor". The idea is to use a well-known crystalline material as a "sensor" to study the crystal deformations introduced by a deposited layer. The comparison with finite element simulations (FEM) allows one to determine the mechanical properties (internal stress and Young's modulus) of these deposited layers. Then, to get closer to the actual structure of MOS devices, I studied and explained the strain introduced by an array of poly-Si lines deposited on a silicon substrate, covered by a stressed layer of SiN. Using this approach, I finally studied the strain distribution in "real" MOSFET devices ("n" and "p" types) made by the "28 nm" technology node. More precisely, I sought to understand the effect of the different technological steps on the final strain distribution in "complete" devices. I was able to show that the introduction of some "components" (spacers, contacts) or the reduction of "size" can significantly affect/reduce the beneficial effects expected using this technological approach

El ejemplo irlandés ante la crisis financiera

El sistema financiero europeo se encuentra en un momento crítico. La falta de medidas para reestructurar y sanear un sector bancario aún renqueante amenaza la recuperación económica. En este contexto, Irlanda está destacando sobre el resto por sus medidas audaces para combatir el déficit público más alto de la zona euro y recuperar al mismo tiempo la confianza en su maltrecho sistema financiero. En este ARI se estudia la estrategia concreta planteada por las autoridades irlandesas para hacer frente a su crisis financiera. Con objeto de analizar los elementos fundamentales de esta política, se repasa asimismo la gestión que se hizo de la crisis japonesa en la década de los 90. Con ello se pretende establecer un análisis comparativo entre estrategias de gestión de crisis muy diversas y estudiar sus posibles consecuencias

Low income as a determinant of exercise capacity in COPD.

Exercise capacity (EC) is a critical outcome in chronic obstructive lung disease (chronic obstructive pulmonary disease (COPD)). It measures the impact of the disease and the effect of specific interventions like pulmonary rehabilitation (PR). EC determines COPD prognosis and is associated with health-care utilization and quality of life. Field walking tests and cardiopulmonary exercise test (CPET) are two ways to measure EC. The 6-minute walking test (6MWT) is the commonest and easiest field test. CPET has the advantage of assessing maximal aerobic capacity. Determinants of EC include age, gender, breathlessness, and lung function. Previous research suggests that socioeconomic status (SES), a meaningful factor in COPD, may also be associated with EC. However, those findings have not been replicated. We aimed to determine whether SES is an independent factor associated with EC in COPD. For this analysis, we used the National Emphysema Treatment Trial (NETT) database. NETT was a multicenter clinical trial where severe COPD patients were randomized to lung volume reduction surgery or medical therapy. Measures used were taken at baseline, postrehabilitation. Patients self-reported their income and were divided in two groups whether it was less or above US$30,000. Patients with a lower income had worse results in 6MWT ( p < 0.0001). We found an independent association between income and the 6MWT in patients with severe COPD after adjusting for age, gender, lung function, dyspnea, and living conditions ( p < 0.0007). One previous publication stated the relationship between income and EC. Our research confirms and extends previous publications associating EC with income by studying a large and well characterized cohort of severe COPD patients, also addressing EC by two different methods (maximal watts and 6MWT). Our results highlight the importance of addressing social determinants of health such as income when assessing COPD patients

Business English and Business French:a comparative analysis of teaching strategies and firms' needs.

Following T. Dudley-Evans’ suggestions, in order to analyse languages for specific purposes, it is possible to argue that present teaching experience is characterized by certain common aspects, such as teachers’ insufficient extra-linguistic knowledge; lack of adequate teaching materials; learners’ different levels of linguistic competence and lack of motivation. Futhermore, Business Languages imply an additional aspect to be investigated, a sort of ‘side effect’: rapid changes in the market determine a necessity, that of naming new features and conditions, hence the question of word-formation and transparency arises. Moving from an analysis of language curricula at the University of Catania, Department of Business Economics, this paper will seek to explore adopted teaching methods in order to point out the importance of integrating language and content, as stated by Fortanet-Gómez and Räisänen. The study’s diachronic and synchronic evaluation of the applied approaches will lead to suggestions in the design of modules, taking into account the role played by both Business English and Business French, in terms of teaching implications and job opportunities. The main aim is to provide a potential answer to the following question: To what extent are companies aware of the need to invest in languages, intercultural and interpreting skills, and the management of linguistic diversity?

Business English and Business French:a comparative analysis of teaching strategies and firms' needs.

Following T. Dudley-Evans' suggestions, in order to analyse languages for specific purposes, it is possible to argue that present teaching experience is characterized by certain common aspects, such as teachers' insufficient extra-linguistic knowledge; lack of adequate teaching materials; learners' different levels of linguistic competence and lack of motivation. Futhermore, Business Languages imply an additional aspect to be investigated, a sort of 'side effect': rapid changes in the market determine a necessity, that of naming new features and conditions, hence the question of word-formation and transparency arises. Moving from an analysis of language curricula at the University of Catania, Department of Business Economics, this paper will seek to explore adopted teaching methods in order to point out the importance of integrating language and content, as stated by Fortanet-Gómez and Räisänen. The study's diachronic and synchronic evaluation of the applied approaches will lead to suggestions in the design of modules, taking into account the role played by both Business English and Business French, in terms of teaching implications and job opportunities. The main aim is to provide a potential answer to the following question: To what extent are companies aware of the need to invest in languages, intercultural and interpreting skills, and the management of linguistic diversity? </p