Simulation de profils de gravure et de dépôt à l’échelle du motif pour l’étude des procédés de microfabrication utilisant une source plasma de haute densité à basse pression

En lien avec l’avancée rapide de la réduction de la taille des motifs en microfabrication, des processus physiques négligeables à plus grande échelle deviennent dominants lorsque cette taille s’approche de l’échelle nanométrique. L’identification et une meilleure compréhension de ces différents processus sont essentielles pour améliorer le contrôle des procédés et poursuivre la «nanométrisation» des composantes électroniques. Un simulateur cellulaire à l’échelle du motif en deux dimensions s’appuyant sur les méthodes Monte-Carlo a été développé pour étudier l’évolution du profil lors de procédés de microfabrication. Le domaine de gravure est discrétisé en cellules carrées représentant la géométrie initiale du système masque-substrat. On insère les particules neutres et ioniques à l’interface du domaine de simulation en prenant compte des fonctions de distribution en énergie et en angle respectives de chacune des espèces. Le transport des particules est effectué jusqu’à la surface en tenant compte des probabilités de réflexion des ions énergétiques sur les parois ou de la réémission des particules neutres. Le modèle d’interaction particule-surface tient compte des différents mécanismes de gravure sèche telle que la pulvérisation, la gravure chimique réactive et la gravure réactive ionique. Le transport des produits de gravure est pris en compte ainsi que le dépôt menant à la croissance d’une couche mince. La validité du simulateur est vérifiée par comparaison entre les profils simulés et les observations expérimentales issues de la gravure par pulvérisation du platine par une source de plasma d’argon.With the reduction of feature dimensions, otherwise negligible processes are becoming dominant in microfabricated profile evolution. Improved understanding of these different processes is essential to improve the control of the microfabrication processes and to further decrease of the feature size. To help attaining such control, a 2D feature scale cellular simulator using Monte-Carlo techniques was developed. The calculation domain is discretized in square cells representing empty space, substrate or mask of the initial system. Neutral and ion species are inserted at simulation interface from their respective angular and energy distributions functions. Particles transport to the feature surface is calculated while taking into account ion reflection on sidewall and neutral reemission. The particles-surface interaction model includes the different etching mechanisms such as sputtering, reactive etching and reactive ion etching. Etch product transport is also taken into account as is their deposition leading to thin film growth. Simulation validity is confirmed by comparison between simulated profiles and experimental observations issued from sputtering of platinum in argon plasma source

Modeling the Tribomechanical Properties of Multifunctional Thin Film Coatings

RÉSUMÉ L’adoption des traitements de surface par dépôt de revêtements à couche mince s’est rapidement propagée dans divers champs industriels et technologiques tels que les outils d’usinage, les revêtements protecteurs, les revêtements décoratifs, les surfaces hautement réfractaires, les filtres optiques, les composantes optoélectroniques, les dispositifs magnétiques et sensoriels, les prothèses biomédicales et la microélectronique. Avec l’augmentation des requis de performance, les revêtements utilisés pour ces dispositifs doivent être adaptés et conçus pour survivre aux conditions tribomécaniques d’opérations, et ce pour la durée de vie attendue. Pour atteindre cette cible, le concept du design par revêtements multifonctionnels a largement été embrassé par la communauté. Cette approche consiste à déposer une multicouche dans laquelle chacune des couches joue un rôle spécifique dans le fonctionnement global du dispositif. En revanche, avec l’augmentation de la complexité et des subtilités impliquées dans le design de couches multifonctionnelles, un besoin important de développer des outils et modèles prédictifs se manifeste. Par conséquent, l’objectif principal de cette thèse est de développer des modèles numériques reproduisant les conditions tribomécaniques à l’échelle des revêtements; premièrement pour élucider les mécanismes fondamentaux responsables de la dégradation des surfaces revêtues et dans un deuxième temps assister le design de l’architecture des revêtements pour augmenter leur résilience structurale. Lors de l’accomplissement de cette thèse, trois principaux sujets ont été approfondis. La première étude concerne la réponse mécanique d’un revêtement bicouche déposé sur acier, en particulier l’influence d’une inter-couche à haute capacité de charge sur la formation d’empreintes résiduelles ainsi que sur la défaillance du revêtement de surface. En exploitant un modèle de mécanique des milieux continus quasi statique, nous avons caractérisé et prédit les conditions critiques qui mènent à ce type d’endommagement. La deuxième étude porte sur la formation d’un réseau de fissure à la surface d’un revêtement optique déposé sur un substrat de polymère. À l’aide d’essais de traction in situ et d’un modèle à éléments finis en contraintes planes correspondant, nous avons étudié la fracturation et la ténacité de différentes configurations multicouches. En commençant par la caractérisation des propriétés de rupture de monocouches, nous avons clarifié le chemin de fracturation à travers le revêtement et ainsi identifié les paramètres critiques responsables de la défaillance catastrophique du film. ----------Abstract The adoption of thin film coating technologies has been quickly spreading to numerous major industrial and technological fields including machining tools, protective coatings, decorative films, high temperature resistant surfaces, optics, optoelectronic, magnetic and sensorics devices, biomedical prosthetic and microelectronics. As the requirements for high performance continuously increase, the coating of thee components must be adapted and tailored to withstand the tribomechanical solicitations to which they are subjected during the expected lifetime under their typical operation conditions. To meet this objective and associated challenges the multifunctional coating design concept has been widely adopted by the community. In this approach, a layered material is deposited on a supporting substrate in which each layer serves a specific role to the overall device functionality. However, as the complexity and intricacies involved in the design of such multifunctional coatings increase, so is the need for predictive modeling tools to assist in this task. Accordingly, the main objective of this thesis is to develop coating-scale tribomechanical numerical models, first to uncover the underlying mechanisms responsible for the degradation of the coated surfaces, and secondly to guide the coating architectural design to further improve the surface resilience. This thesis presents several case studies which are divided into three principal investigations. In the first study, we investigated the tribomechanical response of a duplex coated steel substrate, most notably the influence of a load-carrying underlayer on the formation of permanent indents and failure of the top coating. Using a quasi-static continuum mechanics indentation model, we were able to characterize and predict the critical conditions which lead to the apparition of the related surface damage. The second case study was related to the formation of crack patterns at the surface of an optical film deposited on a polymer substrate. Using an in situ tensile experiment and a corresponding plane strain finite element model, we investigated the fracturability and toughness of different stack configurations. By first characterizing the fracture properties of the single layers individually, we were able to uncover the fracture pathway in a multilayer coating and identify the most critical parameters responsible for the catastrophic failure of the stack. Finally, we probed the potential application of bio-inspired functionally graded coatings for enhanced protection against erosive wear. The influence of the mechanical depth profile on the load spreading and crack driving forces were investigated

Canadian mutual fund flows and performance : non-linearity, frictions and diminishing returns to scale

This thesis investigates the nature of the relationship between mutual fund flows and fund performance in Canada. Specifically, we investigate the non-linearity (or "asymmetry") of the relationship, and how the relationship differs for equity and fixed-income funds using both excess and raw returns. We also test whether frictions prevent investors from punishing poor performers, and whether there are decreasing returns to scale in mutual fund management. Using a sample of 119 equity and 44 fixed-income funds managed by public fund sponsors, we find that when fund performance is measured on a risk-adjusted basis versus benchmark returns, there is evidence of rational asymmetry in the flow-performance relationship for Canadian equity funds. We note that non-performance factors, especially prior flow, are significant predictors of funds flow for both equity and fixed-income funds. We also find that frictions do affect the flow-performance relationship, and that returns to scale in mutual fund management appear to be constan

Large-scale genome-wide association studies and meta-analyses of longitudinal change in adult lung function.

BACKGROUND: Genome-wide association studies (GWAS) have identified numerous loci influencing cross-sectional lung function, but less is known about genes influencing longitudinal change in lung function. METHODS: We performed GWAS of the rate of change in forced expiratory volume in the first second (FEV1) in 14 longitudinal, population-based cohort studies comprising 27,249 adults of European ancestry using linear mixed effects model and combined cohort-specific results using fixed effect meta-analysis to identify novel genetic loci associated with longitudinal change in lung function. Gene expression analyses were subsequently performed for identified genetic loci. As a secondary aim, we estimated the mean rate of decline in FEV1 by smoking pattern, irrespective of genotypes, across these 14 studies using meta-analysis. RESULTS: The overall meta-analysis produced suggestive evidence for association at the novel IL16/STARD5/TMC3 locus on chromosome 15 (P  =  5.71 × 10(-7)). In addition, meta-analysis using the five cohorts with ≥3 FEV1 measurements per participant identified the novel ME3 locus on chromosome 11 (P  =  2.18 × 10(-8)) at genome-wide significance. Neither locus was associated with FEV1 decline in two additional cohort studies. We confirmed gene expression of IL16, STARD5, and ME3 in multiple lung tissues. Publicly available microarray data confirmed differential expression of all three genes in lung samples from COPD patients compared with controls. Irrespective of genotypes, the combined estimate for FEV1 decline was 26.9, 29.2 and 35.7 mL/year in never, former, and persistent smokers, respectively. CONCLUSIONS: In this large-scale GWAS, we identified two novel genetic loci in association with the rate of change in FEV1 that harbor candidate genes with biologically plausible functional links to lung function

Family Experiences with Care for Children with Inherited Metabolic Diseases in Canada: A Cross-Sectional Survey

Background and Objective: Children with inherited metabolic diseases often require complex and highly specialized care. Patient and family-centered care can improve health outcomes that are important to families. This study aimed to examine experiences of family caregivers (parents/guardians) of children diagnosed with inherited metabolic diseases with healthcare to inform strategies to improve those experiences. Methods: A cross-sectional mailed survey was conducted of family caregivers recruited from an ongoing cohort study. Participants rated their healthcare experiences during their child’s visits to five types of healthcare settings common for inherited metabolic diseases: the metabolic clinic, the emergency department, hospital inpatient units, the blood laboratory, and the pharmacy. Participants provided narrative descriptions of any memorable negative or positive experiences. Results: There were 248 respondents (response rate 49%). Caregivers were generally very or somewhat satisfied with the care provided at each care setting. Appropriate treatment, provider knowledge, provider communication, and care coordination were deemed essential aspects of satisfaction with care by the majority of participants across many settings. Memorable negative experiences were reported by 8–22% of participants, varying by setting. Among participants who reported memorable negative experiences, contributing factors included providers’ demeanor, lack of communication, lack of involvement of the family, and disregard of an emergency protocol letter provided by the family. Conclusions: While caregivers’ satisfaction with care for children with inherited metabolic diseases was high, we identified gaps in family-centered care and factors contributing to negative experiences that are important to consider in the future development of strategies to improve pediatric care for inherited metabolic diseases

The clinical application of genome-wide sequencing for monogenic diseases in Canada: Position statement of the Canadian College of medical geneticists

Purpose and scope: The aim of this Position Statement is to provide recommendations for Canadian medical geneticists, clinical laboratory geneticists, genetic counsellors and other physicians regarding the use of genome-wide sequencing of germline DNA in the context of clinical genetic diagnosis. This statement has been developed to facilitate the clinical translation and development of best practices for clinical genome-wide sequencing for genetic diagnosis of monogenic diseases in Canada; it does not address the clinical application of this technology in other fields such as molecular investigation of cancer or for population screening of healthy individuals. Methods of statement development: Two multidisciplinary groups consisting of medical geneticists, clinical laboratory geneticists, genetic counsellors, ethicists, lawyers and genetic researchers were assembled to review existing literature and guidelines on genome-wide sequencing for clinical genetic diagnosis in the context of monogenic diseases, and to make recommendations relevant to the Canadian context. The statement was circulated for comment to the Canadian College of Medical Geneticists (CCMG) membership-at-large and, following incorporation of feedback, approved by the CCMG Board of Directors. The CCMG is a Canadian organisation responsible for certifying medical geneticists and clinical laboratory geneticists, and for establishing professional and ethical standards for clinical genetics services in Canada. Results and conclusions: Recommendations include (1) clinical genome-wide sequencing is an appropriate approach in the diagnostic assessment of a patient for whom there is suspicion of a significant monogenic disease that is associated with a high degree of genetic heterogeneity, or where specific genetic tests have failed to provide a diagnosis; (2) until the benefits of reporting incidental findings are established, we do not endorse the intentional clinical analysis of disease-associated genes other than those linked to the primary indication; and (3) clinicians should provide genetic counselling and obtain informed consent prior to undertaking clinical genome-wide sequencing. Counselling should include discussion of the limitations of testing, likelihood and implications of diagnosis and incidental findings, and the potential need for further analysis to facilitate clinical interpretation, including studies performed in a research setting. These recommendations will be routinely reevaluated as knowledge of diagnostic and clinical utility of clinical genome-wide sequencing improves. While the document was developed to direct practice in Canada, the applicability of the statement is broader and will be of interest to clinicians and health jurisdictions internationally

A value-based comparison of the management of ambulatory respiratory diseases in walk-in clinics, primary care practices, and emergency departments : protocol for a multicenter prospective cohort study

Background: In Canada, 30%-60% of patients presenting to emergency departments are ambulatory. This category has been labeled as a source of emergency department overuse. Acting on the presumption that primary care practices and walk-in clinics offer equivalent care at a lower cost, governments have invested massively in improving access to these alternative settings in the hope that patients would present there instead when possible, thereby reducing the load on emergency departments. Data in support of this approach remain scarce and equivocal. Objective: The aim of this study is to compare the value of care received in emergency departments, walk-in clinics, and primary care practices by ambulatory patients with upper respiratory tract infection, sinusitis, otitis media, tonsillitis, pharyngitis, bronchitis, influenza-like illness, pneumonia, acute asthma, or acute exacerbation of chronic obstructive pulmonary disease. Methods: A multicenter prospective cohort study will be performed in Ontario and Québec. In phase 1, a time-driven activity-based costing method will be applied at each of the 15 study sites. This method uses time as a cost driver to allocate direct costs (eg, medication), consumable expenditures (eg, needles), overhead costs (eg, building maintenance), and physician charges to patient care. Thus, the cost of a care episode will be proportional to the time spent receiving the care. At the end of this phase, a list of care process costs will be generated and used to calculate the cost of each consultation during phase 2, in which a prospective cohort of patients will be monitored to compare the care received in each setting. Patients aged 18 years and older, ambulatory throughout the care episode, and discharged to home with one of the aforementioned targeted diagnoses will be considered. The estimated sample size is 1485 patients. The 3 types of care settings will be compared on the basis of primary outcomes in terms of the proportion of return visits to any site 3 and 7 days after the initial visit and the mean cost of care. The secondary outcomes measured will include scores on patient-reported outcome and experience measures and mean costs borne wholly by patients. We will use multilevel generalized linear models to compare the care settings and an overlap weights approach to adjust for confounding factors related to age, sex, gender, ethnicity, comorbidities, registration with a family physician, socioeconomic status, and severity of illness. Results: Phase 1 will begin in 2021 and phase 2, in 2023. The results will be available in 2025. Conclusions: The end point of our program will be for deciders, patients, and care providers to be able to determine the most appropriate care setting for the management of ambulatory emergency respiratory conditions, based on the quality and cost of care associated with each alternative