Analyse morphologique de films CrN. Corrélation entre contrainte résiduelle et résistivité de films de chrome

Les films minces de nitrure de chrome ont sensiblement attiré l'attention, ces dernières années. Attrait du à leurs excellentes propriétés physiques, chimiques et mécaniques. Une partie de cette étude a porté sur la caractérisation morphologique de couches minces dures de nitrure de chrome (Cr-N), élaborées par PVD sur substrats de silicium (100) par pulvérisation magnétron. Nous avons considéré l'influence de la température de recuit sur l'adhérence et la stabilité thermique de ces films. Nous avons procédé à des caractérisations en microscopie électronique à balayage (MEB) équipé en microanalyse X (EDX).Des recuits d'une heure, entre 600°C et 1000°C sous azote N2, effectués sur des revêtements CrN,de différentes épaisseurs entre 0.5 et 1µm, ont montré la stabilité thermique de ces revêtements aux basses températures. Les résultats obtenus en MEB et EDX sont comparés aux résultats en DRX. Cette étude porte aussi sur des dépôts de couches de chrome élaborés par pulvérisation RF cathodique (PVD). L'analyse des contraintes résiduelles par le dispositif des anneaux de Newton, pour différentes épaisseurs, montre l'existence d'un pic de contraintes entre 170 et 200 nm. La méthode des quatre pointes a été utilisée pour déterminer la résistivité des couches de chrome. La résistivité décroît fortement pour les petites épaisseurs (< 100nm), pour ensuite se stabiliser à une valeur moyenne de 30µ.Ohm.cm. Une corrélation entre l'évolution des contraintes et de la résistivité nous a permis de faire un essai d'interprétation sur la croissance des films

Effect of substrate-target distance and sputtering pressure in the synthesis of AlN thin films

In this work, we analyze the influence of the processing pressure and the substrate–target distance on the synthesis by reactive sputtering of c-axis oriented polycrystalline aluminum nitride thin films deposited on Si(100) wafers. The crystalline quality of AlN has been characterized by high-resolution X-ray diffraction (HR-XRD). The films exhibited a very high degree of c-axis orientation especially when a low process pressure was used. After growth, residual stress measurements obtained indirectly from radius of curvature measurements of the wafer prior and after deposition are also provided. Two different techniques are used to determine the curvature—an optically levered laser beam and a method based on X-ray diffraction. There is a transition from compressive to tensile stress at a processing pressure around 2 mTorr. The transition occurs at different pressures for thin films of different thickness. The degree of c-axis orientation was not affected by the target–substrate distance as it was varied in between 30 and 70 mm

Granzyme B-induced mitochondrial ROS are required for apoptosis

Caspases and the cytotoxic lymphocyte protease granzyme B (GB) induce reactive oxygen species (ROS) formation, loss of transmembrane potential and mitochondrial outer membrane permeabilization (MOMP). Whether ROS are required for GB-mediated apoptosis and how GB induces ROS is unclear. Here, we found that GB induces cell death in an ROS-dependent manner, independently of caspases and MOMP. GB triggers ROS increase in target cell by directly attacking the mitochondria to cleave NDUFV1, NDUFS1 and NDUFS2 subunits of the NADH: ubiquinone oxidoreductase complex I inside mitochondria. This leads to mitocentric ROS production, loss of complex I and III activity, disorganization of the respiratory chain, impaired mitochondrial respiration and loss of the mitochondrial cristae junctions. Furthermore, we have also found that GB-induced mitocentric ROS are necessary for optimal apoptogenic factor release, rapid DNA fragmentation and lysosomal rupture. Interestingly, scavenging the ROS delays and reduces many of the features of GB-induced death. Consequently, GB-induced ROS significantly promote apoptosis

Characterization of Nitride Thin Films Using SEM and EDX

The chromium nitride thin films have became more and more popular in the last years because of their very good physical, chemical and mechanical properties. The present study relates to thermal stability of hard thin films of chromium nitride CrN, carried out physical vapour deposition. We studied the influence of the annealing temperature on the morphology of CrN films, deposited on silicon substrate using magnetron sputtering. The characterizations are examined using scanning electron microscope equipped with energy dispersive X-ray spectroscopy. Annealing treatments in $N_2$ at 600-1000C for 1 h are performed on CrN coating samples for 530 nm thickness. At low temperature, the results show a thermal stability of these coatings. The $Cr_2O_3$ phase is completely replaced by the CrN phase at temperature above 1000°C. The results given by scanning electron microscopy-energy dispersive X-ray spectroscopy and X-ray diffraction are compared

Ordonnancement reparti

Collection techniques de l ingenieurtraite Mesures et controle Article R8056resum

Scheduling in Real-Time Systems

ISBN: 0-470-84766-2Hardcoveroctober 2002* Real-time systems are used in a wide range of applications, including command and control systems, flight control, telecommunication systems, and online purchase payment* Provides an accessible yet comprehensive treatment* of real-time computing and communications systems* Outlines the basics of real-time scheduling and scheduling policies designed for real-time applications* Each chapter contains examples and case studies along with test exercises and solution