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We investigate the nucleation and growth of two cobalt alloys (CoWB and Pd-CoWP) used to encapsulate copper interconnects. We demonstrate that very uniform deposits are obtained across 300 mm wafers, with accurate thickness control. However, large local thickness variations are observed, possibly compromising the continuity of thin deposits. The origin of this phenomenon is first investigated by electron back scatter diffraction. A clear correlation between areas of dense Pd nucleation and the (111) grains of the polycrystalline copper surface is demonstrated. Then, an epitaxial relationship between the cobalt alloys and the underlying copper substrate is evidenced by TEM characterization. Local nucleation density could thus be affected by the substrate orientation, accounting for thickness inhomogeneities after growth. © 2010 Elsevier B.V. All rights reserved.

To date, most HCA (High Content Analysis) studies are carried out with adherent cell lines grown on a homogenous substrate in tissue-culture treated micro-plates. Under these conditions, cells spread and divide in all directions resulting in an inherent variability in cell shape, morphology and behavior. The high cell-to-cell variance of the overall population impedes the success of HCA, especially for drug development. The ability of micropatterns to normalize the shape and internal polarity of every individual cell provides a tremendous opportunity for solving this critical bottleneck (1-2). To facilitate access and use of the micropatterning technology, CYTOO has developed a range of ready to use micropatterns, available in coverslip and microwell formats. In this video article, we provide detailed protocols of all the procedures from cell seeding on CYTOOchip micropatterns, drug treatment, fixation and staining to automated acquisition, automated image processing and final data analysis. With this example, we illustrate how micropatterns can facilitate cell-based assays. Alterations of the cell cytoskeleton are difficult to quantify in cells cultured on homogenous substrates, but culturing cells on micropatterns results in a reproducible organization of the actin meshwork due to systematic positioning of the cell adhesion contacts in every cell. Such normalization of the intracellular architecture allows quantification of even small effects on the actin cytoskeleton as demonstrated in these set of protocols using blebbistatin, an inhibitor of the actin-myosin interaction.

International audience; We report the fabrication of a 3D micropatterned agarose substrate that enables the culture of single or multiple cells. Patterning was performed on dried agarose using deep UV irradiation leading to 6-microm-deep micropatterns of 25-70 microm in diameter. Cell adhesion was facilitated by the specific grafting of ECM (extra cellular matrix) proteins such as fibronectin into the micropatterns. We show that the pattern size induced the adhesion of one or more cells, thus allowing precise control of the cell number used in the assay, and that cells proliferated similarly as in standard culture conditions. Moreover, cell polarity appeared well preserved on this substrate, so polarized cells like hepatoma HepaRG cells might maintain their differentiation status and act as primary human hepatocytes for hepatotoxicity testing. These 3D patterned culture slides have been successfully used for in situ comet assays and there is evidence that the genotoxic effects of sub-cytotoxic concentrations of drugs could be analyzed in a large number of single HeLa cells. Coupled with the parallel-based design of the 3D micropatterning, which allows automated image analysis, these results strongly indicate that this new cell array system is suitable for high-throughput cytotoxicity and genotoxicity screening applications.

International audience; Sensitive and accurate characterization of films thinner than a few nm used in nanoelectronics represents a challenge for many conventional production metrology tools. With capabilities in the 1010 at/cm2, methods usually dedicated to contamination analysis appear promising, especially Total-reflection X-Ray Fluorescence (TXRF). This study shows that under usual configuration for contamination analysis, with incident angle smaller than the critical angle of the substrate, TXRF signal saturation occurs very rapidly for dense films (below 0.5 nm for HfO2 films on Si wafers using a 9.67 keV excitation at 0.5°). Increasing the incident angle, the range of linear results can be extended, but on the other hand, the TXRF sensitivity is degraded because of a strong increase of the measurement dead time. On HfO2 films grown on Si wafers, an incident angle of 0.32° corresponding to a dead time of 95% was used to achieve linear analysis up to 2 nm. Composition analysis by TXRF, and especially the detection of minor elements into thin films, requires the use of a specific incident angle to optimize sensitivity. Although quantitative analyses might require specific calibration, this work shows on Co–based films that the ratio between minor elements (W, P, Mo) and Co taking into account their relative sensitivity factors is a good direct reading of the composition

International audience; We report the study of the trapping process of benzene and toluene in porous, hybrid organic–inorganic materials prepared via the sol–gel process. In particular, the kinetics of diffusion of the pollutants within the matrices are studied as functions of the composition, polarity and thickness of the matrix. The concentrations of the pollutants in the air are directly measured via their absorbance in the UV, using three different protocols of exposure of the sensor to the pollutants. A threshold of detection of 60 ppb is achieved when the sensor is a monolith of hybrid TMOS/MeTMOS of stoichiometry 9/1.

International audience; Low cost materials based on hybrid organic–inorganic sol–gel systems have been developed for use in the trapping and detection of monocyclic aromatic hydrocarbon contaminants emitted into the atmosphere. To this end, two strategies are followed; the first one aims at tailoring the pore size in order to selectively trap and discriminate benzene and toluene. The second is to decrease the pore polarity in order to eliminate the main interfering gas of the atmosphere, water vapor. The results of these strategies are reported in this paper. After describing the synthesis of silicon hybrid xerogels and thin films and the characterisation of their structural properties, we report the study of the local polarity of the pores, of the porosity and optical properties of the materials. These characterisation data will enable us to define the materials suited for hosting benzene and toluene.