Mesure de module d’Young d’un film mince à partir de mesures expérimentales de nanoindentation réalisées sur des systèmes multicouches

La nanoindentation est une technique de caractérisation bien adaptée pour déterminer les propriétés mécaniques des couches minces. Cependant, pour des couches d’épaisseur de quelques centaines de nanomètres, le substrat et les couches sous-jacentes sont sollicités et les mesures ne sont pas reliées de façon simple aux propriétés du film mince. Le présent travail est une extension du modèle analytique de Bec et al. dans le cas d’un film mince déposé sur un système multicouche. Des résultats expérimentaux obtenus par nanoindentation d’un empilement de couches de matériaux possédant des modules d’Young notablement différents (échantillon multicouche Au/Ti/SiO2 déposé sur un substrat de Si monocristallin), sont analysés par cette méthode. Le module d’Young calculé pour l’or avec le modèle multicouche est de 81 GPa, ce qui est en accord avec la littérature (EAu = 80 GPa). Les résultats montrent que le modèle développé est approprié pour déterminer le module d’Young d’une couche mince déposée sur un système multicouche

Mesure de module d'Young d'un film mince à partir de mesures expérimentales de nanoindentation réalisées sur des systèmes multicouches

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Quantitative evolution of electrical contact resistance between aluminum thin films.

International audienceIn the field of electrical contact, to explain the evolution of electrical resistance as a function of the applied load, it is necessary to take into account the fracture of the native oxide of a metal. This work investigates the role played by the native alumina present at the surface of Al thin film in the formation of micro-contacts as a function of the applied load and loading rate. Thin aluminum films (1 mu m) are sputtered on silica rods (curvature radii of 3 mm and 6 mm). Model crossed rods electrical contact experiments are performed for pressures ranging from 100 MPa up to 1.7 GPa. The following evolution of the electrical contact resistance is proposed. At low loads, the contact is first established without native oxide fracture leading to high levels of electrical resistance by tunneling effect (MOhm). Then fracture of native alumina is associated with the decreasing of the electrical contact resistance between kOhm to Ohm. Extrusion of aluminum through cracks is assumed to be responsible for good ohmic contact where cracks overlap. We show a strong influence of loading rate and contact geometry are investigated. At maximum load, the electrical contact resistance reaches a limit (<100 mOhm), which is controlled by experimental geometry and intrinsic resistivity of the thin film. Current line spreading is modeled for this geometry and non negligible correction is carried out

Central region upgrade for the Jyväskylä K130 cyclotron

The Jyväskylä K130 cyclotron has been in operation for more than 25 years providing beams from H to Au with energies ranging from 1 to 80 MeV/u for nuclear physics research and applications. At the typical energies around 5 MeV/u used for the nuclear physics program the injection voltage used is about 10 kV. The low voltage limits the beam intensity especially from the 18 GHz ECRIS HIISI. To increase the beam intensities the central region of the K130 cyclotron is being upgraded by increasing the injection voltage by a factor of 2. The new central region with spiral inflectors for harmonics 1-3 has been designed. The new central region shows better transmission in simulations than the original one for all harmonics and especially for h=2 typically used for nuclear physics. The engineering design for the new central region is being done.nonPeerReviewe

Electro-mechanical studies of micro-tube insertion into Al-Cu pads for 10 mu m pitch interconnection technology and 3D applications

21st International Workshop on Materials for Advanced Metallization (MAM), Minatec Campus, Grenoble, FRANCE, MAR 11-14, 2012International audienceVarious interconnection technologies such as reflow soldering, thermo-compression, Direct Bond Interconnect (DBI), Solid Liquid Inter Diffusion (SLID) and insertion are under intense investigation in order to accommodate the latest revision of the International Technology Roadmap for Semiconductors (ITRS). The room-temperature insertion technology has been proposed and developed using micro-tubes as inserts to address most of the industrial bonding issues. In the present work, we experimentally study the electrical and mechanical behavior of a single golden micro-tube and its insertion into Al-0.5Cu pads. A modified nano indenter coupled with an electrical measurement device were used in order to determine the insertion mechanisms and mechanical behavior during large plastic deformation of the gold and Al-Cu. Furthermore, finite element (FE) simulations are added to complete the analysis. The numerical load and displacement results are compared with experiments and complemented with a geometrical cross section examination