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Arts/sciences ; création ; émotion ; empathie ; expérimentation ; expression ; intentionnalité ; interaction ; interdisciplinarité ; interprétation ; modèles ; observation ; perception ; projection ; robots.; National audience; Le projet Novabot consiste en une approche interdisciplinaire, ancrée dans l’articulation des arts de la scène et de la recherche en robotique, du rapport encore inédit entre acteurs et drones. Porté par Youssra Mansar, doctorante en deuxième année de thèse à Aix-Marseille Université, Laboratoire d’Études en Sciences des Arts (LESA, EA 3274), dirigé par deux chercheurs de l’université d’Aix-Marseille, Louis Dieuzayde, Maître de conférences en esthétique théâtrale, et Julien Serres, Maître de conférences HDR en robotique bio-inspirée, ce projet se fonde sur un processus d’expérimentation qui sera finalisé par une création diffusée à son terme sur le plateau du Théâtre Antoine Vitez à Aix-en-Provence. Un surprenant mouvement de curiosité étayé par les progrès de la robotique a permis d’accélérer le développement de robots souvent intriguant, parfois inquiétants, mais surtout vecteurs d’enchantement et d’interaction avec ses homologues humains [1]. Les progrès scientifiques permettent aujourd’hui de robotiser de mini-dirigeables pouvant interagir avec l’Homme [2, 3, 4]. Le projet Novabot met en interaction un acteur et un mini-dirigeable robotisé, partiellement déjà conçu, mais appelé à être développé dans ses capacités de mouvement et de captation filmique de manière complètement automatisée [5]. L’acteur au travail serait mis sous l’observation de l’œil de la caméra de Novabot qui se déplacerait avec lui en maintenant toujours la même distance. Novabot espionnerait ainsi certains éléments généralement peu perceptibles du corps de l’acteur (œil, main, bouche, nuque…) et projetterait sur des écrans installés sur la scène un montage instantané de ces images capturées. Un tel dispositif de captation permettrait de rendre visibles certains aspects de la fabrique du jeu de l’acteur notamment au travers de ses réactions corporelles que le spectateur n’est naturellement pas appareillé à percevoir. Notre recherche consistera donc à explorer la manière dont un drone peut venir augmenter la perception de la performance scénique de l’acteur en opérant une qualité de filmage inédite, retransmise en direct, qui la fragmente, la dissocie, focalisant l’attention sur des détailshabituellement indétectés. Il s’agira d’examiner de manière presque « spectrographique » la surface du corps pour surprendre les mécanismes qui s’y produisent au contact d’un texte, d’appréhender le processus altérant de la dynamique d’une langue poétique au sein d’un corps mouvant qui l’énonce et qui se phénoménalise à son contact. Le texte investi dans ce projet résulte d’un montage de fragments de l’œuvre de Valère Novarina, auteur de théâtre contemporain dont l’oeuvre dynamite et régénère la langue tout en soumettant l’acteur à l’exploit de son énonciation [6]. Louis Jouvet définit le jeu comme un « exercice de déséquilibre de soi » et, en effet, chaque langue poétique déforme et reforme le corps en introduisant un déséquilibre qui vise un nouvel équilibre spécifique à son plan d’action : elle produit un processus continu et sous-jacent de vacillement, de relâchement, d’inflexion, de torsion, de reconfiguration et de transformation. Le corps est en quelque sorte déconstruit afin d’être ensuite recréé selon l’action poétique de la langue qui impulse l’action de jouer. Novabot aura ainsi pour mission de guetter au plus près de l’acteur les indices par lesquels il dévoile le cheminement intérieur de son travail. L’enjeu sera de créer ainsi une sorte d’étude phénoménologique du processus de jeu de l’acteur investi au présent de l’acte d’énonciation. Cette expérimentation sera à même de fournir un matériel de données inédit permettant l’étude des mécanismes de l’énonciation au sein d’un corps en jeu, approfondissant de ce point de vue l’approche théorique de l’acteur. Fragmenter, focaliser et augmenter la perception de la présence actorale auprès du public sera en outre susceptible de créer une immersion de chaque spectateur dans le cœur du procès de fabrication de l’acteur [7].

International audience; The growing need for alternative sources to power Internet of Things and autonomous devices has led to many energy harvesting solutions from ambient energy sources. Use of batteries requires complementary energy source for extending the lifetime of the device. In recent times, triboelectric nanogenerators have gained significant attention in charging applications through ambient energy harvesting field due to their simplicity, efficiency and adaptability to many device configurations in nature. It is deemed to sustainably address power for autonomous smart applications in various environmental conditions. In this work, a state-of-the-art triboelectric nanogenerator based on wind actuated venturi design system is demonstrated in sync with the smart system evolution for powering various sensor nodal network. Using natural wind, the 3D printed wind actuated venturi triboelectric energy harvester converts ambient mechanical energy into electricity. This simple and compact device produces an optimum average power of 1.5 mW and produces a maximum output power density of 2850 mW.m-2 (peak power output of 4.5 mW), which is much higher than the existing reports that use larger surface area at higher wind velocity. Extensive material testing and future implementation in an array of applications aids for environment friendly energy production and increase the role of triboelectric nanogenerator in autonomous applications.

International audience; A compact acquisition system developed for a flexible large area monoport tactile surface is presented in this paper. This sensor requires a single port connection and avoids complicated matrix acquisition system and multiplexing. The tactile surface is based on a coplanar transmission line printedd on a large area flexible substrate. Touching the waveguide generates a reflected signal. A harmonic analysis of this reflected signal at the line input port allows locating the touch event. A compact and low complexity acquisition system has been developed in order to demonstrate the principle and evaluate the feasibility of its integration on the sensor. Theoretical background, design and measurements on the overall sensor are exposed. The acquisition circuit imperfections have been demonstrated experimentally and correction methods have been proposed and implemented. Results are presented, and to assess the precision of the compact acquisition system, they are compared to reference measurements made with a Vector Network Analyzer

International audience; This paper describes the fabrication process and the method to determine the membrane tension and defects of an inkjet-printed circular diaphragm. The membrane tension is an important parameter to design and fabricate an acoustic sensor and resonator with the highest sensitivity and selectivity over a determined range of frequency. During this work, the diaphragms are fabricated by inkjet printing of conductive silver ink on pre-strained Mylar thin films, and the membrane tension is determined using the resonant frequency obtained from its measured surface velocity response to an acoustic excitation. The membrane is excited by an acoustic pressure generated by a loudspeaker, and its displacement (response) is acquired using a laser Doppler vibrometer (LDV). The response of the fabricated membrane demonstrates good correlation with the numerical result. However, the inkjet-printed membrane exhibits undesired peaks, which appeared to be due to defects at their boundaries as observed from the scanning mode of LDV.

International audience; We report a one-pot synthesis of copper antimony sulfide nanocrystals by a facile and easily scalable route using a surfactant assisted solvothermal method. Phase-pure and quasi-monodisperse Cu3SbS4 nanocrystals have successfully been synthetized by adjusting the sulfur to copper molar ratio as well as the surfactant to solvent volumetric ratio. Nanocrystals morphology and chemical composition are characterized. As synthetized and purified nanocrystals are formulated into a colloidal suspension in order to fabricate copper antimony sulfide films. Morphological, electrical and optical characterizations of famatinite films are conducted. The electrical resistivity of the as deposited films is comprised between 10 Ω cm and 48 Ω cm. The optical gap is found to be indirect with a value of 0.82 eV.

International audience; A compact acquisition system developed for a flexible large area monoport tactile surface is presented. This sensor requires a single port connection and avoids complicated matrix acquisition system. The tactile surface is a coplanar transmission line printed on a flexible large area. Touching the waveguide generates a reflected signal analyzed to locate the touch event. Theoretical background, design and measurements' results are presented to assess the compact acquisition system precision

International audience; A flexible large area touch sensor and its acquisition system are presented in this paper. The sensing device is based on a printed coplanar transmission line on a large area flexible substrate. Having a unique connection port, it avoids matrix connections array. Touching the waveguide generates a reflected wave which is analyzed at the input port in order to extract the position of the touch event. A low complexity acquisition system was developed and tested in the objective of having a compact integrated system. Theoretical background, implementation and results obtained on the overall sensor are presented. We demonstrate here the operation of an integrated acquisition system and compare its performance to Vector Network Analyzer-based operation

International audience; Unitary carbon nanoparticles with a well-defined shape and a range of diameters between 50 nm and 300 nm have been synthetized from the pyrolysis of resorcinol formaldehyde copolymer. This divided solid has a molecular organization similar to carbon black with a more regular shape and a higher diameter. Thus, carbon nanospheres appear to be adapted to the development of accurate sensors. Inkjet-printable dispersion was prepared with this material and a mixture of N-methyl-2-pyrrolidone and N-cyclohexyl-2-pyrrolidone. This ink is the proof of concept that it is possible to form continuous layers on polyimide flexible substrate with resistive properties which exhibit temperature sensitivity.

International audience; Amorphous and microcrystalline silicon thin-films are widely used in microelectronics and more specifically in solar cell industry. However vacuum deposition technologies are difficult to scale up to large area. Inkjet printing is a promising candidate and thus the functional properties recovering of printed silicon thin films study is a key issue. Special care is given to silicon ink formulation allowing proper deposition. Inks need to fill requirements in terms of surface tension, viscosity and stability in order to control the thin-film quality. The process requirements imply care of thermal budget. Thus a study of various sintering processes under vacuum and inert atmosphere is presented. Convective, Rapid Thermal and microwave annealing are compared. Electrical, optical and morphological effects of sintering and coalescence on molybdenum electrode and oxidized silicon substrates are presented. The nanoparticles size and surface chemistry as well as the heating method clearly impact the required temperature and time of sintering process. It is thus shown how functional layers can be obtained from silicon nanoparticles dispersion. Microwave annealing, diminishing sintering time and temperature, is clearly a promising candidate to allow a low treatment temperature, thus compatible with glass or other "low temperature" substrate. Mastering deposition of solution processed silicon with controlled physical properties opens the way to third generation solar cells development.

International audience; We present a series of organic thin film transistor (OTFT) devices realized by vacuum evaporation, spincoating, drop casting and inkjet printing and a comparative analysis of their electrical response/behavior obtained under identical measurement conditions. A small molecule, α,ω-hexyl-distyryl-bithiophene DHDS2T, was used as a hole transporting active layer. Structure and morphology of thin films have been studied by atomic force microscopy, X-ray diffraction and optical microscopy. Different parameters linked directly to the processes (solvent, concentration, deposition method, surface, post-treatment...) are identified as key factors controlling film quality/crystallinity and device performances. This systematic study reveals the factors that limit efficient charge transport at the macroscopic scale of the channel length in OTFT devices.

This paper investigates the mechanical deformation and the electrical contact resistance of an electroplated Ni micro-cylinder called micro-insert inserted in an Al thin film. A modified nanoindentation apparatus is used to perform the experiments with [email protected], [email protected] and [email protected] diameters micro-inserts having the same [email protected] height. Mechanical deformation of Ni micro-insert and Al film is described at different maximum loads corresponding to an equivalent stress of 0.8GPa, 1.6GPa and 3.2GPa. At equivalent stress less than 1.6GPa, Ni micro-insert exhibits an elastic deformation while at 3.2GPa it presents an elastic-plastic deformation with a large amount of compression and penetration into micro-insert foundation. Visco-plastic deformation of Al film is noticed during hold at all maximum loads. Beside, Al creep parameters are extracted using a combined Maxwell/Kelvin-Voigt phenomenological model. Mechanical results are coupled to electrical contact resistance measurement.

International audience; In this paper, we demonstrate how to enhance polymer thin-film transistors (PTFTs) performances made by low-cost inkjet printing technique. Indeed, in PTFTs, contact resistances between semiconducting conjugated polymers (SCPs) and Source and Drain (S&D) contacts may dominate the transport properties of such electronic devices. Here, we report measurements of these parasitic resistances for several couples of (i) SCPs, as active material, and (ii) electrodes, as S&D contacts, in bottom-contact inkjetted PTFTs. The differences in PTFT performances are discussed upon these contact resistance. For this, we evaluate the performances of several inkjetted couples of SCP/S&D compared to devices with evaporated metal-based S&D. By this way, we show that inkjet printing is a suitable low-cost technique to dispense polymers and inorganic nanoparticles for direct-writing of PTFTs. A significant reduction in the contact resistance RC was achieved when inkjetted Pedot: Pss-based S&D electrodes are used instead of evaporated metal-based S&D electrodes. The improved efficiency of charge carrier injection is assumed to be due to the formation of a p-doped interfacial layer at the interface between the SCP and the S&D electrodes. All these results pave the way towards flexible electronics applications by using inkjetted polymers both for electrodes and semiconducting active layer on flexible plastic substrate.

International audience; Ultrathin silicon chips are becoming more and more popular because of market demand for small, light, and high- performance products with noticeable request of reliability and flexibility. In this paper, the flexibility of the Integrated Circuit package is investigated using finite-element (FE) analysis. ANSYS software is used to analyze a single ultrathin die package in a smart card under four-point bending with the aim of developing flexible smart card modules using chips with thickness below 50 mum. Thicknesses of different layers and Young's modulus of the die adhesive and the encapsulation resin are investigated to find their relative influence on the bending stress field in silicon. The thicknesses of some layers have important influence on bending stress distribution in the module. Decreased copper thickness can reduce considerably the maximal bending stress in silicon die under the same bending condition. As a result, some criteria for the design optimization are given in order to improve the flexibility of the package.

Photonic sintering is an emerging technology based on the instantaneous conversion ofabsorbed light energy by nanoparticles (NPs) into heat. In this work, it is used oninterconnections printed on flexible substrates by inkjet printing of a metal silver nanoinkwith particle mean diameter of Ø=25nm.A process parameters study has allowed us to link them (energy, frequency) with theinduced sheet resistance (120m!/ ). This has been confirmed through thermal modeling ofthe multilayer system, and also by monitoring the resistance variations in-situ duringphotonic sintering (a few ms) using an innovative characterization tool, allowingmeasurements every 4 μs. The electrical resistance stabilization correlated with the opticalproperties of the film was found to be optimal for an exposition of 2-3J/cm², whichcorresponds to heating up to approximately 200°C.Films microstructure analysis with X-ray diffraction enlightens the link between crystallitescoarsening and defaults density reduction. The minimization of electrical resistivity iscorrelated with neck growth between nanoparticles trigged by surface atomic diffusion.Moreover, a stronger cohesion between NPs improves the mechanical hardness compared toclassical oven curing.The electrical contact resistance (200m!) between a silicon chip interconnection bumpand printed tracks is measured thanks to an in-house setting for electrical measurement withthe nanoindenter. The level of forces to apply (300mN per bump) is optimized and transferredto a thermocompression by industrial equipment. A set of prototypes are fabricated andconfirm the compatibility of these technologies with a future industrial integration., Le recuit photonique est une technologie émergente basée sur la conversion instantanée del’énergie lumineuse absorbée par les nanoparticules (NPs) en chaleur. Dans ces travaux, il estdéployé sur des pistes d’interconnexions imprimées sur support souple par jet de matière, àpartir d’une encre de NPs d’argent (Ø=25nm).Une étude des paramètres du procédé a permis d’établir le lien entre ces derniers (énergie,fréquence) et la résistance carrée (120m!/ ) induite. Celui-ci a été confirmé grâce à unemodélisation thermique multicouches et au développement d’une instrumentation inéditemesurant, toutes les 4μs, les variations de la résistance pendant le recuit photonique (quelquesms). La stabilisation de la résistance corrélée avec les propriétés optiques du film est optimalepour une exposition de 2-3J/cm² induisant un échauffement à environ 200°C.L’analyse de la microstructure des films par diffraction des rayons X met en évidence le lienentre la croissance des cristallites et la résorption des défauts. La minimisation de la résistanceélectrique est corrélée à la croissance du collet entre les nanoparticules par diffusion atomiquede surface. De plus, une meilleure cohésion des NPs améliore la dureté par rapport au recuit àl’étuve.La résistance électrique de contact (200m!) entre les plots d’interconnexion d’une puce ensilicium et les pistes imprimées a été mesurée grâce à un montage dédié de mesure électriqueau nano-indendeur. Les forces à appliquer (300mN par bump)

The objective of this work was to design and fabricate a low cost resonant capacitive acoustic sensor using printing techniques. It falls within the frame of a collaborative research project named “Spinnaker”, set up by TAGSYS RFID, a French company, which has planned to integrate this sensor to improve the geolocalization of their RFID tags. This work started with the design and optimization of the sensor using finite element modeling (COMSOL) and design of experiments (DOE). This first step has enabled the identification of the optimum set of parameters and demonstrated that the output responses were in accordance with the specifications. Then, we have developed the different technological building blocks required for the fabrication of the prototypes using jointly the 2D inkjet printing technique and 3D printing method. The functionality of the sensors has been characterized using both capacitive and acoustic measurements using laser Doppler vibrometer. Experimental results showed that sensitivity and selectivity were within the specifications and in good agreement with the modeling results. Finally, we investigated the piezoelectric approach which could be an interesting option to the capacitive one. Since no inkjet printable piezoelectric ink is commercially available, stable inkjet printable polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) ink has been developed. PVDF-TrFE layers were then successfully printed and characterized. The results were quite promising, however further improvements of the ink and printing process are required before stepping towards piezoelectric based device fabrication., L’objectif de ce travail était de concevoir et réaliser par impression un capteur acoustique capacitif résonant bas coût. Il s’inscrit dans le cadre d’un projet collaboratif de recherche intitulé « Spinnaker », défini par la société Tagsys RFID qui souhaite intégrer ce capteur afin d’améliorer la géolocalisation des étiquettes RFID. Ce travail a débuté par la conception et l’optimisation du design en utilisant la simulation par éléments finis (COMSOL) ainsi que des plans d’expériences (DOE : Design of Experiment). Cette première étape a permis de déterminer les paramètres optimaux et démontrer que les performances obtenues étaient conformes aux spécifications. Nous avons ensuite développé les différentes briques technologiques nécessaires à la réalisation des prototypes en utilisant conjointement l’impression 2D par inkjet et l’impression 3D. Nous avons vérifié la fonctionnalité de ces capteurs à l’aide de mesures électriques capacitives et acoustiques par vibrométrie laser. Nous avons démontré la sélectivité en fréquence des capteurs réalisés et comparé les résultats expérimentaux à ceux obtenus par simulation. Enfin, nous avons enfin exploré la « voie piezoélectrique » qui nous semble être une alternative intéressante au principe capacitif. En l’absence d’encre piézoélectrique commerciale imprimable par jet de matière, nous avons formulé une encre imprimable à base du co-polymère PVDF-TrFE et démontré le caractère piézoélectrique des couches imprimées. Les résultats sont prometteurs mais des améliorations doivent encore être apportées à cette encre et au procédé d’impression avant de pouvoir fabriquer des premiers prototypes.

International audience; A new concept of a thermo-mechanical lateral switch activation is proposed. Embedded in standard aluminium BEOL (Back End Of Line), it is fully integrated in CMOS technology. The simplicity of this low cost one-mask fabrication allows the straightforward scalability of design. Most functional problems have been solved through process, simulation and design: stiction, bending, displacement, and robustness. The present study of a thermo-mechanical MEMS switch focuses on three points. Firstly, the design is modified to increase the apparent area contact and the force applied. Secondly, in order to ensure the reversibility of the movement, a running-in step before operation is implemented. Finally, a new design is proposed, simulated and manufactured to avoid the undesirable activations by spurious homogeneous heating.

International audience; A new oligomer of bithiophene and substituted fluorene has been successfully synthesized, exhibiting good FET performance. Our results show that devices can be obtained from inkjetted OTFTs and elaborated by direct writing without any particular pre-patterning or self-alignment techniques. We have also demonstrated the possibility to fabricate inexpensive OTFTs by direct writing paving the way toward using inkjet printing as the key technology for such applications in plastic electronics. The ease of this technique allows charts a clear path to flexible electronics. © 2006 Elsevier B.V. All rights reserved.

National audience; L'objectif de ce travail est le développement d'une dalle pour une interface tactile innovante sur un support souple. La dalle comporte une ligne de transmission imprimée sur un substrat souple et à port d'entrée unique. Le toucher induit une désadaptation locale qui créé une onde réfléchie. L'analyse du coefficient de réflexion en entrée permet de localiser le point de toucher, en utilisant un système d'acquisition basé sur un analyseur de réseaux vectoriel compact. Ce concept de détection est compatible avec des dalles de très grande surface

In order to carry out electronics functions on flexible substrate, thin film transistor is essential. The aim of this thesis is to increase knowledge on this device.State of art of IGZO TFT is summarized in chapter 1. This part presents thin film transistor and justify the choice of IGZO as the semiconductor material. Then, properties of this amorphous oxide semiconductor are discussed. Finally, this chapter presents the results obtained in the literature for IGZO based thin film transistor.Chapter 2 establishes a link between IGZO properties and sputtering deposition. Films are studied by spectroscopic ellipsometry. Experiments show variations in optical properties due to deposition time, oxygen content and position on the wafer. Resistivity measurements are carried out to understand more deeply the causes of these variations.Chapter 3 develops a complete process to achieve TFT on flexible substrate. The choice of different materials and processes is discussed. The performances of the TFT are investigated versus the annealing time and characterized under mechanical stress. Mobility up to 10 cm2.V-1.s-1 can be achieved after an annealing at 300°C during 1h30. Mechanical stresses show a degradation of the transistor induced by cracks in the oxide layer.Chapter 4 focuses on IGZO's deposition by inkjet printing. An ink is formulated using metallic salts and a solvents mixture. The parameters of the printing system are also optimized. To compare the different techniques of deposition, printed IGZO TFTs are characterized and compared with the one fabricated with the standard PVD deposition technique. Mobility is relatively lower and equals 0.4 cm2.V-1.s-1., Pour réaliser des fonctions électroniques sur support souple, le transistor en couches minces (TFT) est indispensable. Cette thèse a pour objectif d’approfondir les connaissances sur ces dispositifs.L’état de l’art est synthétisé dans le chapitre 1. Cette partie présente tout d’abord les TFT et justifie l’utilisation de l’oxyde d’indium gallium zinc (IGZO). Ensuite les propriétés de cet oxyde semi-conducteur amorphe sont traitées ; et enfin le chapitre fait état des résultats obtenus avec des TFT en IGZO.Le chapitre 2 établie un lien entre les propriétés de l’IGZO et le dépôt par pulvérisation cathodique. L’étude des films a été réalisée par ellipsométrie spectroscopique. Celle-ci a mis en évidence des variations dans les propriétés optiques dues au temps de dépôt, à la concentration en oxygène et à la position sur le substrat. Ces résultats ont été comparés à des mesures de résistivité, pour comprendre plus précisément la cause de ces variations.Le chapitre 3 élabore un procédé complet permettant de réaliser des TFT sur support souple. Le choix des différents matériaux est discuté, et les différents outils de procédés sont adaptés afin de réaliser ces dispositifs. Les TFT obtenus sont caractérisés en fonction du temps de recuit et sous flexion. Ils ont atteint des mobilités 10 cm².V-1.s-1.Le chapitre 4 étudie le dépôt d’IGZO par impression jet d’encre. Une encre a été formulée et les différents paramètres d’impression ajustés. Afin de comparer les différentes techniques de dépôt, des TFT avec canal en IGZO imprimé ont été réalisé et les films imprimés ont été caractérisé par ellipsométrie spectroscopique. Ces dispositifs ont atteint des mobilités de 0,4 cm2.V-1.s-1.

Colloidal suspensions of nanoparticles are increasingly employed in the fabrication process of electronic devices using inkjet-printing technology and a consecutive thermal treatment. The evolution of internal stresses during the conversion of silver nanoparticle-based ink into a metallic thin-film by a thermal sintering process has been investigated by in-situ XRD using the sin2ψ method. Despite the CTE mismatch at the film/substrate interface, the residual stress in silver films (below 70 MPa) remains lower than in conventional PVD thin-films, as a result of the remaining porosity. A Warren-Averbach analysis further showed that the crystallite growth is associated with a minimization of the twin fault density and the elastic microstrain energy above 150°C. A stabilization of the microstructure and internal stress is observed above 300°C. Inkjetprinting technology thus appears as a good alternative to conventional metallization techniques and offers significant opportunities asset for interconnect and electronic packaging. cop. (2014) Trans Tech Publications, Switzerland. 'Conseil General de l'Aube'; Conseil National de la Recherche Scientifique (CNRS); et al; Grand Troyes; Proto Manufacturing; Region Champagne-Ardenne

International audience; Nanostructured silicon-based materials are good candidates for thermoelectric (TE) devices due to their low thermal conductivity, customizable electrical conductivity, and reduced cost. Generally, nanostructured TE bulk materials are obtained through compaction and sintering at high temperature (>1000 degrees C) of silicon nanoparticles (NPs). In order to introduce TE generators in flexible electronic devices, development of thin film TE is needed. Inkjet-printing of silicon NPs-based ink is an interesting technology for this targeted application due to its low cost and additive process. This paper presents the implementation of inkjet-printing of a silicon NPs-based ink toward the fabrication of TE material on flexible substrate and the development of a characterization method for this material. After printing, recovering of electrical properties through sintering is mandatory. Nevertheless, special care must be taken in order to keep thermal conductivity low and reduce the annealing temperature to allow the use of flexible substrates. The functional properties: electrical and thermal (measured by Raman spectroscopy), are studied as a function of the annealing process. Two types of annealing: rapid thermal annealing and microwave annealing, are investigated as well as two atmospheres: inert (N2) and reducing (N-2-H-2 5%).

MAM2013, March 10-13, Leuven, Belgium; International audience; In the context of Back-End of Line (BEoL) roadmap, dimension reduces, density integration increases and new materials are introduced. These points associated to manufacturing thermal budget could induce mechanical failures. Thus, a metallic in situ sensor was developed to study residual stress on a single metal level: using standard CMOS BEoL processing on 8″ silicon wafer, aluminum thin film is patterned on dielectric layer. The sensor is composed by arms and a flexible beam that are fixed to anchors. As the structure is released from its surrounding layer, the relaxation of residual stress induces a displacement of flexible beam. Therefore, the measurement of this displacement allows determining the initial residual stress. Using this structure, the purpose of this paper is not only to determine the residual stress state, but also the thermo-mechanical properties: coefficient of thermal expansion and thermal conductivity. For that reason, new designs are released to address electrical polarization and thus to locally heat this sensor by Joule effect. Due to thermal expansion, the flexible beam will move. The thermo-mechanical properties were determined by coupling SEM electrical nano-probing (displacement of flexible beam and electrical resistance as a function of applied current) with analytical modeling and Multi-physics Finite Element Method (FEM). As a result, a tensile stress state of 190 MPa in arm direction is identified in the aluminum thin film. The coefficient of thermal expansion of 22.5 × 10−6 K−1 and thermal conductivity of 190 W/(K m) were identified, in agreement with literature.

International audience

International audience; A metallic in-situ stress sensor is modified to address electrical polarization and thus to locally heat this sensor by Joule effect. By coupling SEM electrical nano-probing with analytical modeling and multiphysics Finite Element Method (FEM), the thermo-mechanical properties are identified. As a result, a tensile stress state of 190 MPa, coefficient of thermal expansion of 22.5×10-6 K-1 and thermal conductivity of 190 W/(K·m) are identified in the aluminum thin film in agreement with literature. Moreover, high current induces irreversible deformation and breaking. Using multiphysics FE model with identified thermo-mechanical properties, the failure of the sensor under electrical solicitation is investigated. The evolution of local temperature and mechanical deformation on different sensor designs allows the determination of the breaking location and condition.

International audience; A freestanding cross-shaped structure designed as a planar rotation stress sensor [1], [2], [3] is manufactured using standard CMOS technology (Complementary Metal-Oxide-Semiconductor). The fabrication process induces thermal residual stresses which result in out-of-plane bending, which degrades the device reliability and precision. To control such movements, the design was studied under stress compensation using a bilayered aluminum (Al) / titanium nitride (TiN) structure. Likewise, a single layer of aluminum was studied, to determine a technological solution, with better compatibility. Fabrication stresses have been measured using Stoney's formula based on bending of full-wafer coatings. The Finite Element Method (FEM) is used to model the effect of these stresses on the geometry after release, and the results are compared with measurements. For this purpose, a comb-shaped structure has been designed to relate residual stress in a freestanding Al-TiN bi-layered structure with its bending. Based on this, conservation or elimination of TiN layer is judged, so that the design remains planar after release. The model is then applied to the movement of the cross-shaped sensor after release, and a second optimization variable is studied for maximum sensitivity: the shape of the hinge between the two arms of the cross.

National audience; The recent progress in functionalized inks based on metal nanoparticles and their subsequent deposition by inkjet-printing technologies promoted the emergence of printed electronics. Such printed structures can be treated by selective sintering techniques that enable the sintering of 20 nm-nanoparticles at process temperatures compatible with flexible plastic substrates. This article discusses the various aspects related to the production of metal tracks on flexible substrates, from the deposition using direct printing technologies, to the relationship between microstructural characteristics and electrical properties of such structures for the fabrication of devices such as antennas, interconnectsor electrodes.; Le développement récent d’encres fonctionnalisées constituées de nanoparticules métalliques, associé à la maîtrise du procédé d’impression par jet d’encre, a rendu possible l’émergence de l’électronique imprimée. Les structures imprimées peuvent être traitées par des techniques de recuit sélectif qui permettent de réaliser la coalescence de nanoparticules de 20 nm à une température de procédé compatible avec les substrats plastiques flexibles. Cet article aborde les différents aspects liés à la réalisation de pistes métalliques sur substrat souple, depuis les technologies d’impression directes, jusqu’à l’adéquation entre les caractéristiques microstructurales et les propriétés électriques de telles structures pour la fabrication de dispositifs tels que des antennes, des pistes de routage ou des électrodes.

International audience; Contact material and more precisely surface properties are a major issue for RF MEMS ohmic switch reliability. Shallow ion implantation of boron and nitrogen on gold thin film is investigated to increase surface hardness with a limited impact on Electrical Contact Resistance (ECR). The implantation energies were chosen to place the concentration peak of the implanted species at a depth of 100 nm. A microstructural analysis shows that the hardness increases with boron concentration due to a solid solution hardening mechanism, whereas in case of nitrogen, for concentration above 1%, the nitrogen precipitates into a nitride phase correlated to a hardness decrease. The ECR is measured using a Nanoindenter XP which experimental setup reproduces MEMS ohmic switch contact (from 100 μN to 1 mN applied loads under 1 mA). A notable result is obtained with a boron dose of 7.37 x 1016 ions/cm² at 90 keV into gold thin film: 50% hardness increase and 2.6 times higher ECR than pure gold.

RFID solutions will improve the traceability of biological samples stored at low temperature (77 K) in biobanks. To achieve this goal, the reliability of RFID tags is essential. In this paper, we focus on the reliability aspect of RFID tags in harsh environment and more specifically to assembly design optimization through numerical simulations and accelerated life tests. A package-dimensioned model and a wire-interconnect centered model have been used to assess stress distribution in the package and wire bonds. We also develop a specific versatile test bench to apply thermal cycling while monitoring the functionality of the tags. We investigate three different tag configurations and demonstrate that the main failure mode is related to wire breaks. The occurrence of this failure depends mainly on the nature and thickness of the encapsulant resin which induce compressive and tensile stresses during thermal cycling. FEM results are in good agreement with observed failures. © 2013 Elsevier Ltd. All rights reserved.

International audience; Carbon nanoparticles can be obtained by the pyrolysis of thermoset resorcinol (R) and formaldehyde (F) copolymers nanopheres. In comparison with carbon black nanoparticules commonly proposed by chemical products suppliers, their shape is more regular and well defined. In addition R/F carbon nanoparticle can be synthetized with a very narrow granular spreading. Three different synthesis pathways have been tested in the aim to obtain 200 nm diameter monodisperse particles. The polymerization in an emulsion stabilized using electrostatic repulsion, derived from Stöber method, gave the best results. R/F carbon nanoparticles were used to make an inkjet printable dispersion in order to form resistive carbon thin films on Kapton substrate.

International audience; Inkjet printing has a high potential for cost reduction in solar cell and thermoelectric industry. This study demonstrates that silicon thin films can be produced by inkjet-printing of a silicon ink followed by consequent drying and annealing steps. Ink formulation is a crucial parameter for sintering of the silicon nanoparticles and control of the microstructure at low temperature. Evolution of the sintering steps is monitored by scanning electron microscopy and by Raman spectroscopy which offers a fast and precise characterization of the microstructure and chemical composition of the thin films. While denser and more crystalline layers are obtained, cracks appear within thin film and substrate because of stress provoked by oxidation of the surface. Electrical conductivity is improved with higher annealing temperature until a threshold where both physical degradation and oxidation of the layers limits strongly the carrier transport phenomenon. In opposition transmission of the thin films is altered with increasing annealing temperature. Evolution of the thermal conductivity is performed by Raman spectroscopy and can be tailor in a large range between ~1 to ~100 W/mK. Therefore control of the microstructure evolution with applied annealing process allows tailoring of both microstructure and thermal conductivity of the thin films.

This study takes place in the frame of the Inxilicium project from the National Research Agency, which targets the fabrication of silicon thin film solar cells by inkjet-printing. Thanks to their specific properties, silicon nanoparticles are materials with strong potential for technological breakthroughs. Silicon nanoparticle-based inks made by different synthesis routes have been inkjet-printed on different substrates: quartz, metallic electrodes (aluminum, molybdenum) and transparent electrodes (ZnO:Al). Homogeneous and continuous thin films (from several hundreds of nm to some µm thick) have been obtained through optimization of the printing process, the ink/substrate interaction (via substrates surface energy tuning) and the drying step.A posteriori, an annealing step is mandatory for recovering of functional properties. By using nanoparticles with tailored surface physical chemistry, the sintering temperature decreases from 1100 °C to 600 °C. In order to allow the use of this material on flexible and low cost substrates, selective sintering (microwave and photonics) have been also evaluated.Thin film optical properties and electrode/silicon interfaces have been investigated with the purpose to integrate those layers into devices (solar cells…). Metallurgical evolution of Al-Si and Mo-Si physical interfaces has been studied by in situ XRD.This work allowed the fabrication of a PN junction with a photovoltaic behaviour under strong polarization voltage thanks to the development of an innovative thermal pasting process, which opens the way to the reduction of process thermal budget., Cette étude prend place dans le cadre du projet ANR Inxilicium visant à la réalisation de cellules solaires en couches minces de silicium par jet d’encre. Les nanoparticules de silicium sont des matériaux à fort potentiel pour la levée de verrous technologiques grâce à leurs propriétés spécifiques. Des encres de nanoparticules de Si issues de diverses méthodes de synthèse ont été imprimées par jet d’encre sur différents substrats : quartz, électrodes métalliques (aluminium, molybdène) et transparente conductrice (ZnO:Al). L’optimisation du procédé d’impression, de l’interaction encre/substrat (via la modulation de l’énergie de surface des substrats) et de l’étape de séchage a permis l’obtention de couches minces homogènes et continues (plusieurs centaines de nm à quelques µm d’épaisseur)A posteriori, une étape de recuit est nécessaire pour recouvrer des propriétés fonctionnelles. L’utilisation de nanoparticules à la physico-chimie de surface contrôlée fait décroître les températures de frittage de 1100 °C à environ 600 °C. En complément, des recuits sélectifs (micro-ondes et photonique) ont été évalués pour leur application sur des substrats flexibles et bas coûts.Les propriétés optiques et les interfaces électrode/silicium ont été examinées afin d’intégrer ces couches dans des dispositifs (cellule solaire…). La formation de transitions métallurgiques Al-Si et Mo-Si a été étudiées par DRX-in situ. L’ensemble de ces travaux a permis la réalisation d’une jonction PN montrant un comportement photovoltaïque à fort champ grâce aussi à la mise au point d’une méthode innovante de collage ouvrant la voie à une réduction du bilan thermique des procédés de fabrication.

International audience

Several challenges are still holding back the technological transfer of printed electronics to industry in spite of recent progresses. In this thesis work, the printing method of inks based on silver nanoparticles (=25 nm) was optimized according to its rheology and to the fluid/substrate interactions for the fabrication of electrical interconnections with a thickness of 500 nm. These lines were printed on silicon or flexible substrates and annealed either by conventional (oven or infrared) or selective methods (microwave) at temperatures comprised between 100 and 300 °C.A better understanding of the relationship between process and microstructure of these printed thin films, based on several crystallographic equipments (XRD, EBSD and EDX), led to the optimization of nanocrystallites growth with an activation energy of about 3 to 5 kJ•mol-1. In addition to the low residual stress (70 MPa), this optimization is used to achieve low electrical resistivity (3.4 μOhm•cm) associated with a greater coherence of the crystal lattices at grain boundaries. The probability of electron scattering at such interfaces can be further reduced using an innovative approach of oriented crystallite growth by atomic interdiffusion from the substrate.The low mechanical stiffness (E=25 nm) en fonction de sa rhéologie et des interactions fluide/substrat a permis de réaliser des interconnexions électriques d’une épaisseur de 500 nm. Ces lignes imprimées sur des substrats silicium ou flexibles sont ensuite recuites par des méthodes conventionnelles (étuve ou infrarouge) ou sélectives (micro-onde) à des températures comprises entre 100 et 300°C.Une meilleure compréhension de la relation procédé/microstructure des couches minces imprimées, via plusieurs caractérisations cristallographiques (DRX, EBSD et EDX), a permis d’optimiser la croissance des domaines nanocristallins, activée pour des énergies de l’ordre de 3 à 5 kJ•mol-1. Outre les faibles contraintes résiduelles (70 MPa), cette optimisation permet d’atteindre de faibles résistivités électriques (3.4 µOhm•cm) associées à un accroissement de la cohérence des réseaux cristallins aux joints de grains. La probabilité de réflexion des électrons à ces interfaces peut être davantage réduite, grâce à une approche innovante de croissance orientée des cristallites par interdiffusion atomique à partir du substrat.La faible rigidité mécanique (E

International audience; Many adhesion test techniques have been developed to measure the adhesion energy of thin films but they are hard to implement in the case of submicron organic thin films deposited on a flexible substrate. Recently the feasibility and repeatability of the scratch test technique as a tool for testing the adhesion and the damage behaviour of ultra-thin films on polymer substrates has been demonstrated. However, direct comparison of the critical load between samples was not straightforward since different failure mechanisms were induced. In the present work, we have performed nanoscratch experiments on submicron thin films deposited on a flexible substrate. The use of a tip radius of 5 μm enabled a unique delamination mechanism to be induced by localizing and maximizing the stress closer to the interface. We have observed an increase of the critical load on samples processed with an adhesive plasma treatment prior to thin film deposition, confirming the effectiveness of this treatment. We have also performed mechanical ageing tests on specimens and proved that the scratch test technique is sensitive enough to monitor the degradation of the interface properties. Finally, we have discussed some existing energy models. Taking into account some limitations, Laugier's model gives an upper bound for the adhesion energy.

International audience; Inkjet-printing of interconnects is a maskless technology that has attracted great interest for printed electronics and packaging applications. Gemalto is expecting by motivated and developing skills and knowledge in this area to be at the forefront of European Security innovation and to answer to a continuous market pressure for higher security, lower cost and more secure complex systems. With an increasing need for flexible and mass deliveries of advanced secure personal devices such as: electronic passports, ID cards, driver licenses, other smartcards, e-documents and tokens. EMSE is seeing in these new developments an exciting brand new area of research situated between material science and electronics. In this frame, deposit and pattern creation for chip interconnection require specific behaviors which have to be scientifically understood to pursue industrial harmonious implementation. Both groups collaborated on inkjet-printed electronic routing from deposition to sintering and characterization, using collaborative means provided on Micro-PackS platform.

International audience; This paper describes the realization of 13,56MHz spiral antenna for RFID applications on A4 format substrate by an inline inkjet printing process. The first step consists on the printing of five loops of 20% nano-silver ink in a standard class 1 size. An intermediate inline drying step using variable frequency microwave allows the stacking of several silver layers. Else; an interconnecting bridge between the two sides of the spiral antenna is printed on the top of an insulating layer, also fabricated inline using a second printing head. After pasting an adequate chip, the RFID tag is read at a distance of 70mm and has a tuning frequency of 16.2MHz. The magnetic activation field of the tag is measured at 390mA/m by a standard test method and is similar to the performance achieved by commercial RFID tags fabricated by traditional technics.

7 pages; International audience; This paper shows that the well-know chalcogenide Ge2Sb2Te5 (GST) in its amorphous state may be advantageously used as solid electrolyte material to fabricate Conductive-Bridge Random Access Memory (CBRAM) devices. GST layer was sputtered on preliminary inkjet-printed silver lines acting as active electrode on either silicon or plastic substrates. Whatever the substrate, the resistance switching is unambiguously attested at a nanoscale by means of conductive-atomic force microscopy (C-AFM) using a Pt-Ir coated tip on the GST surface acting as a passive electrode. The resistance change is correlated to the appearance or disappearance of concomitant hillocks and current spots at the surface of the GST layer. This feature is attributed to the formation/dissolution of a silver-rich protrusion beneath the AFM tip during set/reset operation. Beside, this paper constitutes a step toward the elaboration of crossbar memory arrays on flexible substrates since CBRAM operations were demonstrated on W/GST/Ag crossbar memory cells obtained from an heterogeneous fabrication process combining physical deposition and inkjet-printing.

Several challenges are still holding back the technological transfer of printed electronics to industry in spite of recent progresses. In this thesis work, the printing method of inks based on silver nanoparticles (=25 nm) was optimized according to its rheology and to the fluid/substrate interactions for the fabrication of electrical interconnections with a thickness of 500 nm. These lines were printed on silicon or flexible substrates and annealed either by conventional (oven or infrared) or selective methods (microwave) at temperatures comprised between 100 and 300 °C.A better understanding of the relationship between process and microstructure of these printed thin films, based on several crystallographic equipments (XRD, EBSD and EDX), led to the optimization of nanocrystallites growth with an activation energy of about 3 to 5 kJ•mol-1. In addition to the low residual stress (70 MPa), this optimization is used to achieve low electrical resistivity (3.4 μOhm•cm) associated with a greater coherence of the crystal lattices at grain boundaries. The probability of electron scattering at such interfaces can be further reduced using an innovative approach of oriented crystallite growth by atomic interdiffusion from the substrate.The low mechanical stiffness (E, Plusieurs défis subsistent pour la migration de l’électronique imprimée vers l’industrie, malgré des avancées récentes. Dans ces travaux de thèse, l’optimisation du procédé d’impression d’encres à base de nanoparticules d’argent (=25 nm) en fonction de sa rhéologie et des interactions fluide/substrat a permis de réaliser des interconnexions électriques d’une épaisseur de 500 nm. Ces lignes imprimées sur des substrats silicium ou flexibles sont ensuite recuites par des méthodes conventionnelles (étuve ou infrarouge) ou sélectives (micro-onde) à des températures comprises entre 100 et 300°C.Une meilleure compréhension de la relation procédé/microstructure des couches minces imprimées, via plusieurs caractérisations cristallographiques (DRX, EBSD et EDX), a permis d’optimiser la croissance des domaines nanocristallins, activée pour des énergies de l’ordre de 3 à 5 kJ•mol-1. Outre les faibles contraintes résiduelles (70 MPa), cette optimisation permet d’atteindre de faibles résistivités électriques (3.4 µOhm•cm) associées à un accroissement de la cohérence des réseaux cristallins aux joints de grains. La probabilité de réflexion des électrons à ces interfaces peut être davantage réduite, grâce à une approche innovante de croissance orientée des cristallites par interdiffusion atomique à partir du substrat.La faible rigidité mécanique (E

Ohmic MEMS switches made by gold thin films are promising devices but their mechanical contacts are one of the critical concerns for enhancing reliability. For this reason, surface processes are investigated in this work to improve both mechanical and electrical contact resistance (ECR) of MEMS gold contacts. Ruthenium ultra-thin films (20 to 100 nm) deposited on a top of gold layer increase surface hardness by a factor of fifteen. In parallel, surface implantations of both boron (, Afin d’améliorer la durée de vie des micro-relais MEMS ohmiques, plusieurs traitements de surface de films minces d’or sont réalisés pour augmenter leur dureté tout en conservant une résistance électrique de contact faible.Les revêtements ultrafins de ruthénium (20 à 100 nm) déposés sur l’or augmentent la dureté des surfaces de contact d’un facteur 15. L’implantation ionique de bore ou d’azote (3,5 ppm à 10 % atomique) à une profondeur de 100 nm dans le film mince d’or permet d’atteindre un gain en dureté de 75%. Le contrôle (AFM, EBSD et DRX) de la microstructure induite met en évidence le durcissement par solution solide par insertion. Mais au-delà de 1% atomique, les atomes d’azote quittent le réseau cristallin de l’or pour former des précipités de nitrure d’or.L’analyse AFM (rugosité et diamètre) des empreintes résiduelles (quelques μm²) réalisées par nano-indentation sphérique, imitant le cyclage et le fluage des surfaces de contact de ces MEMS, démontre l’apport de ces traitements de surface. De plus, leurs résistances électriques de contact, mesurées par nano-indentation instrumentée reproduisant un micro-contact identique à un dispositif réel, sont similaires à celle de l’or pur.La modélisation discrète mécanique du contact rugueux est ajustée à la mesure de la déformation mécanique de nano-rugosités en comparant les relevés topographiques réalisés par AFM avant et après nano-indentation sphérique. La comparaison entre la modélisation et la mesure de la résistance électrique de contact indique que pour les gammes de force utilisées dans les micro-relais MEMS (inférieure au mN), seule une fraction allant de 2% à 9% de la surface de contact réelle est conductrice.

International audience; The effect of thermal profile on microstructure is studied in the frame of thin films deposited by inkjet-printing technology. The role of sintering temperature and thermal ramp is particularly investigated. Fast heating ramps exhibit coarse grains and pores, especially when a hybrid microwave curing is performed. This enhanced growth is attributed to the quick activation of densifying sintering regimes without undergoing thermal energy loss at low temperature. Microstructural evolution of various sintered inkjet-printed films is correlated with electrical resistivity and with the Young's modulus determined by nanoindentation. A strong link between those three parameters is highlighted during experiments giving credit to either a surface or a fully volumetric sintering, according to the process. Sintering is then mainly triggered by surface mass transfer or by grain boundary diffusion respectively. Silver thin-films with an electrical resistivity 4 to 5 times higher than the bulk has been reached in a few minutes and with a Young's modulus of 38 GPa.

International audience; With the recent development of printed electronics on flexible substrate, urge for low temperature sintering process has emerged. In the frame of temperature sensitive substrates like plastics (PET, ABS, PC, etc.) conventional convective oven cannot be suitably used to achieve near‐bulk electrical resistivity. Consequently, several alternative sintering technologies have been reported and tested. In this present work, the prospective advantage of variable frequency sintering is studied for selective and fast sintering of metal inks. This variable frequency mode (VFM) improves the distribution of the electromagnetic field within the cavity and impedes arcing phenomena that could happen on metal surface. Inkjet-printed devices were processed using a VFM mode with a central frequency of 6.425 GHz with a bandwidth of 1.15 GHz and a sweep rate of 0.1 second has been used. A solid calibration step is required for temperature measurements and control during the process. The procedure includes a camera-based observation coupled with a pyrometer and an optic fiber. A reliable determination of the substrate and ink emissivity is compulsory to tailor the temperature feedback so as to not overcome the substrate's glass transition. The direct impact of microwave has been analyzed comparatively to conventional sintering assisted sintering where a thermally conductive susceptor or matrix is exploited. A huge shrink in electrical resistivity is particularly observable for samples prepared with conventional rapid thermal annealing (RTA), while those prepared in VFM quickly exhibit resistivities below 8 μΩ.cm, about 6 time the silver bulk resistivity. The electrical resistivity shrinkage is mainly originating from the contribution of the grain size. Through a strong coupling between microwave and silver nanoparticle, selective sintering of metallic parts is achieved on low temperature substrates enabling very low electrical resistivity without damaging the plastic substrate. These promising results open ways to successful implementation of microwave sintering in industrial process for flexible electronic application.

International audience; The mechanical properties of interfaces and more precisely the adhesion are of great importance for the understanding of the reliability of thin film devices. Organic thin film transistors (OTFT) on flexible substrate are a new class of electronic components. Since these devices are flexible and intended for different fields of application like sensors and displays, they will undergo a lot of mechanical and thermal stress during their useful life. Moreover, interfaces play an important role in the electrical stability of these transistors. In this context, the adhesion of two organic submicron thin films, semi conducting and dielectric respectively, deposited on polymeric substrate were investigated by scratch test method. This study demonstrates the feasibility and selectivity of the scratch test as a tool for assessing the adhesion and the damage behaviour of ultra-thin organic film on flexible plastic substrate. The semi-crystalline substrate presents a brittle cracking damage from a given strain, whereas when covered by the semi-conducting thin film, the sample exhibits a more ductile behaviour. Moreover, this technique has proven to be sensitive enough to highlight the effects of a plasma treatment prior to deposition.

International audience; This paper describes an in-line process for the realization of 3D electronic components on A4 format substrate by piezo inkjet printing. This process is developed within a semi-industrial prototype system named "JETPAC". JETPAC includes an oxygen plasma torch for surface preparation and post-process modules as a variable frequency microwave oven and an UV lamp for metal selective sintering and dielectric ink curing, respectively. JETPAC is used to achieve passive components by chaining conductor and dielectric layers on kapton® substrate: silver nanoparticles based ink is used to print conductors. For multilayer component elaboration, the metal ink is deposited both on kapton® and on printed dielectric materials. Due to a low surface energy (S.E) of the printed dielectric, the realization of efficient silver tracks is compromised. A special process combines O2 plasma treatment and UV exposure before printing, allowing the reaching of S.E. value on dielectric near the optimum one (55mN/m). This pre-process allows printing of well-defined conductive structures on top of the dielectric. In-line sintering of printed structures is then performed using variable frequency microwave source. The process allows the elaboration of multilayer structures including stacked resistors and capacitors. These results make the developed process very promising for the realization by inkjet printing of passive devices for smart tag applications.

These recent years, Organic Field-Effect Transistor (OFET) development has significantly improved it performances and it stability. This was made possible, through a better understanding of the mechanisms governing charge transport in these devices. However, some phenomena remain unclear, in particular, at the interface between the semiconductor and the dielectric. Charge carrier trapping which is one of the main causes of charge transport disturbance in organic transistors, is one of them. So, this work aims to investigate such phenomena in pentacene-based transistors.Polar groups and particularly, hydroxyl groups, located at the insulator-semiconductor interface, are the main sources of charge carriers trapping in OFET. To prevent their presence, an OFET fabrication technology based on a passivating dielectric, poor of hydroxyl groups, calcium fluoride-based interfacial layer has been developed. Effect of this layer on pentacene-based transistors operation has been studied, as well as these devices aging under different storage atmosphere (in vacuum and in air) and under electrical stress.Thus, it has been highlighted that an interfacial layer of calcium fluoride with a too high thickness (around 5 nm) changes pentacene layer morphology which results in a quasi-disappearance of charge transport in pentacene in OFET configuration. Aging studies showed that under the effect of CaF2 interfacial layer, even with a very thin thickness (a few nanometers), a greater quantity of moisture is induced in pentacene layer probably due to the hygroscopic nature of calcium fluoride., Le développement des transistors organiques, ces dernières années, a permis une nette amélioration de leurs performances et de leur stabilité. Ceci a été possible, notamment, grâce à une meilleure compréhension des mécanismes régissant le transport de charges dans ces dispositifs. Cependant, certains phénomènes restent encore à éclaircir, en particulier au niveau de l’interface entre le semi-conducteur et le diélectrique. Le piégeage des porteurs de charges qui est une des principales causes de perturbations du transport de charges dans les transistors organiques, en est un. Cette thèse se propose donc, d’étudier ce phénomène dans des transistors à base de pentacène.Les groupements polaires, et plus particulièrement les groupements hydroxyles, présents à l’interface entre l’isolant et le semi-conducteur, sont les principaux responsables du piégeage des porteurs de charges dans les transistors organiques. Afin de limiter leur présence, une technologie basée sur l’emploi d’une couche interfaciale diélectrique passivante, pauvre en groupements hydroxyles, à base de fluorure de calcium, a été mise en place. L’influence de cette couche sur le comportement de transistors à base de pentacène a été étudiée, de même que le vieillissement de ces dispositifs sous différentes conditions de stockage (sous vide et à l’air) et sous contrainte électrique.Ainsi, il a été mis en évidence qu’une couche de fluorure de calcium d’une épaisseur trop importante (de l’ordre de 5 nm) modifie la morphologie de la couche de pentacène, ce qui se traduit par une quasi-disparition du transport de charges dans le pentacène en configuration de transistor à effet de champ. Les études de vieillissement ont montré que sous l’effet de la couche interfaciale de CaF2, même d’une très fine épaisseur (de quelques nanomètres), une quantité plus importante d’humidité est présente dans la couche de pentacène, probablement à cause de la nature hygroscopique du fluorure de calcium.

International audience; Use of nanoparticle-based solution processed technologies such as inkjet printing of inorganic material offers a potential strong reduction of silicon thin films production cost for large area electronic devices such as thin film transistors, solar cells or thermoelectric devices. After deposition a thermal step is required to restore the material functional properties. Classical thermal heating does not allow sufficient reduction of both process temperature and time. In contrast microwave sintering offers the key advantage of energy and processing time saving. Previous studies on heating of silicon particles have shown strong dependence on the surface chemistry of the particles: the presence of an oxide inhibits sintering below temperatures around 1100 °C. It is shown here by Raman spectroscopy on thin-films that onset of microwave sintering occurs at much lower temperature (~800 °C). Shrinkage of compacts is monitored for both types of sintering using classical thermal dilatometry and custom in situ real time temperature and shrinkage monitoring system. Two shrinkage stages are identified. Principal shrinkage stage during microwave heating takes place at lower temperature than for thermal sintering. Nevertheless densities obtained by microwave annealing are smaller. Major role of cavity atmosphere is put in evidence.

As an alternative technology to replace lithographic process, direct printing of conductive nanofluids can thus be used to fabricate high resolution patterns, such as antennas and conductive redistribution lines. In the past few years, the use of metallic nanoparticles has undergone major development in microelectronics thanks to sintering achievements. To preserve electronic components functionalities, thermal budget need to be carefully considered, and thus a limited sintering temperature below 300°C should be used when printing nanoparticles. Nonetheless, the absence of any compacting step requires an exploration of novel sintering approaches to achieve a sufficient coalescence. In this frame, several sintering processes (thermal oven, rapid thermal annealing, selective microwave and laser curing) have been investigated to optimize the annealing of those thin films. The aim of this work is to analyze the induced microstructure of the above-mentioned sintering processes, and to determine how electrical and mechanical characteristics are consequently impacted. According the sintering technique and process parameters, an average grain size up to one micron can been achieved from initial mean particle size of 40nm, without exceeding a temperature range of 300°C. The microstructure characterization has been performed using electron backscatter diffraction (EBSD) in a field emission gun scanning electron microscope. Microstructural evolution of various sintered inkjet-printed films has thus been correlated with electrical resistivity and with the Young's modulus determined by nanoindentation. A strong link between those three parameters was highlighted during experiments giving credit to either a surface or a fully volumetric sintering, according the process. Sintering is then mainly triggered respectively by surface mass transfer or by grain boundary diffusion. Particular interests are shown for selective sintering especially when using microwaves and laser. Silver thin-films with an electrical resistivity three times higher than the bulk can be reached in a few minutes for a Young's modulus of about 50 GPa. In the meantime, the convective rapid thermal processing exhibits a various electrical resistivity and grain size. A Young's modulus even close to the bulk can be obtained when using a fast temperature ramp at 150 °C/sec for 15 minutes. This microstructural tailoring of printed silver nanoparticles were successfully implemented in the post-process step to achieve 600 nm thick films with very low resistivity and improved mechanical stiffness.

International audience; Printed electronics by inkjet offers enormous potential since it is an additive process allowing accurate deposition of liquids at high speed and without waste. However, one of the challenges in inkjet is the optimization of printing parameters as well as the surface energy between different deposited inks and interfaces. In this paper, an in-line process for the realization of multilayer resistors by drop-on-demand inkjet printing is described. This process is developed within a home-build 'JETPAC' prototype system allowing the printing of both metals and dielectrics. This prototype is used to realize 3D series resistors that were stacked on a top of each other through a passivation layer. Here, the first printing level optimization process includes the tuning of inkjet-printed parameters and the surface energy between the Kapton substrate and both silver and hydrophobic UV dielectric inks. The second printing level optimization process includes the setting of the accurate parameters for the selective microwave sintering of silver nanoparticles. Finally, the resistors printed on a top of each other were interconnected in series via contact pads after alignment step. Results shows that different value of resistors can be achieved in 2x2 mm² surfaces with total thickness of 30 µm. This work shows a unique opportunity of in-line printing and the subsequent selective sintering of silver ink to produce multilayer passive devices and to offset the surface limitation involved in RFID and smart packaging applications.

Stress concentration in through-silicon via (TSV) is studied by a calibrated micro-Raman spectroscopy (μRS) and correlated with numerical simulation. Results show that stress concentration is in transverse direction and it depends on the ratio of via diameter to via spacing. Further investigations on bended TSV lined with copper revealed that the stress level is lower than the one in TSV without copper. Chip-to-wafer 3D-stacking using microinserts thermocompression bonding shows that the 50 μm thick TSVs have negligible mechanical stress effect.

Publication à paraître; National audience

http://www.pfonline.com/articles/an-overview-of-hard-chromium-plating-using-trivalent-chromium-solutions; International audience