This master project concerns a feasibility study about the use of inkjet drop-on-demand to fill through silicon vias in MEMS "via last" microfabrication process. The aim of our research was to develop a comprehensive process based on the use of a dispersion of a gold/tin alloy (Au80Sn 20) of nanoparticles in suspension in a carrier fluid. Our work mainly focused on the preparation of stable suspensions of nanoparticles and on the high precision filling of the vias.;We first developed a method to form a stable suspension of nanoparticles in a carrier fluid using a surfactant, polyvinylpyrrolidone (PVP). Tests performed on various solvents allowed us to determine that isopropanol was the best carrier fluid to achieve high volume fractions of suspended nanoparticles. The volume fraction of the stable dispersion with the highest content reached 11 %.;The conditions to generate stable individual microdroplets from a piezoelectric printing actuator were then analyzed. The generation of monodisperse microdroplets beiing a complex process, partly described by Fromm's theory and the theory of waveguides, we investigated the operating conditions permitting to precisely set the drop volume and ejection velocity. We therefore characterized an "ejectability zone" model universally usable to generate microdrops with desired output parameters based on the amplitude, width, and frequency of the electric pulse applied to the piezoelectric actuator of a print head having a 50 μm diameter aperture.;We also developed a theoretical kinematical model describing the trajectories of microdrops during printing in order to understand the influence of their volume and initial velocity on the accuracy, reproducibility and homogeneity of the deposits in the presence of air fluctuations. This model was implemented in MATLAB and validated in real operating conditions. The results showed that a print head with a 50 μm diameter aperture will generate microdroplets with diameters between 30 and 60 microns with a maximum placement error on the substrate of the order of ± 20 microns. We estimated that filling TSVs with an opening of 70 microns and higher is possible with our inkjet DOD (non defined) process.;Finally, we experimentally addressed the vias filling by studying the behavior of nanoparticles in the vias during the evaporation of the carrier fluid and the annealing of the gold/tin alloy nanoparticles of eutectic composition. This last step revealed the incompatibility of non-homogenous AuSn alloy particles with the temperature window requirement used during sintering. To overcome this defect we replaced the Au80Sn20 by tin nanoparticles to complete our analysis of the impact of the use of PVP in the suspension of nanoparticles on the resistivity after annealing in the vias.;Most aspects of this project being interrelated, much attention has been paid to the study of the influence of the various parameters on the quality of prints realized. The main conclusion is that we are able to validate the use of inkjet technologies as an alternative to perform the filling of TSVs by metal alloy nanoparticles. This conclusion is subject to the feasibility of the adaptation of our suspension and annealing methods to nanopowders alloys other than gold/tin and tin.
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