Film deposition and mechanical properties of silver produced by impaction of nanoparticles
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Nanocrystalline films are promising in various fields such as microelectronics. Low temperature deposition techniques are desirable since they would enable the use of new substrates that are temperature sensitive, leading to a wide range of new applications. This thesis explores nanocrystalline silver film deposition by impacting nanoparticles (NP) onto a substrate, a technique that enables low process temperatures. This work aims at better understanding the physical parameters governing the sticking probability of NP upon impaction. To achieve this, various substrate materials have been used (metallic and non metallic) and the influence of the impacted substrate temperature has been studied, among other experiments. These parameters showed a significant influence on the collection efficiency of NPs. These experimental results are analyzed in light of published computer simulations studies predicting the behavior of impacting NP to deposit nanostructured films. Secondly, a study of the mechanical properties of the deposited films has been attempted. Compression tests have been carried out varying the applied load, loading time and process temperature. The produced films are nanocrystalline and porous (~70% relative density). Densification has been observed even at room temperature, and the goal of this study is to understand which mechanisms cause the densification to occur. The experimental densification data are compared with a model describing the densification of microparticles compacts by hot pressing that has been adapted to nanocrystalline silver, and the mechanisms leading to densification are discussed.