Nanopackaging: From Nanomaterials to the Atomic Scale: Proceedings of the 1st International Workshop on Nanopackaging

International audienceThis book is a first attempt to merge two different communities: scientists and technologists. Therefore, it is not a general overview covering all the fields of nanopackaging, but is mainly focused on two topics. The first topic deals with atomic scale devices or circuit requirements, as well as related recent technological developments; for example, surface science engineering and atomic scale interconnects studies. The second main part of the book brings CNT nano-materials solutions for resolving interconnect or thermal management problems in microelectronics device packaging. This book is not just useful for those who attended the International Workshop on Nanopackaging in Grenoble, but can provide valuable information to scientists and technologists in the nanopackaging community

Effet getter de multicouches métalliques pour des applications MEMS. Etude de la relation Elaboration - Microstructure - Comportement

L'objectif de cette thèse est d'établir les liens entre élaboration, microstructure et comportement des getters non-évaporables (NEG) en couches minces, en vue de leur utilisation dans le cadre du packaging collectif des MEMS sous vide ou sous atmosphère contrôlée. Après une étude bibliographique sur l'herméticité des MEMS et l'effet getter, la modification du comportement de piégeage de gaz par les NEG couches minces, engendré par l'ajout de sous-couches métalliques, est mise en évidence. Afin d'expliquer cette influence, la microstructure des couches minces est étudiée, notamment sa dépendance aux paramètres d'élaboration et aux traitements thermiques. Ensuite, le comportement macroscopique de piégeage de l'azote est caractérisé, de même que les mécanismes microscopiques d'activation et de pompage. Ces derniers permettent finalement d'élaborer quelques recommandations pour l'intégration des NEG couches minces dans les MEMS.Whilst satisfying low-cost requirements, performances and lifetime of many MEMS can be enhanced by performing wafer-level packaging of devices under vacuum or controlled atmosphere conditions. However, this implies the use of non-evaporable getters (NEG) inside MEMS cavities for residual gases removal. Relationships between elaboration, microstructure and pumping behavior of NEG thin films are investigated in this thesis. After a literature review on MEMS hermetic sealing and getter effect, NEG thin films pumping behavior modification by metallic sub-layers addition is presented. Then, in order to explain this modification, elaboration parameters and thermal treatments influence on thin films microstructure is analyzed. Lastly, nitrogen gettering behavior of NEG is characterized, as well as activation and pumping mechanisms. From these results, some recommendations for NEG thin films integration in MEMS are finally proposed.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

Modeling the Elongation of Nanowires Grown by Chemical Bath Deposition Using a Predictive Approach

International audienceThe chemical bath deposition of nanowires is of high interest for a wide variety of optoelectronic, piezoelectric, and sensing devices, but a theoretical description of the elongation process is still missing despite its critical importance. By solving Fick’s diffusion equations in combination with thermodynamic computations, we determine the expression of the axial growth rate of nanowires and its temporal dependence under dynamic conditions, namely, in a sealed reactor, where the depletion of chemical reactants occurs. The theoretical model is found to be in very good agreement with a large set of experimental data specifically collected in the case of the chemical bath deposition of ZnOnanowires. In particular, an activation energy of 198 ± 24 kJ/mol is deduced for the elongation process of ZnO nanowires, involving the energy barriers for both the dehydration process of Zn(II) species (i.e., [Zn(H2O)6]2+ ions) and their subsequent direct incorporation onto the c-plane top faces. This shows its high potential to enable in-depth investigation of the physicochemical processes at work in the chemical bath. By using the theoretical model as a predictive approach, a complete growth diagram reporting the evolution of the length of ZnO nanowires vs effective growth time and temperature is also obtained over a broad range of conditions, revealing its additional high potential for applied research and industrial purposes. The present general approach is further compatible with a broad range of chemicals in solution and of semiconducting materials grown by chemical bath deposition

Effects of zinc nitrate and HMTA on the formation mechanisms of ZnO nanowires on Au seed layers

International audienceThe ability to form ZnO nanowire arrays with dedicated morphological properties is crucial for the development of efficient piezoelectric devices such as piezoelectric nanogenerators and sensors. However, their integration typically requires the use of metallic seed layers for their synthesis by chemical bath deposition, from which their morphological control is still very limited. In this context, the formation mechanisms of ZnO nanowires from Au seed layers are carefully investigated for different precursor (i.e., zinc nitrate and hexamethylenetetramine (HMTA)) concentrations in the range of 1–100 mM, where drastic variations of the morphological properties are observed. By coupling $in\ situ$ pH measurements and thermodynamic computations, we perform an in-depth analysis of the thermodynamic properties of the chemical bath, where the predominant role of the NO$_3$$^–$ ions in the evolution of the pH of the chemical bath is revealed. An original approach is further developed to carefully determine the hydrolysis ratio of HMTA molecules, which is found to vary in the range of 20–45% with the precursor concentration, and to directly impact the supersaturation ratio of Zn(II) species. From these results, we identify the presence of three different growth regimes depending on the precursor concentrations, each of them giving rise to ZnO nanowire arrays with specific morphological properties. These results highlight the critical importance of the thermodynamic properties of the chemical bath in the formation process of ZnO nanowires from Au seed layers and provide key elements of understanding to efficiently optimize their morphology for their integration into piezoelectric devices

Implementing the Reactor Geometry in the Modeling of Chemical Bath Deposition of ZnO Nanowires

International audienceThe formation of nanowires by chemical bath deposition is of great interest for a wide variety of optoelectronic, piezoelectric, and sensing devices, from which the theoretical description of their elongation process has emerged as a critical issue. Despite its strong influence on the nanowire growth kinetics, reactor size has typically not been taken into account in the theoretical modeling developed so far. We report a new theoretical description of the axial growth rate of nanowires in dynamic conditions based on the solution of Fick’s diffusion equations, implementing a sealed reactor of finite height as a varying parameter. The theoretical model is applied in various chemical bath deposition conditions in the case of the growth of ZnO nanowires, from which the influence of the reactor height is investigated and compared to experimental data. In particular, it is found that the use of reactor heights smaller than 2 cm significantly decreases the ZnO nanowire axial growth rate in typical experimental conditions due to the faster depletion of reactants. The present approach is further used predictively, showing its high potential for the design of batch reactors for a wide variety of chemical precursors and semiconductor materials in applied research and industrial production