Dans les systèmes actuels de communication, qu’ils soient terrestre ou spatial, qu’ils soient mobile ou fixe, il y a un réel intérêt à développer des front-ends radiofréquences et hyperfréquences miniatures et performants. Ceci s’applique en particulier aux dispositifs de filtrage où l’encombrement et les facteurs de qualité sont clairement antagonistes. Pour les bandes de fréquences basses aux alentours du GHz, les longueurs d’onde restent encore importantes, rendant difficiles les efforts de miniaturisation. D’autre part il faut aussi s’assurer que ces filtres viendront s’interconnecter aisément avec les autres composants du système, notamment les actifs.Pour toutes ces raisons, le développement de structures de filtres multicouches utilisant des substrats à haute permittivité (εr = 68) selon une approche LTCC apparait comme une alternative intéressante. Elle peut en effet conduire à une réduction significative de l'empreinte (footprint) sans pour autant trop nuire aux performances électriques.Dans le cadre de ce travail, deux structures de filtres multicouches ont été développées pour répondre à des spécifications proposées en bandes L et S, par un équipementier du spatial. Ces filtres ont pour caractéristiques principales un haut niveau de rejection et des faibles pertes dans la bande passante. Pour atteindre les spécifications, un filtre SIW empilé verticalement et un filtre à stubs en court-circuit en configuration triplaque ont été étudiés. Le filtre SIW se distingue par un facteur de qualité élevé, ce qui entraîne des faibles pertes d’insertion et une bonne platitude. La solution à stub permet quant à elle de réduire l’encombrement mais au prix d’un impact sur les performances électriques. Dans les deux cas on tire parti de la souplesse offerte par la technologie LTCC, puisqu’elle offre finalement un degré de liberté supplémentaire, par rapport à une approche planaire classique. Si dans le cas SIW, c’est surtout l’architecture topologique qui a été étudiée finement pour pouvoir agencer et coupler douze cavités, dans le cas du filtre à stub une synthèse mettant à profit tous les degrés de liberté offerts a été spécifiquement développée.Compte tenu de la complexité des filtres, notamment à cause de l’ordre élevé et de la mise en oeuvre de murs « électriques » à partir d’arrangements de via spécifiques, une attention particulière doit être apportée lors des phases de simulation et d’optimisation. De plus la très forte permittivité du substrat ne permet pas d’utiliser de ligne 50 Ohms. Enfin les transitions constituent un point dur de l’exercice surtout dans le cas SIW.Cette thèse co-financée par le CNES (Centre National d'Etudes Spatiales) et Thales Alenia Space, était accompagnée par un projet R&T financé par le CNES. Le fondeur allemand Via Electronic avait en charge la fabrication des filtres. / In current communication systems, whether terrestrial or spatial, whether fixed or mobile, there is a real interest in developing high performance miniature RF front-ends. This is applied in particular to filter devices, in which the size and the quality factors are clearly in conflict. For low frequency bands around the GHz, the wavelengths remain significant, making it difficult the miniaturization efforts. On the other hand, we must also ensure that these filters will be easily interconnected with other other system components, including active devices.For all these reasons, the development of multilayer filter structures using high permittivity substrates (Er = 68) in an LTCC approach is consolidated as an interesting alternative. It may lead to a significant footprint reduction without decreasing the electrical performances.As part of this work, two multilayer filter structures have been developed to meet the given specifications in L and S bands, given by a space manufacturer. These filters have as main features a high rejection level and low losses in the passband. To meet the specifications, a vertically stacked SIW filter and a short-circuited stubs filter in a stripline configuration were studied. The SIW filter is characterized by a high quality factor, which results in low insertion loss and good flatness. The stubs filter allows in contrast to reduce the footprint but at the price of impacting the electrical performance. In both cases we take advantage of the flexibility offered by the LTCC technology as it finally provides an additional freedom degree compared to a conventional planar approach. For the SIW filter, the topological architecture was studied and designed in detail, to be able to arrange and synthetize couplings between twelve cavities. In a similar way, for the stub filter a synthesis that takes profit of all the offered freedom degrees was developed.Given the filters complexity, especially due to the high order and the implementation of “electrical walls" based on specific vias patterns, a close attention must be paid during the simulation and optimization phase. In addition, the high permittivity substrate does not allow to conceive 50-Ohms lines. Finally, access transitions constitute a challenging task, especially for the SIW case.This thesis was co-funded by CNES (Centre National d'Etudes Spatiales) and Thales Alenia Space, and was accompanied by an R&T project funded by CNES. The German foundry Via Electronic was responsible for the filters fabrication.

Neste trabalho descreve-se a implementação da técnica do pulso eletroacústico (PEA) para a determinação de perfis de carga espacial em dielétricos. O método é baseado no sinal acústico gerado pela aplicação de um pulso de tensão elétrica de curta duração na amostra. O sinal acústico gerado é detectado usando-se um transdutor piezoelétrico acoplado à amostra. São discutidos os detalhes experimentais do sistema e os procedimentos matemáticos para o tratamento do sinal elétrico medido. O tratamento matemático do sinal é baseado na técnica de desconvolução que permite determinar a função de transferência do sistema. A função de transferência permite eliminar do sinal medido as distorções introduzidas pelo circuito de medida, pelas reflexões espúrias do sinal acústico, etc.. Mostra-se também os procedimentos matemáticos para se corrigir a atenuação e dispersão do sinal acústico durante a propagação através da amostra. A técnica PEA foi utilizada para o estudo dos perfis de carga espacial injetada em amostras de polietileno sintetizados com diferentes catalisadores: Ziegler-Natta e Metallocene. O campo elétrico aplicado para polarizar as amostras e injetar cargas elétricas nas amostras foi variado de 0,05 MV/cm a 0,9 MV/cm. Nas amostras de polietileno sem aditivos a injeção de cargas elétricas na amostra é bem menor que em amostras com aditivos anti-oxidantes Mostra-se também que o campo elétrico de ruptura depende da carga injetada na amostra, sendo ele maior quando a polaridade da tensão de teste de ruptura é a mesma da tensão aplicada que provocou a injeção de cargas elétricas na amostra. / It is described the implementation of the electroacustic pulse technique, PEA, for the determination of space charge profiles in dielectrics. The method is based on the acoustic signal generated by the application of a voltage pulse with short duration on the sample. The acoustic signal generated by pulse is detected by using a piezoelectric transducer coupled to the sample. Details of the experimental system and of the mathematical procedure for the treatment of the measured electric signals are discussed. The mathematical treatment is based on the deconvolution technique which enables us to obtain the transference function of the system. The use of a transference function eliminates distortions caused by reflections that are introduced by the measurement circuit. Mathematical procedures for the correction of attenuation and dispersion of the acoustic signal during the propagation throughout the sample are also discussed. The PEA technique was used to measure the profiles of injected space charge in polyethylene synthesized using different catalysts: Ziegler-Natta and Metallocene. The electric field applied to polarize and to inject electric charges in the sample was varied form 0.05MV/cm to 0.9MV/cm. In samples of polyethylene without additives it was observed that the injection of charges is less intense than in samples containing anti oxidant additives. It is also shown that the critical electric field for the breakdown depends on the injected charge on the sample being; larger if the rupture tests were performed using the same polarity of the voltage used to pole the samples. Breakdown measurements were also performed with ozone treated samples.

No description available.

A new high-k dielectric material, i.e., zirconium-doped tantalum oxide (Zr-doped TaOx), in the form of a sputter-deposited thin film with a thickness range of 5-100 nm, has been studied. Important applications of this new dielectric material include the gate dielectric layer for the next generation metal-oxide-semiconductor field effect transistor (MOSFET). Due to the aggressive device scaling in ultra-large-scale integrated circuitry (ULSI), the ultra-thin conventional gate oxide (SiO2) is unacceptable for many practical reasons. By replacing the SiO2 layer with a high dielectric constant material (high-k), many of the problems can be solved. In this study, a novel high-k dielectric thin film, i.e., TaOx doped with Zr, was deposited and studied. The film’s electrical, chemical, and structural properties were investigated experimentally. The Zr dopant concentration and the thermal treatment condition were studied with respect to gas composition, pressure, temperature, and annealing time. Interface layer formation and properties were studied with or without an inserted thin tantalum nitride (TaNx) layer. The gate electrode material influence on the dielectric properties was also investigated. Four types of gate materials, i.e., aluminum (Al), molybdenum (Mo), molybdenum nitride (MoN), and tungsten nitride (WN), were used in this study. The films were analyzed with ESCA, XRD, SIMS, and TEM. Films were made into MOS capacitors and characterized using I-V and C-V curves. Many promising results were obtained using this kind of high-k film. It is potentially applicable to future MOS devices.

A new high-k dielectric material, i.e., zirconium-doped tantalum oxide (Zr-doped TaOx), in the form of a sputter-deposited thin film with a thickness range of 5-100 nm, has been studied. Important applications of this new dielectric material include the gate dielectric layer for the next generation metal-oxide-semiconductor field effect transistor (MOSFET). Due to the aggressive device scaling in ultra-large-scale integrated circuitry (ULSI), the ultra-thin conventional gate oxide (SiO2) is unacceptable for many practical reasons. By replacing the SiO2 layer with a high dielectric constant material (high-k), many of the problems can be solved. In this study, a novel high-k dielectric thin film, i.e., TaOx doped with Zr, was deposited and studied. The film’s electrical, chemical, and structural properties were investigated experimentally. The Zr dopant concentration and the thermal treatment condition were studied with respect to gas composition, pressure, temperature, and annealing time. Interface layer formation and properties were studied with or without an inserted thin tantalum nitride (TaNx) layer. The gate electrode material influence on the dielectric properties was also investigated. Four types of gate materials, i.e., aluminum (Al), molybdenum (Mo), molybdenum nitride (MoN), and tungsten nitride (WN), were used in this study. The films were analyzed with ESCA, XRD, SIMS, and TEM. Films were made into MOS capacitors and characterized using I-V and C-V curves. Many promising results were obtained using this kind of high-k film. It is potentially applicable to future MOS devices.

No description available.