Recently, there are great demands for RF band pass filters with smaller size/volume, lighter weight, and higher performance for advanced mobile/wireless communication system. However, fabricated RF filters using traditional lumped element, dielectric resonators, or surface acoustic wave¡]SAW¡^filters have difficulties in on-chip integration, power handling capability, and temperature compensation. Alternatively, thin-film bulk acoustic wave resonator¡]FBAR¡^filters are very suitable devices for MMIC¡¦s since they can be fabricated on Si or GaAs substrates at a lower magnitude than lumped elements or dielectric resonators, plus they have a much lower insertion loss and higher power handling capabilities than surface acoustic wave devices and full integration with other CMOS RF IC circuitry for realizing a goal of system on chip¡]SOC¡^. In their simplest form, practical FBARs consist of a sputtered piezoelectric thin film sandwiched between top and bottom electrodes onto which an electric field is then applied. An FBAR must have two acoustically reflecting surfaces in order to trap energy and produce resonating characteristics. For this purpose, the thin film bulk acoustic resonator has to be isolated acoustically from the substrate. In view of this, in order to obtain a high Q factor and reduce spurious responses, this paper proposed the air gap type resonator using the sacrificial layer etching. The thickness of the AlN thin film used for piezoelectric thin film of Air-gap FBAR is 1um. Pt/Ti with 3000Å/300Å thickness is used as the top and bottom electrode. The device has a resonance frequency of 1.2GHz, and S11-paparameter of -25dB is also obtained.

The scope of this study is to establish extensive material tests to determine the mechanical properties of cellular concrete and evaluate its potential as energy absorption material against air blast load. This study includes a literature review of existing studies on cellular concrete, proportioning, and its mechanical properties, together with studies on the properties and application of other foams such as aluminium and polymer foams. It is concluded that, unlike other foam materials, there is a lack of systematic studies on the mechanical properties of cellular concrete especially for densities less than 1000 kg/m3. The survey also reviewed the existence of materials being used as a sacrificial layer against air blast load, together with the analytical models proposed to determine the parameters required to design a cladding system. As a result it was found that cellular concrete can maintain most of the properties of the cladding materials and can be applied as a new sacrificial layer against the blast load. Extensive material tests are carried out to characterise the effect of ingredients and density on material properties of cellular concrete. Based on the experimental results, an empirical model is proposed which determines the plateau and densification regime of nominal stress-strain curve of the cellular concrete with different densities. The penetration resistance of cellular concrete with different densities under truncated, conical, flat and hemi-spherical solid indenters are studied experimental. By determining the deformation mechanism of cellular concrete under indentation with application of an X-Ray tomography image system, an analytical model is proposed to determine the resistance of cellular concrete under penetration of flat indenter. Experimental closed range blast tests are performed with 1kg and 3kg C4 explosive to determine the mitigation potential of cellular concrete against air blast load. Numerical modelling of the experimental blast test is carried out using Ansys LS-DYNA to evaluate the feasibility of the numerical modelling techniques to predict the response of cellular concrete against air blast load.

Polymer based microelectromechanical systems (MEMS) micromachining is finding more interest in research and applications. This is due to its low cost and less time processing compared with silicon MEMS. SU-8 is a photo-patternable polymer that is used as a structural layer for MEMS and microfluidic devices. In addition to being processed with low cost, it is a biocompatible material with good mechanical properties. Also, amorphous silicon (α-Si) has found use as a sacrificial layer in silicon MEMS applications. α-Si can be deposited at large thicknesses for MEMS applications and also can be released in a dry method using XeF2 which can solve stiction problems related to MEMS applications. In this thesis, an SU-8 MEMS process is developed using amorphous silicon (α-Si) as a sacrificial layer. Electrostatic actuation and sensing is used in many MEMS applications. SU-8 is a dielectric material which limits its direct use in electrostatic actuation. This thesis provides a MEMS process with two conductive metal electrodes that can be used for out-of-plane electrostatic applications like MEMS switches and variable capacitors. The process provides the fabrication of dimples that can be conductive or non-conductive to facilitate more flexibility for MEMS designers. This SU-8 process can fabricate SU-8 MEMS structures of a single layer of two different thicknesses. Process parameters were tuned for two sets of thicknesses which are thin (5-10μm) and thick (130μm). Chevron bent-beam structures and different suspended beams (cantilevers and bridges) were fabricated to characterize the SU-8 process through extracting the density, Young’s Modulus and the Coefficient of Thermal Expansion (CTE) of SU-8. Also, the process was tested and used as an educational tool through which different MEMS structures were fabricated including MEMS switches, variable capacitors and thermal actuators.

Over the past 15 years, research in the field of microfluidics has rapidly gained popularity. By seeking to miniaturize and automate separation-based analysis, microfluidic research seeks to improve current methods through decreased cost, analysis time, and sources of contamination. My work has focused on developing a novel fabrication method, based on standard microfabrication techniques, to create thin-film microfluidic devices. This microfabrication format makes it possible to generate devices that provide high efficiencies, enable mass fabrication, and provide a platform capable of integrating the microfluidic and electronic components necessary for a micro-total analysis system (μ-TAS). Device fabrication combines the processes of photolithography, thermal evaporation, plasma enhanced chemical vapor deposition (PECVD), and wet chemical etching to ultimately provide hollow-core channels. When these microcapillaries are filled with buffer and potentials are applied across them, control of the flow in the channels can be established. By designing intersecting microchannels having an offset “T†geometry, I have been able to inject and electrophoretically separate three fluorescently labeled amino acids and obtain efficiencies of over 2500 theoretical plates. Through the addition of commercially available electroosmotic flow reducing coatings, I have been able to improve the separation of these amino acids, decreasing the run time by approximately 6 fold and increasing the efficiency by as much as 10 fold. Through the use of these coatings I have also been able to carry out electrophoretic separations of three peptides. My most recent work has focused on the polymerization of acrylamide gels in these channels. A method for the selective placement of a gel has been developed using a prepolymer solution with a light-sensitive initiator. Further work to adjust the polymer pore size and interface with ampholyte-containing gels should allow methods such as capillary gel electrophoresis (CGE), preconcentration, and two dimensional (isolectric focusing and CGE) separations to be performed. The development of gel-based analysis methods, along with other fluidic and electrical capacities, should move thin-film microdevices toward the realization of the lab-on-a-chip concept.

No description available.

An alternative indirect integration regime of porous low-k materials was investigated. Based on a single Damascene structure the intra level dielectric SiO2 or damaged ULK was removed by using HF:H2O solutions to create free standing metal lines. The free spaces between the metal lines were refilled with a spin-on process of a low-k material. The persistence of barrier materials and copper against HF solutions, the gap fill behavior of the used spin on glass on different structure sizes and the main challenges which have to solve in the future are shown in this study.

Dans ce travail, nous démontrons que la technique de dépôt multicouche dite layer by layer (LbL) est une technique polyvalente où les propriétés des multicouches telles que l'épaisseur, la charge et la densité peuvent être facilement contrôlées par le choix des polyélectrolytes (PE), le nombre d'étapes et les conditions de dépôt (pH, force ionique, etc.). Nous démontrons que des multicouches de PE faible (PAH / PAA) peuvent être utilisées pour fournir une double fonction aux membranes (PEM) en tant que couche de séparation NF et comme revêtement sacrificiel permettant un nettoyage facile de la membrane. Ces membranes à base de PEM montrent des performances de rejet des solutés dans une gamme typique des membranes NF, c'est-à-dire rejetant peu les ions monovalents (NaCl) (<24%), tout en rejetant> 60% de l'ion divalent SO42- et la molécule organique neutre sulfaméthoxazole (SMX). Par un rinçage et un lavage à contre-courant à basse pression avec une solution stimuli appropriée, nous obtenons un nettoyage sacrificiel réussi d'une membrane colmatée, ce qui ramène la résistance d'une membrane colmatée à celle de la membrane vierge. Après un nouveau dépôt sur la membrane avec le même système PEM, la résistance de la membrane est égale à la résistance du PEM d'origine, ce qui démontre la réutilisation de cette approche. Le mécanisme de rejet des membranes étudiées s'est révélé principalement déterminé par l'exclusion stérique mais aussi par l'exclusion de Donnan. Nous avons étudié notre système PEM pour préparer des membranes pour des applications de nanofiltration résistant aux solvants (SRNF). Des membranes de SRNF avec une couche de séparation de PEM ont été préparées sur un support UF de polyacrylonitrile hydrolysé (PAN-H). Les résultats de cette étude montrent une manière simple et polyvalente d'utiliser le pH pendant le revêtement pour régler les performances de la membrane pour une application SRNF spécifique. Afin d'amener l'approche PEM et du nettoyage sacrificiel à leur maturité et de modifier des modules existants, nous avons simplifié la procédure LbL pour des membranes fibres creuses en utilisant un "dépôt dynamique" ou un "dépôt actif" qui consiste à rincer les solutions du PE à travers le canal interne de la membrane fibre creuse. Cette méthode de dépôt avec sa reproductibilité et son homogénéité permet de revêtir les modules de membrane UF existants. / In this work, we demonstrate that layer by layer (LbL) is a versatile technique where control over multilayer properties such as thickness, charge and density, can be easily achieved simply by the choice of polyelectrolytes, number of coating steps and coating conditions (pH, ionic strength etc.). We demonstrate that multilayers of weak PEs (PAH/PAA) can be used to provide a dual function to membranes (PEM) i.e., as NF separation layer and as a sacrificial coating that allows easy membrane cleaning. These PEM based membranes, shows rejection performance of solutes in a range typical for NF membranes i.e., hardly rejecting monovalent ions (NaCl) (<24%), while rejecting > 60% of the divalent ion SO42- and the neutral organic molecule sulfamethoxazole (SMX). By a rinse and a low pressure backwash with a suitable trigger solution, we obtain a successful sacrificial cleaning of a fouled membrane, bringing the resistance of a fouled membrane back to that of the pristine membrane. Recoating the clean membrane support with the same PEM system brings the resistance of the coated membrane equal to the resistance of the original PEM, demonstrating the re-usability of this approach. The rejection mechanism of the investigated membranes was found to be mainly determined by size exclusion, but influenced by Donnan exclusion. We investigated our weak PEM system to prepare membranes for solvent resistant nanofiltration (SRNF) applications. SRNF membranes with PEM separation layer were prepared on a UF hydrolyzed polyacrylonitrile (PAN-H) support by the LbL method. Results of this study show a simple and versatile way of using pH during coating to tune membrane performance for specific SRNF application. To bring PEM coating and sacrificial cleaning approach into maturity and to coat existing modules we present the simplification of the LbL procedure for hollow fibre membranes by employing "dynamic coating" or "active coating" which involves flushing the PE's solutions through the lumen of the hollow fibre membrane. This coating method with its reproducibility and homogeneity has the potential to coat existing UF membrane modules.

This research explores a novel in-situ technique for monitoring film thickness in the reactive etching process that incorporates a micromachined sensor. The sensor correlates film thickness with changes in resonant frequency that occurs in the micromachined platform during etching. The sensor consists of a platform that is suspended over drive and sense electrodes on the surface of the substrate. As material is etched from the platform, its resonant vibrational frequency shifts by an amount that is proportional to the amount of material etched, allowing etch rate to be inferred. This RIE monitoring methodology exploits the accuracy of resonant micromechanical structures, whereby shifts in the fundamental resonant frequency measure a physical parameter. A majority of these systems require free-standing mechanical movement and utilize a sacrificial layer process as the key technique to develop and release the structure on a substrate. A sacrificial layer technique that incorporates a low temperature sacrificial polymer was utilized to develop and release the suspended RIE sensor with excellent performance and is capable of fabricating other low cost, high performance and reliable suspended MEMS devices. The integration of sensors and electronic circuitry is a dominant trend in the semiconductor industry, and much work and research has been devoted to this effort. The RIE sensor relies on capacitive transduction to detect small capacitance changes and the resulting change in resonant frequency during the RIE process. The RIE sensor's overall performance is limited by the interface circuit, and integration with the proper circuit allows the RIE sensor to function as a highly sensitive measure of etch rate during the RIE process. A capacitive feedback charge amplifier interface circuit, when configured with the RIE senor at the input achieves very low noise sensing of capacitance changes and offers the potential for wide dynamic range and high sensitivity. As an application vehicle, process control was demonstrated in the PlasmaTherm SLR series RIE system located in the Georgia Tech Microelectronics Research Center.

An alternative indirect integration regime of porous low-k materials was investigated. Based on a single Damascene structure the intra level dielectric SiO2 or damaged ULK was removed by using HF:H2O solutions to create free standing metal lines. The free spaces between the metal lines were refilled with a spin-on process of a low-k material. The persistence of barrier materials and copper against HF solutions, the gap fill behavior of the used spin on glass on different structure sizes and the main challenges which have to solve in the future are shown in this study.

Im Rahmen der vorliegenden Arbeit wurden die technologischen Ansätze zur Erzeugung von Mikro-Kavitäten als Grundlage zur Entwicklung und Erprobung neuer Konzepte der MEMS-basierten Aktoren und Sensoren erfolgreich eingesetzt. Im Verlauf der Integration eines IR-Emitters wurde der SON-Prozess weiterentwickelt, um eine hohe und homogene Verteilung der Dotierstoffe innerhalb der SON-Membran zu erreichen. Dabei wurde ein technologischer Ablauf entwickelt, welcher die genannten Randbedingungen erfüllt und darüber hinaus eine optimierte Herstellung anbietet, indem die zeitaufwändige Formierung der Kavität in einem Batch- anstatt eines RTP-Ofens erfolgt. Die Opferschichttechnik wurde bei der Integration von beiden vorgestellten Bauelementen eingesetzt und mit Rücksicht auf die einzelnen Randbedingungen angepasst. So konnte z. B. eine Kavität mit einer Höhe von 700 nm zur Abdeckung von IR-Emitter hergestellt werden, wodurch die thermische Isolation verbessert wurde. Im Konzept des druckempfindlichen Feldeffekttransistors wurde eine Opferschicht mit einer Dicke von 70 nm verwendet, um die Größe der Gate-Kapazität so anzupassen, dass der hergestellte Transistor steuerbar und druckempfindlich ist. Somit konnten die Flexibilität und das Potenzial der beiden Prozessknotenpunkte verdeutlicht werden.:Symbolverzeichnis Abkürzungsverzeichnis 1 Einleitung 1.1 Einführung zum Thema 1.2 Technologien zur Herstellung von Mikro-Kavitäten für MEMS 1.2.1 Silicon-On-Nothing Technologie 1.2.2 Opferschichttechnik 2 Das neue Konzept einer breitbandigen Infrarotquelle 2.1 Grundlegende Ideen der Infrarot-Sensorik 2.1.1 Wechselwirkung von Infrarotstrahlung mit CO2-Gas 2.1.2 Prinzipielle Funktionsweise eines IR-Emitters 2.1.3 CMOS-kompatible Materialien und Integrationsmöglichkeiten eines IR-Emitters 2.1.4 Das neue Konzept eines Infrarot-Emitter-Systems basierend auf monokristallinem Silizium 2.2 Finite-Elemente-Methode-Simulation des IR-Emitter-Systems 2.2.1 Geometrievarianten 2.2.2 Temperaturabhängige elektrische Eigenschaften des Bauelements 2.2.3 Betrachtung der thermischen Verluste 2.2.4 Simulation der Wärmeentwicklung 3 Herstellung und Charakterisierung eines IR-Emitters 3.1 Module der CMOS-basierten 3D-Integration 3.1.1 FEOL - Front End of Line 3.1.2 BEOL - Back End of Line 3.2 Elektrische Charakterisierung des IR-Emitters 3.2.1 I(V)-Spektren 3.2.2 Optische Eigenschaften 3.2.3 Zeitabhängiges Verhalten 4 Das neue Konzept eines druckempfindlichen Feldeffekttransistors 4.1 Einleitung zum Konzept des Bauelements 4.1.1 Konzepte zur Herstellung von MOSFET - basierten Sensoren 4.1.2 Prinzipieller Aufbau und Funktionsweise des neuen Konzepts 4.1.3 Geometrievarianten 5 Herstellung und Charakterisierung eines druckempfindlichen Feldeffekttransistors 5.1 CMOS-basierte 3D-Integration 5.1.1 Herstellung des MEMS-Elements: FEOL - Module 5.1.2 Herstellung des MEMS-Elements: BEOL - Module 5.2 Elektrische Charakterisierung des Feldeffekttransistors 5.2.1 Ausgangskennlinienfeld unter Normaldruck 5.2.2 Eingangskennlinien und deren Besonderheiten unter Normaldruck 5.3 Verhalten des Transistors bei veränderbarem Gasdruck 5.3.1 Designvariante I 5.3.2 Designvariante II 5.3.3 Designvariante III 5.3.4 Druckmessung mit Konstantstromquelle 5.4 Optimierung der Transistoreigenschaften 5.4.1 Anpassung des Gate-Dielektrikums und der Dotierung des Kanals 5.4.2 Ausgangskennlinien unter Normaldruck nach der Optimierung 5.4.3 Eingangskennlinien unter Normaldruck nach der Optimierung 5.4.4 Druckmessung nach der Optimierung 5.4.5 Bewertung der Prozessoptimierung anhand der Referenz-Strukturen 6 Zusammenfassung und Ausblick 6.1 Zusammenfassung zum IR-Emitter 6.2 Zusammenfassung zum Drucksensor Literatur Abbildungsverzeichnis Tabellenverzeichnis