Diamond is widely known for its extraordinary properties, such as high thermal conductivity, energy bandgap and high material hardness and durability making it a very attractive material for microelectronic and mechanical applications. Synthetic diamonds produced by chemical vapor deposition (CVD) methods retain most of the properties of natural diamond. Within this class of material, nanocrystalline diamond (NCD) is being developed for microelectronic and microelectromechanical systems (MEMS) applications. During this research, intrinsic and doped NCD films were grown by the microwave plasma enhanced chemical vapor deposition (MPECVD) method using CH4/Ar/H2 gas mixture and CH4/Ar/N2 gas chemistries respectively. The first part of research focused on the growth and characterization of NCD films while the second part on the application of NCD as a structural material in MEMS device fabrication. The growth processes were optimized by evaluating the structural, mechanical and electrical properties. The nature of chemical bonding, namely the ratio of sp²:sp³ carbon content was estimated by Raman spectroscopy and near edge x-ray absorption fine structure (NEXAFS) techniques. The micro-structural properties were studied by x-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The mechanical properties of the pure NCD films were evaluated by nano-indentation. The electrical properties of the conductive films were studied by forming ohmic as well as schottky contacts. In second part of this study, both free-standing and membrane capped field emitter devices were fabricated by a silicon mold technique using nitrogen incorporated (i.e., doped) NCD films. The capped field emission devices act as a prototype vacuum microelectronic sensor. The field emission tests of both devices were conducted using a diode electrical device model. The turn-on field and the emission current of free-standing emitter devices was found to be approximately 0.8 V/µm and 20 µA, respectively, while the turn-on fields of capped devices increased by an order of magnitude. The emission current in the field emission sensor changed from 1 µA to 25 µA as the membrane was deflected from 280 µm to 50 µm from the emission tip, respectively.

In this research, novel high resolution reinforced diaphragm MEMS piezoresistive pressure sensors were designed, fabricated and tested to measure physical phenomena (such as depth/pressure variations) in the ocean. To complement the physical sensing elements, a microfluidic electrochemical nitrate sensor, was also developed to detect chemical fluxes. The electrochemical sensor was designed and packaged to conform to a flow through system. The multisensor approach will enable better measurement quality compared to the current ocean sensors. This, in turn, will potentially improve the current understanding of physical and biogeochemical processes from coastal to deep-sea environment. The pressure sensor element utilized a reinforced bulk micromachined diaphragm to achieve both higher sensitivity (27% higher, model data) and wider linear pressure operating range (> 400 psi, from combination of inner and outer bridge) compared to the conventional single diaphragm design. A temperature compensation bridge was incorporated on the sensor die to account for temperature drifts. A two-level packaging (wafer and system-level) scheme with protective coatings were developed to test the sensor in "simulated" ocean conditions. Finally, the reinforced diaphragm edge and the bossed structures were designed and fabricated using the masked-maskless etching process and their sensor performance were evaluated against the single diaphragm design. A nanowire-based Electrochemical detection-on-Chip (EoC) system was also developed to detect chemical/biological markers, especially nitrate fluxes. Different sensing modalities,involving a variety of nanosensor electrodes and different assembly techniques were investigated for suitability as electrochemical nitrate sensor. These architectures were also evaluated for robustness as a sensing platform. Enzyme-modified Au nanowires based electrochemical sensor showed excellent sensitivity (µM level) to biomarkers (cholesterol) in biological fluids (blood).These sensors, however, exhibited poor detection limits towards nitrate ions. Doped polypyrrole nanowire electrodes proved to be effective as nitrate sensors. A detection limit of 4.5±1 µM,sensitivity of 1.65 nAµM and stability of <15% variation from interfering ions were achieved on testing in a flow through environment. The nitrate sensor performance was at par with the current state of the art. Additionally, these sensors are batch fabricated (as arrays) reducing cost, require smaller sample volume, lesser space, power and are less prone to contamination problems.

A process for micromachining of micro-mirror devices from silicon-on-insulator wafers was proposed and implemented. Test methods and force applicators for these devices were developed. Following successful fabrication of these devices, a novel process for fabrication of devices out of the plane of the silicon wafer was proposed, so that the devices could be actuated electrostatically. In particular, the process makes use of thick photoresist layers as a sacrificial mold into which an amorphous nickel-phosphorous alloy may be deposited. Ideal design of the electrostatically actuated micro-mirrors was investigated, and a final design was selected and modeled using FEA software, which found that serpentine-hinged devices require approximately 33% of the actuation force of their straight-beamed counterparts. An aqueous electroless plating solution composed of nickel acetate, sodium hypophosphite, citric acid, ammonium acetate, and Triton X-100 in was developed for use with the process, and bath operating parameters of 85°C and 4.5 pH were determined. However, this electroless solution failed to deposit in the presence of the photoresist. Several mechanisms proposed for deposition failure included leaching of organic solvents from the photoresist, oxidation of the nickel-titanium seed layer on which the deposition was intended to occur, and nonlinear diffusion of dissolved oxygen in the solution.

Les MEMS RF sont des composants clés pour le développement de nombreuses fonctions de systèmes hyperfréquences plus efficaces et plus compactes (déphaseurs, module transmission/réception, réseau d’antennes à déphasage, circuits reconfigurables, réseau d’adaptation …). Pour le développement des prochaines générations de systèmes RADAR, Thales s’intéresse notamment à l’intégration de MEMS RF capacitifs pour développer des fonctions reconfigurables pouvant supporter des puissances hyperfréquences de l’ordre de 30 W. Les travaux exposés dans ce manuscrit se sont concentrés sur l’étude de matériaux diélectriques et de techniques de dépôts pour identifier, intégrer et démontrer la viabilité de diélectriques prometteurs pour les MEMS RF capacitifs de puissance. Les aspects relatifs à la fabrication de ces composants ont également été étudiés, particulièrement l’impact de la maitrise des états de surface sur les performances, la tenue en puissance et la défaillance des dispositifs. En outre, ces travaux ont montrés qu’avec l’introduction des matériaux déposés par ALD, la tenue en puissance des MEMS RF capacitifs n’est plus limitée par le diélectrique. En intégrant ces matériaux ALD, l’architecture des dispositifs devient le facteur limitant la tenue en puissance, particulièrement l’épaisseur de la membrane et la configuration du commutateur. En perspectives, différentes architectures ont donc été développées et étudiées pour adresser ces limitations de tenue en puissance. / RF MEMS are key components to improve the efficiency and size of numerous functions of microwave systems (Phase shifter, transmission/reception module, antennas array, reconfigurable systems, impedance matching…). To develop the next generation of RADAR systems, Thales takes special interest in the integration of capacitive RF MEMS devices to demonstrate reconfigurable functions with power handling capabilities up to 30 W. The work reported in this thesis did focus on the study of dielectric materials and deposition techniques to identify, integrate and demonstrate the advantages of promising dielectrics for capacitive RF MEMS power handling. The components fabrication aspects have also been studied, especially the impact of surface state quality on performances, power handling and devices failure mechanisms. Furthermore, this work did point out that with the integration of ALD material, power handling of capacitive RF MEMS is no longer limited by the capacitance dielectric. Furthermore, with the integration of ALD material the components design become the limiting factor for power handling, particularly the membrane thickness and the switch configuration. To open new prospects, several designs have been developed and studied to address these power handling limitations.

Cette recherche dans le domaine des nano-drones a pour ambition de concevoir un objet volant de taille réduite s’inspirant directement de la nature.Dans ce but, un état de l’art a été fait sur les mécanismes de vol des insectes ainsi que sur l’ensemble des solutions à ailes battantes artificielles développées à ce jour. Il ressort de cette analyse d’une part, que les insectes ont une cinématique des ailes singulière reposant sur un mouvement de battement et de torsion en quadrature de phase et d’autre part, que les nano-drones actuels ne s’appuient pas ou très peu sur le comportement dynamique de leurs ailes artificielles pour générer de la portance. Le concept proposé dans le cadre de ce travail se veut en rupture avec ces approches. Il consiste en un couplage vibratoire en quadrature de phase de modes de battement et de torsion appliqué sur des ailes artificielles flexibles afin de reproduire une cinématique proche de celles des insectes avec un unique actionneur. La méthodologie employée s’est traduite par l’élaboration d’un modèle analytique négligeant les efforts aérodynamiques afin de calculer le comportement dynamique et de dimensionner la structure du nano-drone. Les simulations ont mis en évidence l’existence de modes propres de la structure des ailes dont les déformées correspondent aux mouvements de battement et de torsion recherchés. Fait remarquable, une optimisation a permis de rapprocher les fréquences de ces modes tout en conservant une amplitude suffisante de façon à réaliser leur couplage et donc à reproduire la cinématique souhaitée. La portance produite a été ensuite estimée à l’aide d’un modèle aéroélastique qui a montré que le maximum de portance était obtenu pour deux fréquences coïncidant avec une quadrature de phase entre les deux modes. Ces résultats ont par la suite été confirmés à l’aide de mesures expérimentales effectuées sur un banc de mesure spécifique répondant aux contraintes imposées par les prototypes en termes de sensibilité et de comportement dynamique. Les différentes générations de prototypes testées ont été fabriquées au moyen des procédés de microfabrication, ce qui a permis l’intégration d’une membrane d’aile en parylène d’une épaisseur tout à fait comparable à celle existant chez les insectes. La conclusion de cette étude est que nous disposons dorénavant d’un prototype capable de compenser son poids. / This work in the Nano-Air Vehicle field aims to design a small flying object directly inspired by the nature. For this purpose, a state of the art has been performed on insects flight mecanisms and has reviewed the overall artificial flapping wings solutions developped until today. The result of this analysis is on one hand, that insects use a specific wing kinematics which relies on a flapping motion and a twisting motion coupled in a quadrature phase shift and on the other hand, that the existing Nano-Air Vehicles do not exploit the dynamic behavior of their artificial wings to produce lift. The proposed concept in this research is a departure from those other works. It consists of a vibratory coupling in a quadrature phase shift of a flapping and a twisting mode applied on flexible artificial wings in order to reproduce a kinematics close to the insects ones with a single actuator. The used methodology resulted in the development of an analytic modeling which neglects the aerodynamic forces to calculate the dynamic behavior and dimension the prototype structure. Simulations highlighted the existence of eigen modes of the wings structure whose modal shapes match with the wanted flapping and twisting motion. Noteworthy fact, an optimization allowed to get those modes close in frequency while keeping a non-neglectible amplitude in such a way as to couple them and obtain the expected kinematics. The produced lift force is then estimated with an aeroelastic modeling which has shown that the maximum lift is obtained for two frequencies which provide a quadrature phase shift between the two modes. Those results are then validated by experimental measurements performed on a specific bench made according to the constraints due to the prototype in terms of sensitivity and dynamic behavior. The different generations of prototypes tested are produced with microfabrication process, allowing to integrate a wing membrane in parylene with a thickness comparable to the one existing in insects. The conclusion of this study is that we now have a prototype able to compensate its weight.

A novel method of controlling miniature sensors using Handspring Visor Prism PDA has been implemented. A generic motherboard was developed to map the data and address lines from the Visor onto a Complex Programmable Logic Device (CPLD) to provide basic electrical signals to the sensor board. The sensor board housed the sensor and contained application specific circuitry. The PDA, the motherboard, and the sensor board completed the control mechanism for the sensor. Miniature sensors and PDA based control mechanism scaled down the size of the complete system making the unit portable. This unit facilitated a faster analysis of data on field. Two applications were targeted: Flurometer (bio-sensor) and Corner Cube Retroreflector (CCR-optical sensor for communication). A sensor board was developed to control a thermally regulated fluorometer undergoing the Nuclei Acid Synthesis Based Amplification (NASBA) process, which detected the fluorescence from the solution containing target RNA. NASBA runs were conducted using solution containing K. brevis- Red tide organisms to validate the interface of the PDA with a fluorometer. Real time fluorescence plot over time was obtained on the PDA indicating presence/absence of the target RNA; thus, it successfully interfaced the PDA with the fluorometer. Additionally, a sensor board was developed to control the electrostatic actuation mechanism of the MEMS based CCR. Efforts were made to fabricate the vertical mirrors of CCR using wet and dry fabrication techniques.

This thesis explores high voltage converter circuits for MEMS applications using micromachined devices. A novel MEMS based tunable DC-DC converter has been developed. Conventional high voltage converters based on charge pumps are unable to convert voltages to higher than few tens of volts due to power handling limitations of the CMOS components. In order to overcome this limitation a high voltage circuit has been proposed, which when integrated with micromachined switches will generate output voltages in the range of 100 Volts. The converter is based on a two phase switched capacitor circuit, and allows regulation of voltage conversion ratio. Three prototype circuits have been built for proof of concept. A test program has been written for synchronized CPLD based control of the switched capacitors. Individual capacitor fabrication technology is explored using two methods - Porous Silicon and DRIE processing. A micromachined capacitor bank has also been fabricated in silicon using a novel process sequence which provides for critical real estate savings and integration benefits. It enables on-chip integration of numerous microcapacitors, without losing customized configurability of the capacitor bank. The technique utilizes polyimide to facilitate lithography on a highly contoured surface. Plain capacitors have been fabricated on silicon with oxide-nitride-oxide stack being used as the dielectric to provide a building block for further fabrication of a variety of capacitors.

A Corner Cube Retro-reflector (CCR) is a device that can be used as transmitters in wireless free space optical communication systems, or remote sensing instruments. A novel approach to fabricate the CCR is developed, where almost 100% of the planar chip area acts as the CCR compared to the maximum of 33% in the prior MEMS CCRs. Unlike the conventional micro machined CCRs that have two planes (mirrors of the CCR) normal to the surface of the wafer, our approach yields all the mirrors within the bulk of the wafer, ensuring very high packing densities and wide acceptance angles. The crystallography of single crystal silicon wafer along with different micromachining and wafer bonding techniques are used to fabricate and assemble the CCR. The solid models of both the active and passive CCRs were built using Coventorware simulation software. In the active CCRs, one of the mirror was electrostatically actuated; this is simulated using the software. The results which show a three fold decrease in the pull-in voltage as compared to surface micromachined cantilevers with the same dimensions as presented. Fabrication of the passive CCR along with various fabrication and assembling processes used are discussed. Experimental results are presented and then discussed.

Photonic crystals serve as powerful building blocks for the development of lab-on-chip devices. Currently they are used for a wide range of miniaturized optical components such as extremely compact waveguides to refractive-index based optical sensors. Here we propose a new technique for analyzing and characterizing cells through the design of a micro-flow cytometer using photonic crystals. While lab scale flow cytometers have been critical to many developments in cellular biology they are not portable, difficult to use and relatively expensive. By making a miniature sensor capable of replicating the same functionality as the large scale units with photonic crystals, we hope to produce a device that can be easily integrated into a lab-on-chip and inexpensively mass produced for use outside of the lab. Using specialized FDTD software, the proposed technique has been studied, and multiple important flow cytometry functions have been established. As individual cells flow near the crystal surface, transmission of light through the photonic crystal is influenced accordingly. By analyzing the resulting changes in transmission, information such as cell counting and shape characterization have been demonstrated. Furthermore, correlations for simultaneously determining the size and refractive indices of cells has been shown by applying the statistical concepts of central moments.

In this thesis, the mechanical characterization of thin films, bulk materials, compliant MEMS and Microfluidics has been discussed. In chapter1 and chapter 2, the Indentation Size Effect (ISE) has been studied for single crystal aluminum and the substrate effect has also been studied for 200 nm gold film on mica substrate and 50 nm gold film on (100) silicon wafer substrate. The mechanical characterization of super hard SiC films (prepared by CVD) has also been discussed. In chapter 3, the actuation of compliant MEMS devices with a nanoindentation apparatus has been investigated. Friction forces become important at the device level, and the conical tip always makes a crack at the edge of the sliders, thus the slider design needs to be optimized to account for the probe geometry. In chapter 4, the measurement of electrowetting has been outlined. The "airscratch" mode was used to capture the lateral force and normal force during an electrowetting test. With the appearance of surface delamination on the solid surface, the unexpected normal forces can been measured.