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Copper Electrodeposition In Full Wafer Thickness Through-Silicon Vias, Rebecca P. Schmitt

Chemical and Biological Engineering ETDs

Through-silicon vias (TSVs) are a key interconnect technology for advanced packaging of microelectronic devices, and full wafer thickness TSVs are required for certain microelectromechanical systems (MEMS) applications. In this work, electrolytes containing copper sulfate, an acid, chloride, and Tetronic 701 suppressor were implemented for Cu filling of high aspect ratio (10:1), full wafer thickness TSVs. For each electrolyte system, rotating disk electrode voltammetry was used to identify a voltage range for bottom-up Cu filling in the TSVs. Die level feature filling was performed using voltage ramping, which moved active deposition through the vias to yield void-free Cu features. During voltage-controlled …

Low Temperature Tensile Testing Of Independently Fabricated Gold Thin Film Samples, Adnan Raza

Mechanical Engineering ETDs

Tensile testing of free standing thin films is of great importance for determining their material properties. Samples have always been co fabricated with the MEMS device being used as the test apparatus. Consequently, a new device has to be used each time a new sample is tested, resulting in loss of precision. The proposed idea is to independently fabricate free standing gold thin film samples and transfer them to a separately fabricated cascaded thermal actuator setup. Thermal actuators are desirable due to the large deflections and forces they provide while maintaining a relatively low thermal gradient across the test specimen. …

Theory, Fabrication, And Experimentation Of Phononic Crystals In Mems At Micro/Nano Scale: Engineering Of Thermal And Rf Phonons To Applications In Thermoelectrics And Microresonators, Seyedhamidreza Alaie

Mechanical Engineering ETDs

Phononic Crystals (PnCs) are novel materials comprised of a periodic structure of inclusions in a matrix. This periodic arrangement creates phononic bandgaps, and modifies phononic bandstructures of a material. Such a property offers promising applications at the micro and nano scales to engineer acoustic filters, high Q-factor resonators, and thermoelectric properties of materials. Studying PnCs at the micro/nano scale requires specific characterization techniques, which rely on Micro Electro Mechanical Structures (MEMS). This work focuses on the study, and characterization of PnCs using MEMS in view of their prospective applications in thermoelectric materials, microresonators and acoustic filters, and also the prospective …

Characterization Of Mechanical Properties At The Micro/Nano Scale: Stiction Failure Of Mems, High-Frequency Michelson Interferometry And Carbon Nanofibers, Arash Kheyraddini Mousavi

Mechanical Engineering ETDs

Different forces scale differently with decreasing length scales. Van der Waals and surface tension are generally ignored at the macro scale, but can become dominant at the micro and nano scales. This fact, combined with the considerable compliance and large surface areas of micro and nano devices, can leads to adhesion in MicroElectroMechanical Systems (MEMS) and NanoElectroMechanical Systems (NEMS) - a.k.a. stiction-failure. The adhesive forces between MEMS devices leading to stiction failure are characterized in this dissertation analytically and experimentally. Specifically, the adhesion energy of poly-Si μcantilevers are determined experimentally through Mode II and mixed Mode I&II crack propagation experiments. …

Design, Fabrication, And Characterization Of A Mems Based Thermally Actuated Fabry-Pã©Rot Interferometer., Andrew Ian Young

Mechanical Engineering ETDs

MEMS devices have become ubiquitous in consumer devices and are also being used to conduct experiments on the nano and micro scale. There is a growing need to test the properties of materials at the micro and nanoscale. In order to test those materials, a reliable method of sensing displacement is needed. Another growing area of MEMS research is in creating micro optical cavities that allow for manipulation and control of atoms in QED research. This thesis describes a MEMS based thermally actuated Fabry-Pérot cavity interferometer that has potential as a displacement sensing mechanism for use in material testers and …

Modeling The Mechanical Response Of Polycrystalline Thin Films, Pedro Joaquin Madrid

Mathematics & Statistics ETDs

Microelectromechanical systems (MEMS) are part of every modern technological advance. Electrodeposited thin nickel (Ni) polycrystalline films in MEMS often show fiber texture resulting in transverse isotropic elastic properties. It is of interest to determine these elastic properties, in particular the in-plane Young's modulus, since it plays a fundamental role in device performance. The fabrication process of MEMS films introduces uncertainties in the microstructure geometry, crystallographic texture, the crystal elastic constants, the physical film dimensions and other parameters. In this thesis the numerical value of the in-plane Young's modulus of thin Ni polycrystalline films is predicted. The predicted values lie between …

Surface Micromachined Pressure Sensors, William P. Eaton Iv

Electrical and Computer Engineering ETDs

Surface micromachined pressure sensors were designed, modeled, fabricated, and tested. They employed a piezoresistive transduction mechanism and were based upon circular diaphragms, which vary from 50 to 1000 μm in diameter and 1 to 2 μm in thickness. The piezoresistors were placed in Wheatstone bridge configurations to provide simple signal amplification and first order temperature compensation.

Of the different micromachining techniques, surface-micromachining has the advantage of being the most similar to integrated circuit manufacturing. Hence an existing IC equipment set can be used to create mechanical structures. Furthermore, the monolithic integration of a mechanical device with control electronics is simpler …