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Thesis (M.S.)--Rochester Institute of Technology, 1991. / Typescript. Includes bibliographical references.

Today, thin film based devices are found in a wide field of applications. The main reasons are that thin film technology enables access to unique physical properties and possibilities to miniaturize devices. Thin film devices are generally described in terms such as electrical, optical and magnetical properties. However, the lifetime of these devices is often limited by mechanical stresses causing plastic deformation. An effect of the plastic deformation is hillocking where isolated features are created on the film surface. The continual need to improve performance, reduce size as well as cost is pushing thin film structures close to or beyond present fundamental understanding. Further progress requires better understanding of basic phenomena where analytical methods for characterization of thin film deformation play a crucial role. To follow the initial hillock formation during thermal treatments it is essential to have a suitable tool for achieving real-time measurements with high sensitivity over a relatively large area that does not considerably affect the film surface. Methods based on light scattering are generally very sensitive to changes in the surface topography and allow contact free measurements at high speed. In this thesis light scattering methods are investigated as tools for stress analysis of thin metal films. Detection and characterization of isolated surface features using angular resolved scattering has been investigated by simulations. Results were used in development of an optical instrument for simultaneous measurements of initial hillocking and changes in overall film stress. The instrument combines light scattering and laser beam deflection techniques. It is shown how the onset of initial hillocking in aluminum films is accompanied by stress relaxation. Real-time dark field microscopy was demonstrated as a technique for analysis of the lateral hillock distribution. Analysis of the distribution show clustering of hillocks which is supposed to be related to the microstructure of the film. It is demonstrated that copper inclusion can be used to strengthen aluminum films to withstand higher stress before hillocking occurs. The copper content also reduces the grain size and thereby the surface roughness, which results in good or even better optical performance than for pure aluminum films. / <p>NR 20140805</p>

A self-aligning nanostencil mask is used to fabricate circular features of tin, indium and silver on an atomically clean Si(001) substrate. The shadow mask limits deposited material to areas under openings in the mask, leaving adjacent clean areas for material to diffuse. STM, SEM and AFM have been used to study the surface diffusion of these metals in UHV. The diffusion of tin is relatively limited in comparison to the other metals. Indium forms metal islands that dissolve over time and contribute to the spreading of a surrounding single layer film. Lastly, silver forms a film that spreads even in the absence of metal islands.

A self-aligning nanostencil mask is used to fabricate circular features of tin, indium and silver on an atomically clean Si(001) substrate. The shadow mask limits deposited material to areas under openings in the mask, leaving adjacent clean areas for material to diffuse. STM, SEM and AFM have been used to study the surface diffusion of these metals in UHV. The diffusion of tin is relatively limited in comparison to the other metals. Indium forms metal islands that dissolve over time and contribute to the spreading of a surrounding single layer film. Lastly, silver forms a film that spreads even in the absence of metal islands.

In order to meet the demands of the continuous scaling of electronic devices, new technologies have been developed over the years. As we approach the newest levels of miniaturization, current technologies, such as physical vapor deposition and chemical vapor deposition, are reaching a limitation in their ability to successfully fabricate nano sized electronic devices. Supercritical fluid deposition (SFD) is a demonstrated technology that provides excellent step coverage for the deposition of metals and metal oxides within narrow, high aspect ratio features. This technique shows the potential to satisfy the demands of integrated circuit miniaturization while maintaining a cost effective process needed to keep the technology competitive. In order to complement SFD technology heuristics for scale-up, an understanding of the deposition mechanism and kinetics and resolution of integration issues such as interfacial film adhesion must be resolved. It is critical to have a fundamental understanding of the chemistry behind the reaction process in supercritical fluid deposition. For this purpose, a detailed kinetic study of the deposition of ruthenium from bis(2,2,6,6-tetramethyl-3,5-heptanedionato) (1,5-cyclooctadiene) ruthenium(II) is carried out so that growth rate orders and a mechanism can be established. These predictive kinetic results provide the means to control the reaction which allows for overall optimization of the process. Reliability is of the utmost importance for fabricated devices since they must withstand harsh steps in the fabrication process as well as perform and last under standard and extreme usage conditions. One issue of reliability is assessed by addressing the adhesion of the metallization layers deposited by SFD. A quantitative determination of the interfacial adhesion energy of as deposited and pretreated copper metallization layers from SFD onto barrier layers is used to determine the potential for integration of these films for industry standards. Extension of the basics of SFD by performing co-deposition of multiple compounds, layer-by-layer deposition for device fabrication and integration with other unique technologies for novel applications demonstrates the ability of this technique to satisfy a wide range of commercial applications and be used as the basis for new technologies. Co-depositions of Ce/Pt, Co/Pt, Ba/Ti and Nd/Ni for the fabrication of functional direct methanol fuel cell electrodes, magnetic alloys for media storage applications, high k dielectric films for alternative energy storage devices and alternative materials for solid oxide fuel cell cathodes, respectively, are performed. Layer-by-layer deposition with masking is used to fabricate nanometer scale capacitors. Finally, plasma spray technology is combined with the rapid expansion of supercritical solvents technique to form a novel, patent pending, process that is used to fabricate next generation photovoltaic cells.

The maximum sensitivity of a thermal IR sensor can be available either by means of the sensor material, having its own absorbing properties, or by the deposition of an additional absorber structure on the detector surface. In this thesis, the theory of two absorption structures is discussed. The first is called the interferometric absorber structure. The second structure under investigation uses a lead selenide layer for the IR absorption. In the interferometric structure, a new epoxy material SU8-2002 was used as a dielectric medium. This material has a very low thermal conductivity of 0.3 W/mK, which makes it suitable for thermal detectors. The interferometric structure is based on three layers, a 40–60 Å thick Ti layer, a SU8–2002 layer with a thickness of 2000 Å thick and a 2000Å Al layer. Using standard cleanroom processing an interferometric structure was fabricated. Transfer matrix theory was used in order to simulate the interferometric structure and the lead selenide was fabricated by means of an argon-plasma sputtering process. Both fabricated samples were characterized through Fourier transfer infrared (FTIR) spectroscopy together with a specular reflectance accessory. The thicknesses of the added layers were measured using Atomic force microscopy (AFM) for both the interferometric and lead selenide structure.  It was determined  that by changing the reflective index value of the SU8-2002 from the reported value of 1.575 to about 2.40 that this provided a better agreement with the experimental results. The absorption results for the interferometric structure were determined to be approximately 82–98% for the wavelength region of 2-20µm at 30 degree. The PbSe absorption spectra showed 30%–50% absorption for the wavelength region 2.5 – 6.67μm.

xv, 101 p. ; ill. (some col.) A print copy of this title is available through the UO Libraries under the call number: KNIGHT QC176.84.E5 P47 2007 / Silver films with nanoscale to mesoscale thicknesses were produced by chemical reduction onto silica substrates and their physical and electrical properties were investigated and characterized. The method of silver deposition was developed in the context of this research and uses a single step reaction to produce consistent silver films on both flat silica coverslips and silica nanospheres of 250-1000 nm. Both the structure and the electrical properties of the silver films are found to differ significantly from those produced by vacuum deposition. Chemically deposited (CD) silver is not uniformly smooth, but rather is granular and porous with a network-like structure. By quantitatively accounting for the differences in scale, geometry, and microstructure of the CD films, it is found that the same models used to describe the resistivity of vacuum deposited films may be applied to CD films. A critical point in the analysis that allows this relation involves the definition of a geometric parameter, g, which replaces the thickness, t, as the critical length that influences the electrical properties of the film. The temperature dependent properties of electrical transport were also investigated and related to the microstructure of the CD films. A detailed characterization of CD silver as shells on silica spheres is also presented including physical and optical properties. In spite of the rough and porous morphology of the shells, the plasmon resonance of the core-shell structure is determined by the overall spherical shell structure and is tunable through variations in the shell thickness. Preliminary investigations into the electrical transport properties of aggregates of silver coated spheres suggest similarities in the influence scale, geometry, and microstructure to silver films on flat substrates. The aggregates of shells also exhibit pressure related resistance behavior due to the composite structure. / Adviser: Miriam Deutsch

abstract: Nanocrystalline (NC) and Ultrafine-grained (UFG) metal films exhibit a wide range of enhanced mechanical properties compared to their coarse-grained counterparts. These properties, such as very high strength, primarily arise from the change in the underlying deformation mechanisms. Experimental and simulation studies have shown that because of the small grain size, conventional dislocation plasticity is curtailed in these materials and grain boundary mediated mechanisms become more important. Although the deformation behavior and the underlying mechanisms in these materials have been investigated in depth, relatively little attention has been focused on the inhomogeneous nature of their microstructure (particularly originating from the texture of the film) and its influence on their macroscopic response. Furthermore, the rate dependency of mechanical response in NC/UFG metal films with different textures has not been systematically investigated. The objectives of this dissertation are two-fold. The first objective is to carry out a systematic investigation of the mechanical behavior of NC/UFG thin films with different textures under different loading rates. This includes a novel approach to study the effect of texture-induced plastic anisotropy on mechanical behavior of the films. Efforts are made to correlate the behavior of UFG metal films and the underlying deformation mechanisms. The second objective is to understand the deformation mechanisms of UFG aluminum films using in-situ transmission electron microscopy (TEM) experiments with Automated Crystal Orientation Mapping. This technique enables us to investigate grain rotations in UFG Al films and to monitor the microstructural changes in these films during deformation, thereby revealing detailed information about the deformation mechanisms prevalent in UFG metal films. / Dissertation/Thesis / Doctoral Dissertation Mechanical Engineering 2017

A new manufacturing paradigm may lower the cost and environmental impact of existing products, as well as enable completely new products. Large scale, roll-to-roll manufacturing of flexible electronics and other functionality has great potential. However, a commercial breakthrough depends on a lower consumption of materials and energy compared with competing alternatives, and that sufficiently high performance and reliability of the products can be maintained. The substrate constitutes a large part of the product, and therefore its cost and environmental sustainability are important. Electrically conducting thin films are required in many functional devices and applications. In demanding applications, metal films offer the highest conductivity.   In this thesis, paper substrates of various type and construction were characterized, and the characteristics were related to the performance of inkjet-printed metal patterns. Fast absorption of the ink carrier was beneficial for well-defined pattern geometry, as well as high conductivity. Surface roughness with topography variations of sufficiently large amplitude and frequency, was detrimental to the pattern definition and conductivity. Porosity was another important factor, where the characteristic pore size was much more important than the total pore volume. Apparent surface energy was important for non-absorbing substrates, but of limited importance for coatings with a high absorption rate. Applying thin polymer–based coatings on flexible non-porous films to provide a mechanism for ink solvent removal, improved the pattern definition significantly. Inkjet-printing of a ZnO-dispersion on uncoated paper provided a thin spot-coating, allowing conductivity of silver nanoparticle films. Conductive nanoparticle films could not form directly on the uncoated paper.   The resulting performance of printed metal patterns was highly dependent on a well adapted sintering methodology. Several sintering methods were examined in this thesis, including conventional oven sintering, electrical sintering, microwave sintering, chemical sintering and intense pulsed light sintering. Specially designed coated papers with modified chemical and physical properties, were utilized for chemical low-temperature sintering of silver nanoparticle inks. For intense pulsed light sintering and material conversion of patterns, custom equipment was designed and built. Using the equipment, inkjet-printed copper oxide patterns were processed into highly conducting copper patterns. Custom-designed papers with mesoporous coatings and porous precoatings improved the reliablility and performance of the reduction and sintering process.         The thesis aims to clarify how ink-substrate interactions and sintering methodology affect the performance and reliability of inkjet-printed nanoparticle patterns on flexible substrates. This improves the selection, adaptation, design and manufacturing of suitable substrates for inkjet-printed high conductivity patterns, such as circuit boards or RFID antennas.