Página 9 dos resultados de 2573 itens digitais encontrados em 0.080 segundos

‣ Computational and experimental study of instrumented indentation

Chollacoop, Nuwong, 1977-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 175 p.; 4637595 bytes; 6053084 bytes; application/pdf; application/pdf
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The effect of characteristic length scales, through dimensional and microstructural miniaturizations, on mechanical properties is systematically investigated by recourse to instrumented micro- and/or nanoindentation. This technique is capable of extracting mechanical properties accurately down to nanometers, via rigorous interpretation of indentation response. Such interpretation requires fundamental understandings of contact mechanics and underlying deformation mechanisms. Analytical, computational and experimental approaches are utilized to elucidate specifically how empirical constitutive relation can be estimated from the complex multiaxial stress state induced by indentation. Analytical formulations form a framework for parametric finite element analysis. The algorithms are established to predict indentation response from a constitutive relation (hereafter referred to as "forward algorithms") and to extract mechanical properties from indentation curve (hereafter referred to as "reverse algorithms"). Experimental verifications and comprehensive sensitivity analysis are conducted. Similar approaches are undertaken to extend the forward/reverse algorithms to indentations using two ore more tip geometries. Microstructural miniaturization leads to novel class of materials with a grain size smaller than 100 nm...

‣ Microdebonding test for measuring shear strength of the fiber/matrix interface in composite materials

Grande, Dodd Harrison
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 139 leaves; 6113301 bytes; 6113057 bytes; application/pdf; application/pdf
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by Dodd Harrison Grande.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1983.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE; Includes bibliographical references.

‣ Production functions and cost models for fibers in advanced composite materials

Goss, Isabelle
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 147 leaves; 7245912 bytes; 7245670 bytes; application/pdf; application/pdf
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by Isabelle Goss.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1986.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE.; Vita.; Bibliography: leaves 141-146.

‣ Monolithic integration of III-V semiconductor materials and devices with silicon; Monolithic integration of three-five semiconductor materials and devices with silicon

Ting, Steve M. (Steve Ming), 1973-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 152 p.; 11497447 bytes; 11497203 bytes; application/pdf; application/pdf
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by Steve M. Ting.; Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1999.; Includes bibliographical references (p. 145-152).

‣ MOSFET channel engineering using strained Si and strained Ge grown on SiGe virtual substrates

Lee, Minjoo Lawrence, 1976-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 161 p.; 10952694 bytes; 10952453 bytes; application/pdf; application/pdf
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As the economic and technological benefits of scaling in very-large-scale-integrated (VLSI) circuits decreases, the use of alternative channel materials such as germanium and strained silicon ([epsilon]-Si) is increasingly being considered as a method for improving the performance of MOSFETs. While [epsilon]-Si grown on relaxed Si[sub]l-x Ge[sub]x (i.e. single-channel heterostructure) is drawing closer to widespread commercialization, it is currently believed that almost all of the performance benefit in CMOS implementations will derive from the n-MOSFET. [epsilon]-Si p-MOSFETs demonstrate enhanced hole mobility, but the enhancement has been shown to degrade at high vertical fields for reasons that are still poorly understood. Dual-channel heterostructures, where a compressively-strained, Ge-rich layer is grown between the [epsilon]-Si cap and relaxed Si[sub]l-x Ge[sub]x virtual substrate have been shown to offer much larger hole mobility enhancements. One of the primary goals of this thesis is to understand and improve the performance of both single- and dual-channel heterostructure p-MOSFETs. The approach taken was to grow novel heterostructures and then fabricate MOSFETs using a short process flow. Cross-sectional TEM was constantly employed as a way to connect microstructure with mobility characteristics. In this way...

‣ Ab-initio study of cathode materials for lithium batteries

Reed, John Stuart, 1968-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 311 p.; 13157589 bytes; 23099591 bytes; application/pdf; application/pdf
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Using first principles calculations the effect of electronic structure on the stability of positive electrode materials for lithium rechargeable batteries is investigated. The investigation focuses upon lithiated α-NaFeO₂ type 3d transition metal oxide structures. It is found that the ligand field stabilization energy (LFSE) is of particular importance in stabilizing the α-NaFeO₂ type layered structure with general formula Li[sub]x MO₂ (0 <[or equal to] x <[or equal to] 1 and M = Co, Fe, Mn, Ni, ...) at partial lithiation. The key quantity is found to be the difference in LFSE between the 3d metal ion in tetrahedral coordination and octahedral coordination in the cubic close packed (CCP) oxygen framework. If the change in LFSE is small, then the migration of 3d transition metal ions between tetrahedral and octahedral sites generally involves less variation in energy, and hence is easier. This facilitates diffusion of the 3d transition metal ions through the CCP oxygen framework and tends to destabilize the layered structure at partial lithiation. Layered lithium manganese oxide is given particular attention as a material that rapidly transforms to a spinel-like structure with electrochemical cycling. Focus is also placed upon layered lithium cobalt oxide as a material that remains stable in the layered structure with electrochemical cycling. The differing stability of these compounds in the layered structure is explained in terms of LFSE. Spin pairing energy (SPE) is also found to make an important contribution to the energetics of low spin transition metal oxides like lithium cobalt oxide. The influence of SPE on structural stability...

‣ Towards in-situ device fabrication : electrostatic lithography and nanowire field effect devices

Agnihotri, Vikrant, 1981-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 80 leaves; 3840538 bytes; 3849111 bytes; application/pdf; application/pdf
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Electron beams were used to deposit fine line-width charge in electret materials. The electrets were exposed to charged or polarizable nanoparticle precursors. These nanoparticles decorate the charge pattern. Electret materials including Mylar, Polyamide and Teflon were used for this process. Nanoparticles used ranged from carbon black, gold, silver, iron oxide, aluminum oxide and silicon oxide. Multiple nanoparticle delivery methods were employed including immersion in a nanoparticle solution, exposure to a nanoparticle aerosol, electrosprayed nanoparticles and in-situ delivery of nanoparticles. The technique was adapted to produce the fastest known electron beam resist with exposure dosage as low as 10 nC/cm2. We have termed the new resist an electrostatic resist and the technique electrostatic lithography. A novel technique to fabricate logic elements from semiconducting nanowires grown using vapor-liquid-solid mechanism was also developed. The technique involves source, drain, gate-oxide and gate material fabrication using electron beam induced chemical vapor deposition. Field effect transistor and ring oscillator architectures were fabricated using this process. Nanowires were characterized using scanning electron microscopy and transmission electron microscopy. Current-voltage measurements were performed on the nanowire field effect transistors.; by Vikrant Agnihotri.; Thesis (S.M.)--Massachusetts Institute of Technology...

‣ Centrifugal infiltration of particulate metal matrix composites : process development and fundamental studies/

Wannasin, Jessada, 1977-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 125 p.; 5599402 bytes; 5597118 bytes; application/pdf; application/pdf
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A high-pressure liquid infiltration process utilizing centrifugal force was designed and laboratory equipment developed. In this process, a mold containing reinforcing materials was located at the end of an elongated runner, which was filled with a molten metal. Rotation of the runner created centrifugal force driving infiltration. To obtain high pressures, the metal head was controlled to be long and constant throughout the process. Threshold pressures required for infiltration of several packed ceramic powders were determined using the laboratory equipment built. Achievable pressures were up to 150 atm for Sn-15 wt% Pb. The pressures allowed SiC, TiC, and A1203 powders ranging in sizes from 25 [mu]m to 300 [mu]m, packed to a high volume fraction, to be infiltrated by Sn-15 wt% Pb. Threshold pressure results obtained agree well with experimental results previously reported, and with calculated values. Observations of the resulting composite structures showed layering and porosity defects. Layering defects, but no porosity defects, were observed in the composite samples containing coarse powders. In contrast, the composites containing fine powders possess porosity defects, but not layering defects. The layering defect was attributed to the depacking mechanism of the powders during the cold pressing process. The porosity defect was attributed to insufficient applied pressures. A new packing process was proposed to avoid layering in coarse powders. Macrosegregation and microsegregation were limited in all samples. The interparticle spacings of these composites were smaller than the dendrite arm spacing would have been at equivalent cooling rates; thus...

‣ Fabrication of water-soluble gold nanoparticle aggregates

Bennett, Samantha E
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 24 leaves; 1763383 bytes; 1761613 bytes; application/pdf; application/pdf
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Mixed monolayer protected gold nanoparticles were linked using octanedithiol to form aggregates containing hundreds of nanoparticles. These aggregates are an interesting material, posing potential applications in the fields of chemistry, biology and materials science. This study examined the dependence of aggregate size and morphology on temperature of formation, using AFM and TEM imaging. The aggregates formed at 70°C averaged 105nm in width, as compared to 70nm for the room temperature aggregates. The TEM images showed increased density for the 70°C aggregates. In a further study, the room temperature aggregates were functionalized through a place exchange reaction with 1 -mercapto-undecane- l-sodiumsulfonate (MUS), a thiolated ligand with a polar head group. A two-phase test of the water-solubility indicated that the aggregates were fully soluble. TEM images showed a slight increase in size, though similar morphology to the insoluble aggregates. The ability to induce water solubility in the aggregates opens up many potential applications in the field of bionanomaterials.; by Samantha E. Bennett.; Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2006.; Includes bibliographical references (leaves 23-24).

‣ Microfabricated thin-film batteries : technology and potential applications

Greiner, Julia
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 65 p.
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High-energy-density lithium ion batteries have enabled a myriad of small consumer-electronics applications. Batteries for these applications most often employ a liquid electrolyte system. However, liquid electrolytes do not allow for small scale and thin-film production as they require hermetic sealing. The aim for batteries in any size or shape, without the restrictions liquid components pose, has led to the development of solid electrolyte systems. ll-solid-state thin-film batteries add a new dimension to the space of battery applications. The purpose of this thesis is to assess the application potential for solid-state thin-film batteries, particularly with regard to CMOS integration. Such batteries were developed with the aim of creating a power unit on a silicon microchip. The various degrees of integration of thin-film batteries on a silicon wafer are examined. All of them show limitations that make fabrication of batteries on a wafer not viable at present from a business standpoint. A search for other commercializable applications for thin-film batteries leads to solid-state bulk batteries made from thin-film batteries. The underlying technology here as well as the market situation and a potential business model are discussed.; by Julia Greiner.; Thesis (M. Eng.)--Massachusetts Institute of Technology...

‣ Technology and market analysis of standard electronic photonic package

Abdi, Fatwa Firdaus
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 73 leaves
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Electronic industry will suffer a major turn around in the near future. The current infrastructure will no longer be able to support the increasing data rates. All the disadvantages of copper as current legacy are amplified with the level of bandwidth we are going to experience soon. On the other hand, photonic industry is in the need of finding a new demand source to be able to bring back the state of industry to the "boom" era. With both conditions in mind, it is likely for photonic and electronic industry to emerge. However, the platform for the collaboration has not been mature enough. One of the biggest problems in the photonic industry is the high cost of the package. This, so far, has been one of the major issues holding the industry from gaining back to its golden era. In order to overcome this barrier, standardization has been suggested to be implemented in the industry. This thesis examines the current state of optoelectronic industry, as a convergence of photonic and electronic industry. More specifically, the condition of lack of standardization is analyzed and proven to be the case.; (cont.) Interviewing relevant industry players and working closely with the MIT Communications Technology Roadmap-Integration, Packaging and Interconnects Technical Working Group also determine the reason of the condition. Finally...

‣ Particle sensors based on amplified quenching of conjugated polymers for biosensing applications

Liao, Jessica Huien, 1979-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 199 p.
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Conjugated polymers (CP)s display unique material properties that allow for implementation as sensors. For sensors to operate in complex biological environments, it is important to address the issues of sensitivity and specificity. To develop these attributes in a biosensor design, CPbased core-shell particles have been investigated as potential material platforms to detect protease activity. CP-based particles have greater sensitivity versus CPs in solution due to interchain and intrachain interactions afforded in the solid state. The CP core of the particle can be made using layer-by-layer assembly, a versatile technique that forms uniform polymeric films through non-covalent interactions. To measure the response of CP core particles in aqueous environments, a quantitative ratiometric approach was developed to account for system fluctuations encountered with particle dispersions. This method can help assess the molecular design of polymers and quenchers in a systematic approach. CP core particles, because of their electrostatic charge, suffer from nonspecific interactions with other charged species, and thus encapsulating CP particles with a hydrogel shell should create sensor materials with higher specificity.; (cont.) To illustrate this concept...

‣ A cost modeling approach using learning curves to study the evolution of technology

Kar, Ashish M. (Ashish Mohan)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 123 p.
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The present work looks into the concept of learning curves to decipher the underlying mechanism in cost evolution. The concept is not new and has been used since last seven decades to understand cost walk down in various industries. The seminal works defined learning in a narrower sense to encompass reduction in man hours as a result of learning. The work done later expanded this concept to include suppliers, long term contracts, management and some other economic and technological factors. But the basic mechanism in all these study was to look at manufacturing cost in an aggregate sense and use the past data to predict the cost walk down in future. In the present work the focus has shifted from looking at cost in an aggregate manner and understanding it more at a manufacturing level using process based cost modeling. This would give a new perspective to the age old problem of cost evolution. Besides it would also give the line engineers and managers a better insight into the levers which eventually lead to cost reduction at manufacturing level. This is achieved by using learning curves to define the manufacturing parameters based on previous observations. The work further looks at cost evolution for new and non-existent technology for which historic data does not exist. This is achieved by building a taxonomic classification of industry based on certain parameters which can be easily guessed.; by Ashish M. Kar.; Thesis (S.M.)--Massachusetts Institute of Technology...

‣ Polyelectrolyte multilayers incorporating photocrosslinking polymers for controlling 2- and 3-dimensional structure; PEMs incorporating photocrosslinking polymers for controlling 2- and 3-dimensional structure

Olugebefola, Solar Candido Ademola
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 155 p.
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Polyelectrolyte multilayer (PEM) assembly is a technology for building thin films with a number of useful and novel functionalities. PEMs interact favorably with proteins and other biomolecules making them potentially valuable as biomaterials. Many systems of polymers have been studied for use in PEMs, including weak polyelectrolytes such as those containing poly(acrylic acid) (PAA) and poly(allyamine hydrochloride) (PAH), which exhibit pH-dependent behavior. Properties such as thickness, swellability, mechanical stiffness, porosity (and by extention optical properties), and ability to adsorb small molecules are all controlled by the charge density of these polymers in the film and their resultant binding state. Patterning covalent binding through photo-crosslinking in addition to electrostatic binding, can locally override the native tendency to change structure with changes in pH. To achieve this, poly(acrylic acid) was chemically modified through a halide esterification reaction to incorporate photo-crosslinkable vinylbenzyl side groups, making poly(acrylic acid-ran-vinylbenzyl acrylate) (PAArVBA). The chemical modification was characterized by nuclear magnetic resonance spectroscopy (NMR) and light spectroscopy.; (cont.) NMR revealed that up to 6% of vinylbenzyl groups could be appended to PAA while maintaining the viability of the crosslinking group and the solubility of PAA in aqueous solution. Light spectroscopy indicated the location of the absorbance peak of the vinylbenzyl groups at 254 nm and the generation of crosslinking radicals was achieved with a quantum yield of 0.013. These parameters allow the polymer to be used in PEM films and to be crosslinked with a standard UV lamp...

‣ Computational studies of hydrogen storage materials and the development of related methods

Mueller, Timothy Keith
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 199 p.
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Computational methods, including density functional theory and the cluster expansion formalism, are used to study materials for hydrogen storage. The storage of molecular hydrogen in the metal-organic framework with formula unit Zn40(02C-C6H6-COD3 is considered. It is predicted that hydrogen adsorbs at five sites near the metal-oxide cluster, in good agreement with recent experimental data. It is also shown that the metal-oxide cluster affects the electronic structure of the organic linker, qualitatively affecting the way in which hydrogen binds to the linker. Lithium imide (Li2NH), a material present in several systems being considered for atomic hydrogen storage, is extensively investigated. A variation of the cluster expansion formalism that accounts for continuous bond orientations is developed to search for the ground state structure of this material, and a structure with a calculated energy lower than any known is found. Two additional discrete cluster expansions are used to predict that the experimentally observed phase of lithium imide is metastable at temperatures below approximately 200 K and stabilized primarily by vibrational entropy at higher temperatures. A new structure for this low-temperature phase that agrees well with experimental data is proposed. A method to improve the predictive power of cluster expansions through the application of statistical learning theory is developed...

‣ Percolation behavior of diffusionally evolved two-phase systems simulated using phase field methods

Brunini, Victor Eric
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 67 leaves
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Percolation is an important phenomenon that dramatically affects the properties of many multi-phase materials. As such, significant prior work has been done to investigate the percolation threshold and critical scaling exponents of randomly assembled composites. However many materials are non-random as a result of correlations that are introduced during processing. This work seeks to address this case by studying the percolation behavior of diffusionally evolved two phase systems. Specifically, the values of the percolation threshold and critical exponents v, 3, and 7 are presented for two dimensional systems evolved through spinodal decomposition and nucleation and growth.; by Victor Eric Brunini.; Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.; Includes bibliographical references (leaves 66-67).

‣ Evaluation of optical solder for fiber-to-waveguide coupling in silicon photonics

Tjioe, Fidelia
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 59 leaves
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Copper interconnects have shown its limit to meet the bandwidth demand even in the short reach applications due to its increase power consumption, RC delay, EMI, crosstalk and other effects which are aggravated as dimension shrinks. Despite efforts to increase the system performance, e.g. by multicore technology, migration to photonics is unavoidable, as it can give much superior performance. The major impediment to the wide-use of photonics is the cost. Three major components that contribute to the cost escalation are the absence of integrable light source, fast modulator, and effective fiber to waveguide coupler. The latest issue was addressed in this work. Coupling light efficiently from fiber to waveguide is challenging because of the size (6[mu]m core diameter for fiber, 500nm for waveguide), shape, and refractive index (~1.5 for fiber, 3.5 for waveguide) differences. Optical solder was proposed as the gap filler in between the fiber and waveguide to account for the fabrication uncertainties. Together with an inverse taper structure patterned in the waveguide end, the coupling loss was much reduced from 7.5dB (direct butt-coupling), to less than IdB. Besides, optical solder increases the reliability of device, as it prevents moisture and dust from impairing the optically active area of the die. Its fabrication is also integrable with the current CMOS technology. The configuration allows high density optical interconnect at the edges of the die; together with the electrical interconnect spreading across the area of the chip. All these make this system very good potential coupling method to solve one of the major impediments above...

‣ Commercialization of low temperature copper thermocompression bonding for 3D integrated circuits

Nagarajan, Raghavan
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 87 p.
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Wafer bonding is a key process and enabling technology for realization of three-dimensional integrated circuits (3DIC) with reduced interconnect delay and correspondingly increased circuit speed and decreased power dissipation, along with an improved form factor and portability. One of the most recent novel and promising wafer bonding approaches to realizing 3DIC is Low Temperature Thermocompression (LTTC) bonding using copper (Cu) as the bonding interface material. This thesis investigates the LTTC bonding approach in terms of its technological implications in contrast to other conventional bonding approaches. The various technological aspects pertaining to LTTC are comprehensively explored and analyzed. In addition to this, the commercialization potential for this technology is also studied and the economic viability of this process in production is critically evaluated using suitable cost models. Based on the technological and economic outlook, the potential for commercialization of LTTC is gauged.; by Raghavan Nagarajan.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.; Includes bibliographical references (p. 84-87).

‣ Characterization and requirements for Cu-Cu bonds for three-dimensional integrated circuits; Characterization and requirements for copper-copper bonds for 3D IC

Tadepalli, Rajappa, 1979-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 206 p.
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Three-dimensional integrated circuit (3D IC) technology enables heterogeneous integration of devices fabricated from different technologies, and reduces global RC delay by increasing the device density per unit chip area. Wafer-level Cu-Cu thermocompression bonding provides an attractive route to 3D IC fabrication, with Cu serving as both the electrical and mechanical interconnection between adjacent device layers. While the bonding process is currently employed for such applications, the lack of quantitative understanding of the bond quality and reliability has made developing robust processes extremely challenging. The current work addresses this problem through the development and implementation of bond toughness measurement techniques that investigate the effects of thin film patterning, surface chemistry and process parameters on the Cu-Cu bond quality under a range of loading conditions. The four-point bend test was used to quantify Cu-Cu bond toughness, Gc, under mixed-mode loading and to develop an optimized process flow that enabled the creation of high- toughness bonds (> 5 J/m2) at a bonding temperature of 300 oC. Mixed-mode loading induces significant plastic energy dissipation in ductile layers, resulting in an overestimation of the true adhesive strength of the interface.; (cont.) The chevron test method has been developed to allow bond toughness measurements under mode I loading...

‣ Catalytic properties, densification and mechanical properties of nanocrystalline yttria-zirconia-based materials

Cui, Jianyi
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 117 p.
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Alumina, titania, ceria and manganese oxide were either coated onto or doped in cubic 7 mol% Y203-ZrO2 (7YZ) nanocrystals to form nanocomposites for methane combustion. These novel catalysts were very active and thermally stable. In particular, 25 wt% Mn203-coated 7YZ and 25 wt% Mn203-doped 7YZ showed remarkably low light-off temperatures of 3750C and 3580C, respectively. These catalysts were highly attractive as they were competitive with the much more expensive supported noble metal catalysts. Their catalytic activity could be attributed to the availability of active surface oxygen species, which facilitated the methane activation at low temperatures. Nanocrystalline 3 mol% and 8 mol% Y203-ZrO2 (3YZ and 8YZ) were successfully densified with an ultrafine grain size of < 90 nm by pressureless sintering at 11000C and 11500C, respectively. The low-temperature sinterability could be attributed to the well-defined nanocrystalline particles obtained via hydrothermal synthesis, and the effective elimination of secondary porosity through the dry compact processing. Submicron-sized 3 mol% Y203-ZrO2 ceramics with a grain size of - 150 nm was also obtained with commercial TOSOHC powders. Grain growth during densification of TOSOH© powders was successfully suppressed by presintering to 93% density under an argon atmosphere...