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Surface Modification Of 6h-Sic Under Vacuum Annealing Studied By Time Of Flight Positron Annihilation Induced Auger Electron Spectroscopy, Saurabh Mukherjee Jan 2007

Surface Modification Of 6h-Sic Under Vacuum Annealing Studied By Time Of Flight Positron Annihilation Induced Auger Electron Spectroscopy, Saurabh Mukherjee

Material Science and Engineering Theses - Archive

This thesis presents the first study of vacuum annealing of 6H- SiC surface using Time-of-Flight-Positron Annihilation induced Auger Electron Spectroscopy(TOF-PAES) . The study was the first application of a TOF-PAES spectrometer to the SiC. The increased efficiency of the TOF-PAES allows us to see simultaneously for the first time Si-LVV, C-KVV, O-KVV peaks in the PAES spectrum for SiC. The top layer surface concentrations of C, O and Si were monitored by TOF-PAES surface. The results indicate that the SiC surface was initially covered with a layer containing oxygen but largely devoid of Si which was subsequently removed as a …

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Simulation And Development Of Nanoscale Deposition Techniques Using Kinetic Monte Carlo, Corey Clark Jan 2007

Simulation And Development Of Nanoscale Deposition Techniques Using Kinetic Monte Carlo, Corey Clark

Electrical Engineering Dissertations - Archive

Modeling of deposition processes has become of extreme importance due to the small scale of devices and features as well as the reduction of time to market required by industry. Current modeling procedures have focused on individual aspects of growth as well as made assumptions that cause simplification of the problem to the point the models usefulness is limited. The Kinetic Monte Carlo (KMC) model developed in this work combines rate transitions that have been commonly found in KMC simulation along with energy density equations that help explain the transitions and formations of island in alloy deposition. Specifically the model …

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A Weighted Residual Parabolic Acceleration Time Integration Method For Problems In Structural Dynamics, Ali Abolmaali, S.H. Razavi, M. Ghassemieh Jan 2007

A Weighted Residual Parabolic Acceleration Time Integration Method For Problems In Structural Dynamics, Ali Abolmaali, S.H. Razavi, M. Ghassemieh

Civil Engineering Faculty Publications - Archive

In the proposed method, the variation of displacement in each time step is assumed to be a fourth order polynomial in time and its five unknown coefficients are calculated based on: two initial conditions from the previous time step; satisfying the equation of motion at both ends of the time step; and the zero weighted residual within the time step. This method is non-dissipative and its dispersion is considerably less than in other popular methods. The stability of the method shows that the critical time step is more than twice of that for the linear acceleration method and its convergence …

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Commencement Program 2006 December, University Of Texas At Arlington: School Of Social Work, The University Of Texas At Arlington Dec 2006

Commencement Program 2006 December, University Of Texas At Arlington: School Of Social Work, The University Of Texas At Arlington

Commencement Programs, Photos, and Video

No abstract provided.

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Thermal Failure Mechanism And Voltammetry Metrology For Cu/Barrier/Low K Integration, Dongmei Meng Dec 2006

Thermal Failure Mechanism And Voltammetry Metrology For Cu/Barrier/Low K Integration, Dongmei Meng

Material Science and Engineering Dissertations - Archive

The present study investigates the thermal stability of Cu/barrier/porous low κ (PLK) integration first, and then a new characterization method based on voltammetry is developed to characterize quality of diffusion barrier and pore structure in low κ materials and its thermal stability. The study of thermal stability reveals that Cu/barrier/PLK interconnect fails by Cu out-diffusion through the defects of diffusion barrier into the PLK structure, which is driven by oxidation and stress gradient within the interconnect structure. The failure appears to be triggered by defects in diffusion barrier, however, such defects are not effectively detected by TEM observation due to …

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Preparation And Characterization Of Properties Of Electrodeposited Copper Oxide Films, Longcheng Wang Dec 2006

Preparation And Characterization Of Properties Of Electrodeposited Copper Oxide Films, Longcheng Wang

Material Science and Engineering Dissertations - Archive

Copper oxides, including cuprous oxide and cupric oxide, are prepared by electrochemical deposition. The structural, optical and electrical properties of as-deposited copper oxides are evaluated, based on which cuprous oxide is selected as a promising material for photovoltaic applications. Electrodeposited cuprous oxide is a p-type semiconductor with a direct band gap of 2.06 eV. The mechanism of how pH affects the structural and electrical properties of electro-deposited cuprous oxide films is studied. In the pH range of 7.5 to 12.0, there are three different preferred crystal orientations: (100), (110) and (111). With different orientations, cuprous oxide shows different surface morphology …

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Multi-Sensor Fusion Based Control For Autonomous Operations: Rendezvous And Docking Of Spacecraft, Jonathan Bryan Mcdonald Dec 2006

Multi-Sensor Fusion Based Control For Autonomous Operations: Rendezvous And Docking Of Spacecraft, Jonathan Bryan Mcdonald

Mechanical and Aerospace Engineering Theses - Archive

The project considers the problem of motion synchronization of free flying robotic spacecraft and serviceable floating objects in space. The synchronization maneuvers are based on sample and hold nonlinear translational and attitude control laws. GPS pseudorange signals and a vision based sensor unit are modeled to give position measurements; position and velocity estimates are extracted from the measurements based on Extended Kalman Filter models. A sensor data fusion algorithm in the form of a Federated Extended Kalman Filter is implemented that blends the estimates of the individual filters into a global estimate. Nonlinear simulations where a Pursuer spacecraft attempted to …

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Enhancement Of Pool Boiling Heat Transfer Using Thermally-Conductive Microporous Coating Techniques, Joo Han Kim Dec 2006

Enhancement Of Pool Boiling Heat Transfer Using Thermally-Conductive Microporous Coating Techniques, Joo Han Kim

Mechanical and Aerospace Engineering Dissertations - Archive

The present research is an experimental study of the enhancement of boiling heat transfer using microporous coating techniques. The current research is divided into four major phases. During the first phase, the effects of different metal particle sizes in the coating compound for thermally non-conductive microporous coating on pool boiling performance of refrigerants and water are investigated. The test surfaces, solid copper blocks with 1-cm² base, were tested at atmospheric pressure in saturated FC-72, R-123, and water. Results showed that the surface treatment by non-conductive microporous coating significantly enhanced both nucleate boiling and critical heat flux of all three refrigerants. …

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Flexible Microfluidic Circuit With Embedded In-Plane Valve, Srikar C. Paruchuri Dec 2006

Flexible Microfluidic Circuit With Embedded In-Plane Valve, Srikar C. Paruchuri

Mechanical and Aerospace Engineering Theses - Archive

Recent developments in Microfluidic systems have demonstrated many potential applications related to biology, chemistry and medical sciences. Fluidic manipulation with precise volume control is a basic function in these systems, and microvalves play an important role in control and delivery of the fluid sample. One of the key issues in such valve design is to make large membrane deflections compared to the channel dimension. This thesis reports a flexible microfluidic chip with embedded in-plane valves for fluid manipulation. Silicone elastomer (Polydimethylsiloxane - PDMS) is one of the most suitable materials to fabricate microvalve membranes, because of its low Young's modulus, …

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Tracing And Replay Of Real-Time Concurrent Programs In Vxworks, Daxa Keshavji Patel Dec 2006

Tracing And Replay Of Real-Time Concurrent Programs In Vxworks, Daxa Keshavji Patel

Computer Science and Engineering Theses - Archive

Real-time concurrent programs are difficult to analyze, debug and test because of the existence of race conditions. In particular, cyclic debugging requires the ability to reproduce a failed execution. That is, when a failure is observed during a test run, it is often necessary to reproduce the test run as an effort to locate the bug that has caused the failure. However because of the variations in thread scheduling and signal latency, a real-time concurrent execution may not be reproduced simply by re-executing the program under test. In this thesis, we describe a language-based framework for tracing and replay of …

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Performance Analysis Of The Beacon Period Contraction Mechanism In Wimedia Mac For Uwb, Shenjin Sun Dec 2006

Performance Analysis Of The Beacon Period Contraction Mechanism In Wimedia Mac For Uwb, Shenjin Sun

Computer Science and Engineering Theses - Archive

The WiMedia MAC for UWB based WPANs is currently preferred among standards for wireless network since it requires non-infrastructure for ad hoc network, and also supports for Quality of Service (QoS). Without infrastructure, coordination of devices within radio range is achieved by the exchange of beacon frames, which is an overhead in WiMedia MAC, since no data transmission is allowed during Beacon Period (BP). In a dynamic network, devices might leave or join in, so beacon slots will be released or reoccupied with the changing of network. And BP contraction mechanism is aimed at reusing the released beacon slots in …

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Computer-Aided Patient Specific Treatment Planning Of Cryosurgery For Breast Cancer, Junkyu Jung Dec 2006

Computer-Aided Patient Specific Treatment Planning Of Cryosurgery For Breast Cancer, Junkyu Jung

Mechanical and Aerospace Engineering Theses - Archive

Cryosurgery, which is to destroy tumors by use of localized freezing, is an emerging treatment modality for breast cancer as the size of detectable tumor becomes smaller due to more frequent use of various diagnostic imaging including MRI, CT and mammogram. Although general surgical guideline has been developed and its effectiveness has been demonstrated, cryosurgical protocol should be adjusted for a given patient to accommodate patient-specific variations including tumor size, location and geometry of patient's breast. In this study, a computerized treatment planning tool was developed to aid surgeons to determine surgical parameters considering patient specific diagnostic information. This tool …

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Freezing-Induced Microstructural Changes Of Collagen Scaffolds, Jeffrey David Miller Dec 2006

Freezing-Induced Microstructural Changes Of Collagen Scaffolds, Jeffrey David Miller

Mechanical and Aerospace Engineering Theses - Archive

Understanding the effects of freezing on the functional properties of tissues is critical to cryopreservation of native and artificial tissues, and prognosis after cryotherapies. Although investigations have been performed to correlate macroscopic properties such as mechanical properties with freezing parameters, the effects are typically tissue-type dependent and no physical understanding is available to explain these effects. Since the mechanical and optical properties of a tissue are based on the characteristics of its extracellular matrix (ECM), understanding and quantifying these changes could assist in predicting the response a tissue will have to freezing under different circumstances. In this study, the microstructural …

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Micromechanical Analysis Of Yielding For Particulate Filled Composites, Chih-Ta Chen Dec 2006

Micromechanical Analysis Of Yielding For Particulate Filled Composites, Chih-Ta Chen

Material Science and Engineering Theses - Archive

Particulate filled composites are hybrid materials which consist of particulates held together by a matrix. In this thesis, a simulation method to obtain overall failure criterion for particulate filled composites based on the computer software "MATHEMATICA" will be presented. The composite is assumed to fail at the matrix just outside the inclusion. By Self-Consistent Method, the composite can be imaged as an inclusion embedded within effective matrix. The Equivalent Inclusion method is then applied to stimulate the stress field within the inclusion. Stress just outside inclusion can be calculated because interfacial traction force on the boundary of inclusion is continuous. …

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Experimental Investigation Of Shear Capacity Of Precast Reinforced Concrete Box Culverts, Jarrod Clinton Burns Dec 2006

Experimental Investigation Of Shear Capacity Of Precast Reinforced Concrete Box Culverts, Jarrod Clinton Burns

Civil Engineering Theses - Archive

This study presents the experimental investigation of the shear capacity of four precast rinforced concrete box culverts. Each culvert was subjected to a monotomically increasing load through a 20-in x 10-in load plate, designed to simulate a standard HS 20-44 wheel footprint. Each box was instrumented with the following: strain gages, load cell, high-resolution laser sensor, data acquisition hardware and software, and laptop computer. The tests were conducted on 1.22 m x 1.22 m x 1.22 m (4 ft x 4 ft x 4 ft) box culverts, with load being applied at the free spigot end. The location of the …

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Spectroscopic Characterization Of Biliary Tract Tissues In-Vivo To Assist Laparoscopic Cholecystectomy, Sarita Kommera Dec 2006

Spectroscopic Characterization Of Biliary Tract Tissues In-Vivo To Assist Laparoscopic Cholecystectomy, Sarita Kommera

Bioengineering Theses - Archive

Laparoscopic Cholecystectomy is a surgical method for removal of gallbladder when it is diseased with gall stones. Almost 750,000 people are affected with this disease annually in USA. Gall bladder is removed by placing an incision on the cystic duct. This duct is totally embedded in fat (which is a few mm thick) in most of the cases and it becomes a huge problem decreasing the visual capability of the surgeon to distinctly locate the duct. Near Infrared Spectroscopy (NIRS) can solve the fuzziness as it penetrates in a few mm thick tissues. NIRS is one of the simplest techniques …

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Novel Intraocular Drug Delivery System For The Prevention Of Posterior Capsule Opacification, Brett Thomes Dec 2006

Novel Intraocular Drug Delivery System For The Prevention Of Posterior Capsule Opacification, Brett Thomes

Bioengineering Dissertations - Archive

Posterior capsule opacification (PCO) is a major complication associated with the implantation of intraocular lens (IOLs). Evidence suggests that PCO formation is caused by abnormal lens epithelial cell (LEC) migration/proliferation. We hypothesize that pharmacologic agents must target inflammatory cells in addition to LECs to inhibit PCO formation. To successfully target both inflammatory cells and LECs, a novel intraocular drug delivery system (DDS) was developed for implantation in the lens capsular bag. Such a system permits direct delivery of anti-inflammatory and anti-proliferative drugs in the lens capsule for extended periods of time resulting in reduced PCO formation. A lubricious polyurethane coating …

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A Comprehensive Study Of The Effects Of Eeg Electrode Arrays On Mri Signal-To-Noise At 3t, Aman Ish Goyal Dec 2006

A Comprehensive Study Of The Effects Of Eeg Electrode Arrays On Mri Signal-To-Noise At 3t, Aman Ish Goyal

Bioengineering Theses - Archive

Simultaneous EEG-fMRI offers much potential for gaining complementary, noninvasive information about brain function. While much effort has been devoted to the compelling problem of removing ballistocardiogram and gradient artifacts from the EEG waveforms, less attention has been paid to the impact that increasing density of electrode arrays has on the MR images. Initial work reporting the effects of EEG caps and electrodes on the MR image has been site specific, using customized EEG equipment that those research groups built in-house. Therefore these results are hard to generalize to other laboratory environments. A monotonic decrease in SNR of the images has …

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Localization Algorithms For Passive Targets In Radar Networks, Kartik Trasi Dec 2006

Localization Algorithms For Passive Targets In Radar Networks, Kartik Trasi

Electrical Engineering Theses - Archive

In this study, we propose an improved, robust algorithm for passive targets in radar networks. The main objective of this work is to improve the localization accuracy of the algorithm based on signal properties in combination with robust graphical techniques. We present a numerical approach and an experimental validation of the modified algorithm.

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Observer Synthesis For Linear/Nonlinear Dynamical Systems Subject To Measurement Delays, Praveen C. Muralidhar Dec 2006

Observer Synthesis For Linear/Nonlinear Dynamical Systems Subject To Measurement Delays, Praveen C. Muralidhar

Electrical Engineering Theses - Archive

In this research, problems associated with communication delays on the stability of formation of a group of unmanned vehicles is examined and solution to this problem is proposed. Ideally, it is required that the information transfer between the vehicles participating in a cooperative task be available immediately. But, in reality, there is always a delay between the instants at which the information is transmitted by one vehicle and the instant at which it is received by the other vehicles in the formation. A state observer is used to estimate the time delayed signal. The observer consists of two dynamic systems …

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Optimization Of The Tool Path In A Robotic Environment, Mukund Venkatachari Narasimhan Dec 2006

Optimization Of The Tool Path In A Robotic Environment, Mukund Venkatachari Narasimhan

Mechanical and Aerospace Engineering Dissertations - Archive

The rising costs and demand coupled with shrinking energy generating resources has triggered the need for optimum use of energy resources, minimizing the overhead costs and maximizing the profits. Robots have been long touted as a fit replacement of human labor force in manufacturing sectors. Slowly there is increased presence of robots in automobile and electronic industries. Typically they are used for welding, painting, ironing, assembly, pick and place, inspection, and testing. Mass production, fulfilling the ever increasing demand, can be accomplished by robots because of their precision, speed of operation and high endurance capabilities. This dissertation comprises of two …

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Analysis Of Hat Sectioned Reinforced Composite Beams Including Thermal Effects, Kashif Ali Nayyer Syed Dec 2006

Analysis Of Hat Sectioned Reinforced Composite Beams Including Thermal Effects, Kashif Ali Nayyer Syed

Civil Engineering Dissertations - Archive

A simple analytical method for analyzing fiber reinforced polymeric composite beams with hat cross-section is presented. The method includes development of closed-form expression of the axial, bending and their coupling stiffness matrices for the composite beams. The stiffness matrices are obtained by transforming the actual geometrical cross-section of the beam into an equivalent plate using transformation matrices and Parallel Axis theorem. Ply stresses due to mechanical as well as thermal load can easily be obtained at any given location of the beam section. In this approach, the effect of induced in-plane deformation due to bending for an unsymmetrical cross-section is …

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Generation Planning And Market Operation Strategies In The Southwest Power Pool Energy Imbalance Service Market, Kittipong Methaprayoon Dec 2006

Generation Planning And Market Operation Strategies In The Southwest Power Pool Energy Imbalance Service Market, Kittipong Methaprayoon

Electrical Engineering Dissertations - Archive

The transition of the Southwest Power Pool (SPP) from its traditional operation under tariff towards the new market environment has significant impact on the utilities in the SPP footprint, both in terms of planning and operations. The new market regulation creates the need for the utilities to reassess their planning strategy, primarily to ensure that operational decisions conform to the new market rules while remain profitable under the new operating regime. The utilities are referred to as Market Participants (MP) under the new market scheme. The new market environment will expose the MPs to a large amount of information with …

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Fiber Optic Scanner Using Electromagnetic Actuation With Different Ferromagnetic Materials, Pratibha C. Phuyal Dec 2006

Fiber Optic Scanner Using Electromagnetic Actuation With Different Ferromagnetic Materials, Pratibha C. Phuyal

Electrical Engineering Theses - Archive

A fiber optic scanner capable of scanning medical imaging actuated by an external magnetic field is designed and characterized using different magnetized and non magnetized ferromagnetic materials. Cobalt, Iron, Nickel, and Samarium Cobalt powders were used before and after magnetization to perform the actuation. Plastic optical fiber and a silica optical fiber are coated with 70 % enamel paint with 30 % different ferromagnetic materials mixed using brush. Due the low Young's Modulus, the plastic optical fiber could not actuate like silica optical fiber. Therefore, the silica fiber was used to conduct the experiments. The static and dynamic measurements were …

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Miniature Optical Coherence Tomography Probe, Asif Rizwan Dec 2006

Miniature Optical Coherence Tomography Probe, Asif Rizwan

Bioengineering Theses - Archive

A piezo based optical scanner for high speed optical coherence tomography (OCT) has been developed. Design of the miniature probe has been optimized to take advantages of the high speed depth scanning that can be achieved with spectral domain OCT (SD-OCT) systems. Three prototype scanning probes were constructed and tested for OCT imaging. Movies and images of tissues are presented which were taken at frame rates ranging from 50~100fps. Data were acquired at 18000 A-lines per second at an effective integration time of 55us.

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Optical Coherence Tomography Of Oral Mucosa, Nidhi Bharatbhai Mehta Dec 2006

Optical Coherence Tomography Of Oral Mucosa, Nidhi Bharatbhai Mehta

Bioengineering Theses - Archive

Oral cancer causes 120000* deaths annually around the world and 280000* new cases are diagnosed every year. Technology has developed and the death rate of oral cancer has improved over the last few decades; hence to improve the survival rate, development of a technique able to diagnose carcinomas in its early stages is very important. OCT is a non invasive imaging technique capable to provide high resolution microstructure images of tissue. A development of in vivo OCT; capable to image tissue with micrometer resolution and able to identify pre cancerous morphological changes non invasively could improve survival rate in cancer …

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Finite Element Modeling Of Carbon Nanotube Reinforced Polymer Composites And Evaluating Its Thermal Conductivities, Raghuram Basavanahalli Dec 2006

Finite Element Modeling Of Carbon Nanotube Reinforced Polymer Composites And Evaluating Its Thermal Conductivities, Raghuram Basavanahalli

Mechanical and Aerospace Engineering Theses - Archive

High thermal conductivity of carbon nanotubes has motivated us to study and understand the thermal mechanisms in nanocomposites. Though several theoretical models predict a high thermal conductivity for CNT reinforced polymer composites, the experimental validation are not so encouraging. A finite element model of MWNT reinforced nanocomposite is developed based on continuum mechanics approach. The finite element model is a representative volume element (RVE) with single MWNT inclusion. The inclusion is modeled based on the continuum model of MWNT as effective solid fiber [22].The interface resistance between the nanotube and the matrix material is modeled using thermal contact elements. The …

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Structural Analysis Of Fiber Reinforced Composite Materials, Cesar Augusto Rojas Dec 2006

Structural Analysis Of Fiber Reinforced Composite Materials, Cesar Augusto Rojas

Mechanical and Aerospace Engineering Theses - Archive

A study of fiber reinforced composite structures is conducted .This study includes laminate analysis, analysis of laminated composite beams and parametric study of composite beams. Finite element analysis for each beam model is conducted to verify the results obtained by analytical model. The analysis of the laminated beams in this study covers: 1. beam with a solid rectangular cross-section subjected to a transverse load 2. beam with a I-section under bending 3. beam with a squared tubular section under bending 4. beam with truss section under bending One of the principal purposes of this thesis is to create a user …

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Investigation On The Mechanism Of Interface Electromigration (Em) In Copper (Cu) Thin Films, Jee Yong Kim Dec 2006

Investigation On The Mechanism Of Interface Electromigration (Em) In Copper (Cu) Thin Films, Jee Yong Kim

Material Science and Engineering Dissertations - Archive

This study concerns the mechanism of the interface electromigration (EM) in copper (Cu) thin films. While EM in Cu is one of the most concerned reliability failure phenomena in Cu interconnects used microelectronic devices, its mechanism is not well understood yet. In order for better understanding of the EM mechanism, this study attempt to investigate the interface EM mechanism by examining the passivation effects on Cu EM using a cross-strip structure where Cu lines are cross-stripped with different passivation layers. From the observation of the marker polarity (hillocks and voids), the interface EM mechanism is determined whether the passivation layer …

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Acknowledgements, The Mcnair Team Dec 2006

Acknowledgements, The Mcnair Team

McNair Scholars Research Journal

No abstract provided.

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