bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics of Cu Segregation in Al-Cu(1at% Cu) Interconnects Studied by Resistance Measurements
Authors: Kalkman A. J. , Verbruggen A. H. , Janssen G. C. A. M. , Radelaar S. 
Published: June 2019

ABSTRACTThe time-dependence of the growth of Al2Cu precipitates in Al-Cu(lat% Cu) thin films is studied by means of resistance measurements at different temperatures. The samples are annealed at 400°C for 1 hour, and then quickly cooled down to room temperature. Afterwards, the samples are heated within one minute to a measurement temperature between 140 °C and 240 °C. Growth of precipitates causes a well defined decrease in resistance. The observed resistance decrease does not follow an exponential decay. In the investigated temperature range the resistance decrease can be accurately modelled by (R(t)-R∞) = (Ro-R∞)exp(-(t /τ)n), with the time constant τ= τ0 exp(Ea / kT). Excellent fits were obtained resulting in n = 0.66±0.05, independent of temperature, and Ea= 0.81±0.03 eV. This value for the activation energy agrees very well with the activation energy that has been reported in literature for both electromigration failure in Al-Cu and grain-boundary diffusion of Cu in Al. The value we found for n is intriguingly close to 2/3 and deviates strongly from the values of n reported for bulk Al-Cu (n = 1.5–1.8) in the same temperature range.
Thermal Conductivity Measurements of Interlevel Dielectrics
Authors: Varner Elizabeth B. , Marieb Thomas , Mack Anne Sauter , Lee Jin , Meyer William K. , Goodson Kenneth E. 
Published: June 2019

ABSTRACTThe thermal conductivity of interlevel dielectrics (ILD) in interconnect structures is an important parameter in determining the temperature rise in the interconnects during use. Numerous researchers have previously shown that the thermal conductivity of thin film dielectrics can be significantly lower than that of bulk materials. As new materials, such as low-dielectric constant materials, are considered for use as ILD's, methods are needed for measuring the thermal conductivity of the these materials to determine whether they can adequately conduct heat away from interconnect lines. Many methods reported in the literature use patterned metal lines atop the dielectric on a Si substrate as combination Joule heaters and temperature sensors, and extract the thermal conductivity from a model of heat conduction through the dielectric to the substrate. One drawback of these methods is the lack of agreement of the conductivity determined from the different techniques. For example, a thermal conductivity ranging from 0.6 to 1.4 W/m-K was calculated for a 1.25 μm thick PTEOS oxide using five different methods on the same test structure. In this paper we present a unique combination of test structures, experimental methods, and heat conduction models that highlight the limitations of some of the models and methods. We also show good agreement in the thermal conductivity determined from both an experimental method and a finite element model, and suggest that these two techniques yield an accurate measure of the thermal conductivity of thin film dielectrics.
Interconnect Limits on Gigascale Integration (GSI)
Authors: Davis J. A. , Meindl J. D. 
Published: June 2019

ABSTRACTOpportunities for Gigascale Integration (GSI) are governed by a hierarchy of physical limits. The levels of this hierarchy have been codified as: 1) fundamental, 2) material, 3) device, 4) circuit and 5) system. Many key limits at all levels of the hierarchy can be displayed in the power, P, versus delay, td, plane and the reciprocal length squared, L-2, versus response time, τ, plane. Power, P, is the average power transfer during a binary switching transition and delay, td, is the time required for the transition. Length, L, is the distance traversed by an interconnect that joins two nodes on a chip and response time, τ, characterizes the corresponding interconnect circuit. At the system level of the hierarchy, quantitative definition of both the P versus td and the L-2 versus τ displays requires an estimate of the complete stochastic wiring distribution of a chip.Based on Rent's Rule, a well known empirical relationship between the number of signal input/output terminals on a block of logic and the number of gate circuits with the block, a rigorous derivation of a new complete stochastic wire length distribution for an on-chip random logic network is described. This distribution is compared to actual data for modern microprocessors and to previously described distributions. A methodology for estimating the complete wire length distribution for future GSI products is proposed. The new distribution is then used to enhance the critical path model that determines the maximum clock frequency of a chip; to derive a preliminary power dissipation model for a random logic network; and, to define an optimal architecture of a multilevel interconnect network that minimizes overall chip size. In essence, a new complete stochastic wiring distribution provides a generic basis for maximizing the value obtained from a multilevel interconnect technology.
Corrosion Phenomena on the Grain Boundary of AlCu FIlms After Plasma Etching
Authors: Kim C. L. , Kwon K. H. , Yu S. J. , Kim H. J. , Chang E. G. 
Published: June 2019

ABSTRACTThe effect of grain boundary on the corrosion of Al(Cu 1%) etched using SiCl4/Cl2/He/CHF3 gas plasma has been evaluated with XPS (X-ray photoelectron spectroscopy), SEM (scanning electron microscopy) and AES (Auger electron spectroscopy). It was found with SEM that the surface of Al(Cu 1 %) mainly corroded at the grain boundary. Using AES point analysis, the cause of selective corrosion at the grain boundary of Al(Cu 1 %) has been investigated. The results of AES indicated that the contents of F and Cl have made a difference at the analyzed positions. This seems to result from the imperfect crystalline structure of Al(Cu 1%) grain boundary. It was also confirmed that F has passivated the Cl at the grain boundary. The SEM and XPS results implied that Cl incorporated in the grain boundary of polycrystalline Al(Cu 1%) film accelerated the corrosion and could not be easily removed by the subsequent SF6 plasma treatment.
Effects of Local Interfacial Debonding on the Stress Evolution in Aluminum Interconnects
Authors: Shen Y. -L. 
Published: June 2019

ABSTRACTThe evolution of thermal stresses in aluminum interconnects, with the presence of local debonded areas between the aluminum line and the surrounding dielectric, is studied numerically. Local interfacial debonding is presumably due to contamination during the line patterning process. Various geometrical features of the interconnect and the debond segment are assumed, and the resulting stress fields are examined by recourse to two- and three-dimensional finite element analyses. Implications of the findings to the interconnect reliability, particularly stress-induced voiding in aluminum lines, are discussed.
Performance and Reliability of Scaled Gate Dielectrics
Authors: Paulson W. M. , Tobin P. J. , Tseng H-H. , Maiti B. , Gelatos C. , Hegde R. I. , Anderson S. G. H. 
Published: June 2019

ABSTRACTGate dielectrics for advanced ULSI circuits are rapidly scaling below 10 nm. Thinner dielectrics and smaller lateral dimensions are essential to produce high performance transistors for memories, microprocessors and microcontrollers. In this overview we will discuss the factors that affect the performance and reliability of scaled gate dielectrics. Process parameters that affect oxide and oxynitride dielectrics include substrates, pre-gate cleaning, growth parameters and growth techniques as well as oxide and oxynitride dielectric materials. Thin dielectrics require new or modified measurement methods and extensive use of physical analysis techniques such as SIMS, XPS, AFM and TEM to characterize these materials. Boron diffusion through thin gate oxides, HCI stress, and process induced damage can degrade dielectric quality and affect long term reliability. These factors will affect the performance and reliability of circuits with scaled gate dielectrics.
Synthesis of Ultra-thin stacked oxides using low pressure single furnace cluster process
Authors: Roy P. K. , Brady D. , Chetlur S. , Ma Y. , Morse K. 
Published: June 2019

ABSTRACTThis work describes the development of a new grow-deposit-grow cluster process to grow ultra-thin stacked oxides. Two approaches for stacked oxide synthesis are discussed, namely thermal and chemical stacked oxides. Fabrication of chemical stacked oxide involves forming the first grown layer chemically after pre-gate cleaning, subsequent deposition of a TEOS-SiO2 layer and final densification/oxidation in a single low pressure (LP) furnace operation. In comparison, all three steps for thermal stacked oxide are accomplished by the LP cluster operation. Both processes offer the advantages of reduced cycle time and higher throughput to the stacked gate technology that produces superior Si/SiO2 interfaces and exhibits higher resistance to plasma-damage during ultra large scale integrated circuit (ULSI) processing. The quality and electrical characteristics of the stacked oxides are discussed.
In-Situ Stress Measurements During Dry Oxidation of Silicon
Authors: Yu Chia-Liang , Flinn Paul A. , Bravman John C. 
Published: June 2019

ABSTRACTIn this study, we present results of both in-situ and ex-situ measurements of stress generated during dry oxidation of silicon. We show that the mechanical stress in as-grown dry oxides is a strong function of oxidation temperature and oxide thickness, but a weak function of oxygen partial pressure. We have identified a structural relaxation phenomenon after the oxide is formed, and found that the viscosity of the oxide increases with its age; consequently, the stress relaxation slows down due to this increase of viscosity. In this paper, we present a one-dimensional mechanical model to simulate the stress generation and relaxation during dry oxidation of silicon. The simulations of both in-situ and ex-situ tests are in good agreement with the experimental measurements.
Creating Data Packages For Aircraft Resupply
Authors: Yancey R. N. 
Published: June 2019

ABSTRACTThe service of many military aircraft is being extended far beyond original design lives. When the C-130 is eventually retired, for example, it will have been in service for 79 years, well beyond its planned life expectancy of 40 years. Similarly, the line of KC-135's is presently expected to remain operational for 86 years, and the venerable B-52 an astounding 94 years! Not only are inventories of parts in short supply, but it may be necessary to acquire parts no one ever expected to replace. The first step in any reprocurement activity is the creation of a data package that can be submitted to suppliers for bid. If no computer-aided design (CAD) model exists, which is likely with older parts, the demands of modern electronic commerce dictate that one be created. If the original alloy is no longer obtainable, which is also likely with older parts, the demands of functional equivalence dictate that a suitable substitute be found and certified. Computed tomography (CT) offers an ideal way to obtain dimensional and material data critical to reverse engineering efforts. Industrial CT systems have progressed to the point where they can nondestructively measure part dimensions to an accuracy competitive with coordinate measuring machines and a speed competitive with laser scanners. Of the existing methods for obtaining part coordinates, only CT can dimension interior surfaces. Moreover, only CT has the ability to densitometrically quantify internal defects — a key consideration for computer-aided engineering activities. This paper describes the use of CT to help create data packages for resupply efforts and examples are presented.
Non-Destructive Evaluation of the Interface in Reinforced Concrete Using Phase Measurement Interferometry
Authors: Ghandehari Masoud , Krishnaswamy Sridhar , Shah Surendra 
Published: June 2019

ABSTRACTStudying the behavior of steel and concrete as a composite is of fundamental importance to the understanding of the cracking of reinforced concrete structures. In this article, a technique leading toward the development of a constitutive model for the interaction of steel and concrete is described. Experiments are based on pull-out specimens, where the shear stress and the two displacement components at the interface are measured. Phase Measurement Interferometry is used for accurate surface displacement measurement, and crack growth detection. The normal stress is then deduced using the measured crack length and crack opening displacements, along with a fracture mechanics based numerical simulation.
Paint As a Corrosion Sensor; Acrylic Coating Systems
Authors: Zhang J. , Frankel G. S. 
Published: June 2019

ABSTRACTPaint systems containing color-change or fluorescing compounds have been found to be sensitive to underlying corrosion processes by reacting to the pH increase associated with the cathodic reaction that accompanies corrosion. The sensitivity of these coating systems for detection of cathodic reactions associated with corrosion was determined by applying constant cathodic current and measuring the charge at which color change or fluorescence is detected. Visual observation of coated samples with the unaided eye can detect changes resulting from a charge corresponding to a hemispherical pit with depth on the order of 3–15 microns. Electrochemical Impedance Spectroscopy was also performed to test the influence of the indicating compound addition on the coating corrosion protectiveness.
Measurement Challenges Associated With Irradiated Reactor Components
Authors: Doctor Steven R. 
Published: June 2019

ABSTRACTNuclear reactor components are known to degrade as reactors age. The reactor pressure vessel and the reactor internals are subjected to the highest radiation fields and thus, age faster. Some boiling water reactors are experiencing extensive cracking of the core shroud and some pressurized water reactors are experiencing a reduction in their fracture toughness. This paper provides background information on reactor pressure vessel materials, fabrication, and construction practices. It identifies some of the challenges that are associated with the nondestructive measurement of changes in material properties associated with these components. The inspection environment, surface conditions and designs are also discussed.
Energy-Microcrack Growth Measurments for Mortar Cylinders in Compression
Authors: Nagy E. N. , Landis E. N. 
Published: June 2019

ABSTRACTA high resolution three-dimensional scanning technique called x-ray microtomography was applied to measure internal damage and crack growth in small mortar cylinders loaded in compression. Tomographic scans were made at different load increments in the same specimen. Three-dimensional image analysis was used to measure internal crack growth during each load increment. Load-deformation curves were used to measure the work of the external load on the specimen. Non-recoverable work of load was related to measured crack growth to estimate work of fracture in three dimensions. Initial results indicate a roughly linear relationship between work of load and internal crack area.
Development of a Capacitor Probe to Detect Subsurface Deterioration in Concrete
Authors: Diefenderfer B. K. , Al-Qadi I. L. , Yoho J. J. , Riad S. M. , Loulizi A. 
Published: June 2019

ABSTRACTPortland cement concrete (PCC) structures deteriorate with age and need to be maintained or replaced. Early detection of deterioration in PCC (e.g., alkali-silica reaction, freeze/thaw damage, or chloride presence) can lead to significant reductions in maintenance costs. However, it is often too late to perform low-cost preventative maintenance by the time deterioration becomes evident. By developing techniques that would enable civil engineers to evaluate PCC structures and detect deterioration at early stages (without causing further damage), optimization of life-cycle costs of the constructed facility and minimization of disturbance to the facility users can be achieved.Nondestructive evaluation (NDE) methods are potentially one of the most useful techniques ever developed for assessing constructed facilities. They are noninvasive and can be performed rapidly. Portland cement concrete can be nondestructively evaluated by electrically characterizing its complex dielectric constant. The real part of the dielectric constant depicts the velocity of electromagnetic waves in PCC. The imaginary part, termed the “loss factor,” describes the conductivity of PCC and the attenuation of electromagnetic waves.Dielectric properties of PCC have been investigated in a laboratory setting using a parallel plate capacitor operating in the frequency range of 0.1 to 40.1MIHz. This capacitor set-up consists of two horizontal-parallel plates with an adjustable separation for insertion of a dielectric specimen (PCC). While useful in research, this approach is not practical for field implementation. A new capacitor probe has been developed which consists of two plates, located within the same horizontal plane, for placement upon the specimen to be tested. Preliminary results show that this technique is feasible and results are promising; further testing and evaluation is currently underway.
Nde of Tendon Ducts in Concrete Using 3D-Saft
Authors: Krause M. , Wiggenhauser H. , Müller W. , Schmitz V. 
Published: June 2019

ABSTRACTPrestressed or post-tensioned concrete structures are vulnerable to hazardous corrosion, if the tendon ducts are not fully injected with grout. Also compaction faults reduce the concrete strength. Advanced ultrasonic testing techniques and data analysis have been utilized to evaluate ducts in concrete members nondestructively. A laser Doppler vibrometer is used as an ultrasonic receiver to automatically collect the data. With this method ducts could be investigated which are not accessible by other methods as radiography or impact-echo. Encouraging results on different specimens are presented.
Practical Optical Characterization Of Fretted Surfaces
Authors: Gustafson S. C. , Mehta J. R. , Frantziskonis G. N. 
Published: June 2019

ABSTRACTNominally smooth surfaces subjected to repeated contact may develop characteristic fretted textures. An important example concerns fretted surfaces that may develop on disk dovetail joints that secure fan blades in turbine engines. These surfaces may form sites for crack nucleation and subsequent catastrophic disk and engine failure. Thus a practical and reliable method for the nondestructive evaluation of such fretted surfaces is critically needed. In this paper straightforward optical techniques are considered for identifying and quantifying fretted (and other surface damaged) regions. For example, digital images of candidate surfaces may be processed to separate fretted from unfretted regions and to evaluate the relative degree of fretting. Ideally, optical characterization should be rapid, convenient, inexpensive, reliable, and insensitive to details of lighting and image capture.
Pulsed Eddy-Current Measurements of Corrosion and Cracking in Aging Aircraft
Authors: Moulder J. C. , Bieber J. A. 
Published: June 2019

ABSTRACTPulsed, or transient eddy-current methods are an effective tool for quantitative characterization of hidden corrosion and cracking in multi-layer aircraft structures. Eddy currents are the method of choice for this task, since they penetrate multiple layers of metal, whether or not the layers are mechanically bonded. The pulsed eddy-current technique is an important advance over conventional eddy-current methods because it rapidly acquires data over a wide range of frequencies, thereby providing more information than a conventional, single-frequency eddy-current instrument. We have combined a pulsed eddy-current instrument with a portable two-axis scanner to produce an instrument capable of rapidly scanning aircraft lap splices in situ, producing pseudo-color images that reveal hidden corrosion or cracking. A unique feature of time-domain eddy-current data is the ability to selectively filter clutter from the image by time-gating the pulsed signal. Time-gating permits the user to select the inspection depth, thereby eliminating interference from upper layers, air gaps, lift-off variation and fasteners. By using a theoretical model of the pulsed eddy-current system, it is possible to interpret the data quantitatively, yielding quantitative maps of corrosion damage. Some of the same advantages of the pulsed eddycurrent technique apply to the characterization of hidden fatigue cracks as well, although the tieory for crack signals is less advanced.
Electromagnetic Acoustic Resonance To Assess Creep Damage In 2.25Cr-lMo Steel
Authors: Hirao M. , Ogi H. , Ohtani T. , Morishita T. 
Published: June 2019

ABSTRACTMethod of electromagnetic acoustic resonance (EMAR) was applied to the noncontact measurement of the shear wave attenuation during the creep test of 2.25Cr-1Mo steels. Two electromagnetic acoustic transducers were manufactured for this purpose, which generate the polarized shear waves through the magnetostriction effect. The attenuation coefficient increased with the creep deformation. The evolution range of the attenuation was beyond 0.1 μs−1 before the failure, which was much larger than the attenuation variation among the samples.
Ultrasonic Quantification Of Corroded Surfaces
Authors: Mullins W. M. , Shamachary S. S. 
Published: June 2019

ABSTRACTThe surface damage introduced by general corrosion attack of surfaces is considered deleterious to long term structural integrity. As a result, the quantification of this damage represents an interest in the NDE community. In this document, the chemical kinetics of general attack are used to model the morphology of the surface as a function of time of exposure. Timeof- flight ultrasonic data for corroded surfaces are presented which appear to agree with the model predictions. The experimental results are critically reviewed with respect to the practical limitations of the ultrasonic experiments. The effect of exposure on surface morphology and surface stress concentration are shown and related to the classic ultrasonic measurement techniques. The relationships are used to suggest potentially important ultrasonic measurement techniques and to underline the inherent limitations of many classical ultrasonic measurements.
Thermal Wave Imaging For Characterizing Structures In Aging Aircraft
Authors: Han Xiaoyan , Favro L. D. , Thomas R. L. 
Published: June 2019

ABSTRACTWe present examples of the application of thermal wave imaging to the detection of structural defects in aging aircraft. Examples include the imaging of bonded and disbonded internal doublers, together with quantitative corrosion thinning measurements made from thermal wave images of aircraft fuselages and wing skins. We also show example images of impact damage, disbonds and delaminations in composite aircraft materials.
The Role Of Grain Noise In Eddy Current Inspection Of Titanium Alloys
Authors: Blodgett M. P. , Nagy P. B. 
Published: June 2019

ABSTRACTThis paper discusses the role electrical anisotropy plays in the structural integrity assessment of polycrystalline titanium alloys from the standpoint of fatigue crack detection and the related issue of microstructural noise. In eddy current inspection of noncubic crystallographic classes of polycrystalline metals the electric anisotropy of individual grains produces an inherent microstructural variation or noise that is very similar to the well-known acoustic noise produced by the elastic anisotropy of both cubic and noncubic materials in ultrasonic characterization. The presented results demonstrate that although the electrical grain noise is detrimental in eddy current nondestructive testing for small flaws, it can be also exploited for characterization of the microstructure in noncubic polycrystalline materials such as titanium alloys in the same way acoustic grain noise is used for ultrasonic characterization of the microstructure in different materials.