bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of Integrated Circuits on the Scanning Electron Microscope
Authors: Imai John J. 
Published: June 2020

The SEM plays an important role in the performance of failure analyses of Integrated Circuits. As the complexity and density of electrical functions increases on the silicon chip, the more it is nescessary to analyze the detailed characteristics of the failed device. The types of failures of interest are those that have marginal or catastrophic performance characteristics and show no obvious visual defects.Three aspects of the SEM capabilities will be discussed.Standard high power magnification operationVoltage Contrast mode of operationEmission X-ray analysis operationVarious physical characteristics of an Integrated Circuit can be viewed on the SEM. These characteristics are difficult to view on a high power optical microscope due to the depth of field limitations. These characteristics include the following.Oxide stepsMetalization profile over oxide stepsWire bond analysisEtched metalization characteristicsThe Voltage Contrast mode of operation allows direct visual observation of electrical activity on the surface of the silicon chip.
A Comparative Study of Induced-Arc and Resistive Welds Employing SEM and X-Ray Emission Studies
Authors: Saffir Arthur J. , Zenobia Donald I. 
Published: June 2020

The purpose of this study was to evaluate the two techniques that are commercially used to bond the components of composite electrical contacts. These materials, usually consisting of a precious metal contacting region bonded to a copper substrate, offer substantial economy compared to similar devices made entirely from precious metals. They also possess unique desirable properties useful in other electronic and biomedical applications. However, these advantages can only be realized if the weld can withstand the severe physical and chemical environment in which it must operate.The resistive welds are created by bringing the components into contact and then providing a current in order to create sufficient heat for welding. Induced-arc welding requires more operations: the components are held apart with a relative potential of 10 to 100 volts; then they come into contact very briefly, 50 to 500 μsec; they are immediately drawn apart, striking an arc; finally, after arcing from 300 to 3000 μsec, they are forced together percussively while the current continues to flow.
The Structure of Co-Cu-Ce Permanent Magnet Alloys
Authors: Leamy H. J. , Green M. L. 
Published: June 2020

Following the discovery by Nesbitt et al that Cu additions to Co5Ce produced an age hardenable permanent magnet of exceptional quality, considerable effort has been devoted to understanding the effect of metallurgical processing on these alloys. Aside from work on the Co-Cu-Sm system, direct observation of the alloy structure responsible for the high coercivity of these alloys has not been reported. Our purpose here is to present a preliminary account of such observations.The alloy employed in this study was directionally solidified Co3.8FeO.5CuO.9Ce. The boule was spark cut perpendicular to the growth axis into 1 mm thick wafers, sealed under vacuum in quartz ampoules, and heat treated. The wafers were prethinned by electropolishing and profiled by jet polishing in H3PO4 saturated with Cr2O3 at 100°C. During jet polishing the samples were sandwiched between gold grids. Final thinning was accomplished by ion milling.
Morphologies of Nonadherent Al2O3 and Matching Substrate Surfaces
Authors: Giggins C. S. , Tien J. K. , Kear B. H. , Pettit F. S. 
Published: June 2020

The performance of most oxidation resistant alloys and coatings is markedly improved if the oxide scale strongly adheres to the substrate surface. Consequently, in order to develop alloys and coatings with improved oxidation resistance, it has become necessary to determine the conditions that lead to spallation of oxides from the surfaces of alloys. In what follows, the morphological features of nonadherent Al2O3, and the substrate surfaces from which the Al2O3 has spalled, are presented and related to oxide spallation.The Al2O3, scales were developed by oxidizing Fe-25Cr-4Al (w/o) and Ni-rich Ni3 (Al,Ta) alloys in air at 1200°C. These scales spalled from their substrates upon cooling as a result of thermally induced stresses. The scales and the alloy substrate surfaces were then examined by scanning and replication electron microscopy.The Al2O3, scales from the Fe-Cr-Al contained filamentary protrusions at the oxide-gas interface, Fig. 1(a). In addition, nodules of oxide have been developed such that cavities were formed between the oxide and the substrate, Fig. 1(a).
Interface Microstructures in Boron-Aluminum Composites
Authors: Hancock J. R. , Shaw G. G. 
Published: June 2020

High-resolution studies of interface microstructures provide unique information on the role of interfaces in the mechanical behavior of boron-aluminum composites; some results related to diffusion kinetics, phase transformations, and bond integrity are presented below. Composite specimens were thinned for transmission electron microscopy by ion-bombardment.The degradation of boron filaments in aluminum alloys is the result of chemical interaction over distances estimated to be < 2000 A (angstroms). Figure 1a shows a representative interface microstructure in a boron-6061 aluminum composite which was degraded during diffusion bonding at 500°C, 1 hr, 4000 psi. Aluminum boride(s) formed at intermittent sites at interfaces and reduced the ultimate tensile strength to only ≲ 60% of predicted values. A comparable interface is shown in Figure lb in a composite which was fabricated at 475°C; interface reaction products did not form and mechanical properties indicated that no degradation occurred.
The Effect of Inelastic Scattering on Aperture Contrast, Phase Contrast, and Electron Diffraction of Biological Objects
Authors: Turner J. N. 
Published: June 2020

It has become increasingly obvious to all biological electron microscopists that staining and shadowing techniques must be eliminated, and the rapidly advancing technology of water trapping devices demands it. If we are to view biological systems at the molecular level or in a condition approaching the physiological state, contrast must be enhanced by electron optical means, not by specimen alteration.Therefore, we have investigated Zernike type phase contrast, the principle of which is shown in Fig.1. Our phase plates consist of a carbon film carried on a 30μ objective aperture and are centrally drilled with a laser microscope made available by the American Optical Co. Because our phase plates incorporate a 30μ aperture the results are expressed as a ratio of phase contrast to 30μ aperture contrast. Fig.3 shows the early results of Dr. H. M. Johnson, previously of this laboratory.
Closed Circuit TV Microscopy
Authors: Marsh Peter A. , Price L. Dale , Mullens Troy J. 
Published: June 2020

We recently installed a fiber optics TV display system made by N. V. Philips Gloeilampenfabrieken, Eindhoven, Holland, on our EM-300. The TV chain consists of a highly efficient transmission fluorescent screen deposited onto a fiber optics disc. In direct contact with this disc is a fiber optics window on a special Plumblcon tube in the TV camera. The camera signal is viewed on a 12-inch monitor having an EIA scanning system, 525 lines/sec, 30 frames/sec, 2:1 interlace. Horizontal resolution is 135 lines with a band width of 5 MHz.The camera and fiber optic adaption piece is fitted at the bottom of the microscope column in place of the 70 mm camera. Normal use of the 35 mm and plate cameras remains possible. If desired, the TV system and the 70 mm camera can be interchanged in less than 30 minutes. Cables connect the camera to a control unit and control box.
Hydrogen-Assisted Cracking by Microscopic Plasticity Mechanisms
Authors: Beachera C. D. 
Published: June 2020

The recently proposed model for hydrogen-assisted cracking (hydrogen “embrittlement”) which states that such cracking in steels occurs by hydrogen diffusing into the metal ahead of the crack and lowering the local resistance to plastic flow has been further substantiated in other steels.The term hydrogen “embrittlement” was coined long before electron fractography, and it is based on the observation that many steels that normally show considerable ductility when tested in the absence of hydrogen, frequently lose this macroscopic ductility when the steels contain hydrogen and are maintained under a high stress. Electron fractography has shown that, while this macroscopic plasticity is minimized, it still persists on the microscopic scale. This plasticity may be seen in Figs. 1 and 2, for two different steels. Figure 1 is from the fracture surface of a 13Cr-8Ni-Mo steel and Fig. 2 is from a 250 ksi yield strength grade of maraging steel.
The Atom Probe and Its Application to Steels
Authors: Brenner S. S. , Miller M. K. 
Published: June 2020

Solute atoms, even in minute quantities, often markedly influence the processing and properties of solids. To understand these effects requires the analysis of highly localized regions. Many techniques have been developed to make such measurements. Among these is the atom probe (AP) which is unique in its atomic-dimensioned spatial resolution and its mass-independent sensitivity.The AP consists of a field-ion microscope (FIM) and a time-of-flight mass spectrometer, Fig. 1. The needle-shaped specimen is mounted on a cryogenically-cooled goniometer stage facing a CEMA and phosphor screen. A central hole in the imaging assembly serves as the entrance aperture to the spectrometer flight tube which is typically 1-2 mm in length. The only focusing lens is an Einzel lens which converges the trajectories of the ions entering the drift tube. Ancillary equipment includes power supplies to provide the specimen with short (20 ns) high voltage pulses superimposed on a DC potential of up to 30 kV.
Cryoprotection of Electron-Irradiated Organic Crystals
Authors: Müller K.-H. , Zemlin F. , Zeitler E. 
Published: June 2020

There is an urgent interest in analyzing the structure of biomolecules by EM imaging. In order to reduce the quantum noise under the level of the inherent contrast C of the structure imaged, a minimum dose Dm=4/C2r2is required when a structure detail of size r is to be detected. (The factor 4 is just the square of the signal-to-noise ratio, justified by experiments.) Setting r to about .4 nm and C to about 10% the required minimum dose amounts to 2000 e/nm2. Unfortunately at room temperature this minimum dose destroys most biomolecules. One way out of this dilemma seems to be cooling the specimen to He temperature.Experiments in an improved superconducting electron microscope (Siemens system 2) have been performed with the aim of confirming and/or refuting measurements by others in this very well defined experimental situation. The fading of diffraction patterns was used to characterize the radiation damage (Fig. 1), yet the implication for the image formation was introduced by the size of the pixel.
Defect Structure and Composition of Fe1-xO
Authors: Lebreton C. , Hobbs L. W. 
Published: June 2020

Wüstite, Fe1-xO, is the principal oxide scale formed on iron above 843 K. Wüstite exhibits a broad range of non-stoichiometry (0.05 < x < 0.15), and even in equilibrium with iron maintains a minimum 5% iron deficiency. Its large departures from stoichiometry are accommodated by octahedral iron vacancies which associate into tetrahedral complexes about ferric ion interstitials. Despite a great many studies, further details of the defect structure have been slow in coming. We report here additional defect microstructure information for wüstite in equilibrium conditions and after annealing below the 843 K eutectoid, as revealed by electron diffraction, high-resolution dark-field and lattice-imaging techniques.Single crystals, prepared by a floating-zone method, were equilibrated within the wüstite phase field in CO/CO2 atmospheres providing controlled oxygen fugacity. Samples were oil-quenched so that they reached room temperature within a few seconds and are therefore expected to have retained the initial equilibrium structure.
High Resolution Imaging of Semiconductor Interfaces
Authors: Sinclair R. , Ponce F. A. , Yamashita T. , Bravman J. C. 
Published: June 2020

One of the most important commercial areas in contemporary materials science concerns the miniaturization of integrated circuits. As the size of such devices decreases, their operation becomes more critically influenced by the presence of defects and by the nature of the interfaces involved. High resolution TEM can play an important role in determining fundamental aspects of the structure of these materials. The present article describes some of our recent work on this problem.The first important step in this business is the fabrication of good specimens. It is necessary to arrange for the interface or defect in question to be parallel to the electron beam for obtaining the maximum degree of structural information. This requires making “cross-section” TEM specimens which is achieved by the following procedure. Firstly, several circuits are sandwiched together using an appropriately strong glue (e.g., “Micromeasurements 610”). They are then sliced into thin slabs (approximately 1 mm thick) using a diamond saw, cut into 3 mm diameter discs, mechanically polished to reduce the thickness and finally ion-beam milled to electron transparency. The composite is generally fragile and so careful handling is required in each of these stages. The yield of high quality specimens for high resolution work is often low and perfection of the experimental approach is necessary before it becomes routine.
The Morphology and Crystallography of Diesel Particulate Emissions
Authors: Stevenson R. 
Published: June 2020

A study has been made of the morphology and crystallography of particulate emissions from indirect injection diesel engines. This particulate matter consists substantially of carbon (although hydrocarbons can be extracted with solvents). Samples were collected in a diluted exhaust stream on amorphous carbon films and examined in a JEM-200C electron microscope operated in the TEM mode with an accelerating voltage of 200 KV.The morphology of the diesel particles, as shown in Fig. 1, markedly resembles carbon blacks and consists of an agglomeration of quasispherical subunits arranged in chains or clusters. Only limited changes in morphology were observed as the number of subunits in the particle increased (although larger particles tended to be more cluster-like than the extended chain shown in Fig. 1). However, a dramatic effect of the number of subunits was observed on the character of the diffraction pattern. Smaller particles yielded a diffraction pattern consisting of very diffuse rings typical of turbostratic carbon; the diffraction patterns from the larger particles, however, although qualitatively similar, exhibited much sharper and less diffuse ring patterns.
Preliminary Characterization of Pacific Ocean Manganese Nodules
Authors: Huggins C. W. , Haynes B. W. , Virta R. L. 
Published: June 2020

For the past year the Bureau of Mines, Avondale Research Center, has been doing extensive characterization on Pacific Ocean nodules from the Clarion-Clipperton fracture zone, which extends from off the coast of Mexico and Central America in a general east-west direction toward the Hawaiian Islands. These nodules are a potentially valuable new source of Ni, Co, Cu, and Mn. All of these metals are essential to the U.S. economy. Three million tons of nodules would produce about 75 percent of the domestic need for Mn, 10.0 percent for Ni, 1.2 percent for Cu, and 45 percent for Co.Manganese nodules (figure 1) are basically concretions of hydrous manganese oxides and appear to have a simple concentric layer growth structure forming around a nucleus. The growth rate ranges from 1 to 10 mm per million years depending on surrounding conditions. After deposition, only minor changes occur in a layer. These changes include replacement of some Mn by other metals such as Co, Ni and Cu in the water circulating through pores in the nodule. Some of the minerals deposited initially have partial replacement by oxides.
Direct Electron Beam Fabrication of a Photo-Conductor
Authors: Joy David C. , Schmidt Paul H. , Kaplan M. L. 
Published: June 2020

Electron beam irradiation of organic molecular crystals almost invariably leads to a rapid loss of crystallinity, followed by gross mass loss at higher doses. One interesting exception to this sequence of events was described, by Jones, Thomas and Williams who showed that the irradiation of p-terphenyl, at temperatures below 130°K, converted the stable triclinic phase to the characteristic room temperature monoclinic structure. For doses above 0.16 coulomb.cm-2 this transformation was permanent and could not be reversed by thermal cycling. We report here another electron-beam induced transformation, the end product of which has technologically useful properties.3,4,9,10-Perylenetetracarboxylic di-anhydride, C24H8O6 (PTCDA), the structure of which is shown in figure 1, when vapor deposited to a thickness of a few thousand angstroms forms a red transparent organic film. In this form it is stable to relatively high temperatures (300°C) does not appear to degrade after several months of room temperature storage and is electrically insulating.
A Practical Method for Removing Plural Scattering from Core Edges in EELS
Authors: Leapman R.D. , Swyt C.R. 
Published: June 2020

Core edges in electron energy loss spectra are generally complicated by thickness effects involving plural inelastic scattering. The fine structure can be modified and errors can be caused in quantitation based on measured edge intensities. Sometimes plural scattering can confuse even identification of elements. In this paper we describe a practical method for eliminating these difficulties.We derive the single scattering distribution, assuming valence electron excitation is small in the core loss region, a reasonable approximation for edges above 100 or 200 eV and for thicknesses of a few hundred Å. We can then separate the spectrum into a “high loss” region H(E) consisting of core edges (less background) and a “low loss” region L(E) containing the zero loss peak, plasmons and one-electron excitations.
Imaging and Analysis of Surfaces Using Diffracted Electrons
Authors: Cowley J. M. 
Published: June 2020

Electrons diffracted from the surfaces of crystals have recently been used very effectively for the imaging of the structure of the surfaces in both TEM and STEM instruments. With an ultra-high vacuum TEM instrument the group at Tokyo Institute of Technology have demonstrated the value of the technique for imaging monatomic surface steps, dislocations and surface superlattices on silicon. With a STEM instrument it is possible to combine imaging with a lateral resolution of 10A or better, and microdiffraction and microanalysis of small areas of the surface. In this paper we report further STEM observations illustrating some characteristics of these modes of surface study.Figure 1 shows two views, with different magnification, of the surface of a bulk MgO crystal, having dimensions 0.5 to 1mm, formed by cleaving a larger crystal. In order to mount such crystals with a minimum of handling and without adhesives which might introduce impurities they were enclosed in precleaned folding grids for mounting in the high resolution goniometer cartridge. The images were obtained using the (600) reflection with the beam close to the [010] direction.
Experiments in Bright-Field Imaging with Hollow-Cone Illumination
Authors: Kunath W. , Weiss K. , Zeitler E. 
Published: June 2020

Bright-field images taken with axial illumination show spurious high contrast patterns which obscure details smaller than 15 ° Hollow-cone illumination (HCI), however, reduces this disturbing granulation by statistical superposition and thus improves the signal-to-noise ratio. In this presentation we report on experiments aimed at selecting the proper amount of tilt and defocus for improvement of the signal-to-noise ratio by means of direct observation of the electron images on a TV monitor.Hollow-cone illumination is implemented in our microscope (single field condenser objective, Cs = .5 mm) by an electronic system which rotates the tilted beam about the optic axis. At low rates of revolution (one turn per second or so) a circular motion of the usual granulation in the image of a carbon support film can be observed on the TV monitor. The size of the granular structures and the radius of their orbits depend on both the conical tilt and defocus.
The Selection of Beams for Multi-Beam Dynamical Theory Calculations Used for Weak-Beam Dark Field Image Interpretation
Authors: Avalos-Borja M. 
Published: June 2020

The use of computers as aid for TEM image interpretation has increased considerably during the recent years. In particular, the interpretation of weak-beam dark field (WBDF) equal thickness fringes for the determination of the habit of nanometer-size crystallites has been emphasized to be dependent on the concomitant ability of image intensity calculations using the many- beam dynamical theory (DT). On the other hand, some researchers have been using simple 2-beam kinemathical theory (KT) calculations for similar image interpretations. No attempt has been reported to quantify the necessity and the limitations of either approach. We are now reporting first results of comparative DT and KT calculations, emphasizing the definition of the number and selection criterion of the beams that should be included in DT calculations which are intended to be superior in accuracy to KT calculations.We modified a program developed by Yacamán, following the n-beam dynamical theory principles, to accept up to 100 beams at various selection criteria, and studied the influence of the number and selection criterion of the beams included in the calculation on the extinction distance and its dependence on the crystal thickness.
Grain Boundary Segregation of Bismuth in Copper
Authors: Michael J. R. , Williams D. B. 
Published: June 2020

Bismuth is known to segregate to grain boundaries in copper resulting in embrittlement and intergranular failure at low stress levels. This segregation has been studied primarily by Auger Electron Spectroscopy (AES). The applicability of scanning transmission electron microscopy (STEM)and Energy Dispersive Spectroscopy (EDS) to the study of equilibrium grain boundary segregation has already been demonstrated and the aim of this study is to determine the degree of segregation as a function of time and temperature. The major advantage of STEM over AES is that STEM does not require fracturing of the specimen, so the boundaries to be studied are left undisturbed. Thus, this technique is also applicable to systems which do not exhibit intergranular fracture.Cu-Bi specimens were prepared by evaporating Bi onto both sides of 3mm Cu discs, which were then heated for 1 week at 400°C to allow the Bi to diffuse into the Cu. The samples were then aged at 450, 550, 600, 650, and 700°C for 3 days and 12 days, ion-thinned and then examined in a Philips EM 400T TEM/STEM with an EDAX detector and EDAX 9100 analyzer. If necessary, the specimens were tilted such that the boundaries were parallel to the electron beam.