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The angular resolution of electron backscatter diffraction (EBSD) measurements can be significantly improved using an analysis based on determination of small shifts in features from one pattern to the next using cross-correlation functions. Using pattern shift measurements at many regions of the pattern, errors in the best fit strain and rotation tensors can be reduced. The authors show that elements of the strain tensor and small misorientations can be measured to ±10 -4 and ±0.006° for rotations. We apply the technique to two quite different materials systems. First, we determine the elastic strain distribution near the interface in a cross-sectioned SiGe epilayer, Si substrate semiconductor heterostructure. The plane stress boundary conditions at the sample surface are used to separate every term in the strain tensor. Second, the applicability to structural materials is illustrated by determining the lattice curvature caused by dislocations within the plastic zone associated with the wake and tip of a fatigue crack in a Ni based superalloy. The lattice curvatures are used to calculate the geometrically necessary dislocation content in the plastic zone. © 2006 Institute of Materials, Minerals and Mining.

The diffuseness of electron back scatter patterns (EBSPs) is observed to increase with plastic strain. The application of this technique to deformation studies has been limited by the lack of a general method of measuring the pattern quality. The degradation of EBSPs by cold work was thus thoroughly investigated using the A1 6061 alloy for the purpose. Methods of enhancing the Kikuchi band contrast by removal of the background intensity variation from digital images of 〈112〉 zone axes present in the EBSP have been developed. The contrast of the Kikuchi bands was quantified using the root mean square intensity of averaged band profiles, while the sharpness of the patterns was assessed by the attenuation of high frequency components of Fourier transforms of the enhanced images and of the averaged band profiles. Tilt was found to effect contrast but not sharpness, while cold work reduced both. However, surface contamination produced effects that were very similar to those of specimen deformation. A method is presented for quantitative determination of EBSP quality, which is independent of grain orientation and is based on the first moment of power spectra (the square of the Fourier transform) of features common to all patters to be compared.

Distributions of equivalent plastic strains in an A16061/SiC fibre composite measured using the electron back scatter pattern (EBSP) technique were compared to plastic strain and stress distributions calculated using a continuum mechanics model solved by finite element analysis (FEA). Close to the interface EBSP measurements indicated higher dislocation densities than expected for strains calculated in such a region using the FEA model, the excess dislocations presumably being necessary to preserve the continuity of the interface. EBSP measurements also indicated considerable dislocation density in matrix regions where the FEA model calculated small plastic strains due to the production of a nearly hydrostatic tensile stress state. Inhomogeneities in the microstructure of the real matrix material can generate local shear stresses and so lead to production of dislocations even though the far field stress state has no shear component. Thus the dislocation density was controlled by the magnitude of the hydrostatic tension rather than the deviatoric stress components.

Electron backscatter diffraction (EBSD) is a scanning electron microscope-based technique principally used for the determination and mapping of crystal orientation. This work describes an adaptation of the EBSD technique into a potential tool for crystal phase determination. The process can be distilled into three steps: (1) extracting a triclinic cell from a single EBSD pattern, (2) identifying the crystal symmetry from an examination of the triclinic cell, and (3) determining the lattice parameters. The triclinic cell is determined by finding the bands passing through two zone axes in the pattern including a band connecting the two. A three-dimensional triclinic unit cell is constructed based on the identified bands. The EBSD pattern is indexed in terms of the triclinic cell thus formed and the crystal orientation calculated. The pattern indexing results in independent multiple orientations due to the symmetry the crystal actually possesses. By examining the relationships between these multiple orientations, the crystal system is established. By comparing simulated Kikuchi bands with the pattern the lattice parameters can be determined. Details of the method are given for a test case of EBSD patterns obtained from the hexagonal phase of titanium.

The resolution limit of Orientation Imaging Microscopy in the Scanning Electron Microscope is between 20 nA and 80 nA depending on the basic resolution/beam current performance of the SEM, the sample atomic number and the level of residual strain within it. The newer technique of orientation imaging in the transmission electron microscope, TEM, improves on this resolution limit by a factor of five to ten. The new technique is based on a novel procedure for determining the crystallography of separate small volumes in the sample by examination of a large series of dark field images. Each image is recorded for a different diffraction condition. This is achieved by using a computer to direct the electron beam onto the same area of the sample so that it covers all directions within a cone of semi-apex angle 3 degrees. Analysis of the intensity of the same point in each of the dark field images permits reconstruction of a diffraction pattern for that point providing the data to calculate its crystal orientation. The process is repeated for each point in the image. The Orientation Image Micrograph is constructed from the orientations so determined. The technique is shown to be capable of producing orientation micrographs of high spatial resolution for unstrained samples. For highly strained samples difficulties are encountered in accurately indexing the complicated diffraction patterns that are observed. Methods to improve the indexing procedures involve determining the sub-cell structure first from a comparison of patterns from adjacent pixels and then summing all patterns belonging to a single sub-cell. The resultant improvement in pattern quality permits more reliable determination of orientation. Examples of this procedure are taken from studies of deformed aluminum.

This paper describes progress in improving the spatial resolution of the well-established Orientation Imaging Microscopy technique, OIM, by developing an analogous procedure for the transmission electron microscope. The transmission orientation micrographs are obtained by recording a large series of dark field micrographs taken from the chosen area in the specimen. This area is selected so that it contains all of the grains of interest and is imaged at sufficiently high magnification to yield the spatial resolution required. The changing intensity of each pixel in different dark field micrographs permits the equivalent of a diffraction pattern for that pixel to be constructed. This enables determination of the lattice orientation of small volumes in the sample corresponding to that imaged in each individual pixel. Experimentation has shown that problems arise however, that decrease the fraction of correctly measured points due to ambiguities in determining the index of higher order reflections, especially when the total number of reflections observed is small. The solution has been to both modify the indexing procedure and to sum the diffraction vectors observed within a single grain. The paper concentrates on a detailed analysis of a heavily deformed aluminium sample, chosen because of the fragmentation of the structure.

High-temperature oxidation of steel has been extensively studied. The microstructure of iron oxides is, however, not well understood because of the difficulty in imaging it using conventional methods, such as optical or electron microscopy. A knowledge of the oxide microstructure and texture is critical in understanding how the oxide film behaves during high-temperature deformation of steels and more importantly how it can be removed following processing. Recently, electron back-scatter diffraction (EBSD) has proved to be a powerful technique for distinguishing the different phases in scales. This technique gives valuable information both on the microstructure and on the orientation relationships between the steel and the scale layers. In the current study EBSD has been used to investigate the microstructure and microtexture of iron oxide layers grown on interstitial free steel at different times and temperatures. Heat treatments have been carried out under normal oxidation conditions in order to relate the results to real steel manufacturing in industry. The composition, morphologies, microstructure and microtexture of selected conditions have been studied using EBSD.

Ten years ago electron backscatter diffraction (EBSD) became available to a wider group active in materials research. This paper highlights some of the more significant developments in camera technology and software developments that have arisen since then. The use of slow-scan charge couple device cameras for phase identification and rapid determination of orientation image micrographs is reviewed. The current limiting spatial resolution of the technique is shown to be less than 10 nm. A procedure for improving lattice spacing measurement by utilizing the full resolution of the camera is described with experimental measurements on silicon and nickel showing relative errors of plus/minus 3%. An investigation of partially recrystallized aluminium shows how the recrystallized fraction can be extracted with confidence but that the mapping of substructure in the highly deformed regions is questionable. Phase identification is described for complex cases in which the phase data tabulated in standard databases do not correspond to what is observed in the EBSD patterns. Phase mapping in a complex mineral in which chemical data and EBSD data are collected simultaneously is shown to be improved by recording both the chemical and the EBSD data into computer memory and proceeding with the phase discrimination and orientation measurement in off-line analysis.

Orientation Imaging Microscopy is currently the most rapidly growing combined metallographic and crystallographic technique today. The first OIM was recorded by Wright in 1991, and published soon after, Adams et al. (1993). The technique is based on the original works on Electron Backscatter Diffraction (EBSD) by Venables and Hariand (1973), and Dingiey (1984, 1987). By 1994 some number of papers on the subject had been published. At the time of writing the authors are aware of over 600 publications that have utilized the technique and there are in excess of 400 systems in use worldwide.

Orientation Imaging Microscopy (OIM) is a rapid and spatially specific technique for automatically measuring individual crystallographic orientations in a polycrystalline sample. The technique is based on electron backscatter diffraction in the scanning electron microscope (SEM). While the OIM technique has seen many applications to the investigation of structure/ property relationships in polycrystalline materials, with grain sizes ranging from millimeters to submicron, it is not easily applied to the characterization of microstructures at the nanometer scale due to the inherent resolution limitations of the SEM. Thus, a complementary technique for the transmission electron microscope (TEM) would be advantageous for the study of local orientation in submicron structures such as those that exist in nanocrystalline materials and deformed materials.

Orientation Imaging Microscopy (OIM) in the scanning electron microscope (SEM) has proven itself to be a powerful tool for investigating local orientation relationships in polycrystalline microstructures. Because of the inherent limitations of electron backscatter diffraction in the SEM, the OIM technique is limited to the investigation of structures at the micron scale. A parallel technique for the transmission electron microscope (TEM) would enable similar studies of local orientation relationships in smaller scale structures to be performed. This report reviews development work on adapting the OIM technique to the TEM using dark field imaging and presents some preliminary results.

The advance in Electron Backscatter Diffraction known as High Resolution EBSD has permitted the strain tensor components and neighbour disorientation measurements to be mapped at resolutions better than 2 parts in 10000. Following earlier research into this technique which was focused on verifying the sensitivity and accuracy of the measurements, recent studies have involved investigations on semiconductor and metallic polycrystalline materials. In particular observations of localized regions where residual strains exceeded the macroscopic yield stress have been thoroughly investigated to eliminate experimental error as a possible explanation. No such cause was found. Strain measurements on polycrystalline steels in uniaxial tension and during thermal stress relieving thermal treatment have also been carried out. Maps of the strain distribution during elastic loading and early stages of plastic flow showed hot spots of high strain as in the static tests but overall the measured elastic strain was equal to the applied strain.

The role of crystallographic texture in electromigration resistance of interconnect lines is well documented. The presence of a strong (111) fiber texture results in a more reliable interconnect structure. It is also generally accepted that grain-boundary diffusion is the primary mechanism by which electromigration failures occur. It has been difficult to this point, however, to obtain statistically reliable information of grain-boundary structure in these materials as transmission electron microscopy investigations are limited by tedious specimen preparation and small, nonrepresentative, imaging regions. The present work focuses upon characterization of texture and grain-boundary structure of interconnect lines using orientation imaging microscopy, and particularly, upon the linewidth dependence of these measures. Conventionally processed Al–1%Cu lines were investigated to determine the affects of a postpatterning anneal on boundary structure as a function of linewidth. It was observed that texture tende...

We have developed a system using ‘forescatter detectors’ for backscattered imaging of specimen surfaces inclined at 50–80° to the incident beam (inclined-scanning) in the SEM. These detectors comprise semiconductor chips placed below the tilted specimen. Forescatter detectors provide an orientation contrast (OC) image to complement quantitative crystallographic data from electron backscatter patterns (EBSP). Specimens were imaged using two detector geometries and these images were compared to those collected with the specimen surface normal to the incident beam (normal-scanning) using conventional backscattered electron detector geometries and also to an automated technique, orientation imaging microscopy (OIM). When normal-scanning, the component of the BSE signal relating to the mean atomic number (z) of the material is an order of magnitude greater than any OC component, making OC imaging in polyphase specimens almost impossible. Images formed in inclined-scanning, using forescatter detectors, have OC and z-contrast signals of similar magnitude, allowing OC imaging in polyphase specimens.OC imaging is purely qualitative, and by repeatedly imaging the same area using different specimen-beam geometries, we found that a single image picks out less than 60% of the total microstructural information and as many as 6 combined images are required to give the full data set. The OIM technique is limited by the EBSP resolution (1–2°) and subsequently misses a lot of microstructural information. The use of forescatter detectors is the most practical means of imaging OC in tilted specimens, but it is also a powerful tool in its own right for imaging microstructures in polyphase specimens, an essential asset for geological work.

A new microscopy, called Orientation Imaging Microscopy, is described. Imaging results from precise measurements of local lattice orientation rapidly obtained by Backscattered Kikuchi Diffraction. The hardware configuration of the microscope is described and a description of image formation presented. Applications to several materials of differing lattice structure are described. Connections of the microscopy with various aspects of modern texture analysis are emphasized.

The established electron backscatter diffraction (EBSD) technique for obtaining crystallographic information in the SEM has been adapted to permit elastic strain measurement. Basically, the displacement of crystallographic features in an EBSD pattern, such as zone axes, which result from strain in a crystal, is determined by comparing those same features as they appear in a pattern from an unstrained region of the crystal. The comparison is made by cross-correlation of selected regions in the two patterns. Tests show that the sensitivity to displacement measurement is 1 part in 10 000, which translates to a strain sensitivity of 2 parts in 10 000. Eight components of the strain tensor are determined directly and the ninth is calculated using the fact that the free surface of the sample is traction-free. Examples discussed are taken from studies of a lenticular fracture in germanium, the strain distribution surrounding a carbide precipitate in a nickel base alloy and grain boundary studies in another nickel base alloy.

International audience; High resolution EBSD directly compares electron backscattering patterns (EBSPs), generated in a scanning electron microscope, to measure relative strain and rotation to a precision of ∼10−4 in strain and 10−4 rad (0.006°) in rotation. However the measurement of absolute strain and rotation requires reference EBSPs of known strain and orientation (or a far field region of known strain). Recent suggestions of using simulated EBSPs with known strain show much promise. However precise measurement of the experimental geometry (pattern centre) is required. Common uncertainties of 0.5% in pattern centre result in uncertainty of ∼10−3 in strain state. Aberrations in the compact lenses used for EBSP capture can also result in image shifts that correspond to strains/rotations of ±10−3 between experimental and simulated EBSPs. Simulated EBSPs can be generated using dynamical or kinematic models (or a combination of the two). The choice in simulation model has a significant effect on the measured shifts, particularly at zone axis and high structure factor bands, due to large intensity variations, and for simple kinematic simulations can result in the measurement of rogue shifts and thus erroneous strain measurements. Calibrant samples of known strain provide a method of measuring the experimental geometry but imprecise stage movement combined with the high depth of field in the SEM could also result in uncertainties in strain of ∼10−3.

In this chapter we review the progress that has been made toward elastic strain (i.e., stress) mapping using electron backscatter diffraction. In particular we focus on development of an analysis method based on using cross-correlation to determine small shifts in the EBSD patterns with respect to a reference pattern. The pattern shifts are determined at many subregions dispersed across the wide angular span of the EBSD pattern, and the magnitude and angular distribution of shifts allows the strain and rotation tensor to be determined. Pattern shifts at a resolution of ±0.05 pixels, or in some cases even better, have been reported, which corresponds to a sensitivity of ∼±10-4 in the components of the strain and rotation tensor. © Springer Science+Business Media, LLC 2009. All rights reserved.

In this paper, we describe the use of electron back scatter diffraction (EBSD) to study strain variations in crystalline samples at the nanoscale. The analysis relies on cross correlation measurements of small shifts in the EBSD pattern measured at many points dispersed across the pattern. The method allows the full strain tensor, and lattice rotations to be obtained at a sensitivity of ∼10 -4. The method is applied to study variations of strains and rotations near the surface of 200 nm thick epitaxial layers of Si 0.85Ge 0.15 grown on a Si substrate patterned with rectangular and square mesa. Linescans across rectangular mesas show that strain relaxation and accompanying lattice rotations are restricted to the edges of wide mesas but that the relaxation extends across the entirety of mesas narrower than ∼6 μm. Two dimensional maps of the strain variation in a ∼3 μm wide square mesa are also presented. © 2008 Elsevier Ltd. All rights reserved.

Ni n /Fe n multilayers have been grown, in Ultra High Vacuum (UHV) conditions, on 150 nm Cu(111) single crystals grown, in-situ, on mica(0001) substrates. Modulation wavelength ranged from 2 n = 30 monolayers (ML) to 2 n = 6 ML. X-ray diffractometry of samples showed satellite peaks corresponding to a range of modulations implying that the layering was incommensurate. Cross-sectional Transmission Electron Microscopy (TEM) confirmed layering persisted even at modulations of n = 3 ML. Plan view TEM electron diffraction showed a transition from fcc(111)/fcc(111) to fcc(111)/bcc(110) layering as n increased. The transition was not sharp but progressive with a midpoint at about n = 10 ML. Room temperature measurements of saturated magnetic moment per volume, using a vibrating sample magnetometer, varied with modulation layer thickness. The moment per volume for the fcc material with a [111] plane spacing of 0.2059 nm (equivalent to a lattice parameter of 0.357 nm) was a factor of three less than for an homogeneous NiFe alloy. It is noted that this lattice parameter coincides with the range predicted by theorists for a change in fcc Fe-Fe magnetic coupling.

Various factors affecting the matrix properties of metal-matrix composites have been investigated by a series of experiments on the unreinforced matrix material. The effect of the rate of cooling from the fabrication temperature to room temperature is studied by comparing the stress-strain behaviour of quenched and air-cooled specimens. During cooling, fibres constrain the contraction of the matrix owing to the difference in thermal-expansion coefficients of the two materials. The effect of this constrains was simulated by clamping aluminum specimens to a steel plate during heat treatment. It was found that the main effect of the constraint was to produce strain-hardening and a much sharper yield point. The strain-hardened stress-strain curve can be predicted in terms of the material's room-temperature stress-strain curve if the temperature change and the coefficients of thermal expansion of the fibre and matrix are known. Subsequent ageing of the matrix was also examined. The presence of rseidual stress does not affect the amount of age-hardening. However, the effect of prior plastic deformation reduces the amount of precipitation-hardening. Creep of the matrix during cooling appears to be negligible, but some relaxation of residual stress in the matrix material may subsequently occur at room temperature.

A new method of predicting secondary recrystallization has been developed and tested against data obtained from X-ray pole figures of Fe-3% Si alloy. The X-ray data from primary recrystallized material is analysed using the “vector method” to yield relative intensities of grain orientations. They are classified into one of 1296 orientations. Frequencies, IC, of coincidence orientation relationships between the grain orientations so formed and selected (hypothetical) secondary recrystallization nuclei in the matrix are calculated and the product, PCN, of intensity of selected nuclei actually present and IC are made. It is shown that a critical value of PCN needs to be exceeded for secondary recrystallization to occur.

Electron backscatter diffraction is shown to have a spatial resolution between 5 nm and 10 nm and is well suited for the investigation of nano crystalline materials. A study of texture and mesotexture in copper Damascene interconnect lines is used as an illustration. Samples were prepared by electro deposition from baths of different compositions and under various power cycles. The resulting grain structures were visually smaller than the 0.3 micron interconnect line width. However, if twin boundaries were considered as substructure rather than true grain boundaries, the effective grain size become larger than the line width. The bath composition affected the 111 texture component from times 5 random to 26 times random whereas different power cycles affected the texture much less. For structures with a grain size smaller than 20 nm a new transmission electron microscope technique has been developed. Automated examination of a sequence of dark field images collected from a selected area lead to the reconstruction of a diffraction pattern for each pixel within the area. These patterns are indexed automatically, permitting crystal orientation as a function of spatial positioning to be mapped. The resulting orientation information is equivalent to that obtained using electron backscatter patterns. The practical resolution limit of this technique approaches 1 to 2 nanometers.

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

This introductory chapter traces the development of the automated detection and indexing of electron diffraction patterns in both the scanning and transmission electron microscopes. Though electron backscatter diffraction (EBSD) is the best known of these, the procedures have been extended recently to the transmission electron microscope and a review would not be complete without including this new work.

Venables (1973) coined the term electron backscatter diffraction (EBSD) to describe backscatter Kikuchi diffraction in the scanning electron microscope (SEM). The first commercial system was produced by Moon and Harris of Custom Camera Designs in 1984 and was an outgrowth of the system designed by Dingley at the University of Bristol. This design was later provided to both Oxford Instruments and Ris0 National Laboratory out of which the OPAL™ and HKL™ systems evolved. The first fully automated EBSD system capable of automatic indexing of EBSD patterns and subsequent mapping of the spatial distribution of crystallographic orientation was introduced by Wright (1992). The term Orientation Imaging Microscopy or OIM™ was coined to describe this automated technique for forming images by mapping orientation data obtained from automated EBSD (Adams et al., 1993). Dingley and Adams co-founded TSL (or TexSEM Laboratories) in 1994 to produce the first commercial automated EBSD system based on the system developed by the group at Yale University (Adams, Wright, and Kunze). TSL adopted the name OIM™ for its automated EBSD products. Much of what was included in the original TSL system has become a standard for modern EBSD systems.

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2006

SUMMARY High dislocation densities in the matrices of metal-matrix composites (MMCs) contribute to the strengthening of particulate MMCs, whilst heterogeneous nucleation of precipitates at these defects can cause marked differences in the age hardening of many matrix alloys. Electron back-scatter patterns (EBSPs) and transmission electron microscopy (TEM) have been used to examine the dislocation distribution in continuous-fibre SiC/Al alloy MMCs. TEM observations showed dislocation densities as high as 3 times 1014m−2, with a marked increase as thinner matrix regions were observed. From EBSP measurements on bulk specimens, a much lower dislocation density of 2 times 1012 m−2 was estimated. To resolve this discrepancy, EBSP measurements were made from thinned TEM specimens and these showed that the dislocation density had increased during specimen thinning. However, both TEM and EBSP measurements from unreinforced matrix material prepared for TEM using the same procedures showed no such increase in dislocation density. Redistribution of internal stresses during thinning of the composite to a transparent foil must therefore be the cause of the observed rise in dislocation density. The EBSP technique was demonstrated to be an excellent means of examining the distribution of plastic deformation in MMCs. It was concluded that TEM measurements of dislocation densities in continuous-fibre MMCs can be erroneously high.

Current trends seek to make TEM operation more routine and productive. One of these follows the lead made in scanning electron microscopy in which the spatial distribution of crystallographic data over a selected area of a sample surface is determined by automated recognition of Backscatter Kikuchi patterns (EBSD), Adams et al . This method has been extended to the TEM in a novel manner, Wright et al . Dark field images are collected sequentially from the area of interest for all possible incident beam directions over a solid cone of semi-apex angle up to 4 degrees, Figure 1. The images are recorded directly into a computer. Off line automated analysis follows in which all dark field images are searched to determine the beam conditions under which each pixel in the image brightens, i.e. when the corresponding point in the sample came into a diffraction condition. The measurement of three such non-coplanar conditions for a pixel leads to the determination of the corresponding crystallographic orientation. The accuracy of orientation measurement has been improved to 1 degree by the fitting of the determined diffraction vectors to the surface of the Ewald sphere. The analysis allows grain maps to be reconstructed from which grain size distribution can be automatically determined. Figure 2.

X-ray diffractometry at grazing incidence has been performed upon Nin/Fen multilayers with 610mpl. Each X-ray scan revealed a series of peaks which corresponded to integer monolayer differences in modulation periodicity. In contrast, interfacial alloying would have produced a broad single peak.M-H loops were performed on the samples for the range of temperatures 6The ratio of remnant magnetisation at low temperature to that at room temperature, RT, was greater than unity for all the samples measured. The ratio increased as the modulation period of the samples decreased. This is consistent with a modulation period dependence of the Curie temperature of the Ni/Fe multilayers.

While orientation imaging microscopy (OIM) via automatic analysis of electron backscatter diffraction patterns (EBSPs) has become routine, methods for analyzing results obtained by OIM are still maturing. Interrogating the OIM data to distinguish between deformed, recovered and recrystallized material in a polycrystalline sample is one example. An advantage for using OIM data in such a case is that the corresponding textures can also be determined providing more information regarding these processes. This work reports on two different approaches for distinguishing between these structures from OIM data on a sample of partially recrystallized low-alloy steel.The first approach is, in a sense, patterned after that used in optical microscopy; where, deformed material can be identified because it is more deeply etched than recrystallized material. A similar approach Can be used in OIM by considering the quality of EBSPs. EBSPs from deformed material are more diffuse than patterns obtained from recovered or recrystallized material. At each measurement point in an OIM scan an image quality (IQ) parameter is determined for the corresponding EBSP. The IQ is mapped onto a gray scale and an image is formed from the OIM data as shown in Fig. 1. In this image the measurement points are shaded so that points with associated EBSPs of high IQ receive a lighter shade of gray than points with a lower IQ. The deformed regions can then be identified by the darker regions in the OIM map. However, this method has some drawbacks. The first is that the IQ parameter is not sensitive enough to distinguish recovered material from recrystallized material.

The correlation of aluminum alloy reliability data to microstructure has long been the goal of those scientists seeking to model electromigration behavior of interconnects. Traditionally, microstructural information has been acquired through x-ray diffraction , and transmission electron microscopy (TEM). However, each of these techniques is capable of delivering only part of the characterization whole. We describe the application of orientation imaging microscopy (OIM) to thin aluminum alloy films and demonstrate its versatility in providing the key microstructural reliability parameters: namely texture and grain size, as well as providing insight to the microstructure of grain boundaries.OIM was performed on an electromigration test structure (figure 1). The Al-alloy was deposited on titanium and capped with an anti-reflective titanium nitride. Subsequently, the test structure was patterned and capped with a multilayer blanket consisting of silicon nitride (SiN), and SiO2. The structure was annealed after the SOG deposition at 450° C for 90 minutes, seeing no electrical stressing. The die was removed from the package and deprocessed before the OIM was acquired.

Epitaxial growth of iron and vanadium films vacuum-evaporated onto a copper (111) buffer layer was examined by transmission electron microscopy. In order to reveal fine details of each film, an ion-milling system was effectively applied. The pseudomorphism of thin iron films evaporated onto copper was discussed according to the electron diffraction pattern and moiré fringes observed in two-layer films. The coexistence of two typical orientation relationships between bcc and fcc metal films, namely Kurdjumov-Sachs and Nishiyama-Wassermann orientations, and continuous distribution between them were confirmed by electron diffraction patterns for two-layer films, Fe/Cu and V/Cu.

Backscatter Kikuchi diffraction has been applied to an investigation of a selection of nickel sulfide crystals. In the first instance the technique itself was investigated to see whether it could be used successfully to distinguish between the space groups P21/a{\bar 3} (Pa{\bar 3}) of pyrite and Pnnm of marcasite. Subsequently, it was used to investigate the structure of a thin epilayer which was observed to have grown on selected facets of a certain synthetic nickel pyrite crystal. The epilayer was shown to be rhombohedral with possible space groups R{\bar 3}2/m (R3m) and lattice parameters ar = 6.4 A, αr = 36°. In an attempt to positively identify this structure, the technique was applied to a number of related compounds including the mineral millerite (NiS, R3m), α-NiS – a high temperature polymorph of millerite (P63/mmc and P63mc), and the layer compound NiI2 (R{\bar 3}m). It was concluded that the epilayer was most probably NiCl2 formed by reaction of the NiS2 crystal with chlorine contained in the carrier gas used during the chemical vapour deposition growth process.

Two evaporation units have been constructed for preparation of metal multilayers using thermal and electron bombard sources. CuNi, CuV and CuFe multilayers have been produced with the explicit intention of correlating physical properties with structure as determined by Transmission Electron Microscopy (TEM). Low temperature resistivity and interdiffusion measurements have been performed upon a series of CuNi foils over the modulation wavelength range 1.6 nm to 10 nm. An anomalously high residual resistivity and interdiffusion coefficient were obtained for a modulation wavelength of 2.8 nm to 3.0 nm, the resistivity peak persisting after annealing of the foils for 100 hrs at 380°C even though the x-ray satellite reflections had vanished. TEM, however, indicated that interfacial defects were retained during this treatment. Annealing the foils at 480°C for three hours resulted in a loss of the anomalous resistivity peak, x-ray satellite reflections and interfacial structure.

Bilayers of Cu/Fe and Cu/V and multilayers of Ni/Fe have been grown under high vacuum and ultra high vacuum conditions respectively with [111] epitaxy. Multilayer layer thicknesses ranged from 3 monolayers to 15 monolayers per layer. Improved epitaxy of the UHV growth was, we believe, due to the better vacuum although perfect material could only be obtained for growth within a narrow and shifting substrate temperature ‘window’. Possible shortfall in the quality of the Cu backing layer epitaxy was averted by a 2hr anneal at 425°C.In the Fe/Ni multilayers the Fe was observed to adopt the FCC lattice rather than the equilibrium BCC lattice for layer thicknesses less than 10 monolayers. This change of structure coincided with a reduction in sample magnetic moment per volume attributed to a collapse of the Fe moment to a value 7 times less than bulk.

When iron and vanadium films vaccum-deposited onto copper (111) surface were thicker than 10 and 15 nm, respectively, regular textural patterns were observed in their images of transmission electron microscopy (TEM). The textural patterns were composed of numerous rectangles like laths and showed remarkable contrast at defocussing conditions of TEM, similar to Fresnel contrast. The size of each rectangle composing texture changed with the film thickness and substrate temperature. The most remarkable textural pattern was observed in three-layer film, V/Fe/Cu, and a similar pattern was also observed in the carbon replica taken from its film surface. Therefore, the textural pattern reflects the surface microtopography of each film.