[en] Electromigration is a phenomenon that has attracted much attention in the semiconductor industry because of its deleterious effects on electronic devices (such as interconnects) as they become smaller and current density passing through them increases. However, the effect of the electric current on the microstructure of interconnect lines during the very early stage of electromigration is not well documented. In the present report, we used synchrotron radiation based polychromatic X-ray microdiffraction for the in-situ study of the electromigration induced plasticity effects on individual grains of an Al (Cu) interconnect test structure. Dislocation slips which are activated by the electric current stressing are analyzed by the shape change of the diffraction peaks. The study shows polygonization of the grains due to the rearrangement of geometrically necessary dislocations (GND) in the direction of the current. Consequences of these findings are discussed

[en] Determination of the strains in a polycrystalline material using 4-D XRD reveals sub-grain and grain-to-grain behavior as a function of stress. Here 4-D XRD involves an experimental procedure using polychromatic micro-beam X-radiation (micro-Laue) to characterize polycrystalline materials in spatial location as well as with increasing stress. The in-situ tensile loading experiment measured strain in a model aluminum-sapphire metal matrix composite using the Advanced Light Source, Beam-line 7.3.3. Micro-Laue resolves individual grains in the polycrystalline matrix. Results obtained from a list of grains sorted by crystallographic orientation depict the strain states within and among individual grains. Locating the grain positions in the plane perpendicular to the incident beam is trivial. However, determining the exact location of grains within a 3-D space is challenging. Determining the depth of the grains within the matrix (along the beam direction) involved a triangulation method tracing individual rays that produce spots on the CCD back to the point of origin. Triangulation was experimentally implemented by simulating a 3-D detector capturing multiple diffraction images while increasing the camera to sample distance. Hence by observing the intersection of rays from multiple spots belonging to the corresponding grain, depth is calculated. Depth resolution is a function of the number of images collected, grain to beam size ratio, and the pixel resolution of the CCD. The 4DXRD method provides grain morphologies, strain behavior of each grain, and interactions of the matrix grains with each other and the centrally located single crystal fiber

[en] Synchrotron polychromatic X-ray microdiffraction is a particularly suitable technique to study in situ the effect of electromigration in metal interconnects as add spatial resolution to grain orientation and strain sensitivity. This technique has been extensively used at the Advanced Light Source to monitor changes in aluminum and copper interconnect test structures while high-density current is passed into them during accelerated tests at elevated temperature. One of the principal findings is the observation of electromigration-induced plasticity in the metal lines that appear during the very early stages of electromigration. In some of the lines, high density of geometrically necessary dislocation are formed leading to additional diffusion paths causing an enhancement of electromigration effect at test temperature. This paper presents an overview of the principal results obtained from X-ray microdiffraction studies of electromigration effects on aluminum and copper interconnects at the ALS throughout continuous efforts that spanned over a decade (1998-2008) from approximately 40 weeks of combined beamtime.

[en] The rotation of Sn grains in Pb-free flip chip solder joints hasn't been reported in literature so far although it has been observed in Sn strips. In this letter, we report the detailed study of the grain orientation evolution induced by electromigration by synchrotron based white beam X-ray microdiffraction. It is found that the grains in solder joint rotate more slowly than in Sn strip even under higher current density. On the other hand, based on our estimation, the reorientation of the grains in solder joints also results in the reduction of electric resistivity, similar to the case of Sn strip. We will also discuss the reason why the electric resistance decreases much more in strips than in the Sn-based solders, and the different driving force for the grain growth in solder joint and in thin film interconnect lines

[en] Ferroelectric materials, such as BaTiO₃, have piezo electric properties that make them attractive for microelectronic and sensing applications. It is well known that the application of mechanical stress or electric field can alter the domain structure inferroelectrics. Indeed, the constitutive behavior of a ferroelectric is largely governed by the formation, movement and interact ion of its domains. Therefore, it is crucial that the micro mechanics of domains and their effect on internal stresses in ferroelectrics be understood. Here we show that the emerging technique of scanning X-ray micro diffraction can be used to measure directly, for the first time, the local triaxial strain fields around 90 degrees domains in single-crystal BaTiO₃. Specifically, residuals train maps in a region surrounding an isolated, approximately 40 (micro)m wide, 90 degrees domain were obtained with 3 (micro)m resolution, revealing significant residual strains. This information is critical for accurate micromechanical modeling of domain behavior in ferroelectrics

[en] We describe a method for direct determination and visualization of the distribution of charge in a composite electrode. Using synchrotron X-ray microdiffraction, state-of-charge profiles in-plane and normal to the current collector were measured. In electrodes charged at high rate, the signatures of nonuniform current distribution were evident. The portion of a prismatic cell electrode closest to the current collector tab had the highest state of charge due to electronic resistance in the composite electrode and supporting foil. In a coin cell electrode, the active material at the electrode surface was more fully charged than that close to the current collector because the limiting factor in this case is ion conduction in the electrolyte contained within the porous electrode.

[en] Compressed thin films deposited on substrates may buckle depending on the geometrical and mechanical properties of the film/substrate set. Until recently, the small dimensions of the buckling have prevented measurements of their local in plane internal stress distribution. Using a Scanning X-ray Micro diffraction (mSXRD) technique developed at a 3rd generation x-ray synchrotron source, we obtained thin film internal stress maps for circular blisters and telephone chord buckling with micrometric spatial resolution. A fair agreement was found between the film delamination topology observed by optical microscopy and the measured stress maps. We evidenced residual stress relaxation associated with the film buckling: the top is essentially stress-free while adherent region exhibits large compressive stresses

[en] Residual elastic strain in naturally deformed, quartz-containing rocks can be measured quantitatively in a petrographic thin section with high spatial resolution using Laue microdiffraction with white synchrotron x-rays. The measurements with a resolution of one micrometer allow the quantitative determination of the deviatoric strain tensor as a function of position within the crystal investigated. The observed equivalent strain values of 800-1200 microstrains represent a lower bound of the actual preserved residual strain in the rock, since the stress component perpendicular to the cut sample surface plane is released. The measured equivalent strain translates into an equivalent stress in the order of ∼ 50 MPa

[en] The nature and proportion of Zn species present in an agricultural soil overlaid by a dredged contaminated sediment have been untangled by the novel combination of three non-invasive synchrotron-based x-ray techniques: x-ray microfluorescence (μSXRF), microdiffraction (μXRD), and absorption spectroscopy (EXAFS). One primary (franklinite) and two secondary (phyllomanganate and phyllosilicate) Zn-containing minerals were identified in the initial soil, and another primary (ZnS) and a new secondary (Fe-(oxyhydr)oxide) Zn species in the covered soil. The quantitative analysis of EXAFS spectra recorded on bulk samples indicated that ZnS and Zn-Fe (oxyhydr)oxides amounted to 71+-10 percent and 27+-10 percent, respectively, and the other Zn species to less than 10 percent. The two new Zn species found in the covered soil result from the gravitational migration of ZnS particles initially present in the sediment, and from their further oxidative dissolution and fixation of leached Zn on F e (oxyhydr) oxides

[en] Uranium(U) solid-state speciation in vadose zone sediments collected beneath the former North Process Pond (NPP) in the 300-Area of the Hanford site (WA, USA) was investigated using multi-scale techniques. In 30-day batch experiments, only a small fraction of total U (∼7.4%) was released to artificial groundwater solutions equilibrated with 1% pCO₂. Synchrotron-based micro X-ray fluorescence spectroscopy (XRF) analyses showed that U was distributed among at least two types of species: (1) U discrete grains associated with Cu, and (2) areas with intermediate U concentrations on grains and grain coatings. Metatorbernite (Cu[UO₂]₂[PO₄]₂ · 8H₂O) and uranophane (Ca[UO₂]₂[SiO₃(OH)]₂ · 5H₂O) at some U discrete grains, and muscovite at U intermediate concentration areas were identified in synchrotron-based micro X-ray diffraction (XRD). SEM/EDS analyses revealed 8-10 (micro)m size metatorbernite particles that were embedded in C-, Al-, and Si-rich coatings on quartz and albite grains. In (micro)- and bulk-X-ray Absorption Structure ((micro)XAS and XAS) spectroscopy analyses, the structure of metatorbernite with additional U-C and U-U coordination environments were consistently observed at U discrete grains with high U concentrations. The consistency of the (micro)- and bulk-XAS analyses suggests that metatorbernite may comprise a significant fraction of the total U in the sample. The entrapped, micron-sized metatorbernite particles in C, Al, and Si rich coatings, along with the more soluble precipitated uranyl carbonates and uranophane, likely control the long-term release of U to water associated with the vadose zone sediments