bluuebunny/crossref_metadata_2025_split huggingface dataset:
Strength-Flaw Relationship of Corroded Pristine Silica Studied by Atomic Force Microscopy
Authors: Zhong Qian , Inniss Daryl , Kurkjian Charles R. 
Published: April 2011

ABSTRACTGlass strength is controlled by microscopic surface flaws. Attempts to quantify the strengthflaw relationship for corroded silica fibers have been unfruitful, principally because of the difficulty in identifying the nanometer-sized, strength-controlling flaws on a uniformly corroded surface. In this paper, studies on corrosion of pristine silica optical fibers by HF vapor are presented. The HF-treated fibers exhibit strength degradation and contain well-defined, spatially-resolved surface flaws, which are characterized with an atomic force microscope. Excellent strength agreement is obtained for all chemically corroded fibers when the flaws are modeled as partially embedded hemispheres (i.e., blunt flaws). The implication of these results to the corrosion and fatigue process of silica glasses is discussed, since all previous analyses have assumed the strength-controlling flaws to be sharp.
3-D Imaging of Crystals at Atomic Resolution
Authors: O'keefe M.A. , Downing K.H. , Wenk H-R. , Meisheng Hu 
Published: April 2011

ABSTRACTElectron crystallography has now been used to investigate the structures of inorganic materials in three dimensions. As a test of the method, amplitudes and phases of structure factors were obtained experimentally from high resolution images of staurolite taken in a number of different projections. From images in five orientations, a three-dimensional Coulomb potential map was constructed with a resolution of better than 1.4Å. The map clearly resolves all the cations (Al,Si,Fe) in the structure, and all of the oxygen atoms. This method promises great potential for structure determinations of small domains in heterogeneous crystals which are inaccessible to x-ray analysis. Three-dimensional structure determinations should be possible on small domains only approximately 10 unit cells wide, and may resolve site occupancies in addition to atom positions. Given a microscope stage with a suitable range of tilt and enough mechanical stability, the method could also be applied to small crystalline particles larger than about 50Å to 100Å. In addition, it may be possible to apply the method to derive the two-dimensional structure of periodic defects.
Analysis of Interface Dynamics in Solid-State Phase Transformations by In Situ Hot-Stage High-Resolution Transmission Electron Microscopy
Authors: Howe James M. , Benson W. E. , Garg A. , Chang Y.-C. 
Published: April 2011

ABSTRACTIn situ hot-stage high-resolution transmission electron microscopy (HRTEM) provides unique capabilities for quantifying the dynamics of interfaces at the atomic level. Such information is critical for understanding the theory of interfaces and solid-state phase transformations. This paper provides a brief description of particular requirements for performing in situ hot-stage HRTEM, summarizes different types of in situ HRTEM investigations and illustrates the use of this technique to obtain quantitative data on the atomic mechanisms and kinetics of interface motion in precipitation, crystallization and martensitic reactions. Some limitations of in situ hot-stage HRTEM and future prospects of this technique are also discussed.
Chip Surface Damage Induced by Internal Stress of Lead–ON–Chip (Loc) Packages
Authors: Amagai Masazumi , Kawasaki Eiji 
Published: April 2011

ABSTRACTIn lead–on–chip (LOC) packaging technology, the lead fingers are attached directly to the surface of the chip using a double–side adhesive tape. This method of chip attachment naturally concerns with regards to stress on the polyimide coated chip surface. Device failure related to fracture in the passivation layers and the Al–Si metal has been observed in temperature cycle tests. The dominant issue is polyimide cracking due to mechanical stress caused by internal stress of LOC packages. To investigate the effect of polyimide characterization, devices were fabricated with different polyimides. The degree of polyimide cracking was determined with scanning electron microscope (SEM) technique. The polyimides were characterized with chemicals, tensile measurement tester, thermal analyzer, fourier transform infrared spectroscope (FTIR), computer simulation and various package-level reliability tests. The results of the characterization and an explanation of the primary factors affecting chip surface damage are presented in this paper.
X-Ray Strain Measurements in Fine-Line Patterned AL-CU Films
Authors: Marcus M. A. , Flood W.F. , Cirelli R. A. , Kistler R. C. , Ciampa N. A. , Mansfield W. M. , Barr D. L. , Volkert C.A. , Steiner K. G. 
Published: April 2011

ABSTRACTIn order to better understand the mechanics of metallization structures having very fine features, we performed in-situ, temperature-dependent X-ray strain measurements on Al-Cu films patterned into gratings with linewidths of 0.2-0.8μm, with and without a dielectric covering In comparison with earlier work on coarser structures, we find larger strains and less hysteresis, indicating an increased yield stress. The stress in unpassivated lines is almost independent of the linewidth. The slope of the stress/temperature curves for passivated lines increases with decreasing linewidth, so that the compressive stress at 500°C reaches 900MPa for the narrowest lines. The tensile stress at RT is smaller for the narrower lines, suggesting that these lines may not stress-void as much as wider ones. The significance of these results for stress voiding and electromigration will be discussed.
Thermally Induced Stresses in Passivated Thin Films and Patterned Lines of AlSiCu
Authors: Burges U. , Helneder H. , KÖrner H. , Schroeder H. , Schilling W. 
Published: April 2011

ABSTRACTA bending beam technique was used to measure the mechanical stresses in AlSi(l%)Cu(0.5%) blanket films as well as in patterned lines (aspect ratio: 0.8) - unpassivated and passivated with SiNx - during thermal cycling from –170°C or room temperature to 450°C.Main results are:a) No significant differences in unpassivated and passivated blanket films with thickness ranging from 0.2 µm to 3.2 µm.b) In unpassivated patterned lines of 0.8 µm thickness the stresses across the lines are very small, while parallel to the lines they show nearly elastic behaviour, except at high temperatures.c) In passivated patterned lines the stresses are much higher than in blanket films, very similar parallel and across the line and nearly elastic. The stress relaxation is small compared with blanket films and depends strongly on the temperature.
Line-Width Dependence of Stress in Passivated Al Lines During Thermal Cycling
Authors: Chidambarrao D. , Rodbell K. P. , Thouless M. D. , DeHaven P. W. 
Published: April 2011

ABSTRACTWe have obtained theoretical stress-temperature curves for passivated Al lines undergoing thermal cycling. A finite element plane-strain cross-sectional analysis with a time-dependent constitutive property for Al, based on equations for discreteobstacle controlled plasticity, was performed. The parameters for this Al constitutive relation were obtained by fitting with experimentally obtained stress-temperature curves for Al blanket films on silicon. Theoretical results agree well with the x-ray diffraction experimental data of Besser et al.1 Using a time-dependent property for Al helps match the data better than a time-independent property. Theoretical stress-temperature curves were also obtained for the longitudinal, transverse, and normal stress components in aluminum lines for line-widths ranging from 0.5 to 10 µm. The hysteresis of the stress-temperature curve of Al gets less as the line-width gets smaller. All stress components in the Al line change substantially with linewidth for the same oxide thickness.
Electromigration Failure of Narrow Al Alloy Conductors Containing Stress - Voids
Authors: Oates A. S. , Lloyd J. R. 
Published: April 2011

ABSTRACTElectromigration and stress - induced voiding are two of the most important metallization failure mechanisms for integrated circuits. These mechanisms are not independent since stress voiding may affect electromigration. In this paper we examine the impact of stress voiding on electromigration failure of narrow Al alloy stripes, and show that the major effects of stress voiding are significant reductions in failure times, and a non-Arrenhius temperature dependence of the lifetime. We propose a model to explain these effects based on the formation of flux divergences at pre-existing voids due to stress gradients.
Segregation of Copper in Dilute Aluminum - Copper Alloys for Interconnects
Authors: Smith D.A. , Small M.B. , Garratt-Reed A.J. 
Published: April 2011

ABSTRACTIt is well known that the resistance to electromigration of aluminum-based interconnects is enhanced by alloying with copper. The mechanism is thought to involve the segregation of copper to the grain boundaries. The copper concentration at grain boundaries has been measured in well annealed alloys, with the compositions A1-0.5wt% Cu and AI-2wt%Cu using a VG HB5 STEM. The grain structure was stabilized by an anneal at 673K for one hour and the grain boundaries were loaded with copper by an anneal for 90 hours at 503K. It was found that the copper concentration varied from boundary to boundary. With the assumption that the copper was concentrated in a single layer the saturation concentration of copper was found to be in the range 0.025 to 0.25. This corresponds to an enhancement of the copper concentration relative to that in the grain interiors by a factor in the range between 3 and 30. The higher value approaches the copper concentration which would correspond to a monolayer of theta phase. Extensive surface segregation, amounting to a monolayer equivalent was also detected.
Passivation Design / Electromigration Performance Correlations in Layered Aluminum Metallizations
Authors: Graas Carole D. , Ting Larry L. 
Published: April 2011

ABSTRACTThe study presented in this paper establishes correlations between key passivation morphological characteristics and metal electromigration performance. This was done by using test structures including extrusion monitors which provided narrow gaps along both sides of the test stripes. The parameters studied were: (1) the nature of the gap filling (oxide process and step coverage), (2) local oxide planarization, and (3) oxide thickness above the leads tested. Failure analysis was conducted by SEM cross-sections of cracked passivation areas. We observed that in the case of aluminum metallizations capped by a thin anti-reflective coating (ARC) layer, failure occurred in all cases by aluminum extrusion from the top corners of the leads, and at 45 degree angles into the passivation. Ultimately, the lifetime was dependent on oxide thickness above the test leads rather than gap-filling characteristics.
Epitaxial Relationships and Electrical Properties of SrTiO3 Films on Various Thin -Fluoride/Si Structures
Authors: Moon B. K. , Ishiwara H. 
Published: April 2011

AbstractCrystalline strontium titanate (SrTiO3:STO) films were grown on Si(111) and Si(100) substrates using thin SrF2 and CaF2 buffer layers by two-step growth method. In all cases, fluoride buffer layers were effective in growing STO films on Si substrates, which is probably due to that fluoride buffer layers have excellent crystallinity and they can prevent formation of amorphous SiO2 layers on Si substrates at the initial stage of the STO deposition. It was found from X-ray diffraction and pole-figure measurements that (110)-oriented STO crystallites with three different positions to the substrate were grown on Si(111) substrates for both SrF2 and CaF2 buffer layers. In constrast, (100)-oriented STO films with 12-fold symmetry were grown on a SrF2/Si(100), and mixed (110)- and (100)-oriented STO crystallites were grown on a CaF2/Si(100) structure. It was concluded from these results that better crystallinity of STO films can be obtained on the SrF2 buffer layer in case of Si(111) and on the CaF2 buffer layer in case of Si(100). It was also found from I-V and C-V analyses that the STO films have good insulating and dielectric characteristics. For a SrTiO3 film on SrF2/Si(111) structure, the best values of breakdown field (at l.μA/cm2), resistivity (at IMV/cm) and dielectric constant were 2.3MV/cm, 8.2 × 1012 Ωcm and 72, respectively.
Molecular Layer Epitaxy of Perovskite-Based Oxides by Laser MBE
Authors: Yoshimoto M. , Maeda T. , Gonda S. , Shimozono K. , Koinuma H. , Ishiyama O. , Shinohara M. 
Published: April 2011

AbstractMolecular layer epitaxy and the topmost surface structure in laser MBE of perovskite and other related oxides were investigated by in situ RHEED, in situ angle-resolved XPS (ARXPS) and ex situ co-axial ISS (CAICISS) analyses. Two-dimensional epitaxial growths of SrTiO3 (001) and BaCuO2(001) on SrTiO3(001) substrate were achieved by optimizing the growth conditions. Periodicities of RHEED oscillation corresponded well to the growth of a repeating unit cell (molecular layer). ARXPS and CAICISS spectra revealed that (Sr-0) atomic plane came at the top of SrTiO3(001) film growing on SrTiO3 (001) substrate with (Ti-O) atomic plane on the top. This indicates the structural conversion of the topmost atomic layer from TiO2 to SrO occurred during the SrTiO3 homoepitaxial growth.
The Influence of Processing Parameters on the Development of Biaxially Aligned Zirconia Thin Films Deposited by Ion Beam Assisted Deposition
Authors: Sonnenberg Neville , Ressler Kevin G. , Mcintyre Paul C. , Cima Michael J. 
Published: April 2011

AbstractDeposition of high quality superconducting thin films requires lattice-matched single crystal substrates. This greatly reduces the number of candidate materials to a few expensive substrates that are only available in small sizes. Inexpensive, low-dielectric constant amorphous or polycrystalline substrates would greatly enhance the feasibility of superconducting devices such as HTSC multichip modules. Deposition of HTSC films on aligned dielectric layers allows the use of amorphous and polycrystalline substrates in these structures. Biaxially aligned zirconia thin films have been deposited using ion beam assisted deposition (IBAD) on pyrex, quartz, and Hastelloy substrates. Deposition rate, substrate temperature, ion beam energy, and other processing parameters control the orientation of films deposited by ion beam assisted deposition. Biaxially aligned (200) oriented zirconia has been deposited by IBAD on all three substrates without active substrate heating. Biaxial alignment was not observed in films deposited at 400°C. Increased ion beam energy promotes polycrystalline nucleation at lower temperatures, which is important to the development of biaxial alignment. Other faster growing orientations begin to dominate as the temperature is increased. These results are consistent with a growth and extinction model.
Examination of Particles and Outgrowths on the Surface of Epitaxial Yba2Cu3O7 Thin Films
Authors: Norton M. Grant , Biggers Rand R. , Maartense I. , Moser E. K. , Brown Jeff L. 
Published: April 2011

AbstractThe surface morphology of Yba2Cu3O7 thin films formed on (001)-oriented LaAlO3 substrates by pulsed-laser deposition has been examined using electron and scanning probe microscopies. The observed surface features can be divided into two types: particles formed as a result of material (often molten) ejected from the target and outgrowths formed as a result of nucleation and growth processes on the substrate and/or the film surface. Where both types of surface feature occur on a particular film the outgrowths are always more numerous. The density of outgrowths is strongly related to the deposition parameters and, as a consequence, with the film growth mechanism.
MBE Growth of CoO and Fe3O4 films and CoO/Fe3O4 multilayers
Authors: Wolf R. M. , Veirman A. E. M. De , Sluis P. Van der , Zaag P. J. van der , Stegge J. B. F. aan de 
Published: April 2011

AbstractThe growth of CoO and Fe3O4 single crystalline layers has been studied. CoO and Fe3O4 can be grown under similar growth conditions in a small pressure window. (001) oriented CoO/Fe3O4 multilayers were grown on MgO and MgAl2O4 substrates. On MgO substrates coherent heteroepitaxial growth was observed in the multilayers resulting in high crystalline quality multilayer structures with 0.018° FWHM of the multilayer rocking curve. The mean interface roughness is 4Å as determined by low angle X-ray reflection measurements and HRTEM observations.
Growth of Epitaxial KNbO3 Thin Films
Authors: Graettinger Thomas M. , Morris P. A. , Roshko A. , Kingon A. I. , Auciello O. , Lichtenwalner D. J. , Chow A. F. 
Published: April 2011

AbstractKNbO3 possesses high nonlinear optical coefficients making it a promising material for frequency conversion of infrared light into the visible wavelength range using integrated optical devices. While epitaxial thin films of KNbO3 have previously been grown using ion beam sputtering, defects (i.e. grain boundaries, domains, surface roughness) in these films resulted in high optical losses and no measurable in-plane birefringence. Previous films were grown on MgO substrates, which have a >4% lattice mismatch with KNbO3. In the work reported here, we have grown films on MgO, MgA12O4, NdGaO3, and KTaO3 to investigate the role of lattice mismatch on the resulting film quality. Films have also been grown with and without oxygen ion assistance. The orientations, morphologies, and defects in the films were examined using x-ray diffraction and AFM to determine their relationships to the growth conditions and substrate lattice mismatch.
Epitaxial Growth of (110) KnbO3 Films on (100) MgO Substrates via Sol-Gel Processing
Authors: Derderian Garo J. , Barrie James D. , Aitchison Kenneth A. , Mecartney Martha L. 
Published: April 2011

AbstractEpitaxial, single phase (110) KnbO3 films were grown on (100) MgO substrates using a sol-gel process employing ethoxide precursors in methanol. The degree of epitaxy was dependent on both the annealing temperature and the amount of potassium in the film. Excess potassium in the sol-gel solution (K/Nb = 1.2) was necessary to produce single phase films. An amorphous or polycrystalline MgO interfacial layer was observed in some films, postulated to have developed after nucleation of KnbO3 and due to a highly defective surface layer.
The MBE Growth and Optical Quality of BaTiO3 and SrTiO3Thin Films on MgO
Authors: McKee R. A. , Walker F. J. , Specht E. D. , Alexander K. B. 
Published: April 2011

AbstractHigh quality epitaxial BaTiO3 and SrTiO3 have been grown on MgO, stabilized at a one unit cell height, and grown to film thicknesses of 0.5 - 0.7 μm. These relatively thick films remain adherent when thermally cycled between growth temperatures and room temperature, are crack free with high optical quality, and have both in-plane and out-of-plane X-ray rocking curves of 0.3–0.5°. These films have been grown using molecular beam epitaxy (MBE) methods starting with the TiO2 layer of the perovskite structure. The TiO2-Iayer/MgO interface uniquely satisfies electrostatic requirements for perovskite heteroepitaxy and provides the template structure that leads to the high quality films that are obtained. Wavelength dependence of optical loss has been characterized between 475 nm and 705 nm with loss coefficients < 1dB/cm being obtained at the He-Ne wavelength.
The Influence of RTA Heating Rate on the TiSi2 and Si - TiSi2 Interface Roughness
Authors: Lagana A. A. M. , Valente M. C. , Pedrine A. G. , Filho J. C. de Souza , Stuart J. W. , Santiago-Avilés J. J. 
Published: April 2011

ABSTRACTIn TiSi2 metallized devices, the second distribution of leakage current (I>lμA) is caused by the Si/TiSi2 interface roughness. In this work, 40gm thick Ti films are sputtered onto Si waters. RTA was done in N2 atmosphere. Heating rates of 0, 0.5, 1, 5, and 100°C S−-1 are examined. Samples are characterized by AFM, RBS, XRD and laser light scattering methods. The parameters related to roughness are heating rate sensitivity and oxygen contamination which decreases the roughness on the interface.
Rapid Thermal Oxidation for Passivation of Porous Silicon
Authors: BÁrsony I. , Klappe J.G.E. , Vázsonyi É. , Lohner T. , Fried M. 
Published: April 2011

ABSTRACTChemical and mechanical stability of porous silicon layers (PSL) is the prerequisite of any active (luminescent) or passive (e.g. porous substrate) integrated applications. In this work X-ray diffraction (XRD) was used to analyze quantitatively the strain distribution obtained in different morphology PSL that were prepared on (100) p and p+Si substrates. Tetragonal lattice constant distortion can be as high as 1.4% in highly porous “as-prepared” samples. Incoherent optical heating RTO is governed by the absorption in the oxidized specimen. PSL show vertical inhomogeneity according to interpretation of spectroscopic ellipsometry (SE) data. Oxygen incorporation during RTO is controlled by specific surface (in p+ proportional, in p inversely proportional with porosity), while the developing compressive stress depends on pore size, and decreases with porosity in both morphologies.
Decomposition of CO2 to Carbon Using Oxygen-Deficient Zn(II)-Bearing Ferrite
Authors: Tabata M. , Kato H. , Tsuji M. , Tamaura Y. 
Published: April 2011

AbstractOxygen-deficient Zn(II)-bearing ferrites (ZnxFe3-xO4-δ, 0≤×≤l, δ>0) have been synthesized and studied for their reactivity in the decomposition of CO2 to carbon at 300 °C. They were prepared by reducing Zn(II)-bearing ferrites with H2 gas at 300 °C. The oxygen-deficient Zn(II)-bearing ferrites consisted of a single phase of a spinel-type structure which was oxygendeficient compared with their stoichiometric compositions. Their lattice constants were larger than those of the corresponding stoichiometric spinels. Decomposition of CO2 to carbon proceeded accompanied by an oxidation of the oxygen-deficient Zn(II)-bearing ferrite. The amount of carbon deposited on the ferrite decreased when Zn content in Zn(II)-bearing ferrite increased. The decrease in the amount of carbon deposited is due to changes in the electron conductivity according to the Zn content in Zn(II)-bearing ferrite. These changes contribute to their reactivity for decomposition of CO2 to carbon.
Methanation of CO2 on Ni(II)-Bearing Ferrite (NixFe3-xO4-δ; x=0.39, δ>0) in Flow System
Authors: Kato H. , Tabata M. , Tsuji M. , Tamaura Y. 
Published: April 2011

AbstractThe methanation of CO2 has been studied by using reduced Ni(II)-bearing ferrite (NixFe3-xO4-δ; x=0.39, δ=0.1∼0.2) in an H2/CO2 mixed gas flow system. A yield of 31% and a high selectivity of 89% were obtained in the methanation for 6h using the H2-reduced Ni(II)-bearing ferrite. The X-ray diffractometry showed that the reduced Ni(II)-bearing ferrite during the methanation retained the spinel-type structure whose lattice constant increased from 0.8375 to 0.8379 nm. The chemical analysis corroborated an increase in the mole ratio of Fe2+/Fetotal in the Ni(II)-bearing ferrite. These results suggest that oxygen-deficient sites were formed in the spinel structure of the reduced Ni(II)-bearing ferrite. It has been found from the analysis using the Langmuir isotherm for dissociative adsorption that CO2 is adsorbed onto oxygen-deficient sites to be decomposed to an elemental carbon and two oxygen-deficient ions. The methanation of CO2 is considered to proceed owing to the oxygen deficient sites. It is considered that the methanation consists of three elementary reaction steps: 1) Formation of oxygen-deficient sites by H2-reduction, 2) Reduction of CO2 to carbon and Incorporation of two oxygen ions of the CO2 into the oxygen-deficient sites, and 3) Hydrogenation of the deposited carbon to CH4.