bluuebunny/crossref_metadata_2025 huggingface dataset:
Straight Wall Bumps for High Lead Count Devices: Photolithography and Physical Properties.
Authors: Milosevic Ivana , Jasper Joerg
Published: March 2011

This paper will report on a novel photolithographic process suitable for the fabrication of gold bumps on high lead count devices. Utilizing a photosensitive polyimide, straight wall bumps are grown completely recessed within the polyimide layer to a typical height of 25 microns.

The photolithographic step of the bumping process will be described. Good layer uniformity in conjunction with exposure in vacuum hard contact mode leads to practically vertical walls of the opening in the polyimide layer after develop.

Straight wall gold bumps have been electroplated in 30 micron wide openings with a 50 micron centerline spacing. This density is beyond the present spacing capability of TAB in production. The bumping process is no longer the limiting factor in high lead count device fabrication.

Potential residues in the polyimide openings would result in bad bump adhesion strength and high bump contact resistance to the underlying metallization. These two parameters were used for the process optimization.
Solder Joining Technology
Authors: Koopman Nick
Published: March 2011

An in-depth review of controlled collapse chip connections (c-4), or otherwise known as Flip Chip Solder Joining Technology, is present. The C4 joint utilizes solder bumps deposited on wettable terminals on the chip and a matching footprint of the substrate. The upsidedown chip (flip chip) is aligned to the substrate and all joints are made simultaneously by reflowing the solder. An in depth review of this technology is presented. Materials, design factors, fabrication processes, tools, assembly, rework, and reliability are discussed. Future trends are indicated and comparisons make with wire bonding and Tab (tape automated bonding).
Review of Critical Variables Determining Solder Fatigue Lives
Authors: Solomon Harvey D.
Published: March 2011

The fatigue of solder joints is a dominant factor limiting the long term reliability of electrical devices, especially when modern surface mounting is employed to attach devices to wiring boards. This paper will review the critical variables which determine the fatigue of solder and solder interconnections for the joints encountered with surface mounted devices. Consideration will first be given to the variables determining the displacement that a joint experiences due to an imposed thermal cycle. This displacement will then be related to strains in the joint. These strains are then correlated to the fatigue life. This final correlation requires not only a knowledge of the magnitude of the strain which is being applied, but also nature of the joint geometry, type of solder employed, stress state, the definition of failure, the frequency of fatigue cycling, the introduction of hold times, the environment (both thermal and gaseous) and the occurrence of metallurgical changes. The importance of these critical variables will be discussed along with an outline of design approaches to predict the fatigue life. Data for tests on eutectic Pb-Sn solder and for a Pb rich solder will be presented and used to illustrate the influence of critical variables on the fatigue life and to illustrate design approaches.
Metallization Issues in Advanced Ceramic Substrates:- Microstructural. Microchemistry and Thermal Conductivity in Aln
Authors: Westwood Alistair D. , Notis Michael R.
Published: March 2011

Microchemical and microstructural study has been carried out on the tungsten-aluminum nitride (W-AlN) thick film metallization interface. A reaction has been found to occur with the formation of precipitates at AlN grain boundaries and also within the AlN grains; a thin crystalline grain boundary film was also observed. The interface morphology and chemistry is compared to the molybdenum/manganese-aluminum nitride (MoMn-AlN) interface. The effects of morphology and microchemical variations upon thermal conductivity are discussed.
The Formation of Molecular Composites by a Modified Solgel Process
Authors: Lessard Ronald B. , Wallacet Mary M. , Oertling W. Anthony , Chang Chi K. , Berglund Kris A. , Nocera Daniel G.
Published: March 2011

Standard sol-gel procedures have been modified to permit sol-gel synthesis to be performed at varying hydrogen ion concentrations and in a variety of organic solvents. These modifications greatly expand the variety of guest molecules that can be incorporated into nondense glassy environments. Processing conditions can be controlled such that the guest compounds generally retain their solution properties thereby allowing new molecular composites to be formed. Reported herein is the incorporation of both porphyrins and metalloporphyrins into silica matrices. Electronic absorption, vibrational, and excited state luminescence properties of the resulting composites clearly demonstrate that the molecular and electronic structure of the porphyrins and metalloporphyrins are preserved during sol-gel processing and in the ceramic matrices. This retention of properties has been shown for guest molecules doped into monoliths as well as films.
Highly Emissive Lanthanide Compounds in Sol-Gel Derived Materials
Authors: Lessard Ronald B. , Berglundl Kris A. , Nocera Daniel G.
Published: March 2011

Molecular composites that possess unique emission properties have been prepared by introducing luminescent molecules into sol-gel based silica glasses. The lumophores chosen for study are terbium(III) and europium(III) ions whose emissions are quenched in aqueous and sol-gel environments owing to coordination of water molecules to the lanthanide ion. To overcome the quenching process the ions have been encapsulated within cryptands. The resulting terbium(IU) and europium(III) cryptates possess long-lived excited states in both aqueous solution and solgel glassy matrices. Measurements of the excited state dynamics of these molecularly engineered composites demonstrate the feasibility of tailoring molecules to retain their excited state properties in sol-gel derived glasses.
Single Crystal Zirconia Thin Films from Liquid Precursors
Authors: Miller K. T. , Lange F. F.
Published: March 2011

Epitaxial, single-crystal films of ZrO2 (Y2O3) were formed on (100) oriented single crystal substrates of ZrO2 (9.5 mol% Y2O3) using water-based solutions of zirconium acetate and yttrium nitrate as a precursor. Film compostions of ZrO2 (0 - 40 mol% Y2O3) were examined; since the lattice parameter of ZrO2 (Y2O3) increases with yttria content, the lattice mismatch was systematically varied to a maximum of 1.5%. Precursor films were deposited by spin coating, pyrolyzed, and held for 1 hour at 900°C, 1000°C, and 1100°C. X-ray diffraction showed that a strongly oriented film had developed after pyrolysis of the precursor. In addition, all samples, except those treated at 1100°C containing 6 – 15 mol% Y2O3, gave (111) peaks, indicating film polycrystallinity. Electron back-scattering patterns showed that epitaxial single crystals were formed at 1100°C for films containing 3 – 20 mol% Y2O3. Scanning electron microscopy showed that the epitaxial films had a porous structure. These results indicate that the epitaxy is a two-stage process: oriented nucleation upon pyrolysis, followed, for low mismatches, by subsequent consolidation into a single-crystal film above 1000°C.
Two-Dimensional Processing for Novel Functions
Authors: Yanagida Hiroaki
Published: March 2011

Since many interesting and novel phenomena arise from non-linear interactions between two or more different materials with opposite properties, e.g., acid vs. base, p-type vs. n-type semiconduction, reducing vs. oxidizing, host vs. guest, conducting vs. insulating, etc., it is very important to design or set, the fields where the non-linear interactions take place. This is a very important aspect of materials design. The most interesting and probably most understandable study field for non-linear interactions is interfaces. Since design of interfaces is called “two-dimensional” design [1], and processing is necessary after design, processing may therefore be called “two-dimensional processing” for novel functions.
Plasma Spraying of Zirconia Coatings
Authors: Varacalle D. J. , Smolik G. R. , Wilson G. C. , Irons G. , Walter J. A.
Published: March 2011

As part of an investigation of the dynamics that occur in the plume of a thermal spray torch, an experimental and analytical study of the deposition of yttria-stabilized zirconia has been accomplished. Experiments were conducted using a Taguchi fractional factorial design. Nominal spray parameters were: 900 A, 36 kW, 100 scfh argon primary gas flow, 47 scfh helium secondary gas flow, 11.5 scfh argon powder carrier gas flow, 3.5 lb/h powder feed rate, 3 in. spray distance, and an automated traverse rate of 20 in./s. The coatings were characterized for thickness, hardness, and microstructural features with optical microscopy, scanning electron microscopy, and x-ray diffraction. Attempts are made to correlate the features of the coatings with the changes in operating parameters. Numerical models of the physical processes in the torch column and plume were used to determine the temperature and flow fields. Computer simulations of particle injection (10 to 75 μm zirconia particles) are presented.
Processing and Properties of Nanophase Oxides
Authors: Eastman J. A. , Liao Y. X. , Narayanasamy A. , Siegel R. W.
Published: March 2011

Nanophase oxides (Al2O3, MgO, ZnO and TiO2), with typical grain sizes in the range 2–20 nm, have been synthesized by the condensation of ultrafine particles in a convective inert gas followed by their collection and in-situ consolidation in vacuum at ambient temperature. These new materials, owing to the reduced scale of their grains along with the enhanced cleanliness of their grain boundaries, are found to have significantly improved properties relative to those of their coarser-grained, conventionally-prepared counterparts. Nanophase rutile (TiO2) with an initial mean grain diameter of 12 nm, for example, has been found to sinter at 400 to 600°C lower temperatures than conventional rutile powders, without the need for compacting or sintering aids, while retaining a small grain size. Additionally, the importance of the extremely clean surfaces obtained with the gas condensation method has been demonstrated by comparing the sintering behavior of powders with and without air exposure prior to consolidation. The research completed on the processing and properties of nanophase ceramics is reviewed, and the potential for engineering advanced ceramics using the nanophase processing method is discussed.
The Effect of Processing Parameters on the Growth Rate and Microstructure of Al2O3/Metal Matrix Composites
Authors: Nagelberg Alan S.
Published: March 2011

Ceramic matrix composites can be formed by the directed oxidation of a doped molten aluminum alloy into an inert reinforcement or filler. The resultant ceramic matrix consists of interconnected Al2O3 and partially interconnected metal. The growth kinetics of this Al2O3 /metal ceramic matrix can be altered by numerous parameters. The effect of the growth atmosphere composition and temperature on the composite growth rate is dependent on the alloy dopant utilized. The ceramic matrix formation rate is also dependent on the alloy composition. Likewise, alloy composition has a profound effect on the mechanical properties and microstructure of the composites produced.
Photolithography: a New Tool for Ceramic Science
Authors: Rödel Jürgen , Glaeser Andreas M.
Published: March 2011

A recently developed technique combining photolithography, ion beam milling, and hot pressing allows the production of submicron-scale controlled-geometry, controlled-crystallography pore structures in controlled misorientation bicrystals, single crystal-polycrystal ensembles, and polycrystal-polycrystal ensembles. Such microdesigned interfacial structures provide a new tool for studying fundamental aspects of microstructural evolution. Current applications of the technique, opportunities for future research, and future extensions and refinements of the technique are described.
Packing and Structure in Systems Containing Rod-Like Particles
Authors: Chick Larry A. , Viney Christopher , Aksay Ilhan A.
Published: March 2011

A non-discrete Monte Carlo algorithm is used to model the packing of static rods. The results establish that inter-rod contact results solely from rod motion, not from space-filling effects. As the concentration of static rods is increased, clusters of aligned rods form and grow. The effects of rod motion are inferred through thermodynamic analysis. At sufficiently high rod concentrations, rod motion is expected to cause structural coarsening wherein the rods rearrange into larger but fewer clusters. These results should be considered when modeling the structure and mechanical behavior of whisker- and chopped-fiber-reinforced composites.
Dispersion and Consolidation of the Colloidal Suspension in the Al2O3Powder – Si3N4Whisker System
Authors: Hirata Yoshihiro , Matsushita Shinichi , Nakagan Susumu , Haraguchi Ichiro , Hanada Noriaki , Ishihara Yoshimi , Hori Saburo
Published: March 2011

Whisker-reinforced ceramics have high potential for structural materials application due to their high fracture toughness and high mechanical strength. In this paper, rheological property and consolidation of the colloidal suspension in the alumina powder-silicon nitride whisker system were studied to control the microstructure and density of the green and hot-pressed composite. A12O3particles of average diameter 0.15 μm and Si3N4whisker of average size 0.4 μm × 3.7 μm were electrostatically dispersed in water in pH range 1–11 and consolidated by filtration. A welldispersed state of the composite suspension was achieved at low pH. Decreasing the viscosity while increasing the solid content of the suspension at the same time is the key step in making green compact with higher density and a narrower pore size distribution. These compacts were densified to relative density 98.4–99.4% by hot-pressing at 1500°C at a pressure of 39 MPa in N2atmosphere.
Stability of a Binary Colloidal Suspension and its effect on Colloidal Processing
Authors: Shih Wan V. , Shih Wei-Heng , Liu Jun , Aksay Ilhan A.
Published: March 2011

The stability of a colloidal suspension plays an important role in colloidal processing of materials. The stability of the colloidal fluid phase is especially vital in achieving high green densities. By colloidal fluid phase, we refer to a phase in which colloidal particles are well separated and free to move about by Brownian motion, By controlling parameters such as pH, salt concentration, and surfactants, one can achieve high packing (green) densities in the repulsive regime where the suspension is well dispersed as a colloidal fluid, and low green densities in the attractive regime where the suspensions are flocculated [1,2]. While there is increasing interest in using bimodal suspensions to improve green densities, neither the stability of a binary suspension as a colloidal fluid nor the stability effects on the green densities have been studied in depth as yet. Traditionally, the effect of using bimodal-particle-size distribution has only been considered in terms of geometrical packing developed by Furnas and others [3,4]. This model is a simple packing concept and is used and useful for hard sphere-like repulsive interparticle interactions. With the advances in powder technology, smaller and smaller particles are available for ceramic processing. Thus, the traditional consideration of geometrial packing for the green densities of bimodal suspensions may not be enough. The interaction between particles must be taken into account.
Some Chemical and Structural Aspects of the Bi, Pb-Sr-Ca-Cu-O System
Authors: Takano Mikio
Published: March 2011

Phases and their relations in the Bi, Pb–Sr–Ca–Cu–O system have been studied to afford a sound material scientific base. Of particular interest is the chemically most representative system, Bi–Sr–Cu–O, in which a series of solid solutions expressed as Bi2+xSr2−xCu1+yOz are formed. The superconductor (Tc≃10K) corresponds to an extremely narrow range of 0.1<x<0.13. From the composition dependence of the one-dimensional modulation mode a new important factor controlling the modulation mode has been deduced. Substitution of Pb for Bi in the high-Tc phase has been found to induce a stepwise change of the modulation mode, thus suggesting an ordering of Pb in the BiO layer. [CuO2]∞ planes exist both in the holeand electron-carrier superconductors, but their role in the former type of superconductors has not been known. As one possible contribution to attacking this problem, ACuO2 (A: Ba1/3Sr2/3˜Sr˜Ca2/3Sr1/3 ) crystallizing in /A/CuO2/A/CuO2/A/ structure have been prepared using high pressures of 60kb.
Superconducting Properties of Substituted Oxides Bi2Sr2−xLaxCuO6+y and Bi2Sr2Ca1−xYxCu2O8+y Neutron Diffraction of Bi2Sr1.6La0.4CuO6+y and Bi2CaLaCuO6+y
Authors: Darriet J. , Alonso J. A. , Burlet P. , Chevalier B. , Lepine B. , Rossat-Mignod J. , Soethout C. J. P. , Soubeyroux J. L. , Etourneau J.
Published: March 2011

The substituted oxides Bi2Sr2−xLaxCuO6+y and Bi2Sr2Ca1−xYxCu2O8+y isostructural to the n = 1 and n = 2 members of the high Tc superconductors have been prepared. The solid solution Bi2Sr2−xLaxCuO6+y shows a superconducting transition for 0.2–0.25<x<0.5 with an onset Tc near 30K and zero resistance temperatures which depend on x and the heat treatment. For x = 1 the isostructural phases Bi2ALaCuO6.5+y with A = Ca or Ba have also been synthesized and are not superconducting. A modelfor the localization of the oxygen atoms is proposed based on neutron diffraction of Bi2Sr1.6La0.4CuO6+y and Bi2CaLaCuO6+y.

The Bi2Sr2Ca1−xYxCu2O8+y solid solution exhibits a superconducting transition for 0<x <0.7. The critical temperature remains almost constant (85–90K) for 0<x <0.3 and then decreases rapidly. The oxygen content value 8.65 for Bi2Sr2YCu2O8+y agrees well with the increase of the positive charge when calcium is replaced by yttrium.
Phase Chemistry and Compositional Variability During Processing in the Bi-Pb-Ca-Sr-Cu-O System
Authors: Schwartz Kenneth B. , Thompson Mark , Leong Derek , McConville Richard
Published: March 2011

The formation of superconducting materials in the Bi-Pb-Ca- Sr-Cu-O system was studied to determine the processing parameters and mechanisms responsible for the achievement of superconductivity above 100 K. Non-stoichiometry in the 3-layer superconducting phase (Tc≃100 K) is apparently necessary for formation and appears to be manifested by large vacancy concentrations on the non-Cu-layers of the structure.
Variation of Superlattice Structure of the Bi2Sr2−xCuO6-y Superconductor with Composition and Thermal History
Authors: Chakoumakos B. C. , Budai J. D. , Sales B. C. , Sonder Edward
Published: March 2011

Single crystals of Bi2Sr2−xCuO6−y, (0.1 < x < 0.5, 0 < y < 0.5), were examined using x-ray diffraction techniques. Ditfractometer scans of θ-2θ taken normal to the cleavage planes displayed the even () reflections from = 2 to 26. Weak satellite peaks were observed on either side of each main () reflection, and their intensities relative to the main peak increased as 2θ was increased. With decreasing Sr content, the satellite peaks systematically moved away from the position of the main reflection. In contrast, the positions of the satellite peaks did not change with oxygen content which was varied by up to 0.5 oxygen atoms per formula unit. Since Tc in these crystals is sensitive to oxygen content while the superstructure modulation is not, it is unlikely that superconductivity and the structure modulation are directly related. As shown by a more detailed study of these peaks using a four-circle diffractometer and x-ray precession methods, the satellites that appear in θ-2θ scans are actually the mosaic tails of relatively intense superstructure peaks, positioned off from c* in the b* direction of reciprocal space. Depending on the Sr content of the crystals, generally incommensurate modulations were found with the superstructure periodicity ranging between ˜1/5b* + 0.29c* and ˜1/5b* + 0.65c*. The modulation in Bi2Sr2−xCuO6−y has two components. The component along the b* direction is similar to the superstructure observed in Bi2Sr2CaCu2O7 crystals and thus is probably due to the mismatch between the Bi2O2 layer and the CuO2 layer. The additional component along c* may be due to the ordering of Sr vacancies.
Electron-Doped Superconductivity in CuO2 Layered Compounds with Nd2CuO4− structure
Authors: Takagi H. , Ito T. , Matsubara H. , Watabe H. , Ido T. , Tokura Y. , Uchida S.
Published: March 2011

We have discovered 24 K-superconductivity in a family of compounds Ln2−xCexCuO4−y (Ln=Pr, Nd, Sm). Novel feature of the superconductivity in these family of compounds is that superconductivity is produced by electron-doping in sharp contrast with high-Tc cuprates discovered so far. The effect of doping on physical properties particularly the elecronic phase diagram and transport coefficients which indicate symmetry in many respects between electron- and hole- doping is described.
Antiferromagnetism and onset of Superconductivity in Lanthanum Nickelates
Authors: Spałek J. , Kakol Z. , Honig J. M.
Published: March 2011

Magnetic moment and resistivity measurements are summarized for the La2−xSrxNiO4system. They show that the system undergoes a structural phase separation below 70 K. The majority of the sample is antiferromagnetic (AF) below 650 K (for x = 0) or 20 K (for x = 0) or 20 K (for x ≃ 0.2 while the minority phase (≤1% at 4.2 K) is superconducting (SC). An analysis of the results leads to the conclusion that SC and AF coexist in the minority part of the sample; the pairing takes place between 2p holes which propagate through a lattice containing localized 3d moments which, in the ground state, are ordered antiferromagnetically.
Interface Velocity and Noble Metal Segregation During Ion Beam Induced Epitaxial Crystallization
Authors: Custer J. S. , Thompson Michael O. , Jacobson D. C. , Poate J. M.
Published: March 2011

The interface velocity of Au and Ag doped amorphous Si during ion beam induced epitaxy was measured using in situ time resolved reflectivity. Interfacial segregation coefficients were determined as a function of composition from numerical simulations. At 320°C Au impurities enhanced the velocity by up to a factor of 2.5 compared to the intrinsic case. Silver slightly retarded re-growth by 10 %. These effects are qualitatively similar to the case of thermal solid phase epitaxy. Using the measured impurity profiles and interface velocity, computer simulations relate the segregation coefficient to the concentrations of the impurity at the interface. In both cases, the segregation coefficient increases with increasing interfacial impurity concentration.
Corrosion Resistivity of Cermet Coating Made by Ion Beam Treatment
Authors: Wei Tian , Weiping Cai
Published: March 2011

A cermet coating was obtained on a silicon-deposited pure iron surface by means of a single treatment integrating ion implantation and ion beam mixing. As conpared with either simple ion implantation or simple ion beam mixing,the integrated treatment provides the cermet coating with an electrochemical performance far better than the simple treatments.
Molecular Dynamics Simulations of Low-Energy Ion/Surface Interactions During Vapor Phase Crystal Growth: 10 eV Si Incident on Si(001)2×1
Authors: Kitabatake M. , Fons P. , Greene J. E.
Published: March 2011

Molecular dynamics simulations, utilizing the Tersoff many-body potential, were used to investigate the effects of 10 eV Si atom bombardment of a (001)2×1 terminated Si lattice. The irradiation events were initiated at an array of points in the primitive surface unit cell. Each event was followed to determine kinetic energy redistribution in the lattice as a function of time, projectile and lattice atom trajectories, and the nature, number, and depth of residual defects. Dimer breaking, epitaxial growth, position exchange, and the formation of residual hexagonal and split interstitials were observed. There were no residual vacancies. Impact points leading to each of the above results clustered in distinctly different regions of the surface unit cell. Bulk interstitials were annealed out over time scales corresponding to monolayer deposition during Si MBE.
Molecular-Dynamics Study of the Amorphizatton of CuTi
Authors: Sabochick Michael J. , Lam Nghi Q.
Published: March 2011

Radiation-induced amorphization of the crystalline compound CuTi was investigated by molecular-dynamics simulations using new interatomic potentials derived from the embedded-atom method. Two different approaches to amorphization were tried: one in which Cu and Ti atoms were randomly exchanged, and another in which Frenkel pairs were introduced at random. The potential energy, volume expansion and pair-correlation function were calculated as functions of chemical disorder and atomic displacements. The results indicate that, although both chemical disordering and point-defect introduction increase the system energy and volume, the presence of Frenkel pairs is essential to trigger the crystalline-to-amorphous transition.
Low Energy Ion Bombardment and Microstructural Evolution in Thin Films
Authors: Yang Chih M. , Atwater Harry A.
Published: March 2011

A new approach to modeling the evolution of islands in thin films by growth and coarsening during ion bombardment is described. Solution of a continuity equation and matter conservation relation, coupled with interface-limited and diffusion-limited rate laws for island growth and coarsening allows the kinetics of island evolution to be modeled. Results from the model indicate distinct kinetic paths for island evolution during ion bombardment as a result of growth, enhanced diffusion, island dissociation and monomer sputtering.
Evaluation of Compositional Change in Masklessly Deposited Lines by Micro-Rbs Analysis
Authors: Kinomura A. , Takai M. , Lu Y. F. , Namba S. , Satou M. , Chayahara A.
Published: March 2011

Compositional deviation from the standard stoichiometry of tin-oxide and silicon-oxide lines masklessly deposited by laser-induced thermochemical reaction was investigated by micro Rutherford backscattering (RBS). Micro-RBS spectra of the lines deposited with various laser powers indicated that the stoichiometry of the deposited lines for both tin-oxide and silicon-oxide was improved by the increase in laser power. A tomographic image of the tin-oxide line showed a compositional inhomogeneity across the line.
In-Situ Ion Beam Measurements of Deuterium Loading in Thin Foil Electrochemical Cells
Authors: Knapp J.A. , Guilinger T.R. , Kelly M.J. , Walsh D. , Doyle B.L.
Published: March 2011

A key element of recent assertions of "cold fusion" has been the claim that electrochemical loading of deuterium into Pd electrodes can produce D:Pd levels exceeding 1:1. Using external beam nuclear reaction analysis of Pd foil electrodes in operating electrochemical cells, we have directly monitored deuterium content in-situ. No conditions were found which resulted in loadings higher than ∼0.9.
Time-Resolved Measurements of Solidification and Undercooling in Metals and Alloys
Authors: Atwater Harry A. , West Jeffrey A. , Smith Patrick M. , Aziz M.J. , Tsao J.Y. , Peercy P.S. , Thompson Michael O.
Published: March 2011

We have performed nanosecond-resolution measurements of the lateral electrical resistivity of thin metal films on insulating substrates. Comparison of transient resistivity measurements with optical reflectivity measurements and heat-flow calculations permits the determination of the position and velocity of a planar crystal/melt interface, and an estimate of undercooling during pulsed laser melting of metals. We report detailed results for rapid solidification of Ni, including the observation of hypercooling of .liquid Ni.
Laser Mixing of Titanium on Silicon Carbide
Authors: Jervis T. R. , Hirvonen J-P. , Nastasi M. , Cohen M. R.
Published: March 2011

We have used excimer laser surface processing to melt and mix single Ti layers into the surface of polycrystalline SiC substrates. The mixing of Ti into the surface is very rapid and efficient. Examination of Rutherford backscattering (RBS) data for different mixing conditions shows the formation of a preferred composition at the Ti-substrate interface which propagates from the interface with further mixing. Reconstruction of the RBS spectrum indicates that the composition of the layer is Ti45C37Si18. X-ray diffraction demonstrates the formation of Ti suicides and carbides in the surface region. Profiling of C in both mixed and uncoated samples by 6 MeV He+ scattering demonstrates that laser processing of the SiC does not cause major changes in the stoichiometry of the substrate material.
Microstructural Characterization of Texture in Tungsten Films made by Ion-Assisted Evaporation
Authors: Rajan K. , Roy R. A. , Petkie R. , Ramanathan K. V.
Published: March 2011

The microstructure of tungsten films deposited by ion-assisted evaporation (IAE) has been examined by transmission electron microscopy. It is proposed that grain shape is strongly associated with stress and texture changes in IAE films. Evidence is also found of stress induced damage in the substrate due to stress transfer from the deposited tungsten films.
Migration of Carbon in Tempered Martensitic Steel During Excimer Laser Melting
Authors: Hirvonen J-P. , Jervis T. R. , Zocco T. G.
Published: March 2011

The migration of ion implanted 13C in tempered martensitic steel (nominal composition 1.05 wt. % C, 0.2 wt. % Si, and 0.3 wt. % Mn) during excimer laser melting was examined utilizing the resonance of the l3C(p,γ)14N reaction at Ep = 1747.6 keV. Depth concentration profiles after five and ten laser pulses of 1 J/cm2 revealed a deviation from random walk diffusion in a homogeneous media. This was modelled by using partitionless solidification and solubility controlled flow of carbon in the iron-carbon melt. A diffusion length of nm during the period to τ the melted phase was deduced. Ion implanted surfaces were initially crystalline but significant crystalline to amorphous transformation occurred following laser treatment.
Laser Pulse Triggering of the Explosive Crystallization in Amorphous Si and Ge Thin Films
Authors: Marine W. , Marfaing J.
Published: March 2011

The structure and morphologies of the thin amorphous a-Si and oc-Ge films crystallized “in situ” in an electronic microscope by pulsed YAG laser have been studied using conventional and high-resolution transmission electronic microscopy observations. It is found that the laser induced nucleation rate (I) is laser pulse length dependent. I is about 1021-1022 cm−3 s−1 (α-Si) and 1023-1025 cm−3 s−1 (α-Ge) near the melting point. Explosive dendritic formation is the result of competition between solid state light induced nucleation and melting mediated explosive growth.
Numerical Modeling of Energy-Beam Induced Localized Melting of Thin SI Films
Authors: Im J.S. , Lipman W J.D. , Miaoulis I.N. , Chenb C.K. , Thompson C.V.
Published: March 2011

We have developed a quantitative model, based on a two-dimensional finite difference enthalpy method, which accounts for the localized melting behavior of thin Si films on substrates. The model incorporates radiative and conductive heat flow components and takes account of the phase changes that occur during zone-melting recrystallization. Emphasis is placed on the effects resulting from the differences in reflectivity and emissivity between solid and liquid Si. The model provides quantitative information concerning the temperature profile of the Si film and the configuration of the solid-liquid interface. Results of the analysis indicate that there exist two distinct types of transition behavior: i) reflectivity-change dominated and ii) emissivity-change dominated. Partial melting and a nonplanar solid-liquid interface are characteristics of the reflectivity-change dominated behavior. The emissivity-change dominated behavior, on the other hand, can be characterized by explosive-like melting and a planar solid-liquid interface. The conditions and physical factors which give rise to these behaviors are discussed.
Qualitative Model for Surface Rippling of Zone Melting Recrystallized Silicon-on-Insulator Layers
Authors: Mertens Paul W. , Maes Herman E.
Published: March 2011

In zone melting recrystallization (ZMR) of thin silicon films different mechanisms can lead to thickness variations of the obtained silicon film. In this paper we will concentrate on some of these phenomena. One is the large scale mass transport, which typically leads to a thinned region at the start of the ZMR process. Another one, which is to a certain extent related to the first one, is the typical ripple formation that occurs especially under conditions that are commonly referred to as “low thermal gradient” regime.
Structure of Amorphous A12O3 Produced by Ion Implantation
Authors: Mchargue C. J. , Sklad P. S. , Angelini P. , White C. W. , Mccallum J. C. , Perez A. , Marest G.
Published: March 2011

The amorphous state can be produced in α-Al2O3 by ion beam induced displacements at 77 K or by displacements combined with chemical effects at room temperature. Progress toward understanding the amorphization process has been made from studies of the short-range order, electronic charge on implanted species, and the critical composition for amorphization. Results are presented for implantation of Al + O in the stoichiometric ratio, zirconium, iron, and tin.
Refractive Index Profiles of High Dose Ti Implanted Optical Waveguides in LiNbO3
Authors: Bremer T. , Ashley P.R. , Irmscher R. , Buchal Ch.
Published: March 2011

Single crystalline substrates of LiNb03 have been implanted with 48Ti ions at 200 keV and doses up to 4 × 1017 cm−2. The implants have been performed at wafer temperatures of 77 K, 300 K and 620 K. Immediate subsequent processing at 1273 K in wet oxygen ambient led to good epitaxial regrowth at all doses, if sufficient time was allowed. The maximum observed extraordinary refractive index change after regrowth Δne=0.04, indicating a solubility limit of 3.3×l021 Ti cm−3 corresponding to 18 % of Nb5+ replaced by Ti4+.
Crystallization of Intrinsic Amorphous Layers Produced by Stoichiometric Implantation of Al and O Ions in A-Axis Oriented Al2O3 Single Crystals
Authors: Zhou W. , Cao D.X. , Sood D.K.
Published: March 2011

Isothermal annealing behaviour of intrinsic amorphous layers produced by stoichiometric implantation in a—axis oriented α—Al2O3 single crystals has been studied. The amorphous phase transforms directly to α—Al2O3 at a well defined planar interface which moves towards the free surface. The epitaxial growth slows down after initial rapid crystallization, indicating two separate regimes. The interface velocity shows Arrhenius behaviour in both regimes with activation energies of 0.6 and 0.08 eV respectively. There is an evidence for additional surface or random crystallization into κ or γ-Al2O3 phases within the first few nm on the surface, after prolonged annealing. These results are remarkably different from those reported previously for c–axis oriented Al2O3 crystals, showing the importance of substrate orientation during crystallization. A tentative model to explain the crystallization behaviour is discussed.
Characterization of B and N Implanted Fused Silica
Authors: Arnold G. W. , Brow R. K. , Carr M. J. , Barbour J. C.
Published: March 2011

The implantation of B and N into fused silica can result in chemical incorporation into the glass with a consequent larger increase in refractive index than is possible due to volume compaction alone. B implantation produces anomalously large concentrations of oxygen-vacancy defects which aid in the establishment of B into a borosilicate layer. N implants can result in unreacted N accumulations in addition to N incorporated into a Si-oxynitride layer. The unreacted N can also be incorporated by implantation damage (e.g., Si, Ar, Kr)--before or after N implantation--which provides additional occupancy sites. These results are important with respect to the use of implantation-produced waveguides for optoelectronic devices.
Surface Reaction in NiO CoO MnO and FeO in the Electron Microscope
Authors: Buckett M. I. , Marks L. D.
Published: March 2011

Electron irradiation damage in the metal monoxide series of group Vll and VIII elements -NiO, CoO, MnO and FeO - has been investigated in the non-UHV electron microscope environment. NiO and CoO were also examined in the UHV environment. Each of these materials showed comparatively similar electron-stimulated oxidation of the surface in the non-controlled conventional HREM environment, at a vacuum level of approximately 10–7 Torr; while only ballistic damage was observed in both the NiO and CoO under UHV conditions.
Dual Implantations of Ti and C into Sintered Α-Sic and Hot Pressed Si3n4
Authors: Bhattacharya R.S. , Rai A.K. , Kung S.C. , Patrizio D.
Published: March 2011

Dual ion implantations of Ti+ and C+ into sintered a-SiC and hot pressed SÌ3N4 have been studied by Rutherford backscattering spectroscopy (RBS) combined with plan/cross section view transmission electron microscopy (TEM). The samples were analyzed before and after annealing at 1200°C for 2 hours in a vacuum of 1x10-6 torr. The results were compared with single ion implantation of Ti+. RBS analysis showed that no oxidation occurred during annealing and Ti diffused toward the surface in both SiC and SigN^ Cross section TEM analysis revealed the formation of TiC precipitates in SiC due to both dual (Ti+ + C+) and single (Ti+) ion implantations. Precipitates were found to form in SÌ3N4 as well; however, because of very close proximity of observed d values with those of TiC, TiN and β-SiC, it was not possible to uniquely identify the chemical nature of these precipitates. Thermo-dynamic calculations were performed to explain the observed results.
Effects of O2 Ion Bombardment of Y-Ba-Cu-Oxide during Thin Film Growth
Authors: Metzger G. , Fleddermann C. B.
Published: March 2011

Oxygen ion beam bombardment has been studied as a means for incorporating oxygen into thin films of Y-Ba-Cu-oxide either by enhancing the transport of oxygen to substrates during ion-beam sputtering, or by direct incorporation of oxygen with ion-assisted deposition. Optical emission spectroscopy was used to study the ion-beam bombardment of bulk superconducting targets as the oxygen content of the ion beam was varied. This study showed that oxygen did not directly combine with metallic elements in the target to increase the oxygen content of the stream of particles moving toward the substrate. Addition of a second ion beam directing oxygen ions toward the substrate during film growth caused large variations in the stoichiometry of the deposited films. At low oxygen ion currents, no increase in the oxygen content of the films was detected, while at relatively high currents, the oxygen incorporation increased. However, the sputtering of the metallic components of the film increased as the oxygen beam current increased, leading to very low growth rates.
Thermodynamic and Structural Properties of Mev Ion Beam Amorphized Silicon
Authors: Roorda S. , Sinke W.C. , Poate J.M. , Jacobson D.C. , Fuoss P. , Dierker S. , Dennis B.S. , Spaepen F.
Published: March 2011

Thermodynamic and structural properties of amorphous Si (a-Si), prepared by MeV 28Si+-ion implantation are investigated by differential scanning calorimetry, Raman spectroscopy and X-ray diffraction. The influence of thermal annealing below 500 °C on a-Si is investigated with these different probes. The observed changes result from structural relaxation. Raman spectroscopy and X-ray diffraction show that structural relaxation is accompanied by changes in the average atomic structure.
Spatial Damage Distribution in Electron-Beam Processed Gaas-Algaas Heterostructures, Experiment and Theory
Authors: Smith Doran D. , Fink Tobin , Braddock W. D.
Published: March 2011

The effect of electron beam irradiation on the transport properties of HEMT structures has been studied. The data is found to agree with a model containing no free parameters which predicts the spatial extent of the damage. As grown HEMT material was fabricated into Hall bars. The material was then characterized by measurement of 2D EG number density and drift mobility. The material was then irradiated at constant dose with electron energies between 2.5 and 20 keV. Damage was assessed by changes in the number density and mobility. The number density was essentially unchanged at all energies. No change in mobility occurred for 2.5, 15, and 20 keV, however, a decrease in the mobility occurred for energies from 5.0 to 12.5 keV. These results agree with our model of the electrons energy loss as a function of its path length. The defects are shown to be charged, and possible sources of the defects are discussed.
Changing the Structural State of Amorphous Silicon by Ion Irradiation
Authors: Roorda S. , Sinke W.C. , Poate J.M. , Jacobson D.C. , Dierker S. , Dennis B.S. , Eaglesham D.J. , Spaepen F.
Published: March 2011

Ion beams of keV and MeV energies have been used to bombard amorphous Si (a-Si), which had previously been annealed (‘relaxed’). Analysis by Raman spectroscopy and differential scanning calorimetry shows that when 1 out of every 20 Si atoms is displaced by a nuclear collision, the a-Si returns to its unrelaxed state and cannot be distinguished from as implanted a-Si. Moreover, the kinetics of the heat release on annealing of similarly bombarded crystalline Si (c-Si) are qualitatively identical to those of structural relaxation in a-Si. This implies that the population of ion beam induced defects in a-Si is very similar to that in c-Si. It also shows that defect annihilation is an important ingredient in the mechanism of structural relaxation of a-Si.
As and B Ion Implantation Through Mo and into Mo-Silicide Layers for Shallow Junction Formation
Authors: Angelucci R. , Merli M. , Solmi S. , Armigliato A. , Gabilli E. , Govoni D. , Poggi A.
Published: March 2011

Good quality p+/n and n+/p shallow junctions (< 0.15 um) with reverse current density of few nA/cm2 and low contact resistivity (∼ 5×10–7 Ω cm2) have been fabricated by using Mo suicide and Rapid Thermal Annealing (RTA). The processes of implantation through Mo films and into MoSi2 layers have been comparatively analysed on the basis of SIMS and carrier concentration profiles, TEM observations and DLTS measurements. In the case of n+/p diodes fabricated by ITM technology slightly worse leakage currents have been observed, in spite of the better planarity of the silicide-silicon interface exhibited by these structures.
Change in Magnetic Characteristic Of Stainless-Steel by Laser and Ion Beams
Authors: Sanda Hiroyuki , Takai Mikio , Namba Susumu , Chayahara Akiyoshi , Satou Mamoru
Published: March 2011

Focused Ar-ion laser and MeV ion beams were impinged onto stainless-steel foils to investigate the localized modification of the magnetic property associated with the phase transformation. The magnetic signal intensity of the Ar-ion laser irradiated areas was found to locally decrease at a laser power of 350 mW and almost extinguish at 550 mW with a beam spot size of 13.2 μm (at 1/e intensity) because of the localized retransformation into austenite. On the other hand, the magnetic signal intensity was found to increase by 3 MeV Au+ implantation because of the localized martensitic transformation. The magnetic signal for ferromagnetic substrates was much more enhanced than that for non-magnetic substrates. These results indicate that the beam-induced localized phase-transformation in stainless-steel can be applied to fixed magnetic recording.
Metastable Structures in Quenched Cr-Ti and Electron Irradiated Cu-Ti Alloys
Authors: Sinkler W. , Luzzi D.E.
Published: March 2011

Electron diffraction and imaging are used to characterize and contrast the structures and microstructures of a metastable Cr-Ti phase formed after quenching and a metastable Cu-Ti phase formed during electron irradiation. In both phases, marked structural anisotropies are found which have characteristics common to both of these bcc-based materials. It has been reported in the literature that this quenched-in metastable Cr-Ti phase undergoes a spontaneous structural relaxation into the amorphous state during sub-eutectoid temperature anneals [1]. Despite the similarity of the present experiments to those reported in the literature, an amorphization transformation was not observed. It is argued that the amorphization of this material requires the stabilization of the amorphous phase by an impurity.
Ion Beam Method to Study Fractal Aggregation of Magnetic Particles on Thin Solid Films:
Authors: Ding J.R. , Huang L. , Liu B.X.
Published: March 2011

This paper presents the experimental observations of Fractal Aggregates on thin solid films after either directly thin film deposition or additional ion irradiation. A linear correlation was found between the fractal dimension and the atomic magneton of the aggregating particles of Fe, Co, Cr and Ni.
Adhesion of Silver Films to Ion-Bombarded Alumina
Authors: Erck R. A. , Fenske F. R.
Published: March 2011

Silver films were deposited on alumina substrates using ion bombardment. Adhesion strength was measured as a function of deposition conditions, sputter-cleaning time, and bombarding ion species, using a pull-type adhesion tester. Argon- and argon/oxygen-ion sputtering produced large increases in adhesion strength, with the greatest increases occurring for oxygen-ion bombardment. Adhesion strength increased monotonically as a function of ion sputtering time. At a given deposition rate, further enhancement of adhesion is seen with concurrent ion bombardment.
Irradiation-Induced Grain Growth: Role of Dislocations
Authors: Allen Charles W. , Rehn Lynn E.
Published: March 2011

Existing theories of irradiation-induced grain growth assume that growth occurs by the boundary migration mechanism commonly observed for thermal growth and that it is only the point defects generated si boundaries during the irradiation which are responsible for boundary migration. In contrast, in situ observations during ion irradiation of Au films at temperatures less than 20 K even have clearly demonstrated that growth occurs both by boundary migration and by grain coalescence. Here we present further evidence for the latter. Furthermore, the substantial defect cluster activity observed during irradiation suggests that dislocations play a significant role in the growth phenomenon. Here, we also demonstrate qualitatively that glide of such dislocations to or “through” a boundary can produce essentially the same effect on boundary position or structure that the original point defects would have had if they had migrated individually to or through the boundary. Via dislocation motion, point defects originating far from a boundary may induce boundary migration or boundary structure change, and hence, grain growth.
Uv Excimer Laser-Induced Deposition of Palladium from Palladium Acetate Films
Authors: Esrom Hilmar , Wahl Georg
Published: March 2011

UV excimer laser-induced deposition of palladium from spin coated palladium acetate films in air is described. We have investigated mainly the deposition of palladium on aluminum oxide and quartz substrates and its dependence on the fluence and the number of excimer laser pulses. The decomposition mechanism was studied by measuring in situ the transmitted pulse energy during the exposure process. We have found that the excimer laser-induced decomposition of palladium acetate films is mainly pyrolytic and a simple model can be used to describe the decomposition process.