bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface Stress Effects On Fracture
Authors: Cammarata R.C. , Sieradzki K. 
Published: April 2011

AbstractThe effects of surface stress on fracture are reviewed. Calculations by Thomson et al. seem to suggest that surface stresses do not affect cleavage fracture when the crack propagates in a self similar manner even though the surface stress can lead to large stresses near the crack tip. However, surface stresses may have an important effect on dislocation emission near the crack tip. A simple analysis is offered to show how these effects may be incorporated into a modified Rice ductile-brittle fracture criterion by adding a term to the unstable stacking energy that takes into account the energy to form an incipient ledge.
Mechanical and Thermal Properties of SiC-SiC Composites Made With CVR SiC Fibers
Authors: Kowbel W. , Tsou H. T. , Bruce C. A. , Withers J. C. 
Published: April 2011

ABSTRACTNicalon fiber is the primary reinforcement in SiC-SiC composites currently produced by a variety of techniques including CVI and polymer infiltration. Low strength retention and dimensional change at high temperatures of the Nicalon fibers limits the choice of manufacturing processes which can be employed to produce low cost SiC-SiC composites. MER has developed a SiC reinforcement based upon the conversion of low cost carbon fabric to SiC via a Chemical Vapor Reaction (CVR) process. These new SiC filaments exhibit excellent creep resistance at temperatures up to 1600°C. SiC-SiC composites were fabricated using different types of graphite fabric converted to SiC fabric utilizing the CVR process combined with a polycarbosilane (PCS) infiltration and CVI densification. In addition, enhancement of the composite through-the-thickness thermal conductivity was accomplished via boron doping of the matrix. A correlation between processing conditions, microstructure and properties of the SiC-SiC composites will be presented.
The Effect of Source Microstructure on the Close-Space Sublimation of CdTe Thin Films for Solar Cell Applications
Authors: Albin D. , Rose D. , Swartzlander A. , Moutinho H. , Hasoon F. , Asher S. , Matson R. , Sheldon P. 
Published: April 2011

ABSTRACTThe microstructure of CdTe sources grown on bare 7059 and SnO2-coated 7059 glass substrates used in the close-space sublimation (CSS) growth of CdTe films, is affected by nucleation conditions during their fabrication. For CdTe sources grown on bare glass substrates, denser source microstructures with smaller grains are promoted by low-temperature nucleation conditions. Growth rates of CdTe films deposited using these source plates are inversely proportional to the packing density of the grains. CdTe sources grown on glass undergo significant texture changes during their use in subsequent CSS deposition. CdTe sources grown on SnO2-coated glass substrates exhibit dense structures both with and without low-temperature nucleation and increased grain size with low-temperature nucleation. These source plates show less texture change associated with thermal annealing than their bare-glass counterparts, however, they are much more susceptible to CdO formation during subsequent CSS deposition processes in which oxygen is present. Source oxidation results in a decrease of the (111)/(220) x-ray diffraction intensity. Analysis of the (111)/(220) intensity ratio with and without source oxidation suggests the preferential formation of CdO on the (111) planes. In general, source oxidation appears to be a inversely proportional to the grain size of the source material.
A Model of the Gas-Phase Chemistry of Boron Nitride CVD From BCl3 and NH 3*
Authors: Allendorf Mark D. , Melius Carl F. , Osterheld Thomas H. 
Published: April 2011

ABSTRACTThe kinetics of gas-phase reactions occurring during the CVD of boron nitride (BN) from BCl3 and NH3 are investigated using an elementary reaction mechanism whose rate constants were obtained from theoretical predictions and literature sources. Plug-flow calculations using this mechanism predict that unimolecular decomposition of BCl3 is not significant under typical CVD conditions, but that some NH3 decomposition may occur, especially for deposition occurring at atmospheric pressure. Reaction of BCl3 with NH3 is rapid under CVD conditions and yields species containing both boron and nitrogen. One of these compounds, Cl2BNH2, is predicted to be a key gas-phase precursor to BN.
The Chemistry of Boron and Titanium Diboride Formation: Decomposition of TiCl4 and BCl3 in Hydrogen and Helium*
Authors: Osterheld Thomas H. , Allendorf Mark D. 
Published: April 2011

ABSTRACTMeasurements of the decomposition of mixtures of boron trichloride (BCl3), titanium tetrachloride (TiCl4), and hydrogen at elevated temperatures are presented. The decomposition of BCl3 with hydrogen appears to drive the chemistry in this system. The species depositing boron on the surface contains at least 2 chlorine atoms. Once deposited, the surface chlorine is removed by reaction with hydrogen to form HCl and, presumably, surface B-H bonds.
XPS Studies of the Interactions of Biocells with Various Silicon Based Surfaces
Authors: Seal S. , Krezoski S. , Barr T. L. , Petering D. H. 
Published: April 2011

AbstractSiliceous materials are the principal components of Earth's crust and also have become key ingredients of modem technology. Recently, we have expanded our chemical characterization of complex silicates (e.g., framework [1] and sheet types [2]) to include studies of their interaction with select biocells [3,4]. It is becoming apparent that the surface chemistry of these silicates, and perhaps that of silica itself, plays a key role in the oft resulting cell pathogenesis, thus enhancing the value of further investigations with X-ray photoelectron spectroscopy. The present research describes the unique growth of Ehrlich (murine or rat tumor) cells on Sio and SiO2 wafers, and also on select seaentine silicates (such as chrysotile asbestos). Tbese growth studies were followed by both cell/silicate separations and unique freeze drying [3,4]. XPS examination at select stages discovered cell induced alterations in the Si, O, Mg and particularly Fe chemistry of the silicon based systems as well as corresponding changes in the cell chemistry. Many of these features were confirmed by atomic absorption spectroscopy.
Surface Induced Calcium Phosphate Nucleation and Growth
Authors: Song L. , Campbell A. A. , Li X. S. , Bunker B. C. 
Published: April 2011

AbstractCalcium phosphate nucleation on colloidal oxide surfaces, such as TiO2, SiO2 and Al2MO3, has been studied as a model system to understand the role of surface chemistry on crystal nucleation kinetics and phase formation. The nucleation induction times have been measured using Constant Composition (CC) technique and calcium phosphate phases formation have been determined mainly by X-ray diffraction. The results indicated TiO2 not only significantly reduces the nucleation induction time and interfacial energy but also stimulates octacalcium phosphate formation over dicalcium phosphate dihydrate. SiO2 and Al2O3 have little effect on both nucleation kinetics and phase formation.
Growth Dynamics and Exciton Localization in Strained CdSe Quantum Structures
Authors: Flack F. S. , Hunt A. , Hennessey H. , Samarth N. , Levy J. , Nikitin V. , Crooker S. A. , Awschalom D. D. , Jassim M. Al 
Published: April 2011

AbstractCoherently strained CdSe quantum structures are fabricated under varying dynamical growth conditions during the epitaxy of cubic CdSe on (100) ZnSe. Reflection high energy electron diffraction (RHEED) is employed to monitor the growth mode (2D vs. 3D). Conventional photoluminescence (PL) shows that both growth modes yield quantum structures with high PL efficiencies in which excitons are strongly localized by interface fluctuations at varying length scales. Spatially-resolved, near-field PL from quantum structures formed during 3D growth reveals reproducible fine structure in the PL spectrum attributed to emission from excitons laterally confined to quantum dot-like regions. Transmission electron microscopy (TEM) studies suggest that these observations result from a combination of island growth and strain-driven interdiffusion.
Effects of Birefringence in Ordered GaInP/AlGaInP Lasers
Authors: Moritz A. , Wirth R. , Geng C. , Scholz F. , Hangleiter A. 
Published: April 2011

AbstractTernary semiconductors like GaInP under certain growth conditions exhibit a (partial) chemical ordering in form of a superlattice of alternate Ga-rich and In-rich planes in (111) direction. We have performed measurements of the polarization properties of light propagating in ordered GaInP/AlGaInP quantum well waveguide structures with various amounts of strain and observed a mode conversion between transverse electric (TE) and transverse magnetic (TM) modes for light propagating along (110). Lasers built of ordered material with the cavity in this direction show a distorted polarization of the laser light which depends on ordering and strain. We show that these effects are caused by an optical birefringence due to the reduced symmetry of the ordered material which leads to a coupling of the TE and TM modes. Only a new linear combination of TE and TM modes, the “super-modes”, can propagate in the waveguide without change. Within this simple model the polarization behavior of the light in the waveguide and in lasers can be explained very well.
Modeling of Temperature Increase Due to Joule Heating During Electromigration Measurements
Authors: Liu H. C. Louie , Murarka S. P. 
Published: April 2011

AbstractElectromigration (EM), the mass transport phenomenon under applied electrical field, is known to cause degradation in interconnections and thus to compromise the devices' reliability. High current density and high temperature conditions are usually adopted to evaluate the EM lifetime. Such high current density will raise the temperature at the test sites because of Joule heating. Thus the actual temperature on the test surface, not the ambient temperature, is an important parameter affecting the lifetime of the metallization. A simple model is proposed here to predict the temperature rise in such interconnections and the calculated values agree well with the experimentally measured rise in temperature. Only heat conduction and convection are considered and illustrative equivalent electrical analogy technique is used to solve the problem. This model, using a commercially available spreadsheet and its iteration functions, is shown to match closely with experimental results.
Electromigration in Submicron Wide Copper Lines
Authors: Kononenko O. V. , Matveev V. N. , Koval Yu. I. , Dubonos S. V. , Volkov V. T. 
Published: April 2011

AbstractCopper films were deposited onto oxidized silicon wafers by the self-ion assisted technique. A 0 and 6 kV bias was applied to the substrate during the deposition. The films were patterned into parallel line arrays of 20 lines 0.5 mm long, using electron lithography and dry etching. After patterning, the lines were covered by silicon oxide and annealed in vacuum for 1 hour at the temperature 450° C. Electromigration testing was performed in air in the temperature range from 280° to 350° C and at a current density 3.106 A/cm2.It was found that the resistivities of the films deposited at 6 kV and without bias were 1.7 and 2.0 μΩcm, respectively. The median times to failure are 398.6 and 240 h and the deviations in the time to failure are 0.8 and 0.54 for 6 kV lines and 0 kV lines, respectively. An electromigration activation energy of 0.89 eV was found for 0 kV films.
Phase Formation in Cu(Sn) Alloy Thin Films
Authors: Clevenger L. A. , Arcot B. , Ziegler W. , Colgan E. G. , Hong Q. Z. , d'Heurle F. M. , Cabral C. , Gallo T. A. , Harper J. M. E. 
Published: April 2011

AbstractThe interdiffusion of Cu and Sn and the formation and dissolution of Cu-Sn precipitate phases have been examined for Cu(Sn) alloy thin films. Cu(Sn) films were deposited by electron beam evaporation in either a Sn/Cu bilayer or Cu/Sn/Cu trilayer film structure, with overall Sn concentrations from 0.1 to 5 atomic percent. Analysis by in situ resistivity, calorimetry, electron diffraction and x-ray diffraction measurements indicates that the bilayer and trilayer films form the intermetallic phase η-Cu6 Sn5 during film deposition. Upon heating, the ε-Cu3Sn phase forms at 170°C, then this phase dissolves into the Cu matrix at approximately 350°C. Finally, ζ- Cu10Sn3 phase forms and precipitates after heating to 500°C and cooling to room temperature. The final resistivity of Cu/Sn/Cu films with more than 2 atomic percent Sn was greater than 3.5 μΩ - cm. However, resistivities from 1.9 to 2.5 μΩ - cm after annealing were obtained with Cu/Sn/Cu films containing less than 2 atomic percent Sn.
Chemical Vapor Deposition of Copper Films: Influence Of The Seeding Layers
Authors: Yoon Kyoung-Ryul , Kim Seok , Choi Doo-Jin , Kim Ki-Hwan , Koh Seok-Keun 
Published: April 2011

AbstractThe low pressure chemical vapor deposition of Cu was investigated on TiN substrates that had been locally seeded with thin Cu layers. These Cu layers were 5Å, 40Å and 130Å thick and had been produced by PIB (Partially Ionized Beam) deposition. The growth rate and the XRD peak intensity ratio (I(111)/I(200)) of CVD-Cu increased somewhat in the case of Cu seeded TiN/Si substrates compared with as-received TiN/Si substrate. At the deposition temperature of 200°C, Cu film deposited on the 40Å seeded substrate had the lowest electrical resistivity value, 2.42 μ Ω cm that is as high as 1.5 times the bulk copper value. In adhesion test, as the seeding thickness increased from 0Å to 130Å, the adhesion strength increased from 21 N to 27 N.
Characterization of Dichlorosilane Based Tungsten Silicide Films For Local Interconnects
Authors: Ozkan Cengiz S. , Moinpour Mansour , Sarikay Mehmet 
Published: April 2011

AbstractUltrathin refractory metal silicide films, such as tungsten silicide (WSix) offer a wide range of applications in VLSI and ULSI circuits such as local interconnects, bit lines and wordlines. One practical way of depositing WSix is by a CVD technique in which WF6 is reduced by either SiH4 or SiH2Cl2. For sub 0.5 micron technologies, SiH4 based WSix shows limitations due to poor step coverage and high F incorporation (>1020 atoms/cm3 ). If the reducing agent is changed to SiH2Cl2, then these problems are largely eliminated. However, interactions between processing parameters and film properties to achieve compositionally and structurally uniform films are not well understood. In this investigation, SiH2Cl2 based WSix films (60-200 nm) deposited on undoped poly-Si, doped poly-Si and oxide substrates were studied after a high temperature furnace anneal and oxidation cycle. Electron transparent samples were prepared by a low temperature ion beam technique and the individual films of Si-SiO2-poly Si-WxSiy layers were investigated by high resolution cross sectional transmission electron microscopy, x-ray diffraction and electron nanospectroscopy techniques with a beam energy of 300 kV. RBS measurements were used to determine the composition profile through the depth of the film and Si/W uniformity in terms of Si-rich and W-rich interfaces. SIMS measurements were used to determine the impurity content in the silicide film and at the film/substrate interface. This paper focuses on the processing-structure relationships in terms of development of defect structures within WxSiy, the non-stoichiometric W-Si compositons and related crystal structures and the role of the nucleation step in modulating the Si/W ratio at the WSix, /poly-Si interface and discusses their implications on future process development.
0.1μm Interconnect Technology Challenges and the Sia Roadmap
Authors: Seidel Tom , Zhao Bin , Sematech  , Austin T X 
Published: April 2011

AbstractAnalysis of the National Technology Roadmap for Semiconductors (SIA) indicates a potential crisis in performance and reliability regarding the scaling of interconnects. In the future, increased component density and performance (e.g. logic instructions / sec.) may not be able to be achieved simultaneously for technology generations well before the manufacture of 0.1μm feature sizes circa 2005. Thermal management and engineering of signal noise are key issues. Although much can be done to achieve higher speed with product design architecture, one must consider new material paradigms by 0. 1μm generation to address the RC crisis.Needs exist in low cost simplified processes across a broad area of applications: local salicide interconnects, lower process temperature for poly-metal dielectric (to enable shallower junctions), lower dielectric constant materials for interconnects, and robust barriers for interconnect plugs and wiring metals. A shift to lower dielectric constant (low-k) materials (e.g. SiO-F, polymers, or aerogels) will be used as soon as integrated processes are demonstrated and manufacturing tools become available. The next full generation window of opportunity is the 0.18um generation (1GB) scheduled for manufacturing prototyping in 1998.This paper reviews the overall Roadmap characteristics, major solution strategies, and outlines the challenges in design, technology, and integration for 0.18μm and 0.1μm generations. Topics reviewed include discussion of process architectures and electrical characterization methodologies. Among the most challenging areas we have: control and lowering of contact resistance, manufacturing interconnects at aspect ratios exceeding 4:1, use of very low dielectric constant materials in multilevel counts approaching 6–7, use of controllable ultra thin barrier materials for interconnect plugs and wiring, barriers and cladding for containment and passivation of Cu, development of manufacturing worthy selective processes, engineering stress/electromigration issues and thermal management of low-k dielectric systems. New materials must be introduced into existing technology frameworks while designs migrate to lower voltage operation.
Growth and Analysis of Polycrystalline Carbon for Mos Applications
Authors: Hung Steven C. H. , Hoyt Judy L. , Gibbons James F. 
Published: April 2011

AbstractGraphitic polycrystalline carbon (polycarbon) is a candidate material for gate and local interconnect applications in MOS technology. High conductivity polycrystalline carbon films have been grown using Plasma Enhanced Chemical Vapor Deposition. Methane is used as the carbon source gas, and boron trichloride provides the boron doping. In this work, the electrical properties of polycarbon films are studied as a function of deposition temperature, gas-phase boron-to-carbon ratio, and plasma power. A more uniform grain alignment is obtained for samples deposited at low plasma power (˜ 3 W) and high growth temperatures (˜880°C). In these highly oriented samples, the C-axis tends to be aligned parallel to the growth direction. In-plane film resistivities were obtained by Hall measurements, and it was found that the highly-oriented samples exhibit the lowest resistivity (˜300 μΩ-cm). This result is consistent with the higher in-plane mobility in single crystalline graphite. Although the presence of boron trichloride appears to be important for the growth of polycarbon at low temperatures, the boron concentration in the film does not affect the resistivity as strongly as the grain alignment.
The Effect of Contact Implants on the Patterning of Tungsten Damascene Interconnects
Authors: Gambino J. P. , Jaso M. A. , Levine E. N. 
Published: April 2011

AbstractContact implants can increase the etch rate of BPSG during HF precleans used prior to metallization. As a result, troughs form in the implanted BPSG that can trap metal and cause leakage between interconnects. It is shown that the increase in HF etch rate is especially pronounced for BF2, implants, due to the presence of F. The topography, and hence the leakage, can be reduced by capping the BPSG with an undoped oxide prior to implantation.
Growth of Epitaxial CoSi2 Through a Thin Interlayer
Authors: Tung R. T. 
Published: April 2011

AbstractThe phenomenon of Ti-interlayer mediated epitaxy (TIME) of CoSi2 on Si(100) has attracted much academic and technological interest. As yet, the role of the interlayer, Ti, is not fully understood. The various drawbacks of the TIME process have driven the search for a better interlayer. New results are presented which demonstrate the efficacy of a thin SiOx layer, grown in a peroxide-containing aqueous solution, in inducing nearly perfect epitaxial growth of CoSi2 on practically all surfaces of Si. This technique, dubbed oxide mediated epitaxy (OME), allows a thin layer of epitaxial CoSi2 to grow sub-surface, leaving the SiOx layer largely on the surface of the silicide. An interesting result of the surface oxide cap is a significant re-evaporation of cobalt observed during deposition at elevated temperatures. Thicker (10-30nm), excellent quality, CoSi2 single crystal thin films have been grown by repeated growth sequences on Si(100), (110), (211) and (511). Nearly perfect type A oriented CoSi2 layers were grown on Si(111) using mixed A/B oriented template layers.
Computer Simulation of Xe adsorption in Zeolite Y
Authors: Gupta Vishwas , Davis H. Ted , McCormick Alon V. 
Published: April 2011

AbstractComputer modeling of fluids in zeolites can provide a detailed molecular level understanding of the process of adsorption and diffusion under the influence of the 3-D potential field and the confinement offered by the crystal structure. We have shown that there is a strong link between the location, geometry and energetics of sites and the observed thermodynamics and spectroscopy of the adsorbates. Here we report on the modeling of Xe in zeolite Y, which is of interest both because it is commercially important and because it offers two distinct adsorption sites.
The Synthesis, Structure and Catalytic Properties of Some Aluminophosphate and Gallophosphate Materials Prepared Using Chiral Metal Complex Templates
Authors: Wilkinson A. P. , Gray M. J. , Stalder S. M. 
Published: April 2011

AbstractThe synthesis and crystal structure determination of d,l-Co(en)3.Ga3P4O16, xH2O (Pnna, a = 8.6502(9), b = 21.528(3), c = 13.717(2) Å) is described. This novel layered material contains Ga3P4O163- macroanions. The preparation and preliminary catalytic testing of a vanadium doped aluminophosphate that is isostructural with the gallophosphate is also discussed.
Zeolite Membranes from Kaolin
Authors: Karle B. G. , Brinker C. J. , Phillips M. L. F. 
Published: April 2011

AbstractZeolite films are sought as components of molecular sieve membranes. Different routes used to prepare zeolite composite membranes include growing zeolite layers from gels on porous supports, depositing oriented zeolites on supports, and dispersing zeolites in polymeric membranes. In most cases, it is very difficult to control and avoid the formation of cracks and/or pinholes. Our approach to membrane synthesis is based on hydrothermally converting films of layered aluminosilicates into zeolite films. We have demonstrated this concept by preparing zeolite A membranes on alumina supports from kaolin films. We have optimized the process parameters not only for desired bulk properties, but also for preparing thin (ca. 5 μm), continuous zeolite A films. Scanning electron microscopy shows highly intergrown zeolite A crystals over most of the surface area of the membrane, but gas permeation experiments indicate existence of mesoporous defects and/or intercrystalline gaps. It has been demonstrated that the thickness of the final zeolite A membrane can be controlled by limiting the amount of precursor kaolin present in the membrane.