bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanical Crystallization of Metglas Fe78B13Si9 by Cryogenic High Energy Ball Milling
Authors: Huang B. , Perez R.J. , Crawford P.J. , Nutt S.R. , Lavernia E.J. 
Published: April 2011

AbstractA nanocrystalline material was synthesized by cryogenic ball milling of Metglas Fe78B13Si9 ribbons. The nanocrystalline structure consisted of α-Fe(Si) and Fe2B grains of 2-13 nm in diameter. In the early stages of milling, bending-induced shear bands were formed, followed by the initial stages of crystallization. As the milling proceeded, predominantly wearlike mechanisms caused further crystallization. The crystallization process was slowed considerably by the addition of 17 at.% Ni during cryogenic milling. The results indicate that the 17 at.% Ni did not form a supersaturated solid solution in the metallic glass, but impeded crystallization by reducing the efficiency of bending and wear-like mechanisms during milling.
0.35 μm Technologies in Japan
Authors: Kikkawa Takamaro , Sakai Isami 
Published: April 2011

AbstractThis paper describes silicide and salicide technologies in Japan for 0.35 μm CMOS ULSIs and beyond. Polycide gate electrodes have been developed for CMOS devices from 1.0 μm to 0.35 μm design rule regime, in which Wsi2 has been used dominantly as a silicide gate material. On the other hand, silicide films are formed selectively on source/drain diffusion layers by salicide techniques, in which TiSi2 is used as a salicide material. TiSi2 is also used as a salicide material of both gate electrodes and source/drain diffusion layers for dual gate (n+/p+) CMOS. The TiSi2 thin film is formed by Ti sputtering and subsequent rapid thermal annealing. A preamorphization technique before Ti sputtering has been developed to obtain equal silicide properties on p+ and n+ diffusion layers. A high-temperature Ti sputtering technique has been developed in conjunction with pre-amorphization. CoSi2 and NiSi have also been developed as salicide materials for quartermicron CMOS and beyond.
Stress in Silicon Due to the Formation of Self Aligned Poly-CoSi2 Lines Studied by Micro-Raman Spectroscopy
Authors: Howard D. J. , Wolf I. De , Bender H. , Maex K. 
Published: April 2011

AbstractThe application of CoSi2 in ever shrinking Si CMOS source-drain technologies demands a better knowledge of the states of stress caused by the formation of cobalt-silicides in Si. In this study the variation in local mechanical stress in the silicon substrate near arrays of polycrystalline cobalt-silicide lines was investigated by micro-Raman spectroscopy. The lines were formed by annealing Co sputtered in windows in lithographically patterned, thermal oxide coated Si wafers. The CoSi2 lines varied in width from ˜0.25 to 5.0μ, in number from 2 to 7, and in thickness from ˜ 10 to 230nm. The spacing between lines was 1 and 3 times the line width.Trends in the Si stress between CoSi2 lines are described as a function of line width and line thickness. From the stress measured in the Si, information is obtained about the stress in the CoSi2 lines. In addition, the Si stress due to lines of primarily CoSi phase (monosilicide) is compared with the Si stress due to polycrystalline-CoSi2 (disilicide) lines.Cross section TEM and SEM micrographs of the CoSix line morphologies are used to aid the description of the resulting stress profiles. Some theoretical modeling of the stress in the Si due to the CoSix lines is presented for comparison with the micro-Raman spectroscopy results.
Electrical Characteristics of CoSi2 Layers Formed by Mevva Implantation of Co into Si
Authors: Peng Qicai , WONG S. P. 
Published: April 2011

AbstractHigh dose Co implantation into Si has been performed with a metal vapor vacuum arc (MEVVA) ion source at an extraction voltage of 70 kV to doses from 8×1016 to 6×1017 ions cm−2 at substrate temperatures (Ts) in the range of 210°C to 700°C. Annealing was performed in nitrogen at various temperatures for various time intervals by either furnace annealing (FA) or rapid thermal annealing (RTA). The electrical properties of the CoSi2 layers formed were studied using resistivity and Hall effect measurements from 10 to 300K. We found that for all the samples prepared by MEVVA implantation, as long as a continuous CoSi2 layer was formed after annealing, a strong temperature dependence of the Hall coefficient was observed with a large peak at around 90 to 110K. The magnitude of the peak also varies depending on the substrate parameters and processing conditions. However, the temperature dependence of the resistivity for these CoSi2 layers follows the atthiessen's rule. We also found that it does not require high substrate temperature nor very high temperature annealing in order to form a CoSi2 layers with low resistivity by MEVVA implantation. Such low resistivity CoSi2 layers can be formed with a substrate temperature as low as 210°C after either RTA at high temperature for a few seconds or FA at a relatively low temperature of 750°C for one hour. The dependence of the electrical properties on Ts is also presented and discussed.
Epitaxial Films of Cobalt Disilicide (100) Evaporated onto Si (100) from a Mixed Source
Authors: Goeller P. T. , Wang Z. , Sayers D. E. , Glass J. T. , Nemanich R. J. 
Published: April 2011

AbstractThin films of (100) oriented CoSi2 have been electron beam evaporated onto Si(100)substrates from a mixed Co-Si target. A sharp c(2×2) low energy electron diffraction (LEED)pattern resulted after annealing the films to 800°C. Extended x-ray absorption fine structure (EXAFS) of the film indicated the phase to be CoSi2. Quantitative x-ray photoelectron spectroscopy (XPS) analysis revealed the surface of the film to be slightly Si rich, indicating the Si terminated CoSi2 variant. Analysis of transmission electron microscope (TEM) diffraction patterns also provided evidence of the (100) orientation of the film.
Patterning of Silicide Layers by Local Oxidation
Authors: Dolle M. , Mantl S. , Hacke M. , Mesters S. T. , Bay H. L. 
Published: April 2011

AbstractA novel method for patterning of silicide layers based on local oxidation is presented. We investigated unifom and local oxidation of epitaxial CoSi2 layers on Si(100). During thermal oxidation of CoSi2 a SiO2 surface layer forms and the silicide layer moves deeper into the substrate. Single crystalline CoSi2 layers on Si(100) remain single crystalline even if they are shifted into the substrate several hundred nm. Local oxidation of such a silicide layer allows lateral patterning of the silicide. The oxidized regions of the silicide layer are pushed inwards and separate from the surface layer at a critical oxidation time. This allows the formation of buried patterned silicides or metallized mesa structures. The technique seems to be also applicable for polycrystalline silicides.
Laser Crystallized Polysilicon Thin Films and Applications
Authors: Boyce J. B. , Mei P. , Fork D. K. , Anderson G. B. , Johnson R. I. 
Published: April 2011

AbstractPulsed excimer-laser crystallization of amorphous silicon on non-crystalline substrates is an important processing technique for large-area polycrystalline silicon films and devices. Interest stems, in large part, from proposals to use polycrystalline silicon on glass in large-area electronic applications, such as flat-panel active matrix displays and two-dimensional imaging systems. The polycrystalline silicon is envisioned to increase the functionality and reduce costs over the current circuits that use amorphous silicon. Also, it is found that laser-crystallized polycrystalline silicon exhibits some interesting materials properties, such as a sharp peak in the average grain size with large lateral grain growth as a function of excimer laser energy density. The average grain size increases with increasing laser fluence and peaks on the order of several microns or two orders of magnitude larger than the film thickness. The grain size then decreases with further increases in laser fluence. This peak in grain size is accompanied by a similar peak in the Hall electron mobility. This is a significant relationship for devices since the grain structure has a substantial influence on electrical properties. But to the detriment of device parameters, this large lateral grain growth occurs over a very arrow range of laser fluences and is accompanied by a corresponding peak in the surface roughness of the films. These relationships between laser processing conditions, materials properties, and device parameters force a compromise between large grain size for high mobility and homogeneity of material for uniformity of device characteristics. A window does exist in process parameter space where good-quality devices with uniform characteristics have been obtained. In addition, these attributes have been achieved under conditions that yield good polycrystalline silicon and good amorphous silicon devices on the same wafer within a mm of one another, allowing for hybrid polycrystalline and amorphous silicon circuits.
Silicon Recrystallization in Sipos Material Obtained by Disilane
Authors: Pedroviejo J. J. , Garrido B. , Ferrer J. C. , Cornet A. , Scheid E. , Morante J. R. 
Published: April 2011

AbstractConventional and Rapid Thermal Annealing of Semi-Insulating Polycrystalline Silicon layers obtained by Low Pressure Chemical Vapor Deposition (LPCVD) from disilane Si2H6 have been performed in order to determine the structural modifications induced on the layers by these thermal treatments. The study of these modifications has been carried out by several analysis methods like FTIR, XPS, TEM, RAMAN and ellipsometry. The results obtained are presented, contrasted and discussed in this work.
Mechanical Properties of Thermally Crystallized Boron-Doped Silicon Thin Films
Authors: Scafidi P. , Cali J. , Bustarret E. 
Published: April 2011

AbstractP-type polycrystalline silicon films on silicon wafers were obtained by annealing at 575 °C boron-doped amorphous hydrogenated silicon (a-Si:H) films. During the anneal, the internal stress of the film changed from compression to tension. The crystallization kinetics became faster when increasing the boron concentration. The hardness and elastic modulus of each film were determined by nanoindentation. The elastic modulus increased systematically upon crystallization. Wafer curvature monitoring during the thermal cycle allowed us to derive the thermal expansion coefficient of a-Si:H for different boron doping levels. Above a critical temperature of 320°C, the internal stress of the a-Si:H films rapidly changed toward a tensile state, independent of the boron concentration. Analysis of the hydrogen-bonding configurations by Fourier transform infrared spectroscopy indicated that this rapid stress change was due to hydrogen out-diffusion. The evolution of the internal stress with time was followed during the 575°C crystallization isothermal plateau. The circular blistering and spalling observed upon annealing in some cases of low doping levels was correlated with the presence of microvoids and with the internal stress of the a-Si:H film.
High Performances of Low Temperature (≤ 600°C) Unhydrogenated Polysilicon Thin Film Transistors
Authors: Pichon L. , Raoult F. , Mourgues K. , Bonnaud O. 
Published: April 2011

AbstractLow temperature unhydrogenated polysilicon thin film transistors are elaborated through a fourmask gate aluminium process. Temperature process does not exceed 600°C. Active layer is made of undoped polysilicon layer, an in-situ phosphorus polysilicon layer constitutes source and drain windows and a SiO2 APCVD layer ensures gate insulation. The transistors exhibit electrical properties as good as in the case of hydrogenated ones: a low threshold voltage (VT = 4–5 V), an acceptable optimum field effect mobility (≅ 42 cm2/Vs), a high On/Off state switching, and a high On/Off state current ratio (≅ 107) for a drain voltage equal to 1 V.
Thin Ti/TiN Barriers for Ulsi Application
Authors: Huang C. K. , Wang Shi-Qing 
Published: April 2011

AbstractIn advanced ULSI devices, Ti (titanium)/TiN (titanium nitride) film stack is commonly used as liner materials. Ti is used to reduce contact/via resistance while TiN is utilized as an adhesion/diffusion barrier layer. Ti/TiN liner with optimized thickness combinations should be used for progressively advanced ULSI devices with features of reduced dimensions and increased aspect ratios in order to effectively reduce contact/via resistance, ensure barrier quality, and maximize cross section of metal conductors with low electrical resistivities. This study evaluates the film properties such as sheet resistance, density, stress, grain structures, and reflectance of individual Ti and TiN, and composite Ti/TiN films manufactured by collimated physical vapor deposition (PVD). The film thickness ranges from 5 to 60nm. The dependence of these properties on the film thickness will be discussed.
Strain Measurement and Calculation in Passivated Cu Lines Deposited by Three Different Methods
Authors: Marieb T. , Mack A. S. , Cox N. , Gardner D. , Mu X. C. 
Published: April 2011

AbstractPassivated Cu lines deposited by CVD, electroplating, and sputter-reflow were investigated using x-ray diffraction. Blanket films of the three types were measured for strain and texture post-deposition and after an anneal step to mimic the passivation temperature step. Texture in the CVD films was random, while the electroplated and sputtered films showed a strong {111} texture. Lines were then measured of each type. The measured strain was modeled using finite element calculations. While the strain in Cu was high compared to Al lines of similar geometry, no stress voiding was observed using high voltage scanning electron microscopy.
Dynamic Simulation of Crack Propagation with Dislocation Emission and Migration
Authors: Zacharopoulos N. , Rolovitz D. J. , Lesar R. A. 
Published: April 2011

AbstractWe present a simulation procedure for fracture that self-consistently accounts for dislocation emission, dislocation migration and crack growth. We find that the dislocation microstructure in front of the crack tip is highly organized and shows a complex temporal-spatial evolution. The final dislocation microstructure and the number of emitted dislocations immediately proceeding fracture varies rapidly with the loading rate. For high loading rates, fracture occurs at smaller loads with increasing loading rate. However, the load at fracture shows a maximum with respect to loading rates.
Effect of Crack Blunting on Subsequent Crack Propagation
Authors: Schiøtz J. , Carlsson A. E. , Canel L. M. , Thomson Robb 
Published: April 2011

AbstractTheories of toughness of materials depend on an understanding of the characteristic instabilities of the crack tip, and their possible interactions. In this paper we examine the effect of dislocation emission on subsequent cleavage of a crack and on further dislocation emission. The work is an extension of the previously published Lattice Greens Function methodology[l, 2, 3]. We have developed a Cavity Greens Function describing a blunt crack and used it to study the effect of crack blunting under a range of different force laws. As the crack is blunted, we find a small but noticeable increase in the crack loading needed to propagate the crack. This effect may be of importance in materials where a dislocation source near the crack tip in a brittle material causes the crack to absorb anti-shielding dislocations, and thus cause a blunting of the crack. It is obviously also relevant to cracks in more ductile materials where the crack itself may emit dislocations.
Hydrogen Diffusion in Quartz: A Molecular Dynamics Investigation
Authors: Bongiorno A. , Colombo L. 
Published: April 2011

AbstractWe present a molecular dynamics investigation on hydrogen diffusivity in crystalline quartz by computing the diffusion coefficient over a wide range of temperatures (700K < T < 1500K) and by characterizing the diffusion path and mechanism. Our main findings are: (i) hydrogen diffusion is anisotropically confined along the c-axis in α- and β-quartz; (ii) hydrogen diffuses through a jump-like mechanism; (iii) the temperature-dependent diffusivity follows an Arrhenius law with activation energy of 0.56 eV and 0.27 eV for α-and β-quartz, respectively.
Calculation of Electromagnetic Constitutive Parameters of Insulating Magnetic Materials with Conducting Inclusions
Authors: Kuster Drs. Eric , Moore Rick , Lust Lisa , Kemper Paul 
Published: April 2011

AbstractA Method of Moments (MoM) electromagnetic model of percolating conducting films was applied to calculate the effective parameters of the composite formed by conducting inclusions placed within a dispersive magnetic but nondispersive dielectric matrix. The MoM calculations demonstrate a coupling between the magnetic properties of the matrix and the effective composite permittivity and frequency dispersion of the composite. The coupling of permittivity and permeability is observed near the percolation threshold of the composite and for high conductivity inclusions. The prediction agrees with physical expectations since near percolation the conduction correlation length dominates the effective permittivity of the composite and this correlation length is determined by both the permittivity and permeability of the composite.
Mechanism Of Thermally Assisted Creep Crack Growth
Authors: Golubović Leonardo , Moldovan Dorel 
Published: April 2011

AbstractWe use atomistic Monte-Carlo simulations to investigate the dynamics of cracks which sizes are smaller than the Griffith length. We demonstrate that such cracks can irreversibly grow proviso their size is larger than a certain critical length which is smaller than the Griffith length, as recently suggested [ L. Golubović and A. Peredera, Phys. Rev. E51, 2799 (1995)]. We show here that this thermally assisted creep crack growth is dominated by irreversible changes in the region of the crack tip, primarily in the form of dislocation emissions and nucleation of microcavities and voids. These processes act together during the crack growth: the crack tip region acts as a source for emissions of dislocations which subsequently serve as seeds for creation of vacancy clusters in a region away but still close to the crack tip. Eventually, passages between these vacancy clusters and the mother crack are formed and the crack thus increases in size. As this process repeats, the crack grows.
Mechanism Of Ductile Rupture In The AL/Sapphire System Elucidated Using X-Ray Tomographic Microscopy
Authors: King Wayne E. , Campbell Geoffrey H. , Haupt David L. , Kinney John H. , Riddle Robert A. , Wien Walter L. 
Published: April 2011

AbstractThe fracture of a thin metal foil constrained between alumina or sapphire blocks has been studied by a number of investigators. The systems that have been investigated include Al [1,2], Au [3], Nb [4], and Cu [5]. Except for Al/ Al2O3interfaces, these systems exhibit a common fracture mechanism: pores form at the metal/ceramic interface several foil thicknesses ahead of the crack which, under increasing load, grow and link with the initial crack. This mechanism leaves metal on one side of the fracture surface and clean ceramic on the other. This has not been the observation in Al/ A12O3 bonds where at appropriate thicknesses of Al, the fracture appears to proceed as a ductile rupture through the metal.The failure of sandwich geometry samples has been considered in several published models, e.g., [6,71. The predictions of these models depend on the micromechanic mechanism of crack extension. For example, Varias et al. proposed four possible fracture mechanisms: (i) near-tip void growth at second phase particles or interfacial pores and coalescence with the main crack, (ii) high-triaxiality cavitation, i.e., nucleation and rapid void growth at highly stressed sites at distances of several layer thicknesses from the crack tip, (iii) interfacial debonding at the site of highest normal interfacial traction, and (iv) cleavage fracture of the ceramic. Competition among the operative mechanisms determines which path will be favored.This paper addresses the question of why the fracture of the A1/A12O3 system appears to be different from other systems by probing the fracture mechanism using X-ray tomographic microscopy (XTM). We have experimentally duplicated the simplified geometry of the micromechanics models and subjected the specimens to a well defined stress state in bending. The bend tests were interrupted and XTM was performed to reveal the mechanism of crack extension.
Simulation Of Thermal Stresses, Voids And Fracture At The GaAs/Ceramic Interface
Authors: Strifas Nickolaos , Christou Aris 
Published: April 2011

AbstractStresses induced at the GaAs-Al2O3 interface by large ΔT excursions have been investigated by finite element simulation and have been correlated with experimental results. The effects of power and temperature cycling on crack propagation at the die attach are investigated. The FEA (finite element analysis) method is used to simulate the effect of die attach voids on the peak surface temperature and on the die stresses. These voids in the die attach are identified to be the major cause of die cracking. It was found that stresses developed on the die because of the environmental temperature changes and their dissipation as part of an effective thermal management is necessary to ensure reliable performance.
Stress-assisted Kosterlitz-Thouless Dislocation Nucleation: the Statistical Physics of Plastic Flow
Authors: Selinger Robin L. Blumberg 
Published: April 2011

AbstractThe stress-assisted Kosterlitz- Thouless (K-T) transition was proposed by Khantha, Pope and Vitek [1] as a possible mechanism for the abrupt transition from brittle to ductile behavior of single crystals as a function of temperature. We argue that in a two-dimensional crystal under elevated temperature and applied shear stress, the microscopic mechanism of the stressassisted K- T transition is the nucleation of dislocation dipole pairs with a preferred Burgers vector orientation. This defect population gives rise to an anisotropic hexatic phase with quasi-long range order along one axis and short-range order along the orthogonal axis. The laboratory signature of such a phase is scattering peaks that are “streaked,” i.e. strongly broadened along a single direction. We discuss experimental data for an analogous twodimensional system which displays order of this type. Potential implications for the brittleductile transition in three dimensions are outlined.
Molecular Statics Simulation Of Crack Propagation In A-Fe Using Eam Potentials
Authors: Shastry Vijay , Farkas Diana 
Published: April 2011

AbstractThe behavior of mode I cracks in α-Fe is investigated using molecular statics methods with EAM potentials. A double ended crack of finite size embedded in a cylindrical simulation cell and fixed boundary conditions are prescribed along the periphery of the cell, whereas periodic boundary conditions are imposed parallel to the crack front. The displacement field of the finite crack is represented by that of an equivalent pileup of opening dislocations distributed in a manner consistent with the anisotropy of the crystal and traction free conditions of the crack faces. The crack lies on the {110} plane and the crack front is located either along á100ñ, á110ñ or á111ñ directions. The crack tip response is rationalized in terms of the surface energy (γs) of the cleavage plane and the unstable stacking energies (γus) of the slip planes emanating from the crack front.