bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Dichlorosilane Based Tungsten Silicide Films For Local Interconnects
Authors: Ozkan Cengiz S. , Moinpour Mansour , Sarikay Mehmet
Published: April 2011

Ultrathin 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

Analysis 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

Graphitic 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

Contact 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

The 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

Computer 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

The 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

Zeolite 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.
Synthesis and Crystal Structure of Ulm-16, A New Open Framework Fluorinated Gallium Phosphate with 16-Ring Channels
Authors: Loiseau Thierry , Férey Gérard
Published: April 2011

The synthesis and characterization of ULM-16, a new fluorinated gallophosphate Ga4(PO4)F2• 1.5 NC6H14• 0.5 H2O • 0.5 H3O, is described. This material is hydrothermally prepared at 180°C using cyclohexylamine as the structuring agent. It cristallizes in the orthorhombic space group Pbcn (n° 60) with a = 27.329(4) Å, b = 17.377(2) Å, c = 10.2124(5) Å, V = 4849.6 (9) Å3and Z = 8. The structure is built up from vertex-linked GaO4and PO4tetrahedra, GaO4F trigonal bipyramids and GaO4F2octahedra forming hexameric units and infinite double crankshaft chains (calledccor UUDD). The hexameric unit is similar to that found in ULM-3, ULM-4, ULM-5 and ULM-8. The two types of building units are fully connected by vertex-sharing with respect to a strict Ga-P alternation. The 3-D framework consists of cylindrical tunnels delimited by sixteen and six polyhedra running along [001]. The cyclohexylamine molecules are trapped in the wider pores and interact with the bridging fluorine atoms and hydration water through hydrogen bonds. The ULM-16 topology is closely related to that of ULM-5 where, in ULM-16, the infinite crankshaft chains replace the isolated D4R cages of ULM-5. TGA curve (under argon) indicates that the ULM-16 structure is intact up to 800°C. Structural relationships will be stated explicitly for the different structures of the ULM-n series containing the hexameric units.
A Rapid Supercritical Extraction Process for the Production of Silica Aerogels
Authors: Poco J. F. , Coronado P. R. , Pekala R. W. , Hrubesh L. W.
Published: April 2011

Silica aerogels are a special class of porous materials in which both the pore size and interconnected particle size have nanometer dimensions. This structure imparts unique optical, thermal, acoustic, and electrical properties to these materials. Transmission electron microscopy and small angle x-ray scattering show that this nanostructure is sensitive to variations in processing conditions that influence crosslinking chemistry and growth processes prior to gelation. Recently, Lawrence Livermore National Laboratory (LLNL) has demonstrated that a Rapid Supercritical Extraction (RSCE) process can be used to prepare near-net shape silica aerogels in hours rather than days. Preliminary data from RSCE silica aerogels show that they have improved mechanical properties and slightly lower surface areas than their conventionally dried counterparts, while not compromising their optical and thermal performance.
Sol-Gel Polymerization of Tetraalkoxygermanium and Organotrialkoxygermanium Monomers
Authors: Baugher Brigitta M. , Loy Douglas A.
Published: April 2011

While the sol-gel polymerizations of tetraalkoxy- and organotrialkoxysilanes have been extensively studied, there have been few reports of similar investigations with the analogous tetraalkoxygermanium and organotrialkoxygermanium compounds. Germanium alkoxides have received less attention due, in part to their higher cost, but also their greater reactivity towards hydrolysis and condensation reactions. Germanium oxide materials are potentially interesting because the Ge-O-Ge linkage is labile (compared with the siloxane bond in silica gels and polysilsesquioxanes) opening up the possibility of further chemical modification of the polymeric architecture. This may permit hydrolytic reorganization of germanium oxide networks under relatively mild conditions. In this paper, we will present the results of our investigations of the solgel polymerizations of tetraethoxygermanium 1, tetraisopropoxygermanium 2, and methyltriethoxy-germanium 3 to afford network materials as both xerogels and aerogels.
Activated Carbon Filaments with Mainly Mesopores
Authors: Lu Weiming , Chung D. D. L.
Published: April 2011

Activated carbon filaments of diameter ∼ 0.1 μm, mean pore size (BJH) 65 Å, specific surface area 1540 m2/g and burn-off 64% (yield 36%) were obtained by activating carbon filaments of diameter ∼ 0.1 μm in CO2 + N2 (1:1) at 970°C for 100 min. Prior to this activation, the filaments were surface oxidized by exposure to ozone (0.3 vol.% in air) at 150°C for 3 min.
Upgrading of Heavy Oil From The San Joaquin Valley of California by Aqueous Pyrolysis
Authors: Reynolds John G. , Murray Ann M. , Nuxoll Eric V. , Fox Glenn A. , Thorsness Charles B. , Khan M. Rashid
Published: April 2011

Midway Sunset crude oil and well-head oil were treated at elevated temperatures in a closed system with the presence of water. Mild to moderate upgrading, as measured by increase in API gravity, was observed at 400°C or above. Reduced pressure operation exhibited upgrading activity comparable to upgrading under normal aqueous pyrolysis conditions. Reduced pressure operation was obtained by the use of specific blending methods, a surfactant, and the proper amount of water. The use of metal complexes provided additional upgrading. The best of the minimum set tested was Co(ll) 2-ethylhexanoate. Fe, Zn, Mo, Cu, and Ni complexes also showed some levels of activity.
Flocculation of Colloidal Silica With Aluminum Fractal Polymers
Authors: Lartiges B. S. , Michot L. J. , Bottero J. Y.
Published: April 2011

Flocculation of colloidal silica and Na-montmorillonite was investigated by 27A1 MAS NMR and XRD under various chemical conditions. The results showed that destabilization has many features in common with flocculation by addition of conventional organic polymers.
Quantitative Determination of Chromium Valence in Environmental Samples Using Xafs Spectroscopy
Authors: Peterson M. L. , Brown G. E. , Parks G. A.
Published: April 2011

Synchrotron x-ray absorption fine structure (XAFS) spectroscopy provides quantitative information on the speciation of Cr in complex oxide samples, including the Cr(VI):Cr(III) ratio, without any sample pretreatment. We discuss several XAFS methods that can be used for this purpose, including: (1) measurement of the height of the pre-edge peak of Cr K-edge spectra which is caused by ls→3d electronic transitions occurring predominately in the Cr(VI)O4 tetrahedron; (2) fitting observed XANES spectra using combinations of experimental spectra from Cr(III)- and Cr(VI)-containing model compounds; (3) fitting observed EXAFS spectra using combinations of experimental spectra from Cr(III)- and Cr(VI)-containing model compounds; and (4) ab-initio modeling of observed Cr K-EXAFS spectra using theoretical phase-shift and amplitude parameters for Cr(III)O6 and Cr(VI)O4 models. The first method is shown to be the simplest and most accurate. The samples examined using these methods include highly pure model compounds, Cr3+2O3 and Na2Cr6+O4·4H42O, as well as more complex soil samples taken from Cr-contaminated industrial sites and Cr waste disposal pits. We present XAFS evidence for the reduction of Cr(VI) to Cr(III) after reaction with the Fe(Il)-bearing oxide magnetite, Fe3O4, and show that Cr associated with magnetite in soils is reduced, whereas that associated with non-Fe(II)-bearing silicate minerals is not. Also presented are ab-initio multiplescattering calculations of XANES spectra of an Cr(VI)O4 tetrahedron, which help explain the XANES features of this Cr species in solids and aqueous solutions.
The Evaluation of SrBi2Ta2O9 Films for Ferroelectric Memories
Authors: Gutleben C.D.
Published: April 2011

For use in ferroelectric memories, the layer structure ferroelectric SrBi2Ta2O9 (SBT) appears to have some stability-related advantages over the more commonly known PZT class of ferroelectrics. Currently we are evaluating the feasibility of integrating this material into a state of the art CMOS memory process. Our primary scientific goal is to identify the intrinsic limitations of SBT which may restrict the engineering applications of films grown by even perfectly optimized processes. To this end we have utilized a wide variety of microanalysis probes to examine polycrystaline SBT films grown under various conditions by both MOD and Flash MOCVD. We have found that X-ray diffraction methods must be supplemented by high resolution X-ray photoelectron spectroscopy (XPS) in order to fully analyze the secondary phases which are commonly incorporated in SBT films. The more complete knowledge of film microstructure that this provides has enabled us to relate phase structure to growth and annealing conditions. XPS has also given us some insight into the initial stages of the growth chemistry of SBT on various Pt surfaces.
Effect of Electrodes on Crystallization and Electrical Properties of Ferroelectric Pzt Films Deposited by Rf Magnetron Sputtering
Authors: Ea-Kim B. , Varniere F. , Hugon M. C. , Agius B. , Bisaro R. , Olivier J.
Published: April 2011

The electrical properties and crystallization process of Pb(Zr0.4, Ti0.6)O3or PZT thin films grown by rf magnetron sputtering, from ceramic target, on fiber-textured (111)Pt/TiN/Ti/SiO2/Si and polycrystalline RuOx/SiO2/Si have been studied. It is found that the amorphous as-deposited thin film, processed by rapid thermal annealing (RTA), is transformed to a perovskite PZT at about 700°C. It is pointed out that the “heating rates” to reach 700°C affect the electrical properties of such films: TEM analysis reveal different grain sizes as a function of the heating rate. The XRD show that an oriented (111) PZT is promoted when the film is annealed to the temperatures of 800°C for 5 secondes. For these annealing conditions, the electrical properties of such structure depend strongly on the deposition conditions of PZT. Our process studies show that a thin film PZT deposited on Pt or RuO1.65at 200°C and 1 Pa argon pressure gives good hysteresis loop with high values of Ps and Pr (about 20 and 30 μC/cm2on Pt and RuO1.65respectively) and low leakage current about 10−11A/cm2on Pt and 10−6A/cm2on RuO1.65.
Preparation and Pyroelectric Properties of La-Modified PbTiO8 Thin Films by Rf-Magnetron Sputtering
Authors: Kamada T. , Takayama R. , Tomozawa A. , Fujii S. , IIJIMA K. , Hirao T.
Published: April 2011

High-quality La-modified PbTiO3 (Pb1−xLaxTi1−x/4O3; PLT) thin films were prepared by an rf-magnetron sputtering method. In this method, intermittent deposition was realized by periodical repetition of deposition and nondeposition processes. This deposition was found to enhance the horizontal grain growth of the films. The PLT thin films exhibit the phenomena named “self-polarization” and have high pyroelectric properties (pyroelectric coefficient γ of 5.0×10−8C/cm2K and low dielectric constant εr of 185) without a poling treatment. It was interestingly found that this self-polarization of the PLT thin films depends on the substrate temperature (Ts) and is based on a fairly small difference of the film composition (Pb/Ti). The pyroelectric properties were improved by means of addition of Mg to the PLT thin films. These thin films are expected to offer suitable materials for pyroelectric infrared (IR) sensors. High sensitive pyroelectric IR sensors (single element type and linear array type) were fabricated by using the PLT (x=0. 1) thin films with the new structures and the device processes. The sensors have remarkably high specific detectivity D* of 3.5×108 cm. Hz1/2/W and very fast response. A new compact IR sensing system using the linear array sensor (8 elements) has been developed for a new type of room air-conditioner.
Optical and Electrical Characterizations of Pzt Films With Different O/Pb Stoichiometry
Authors: Hugon M.C. , Kim B. Ea , Varniere F. , Agius B. , Masetti E.
Published: April 2011

Thin films were deposited by radio frequency (rf) magnetron sputtering on Pt/TiN/Ti/SiO2/Si substrates starting from a ceramic Pb(Zr0.4Ti0.6)O3 or metallic Pb1.1(Zr0.4Ti0.6) target. To promote the ferroelectric properties, films were successively processed by rapid thermal annealing (RTA). Before and after the RTA process, the film optical constants, in terms of refractive index and. extinction coefficient, were measured by spectroscopic ellipsometry and spectrophotometry and their values were related to the film composition determined by nuclear microanalysis with a precision better than ±2%. By adjusting the sputtering conditions, it was possible to grow different films with oxygen stoichiometry (O/Pb) in the range of 2.5-4.5. The electrical P-E characterization revealed a strong relation between the optical properties (film composition) before annealing and the hysteresis loop after annealing. This was mainly attributed to changes in the film oxidation during RTA and indicates that ferroelectric properties can be optimized adjusting the O/Pb ratio in the film.
Some new Results on Strontium Bismuth Tantalate Thin-Film Ferroelectric Memory Materials
Authors: Scott J. F. , Hartmann A. J. , Lamb R. N. , Ross F. M. , Vilbis A. DE , Araujo C. A. Paz De , Scott M. C. , Derbenwick G.
Published: April 2011

review is given, emphasizing electron microscopy, XPS, heavy-ion scattering, and very high frequency (1 MHz) hysteresis data, of the materials characteristics of thin films of SrBi2NbTaO9, SrBi2Ta2O9, and related titanates.
Yield Stress of Nano- and Micro- Multilayers
Authors: Hazzledine P. M. , Rao S. I.
Published: April 2011

An outline theory is given for the strengthening in polycrystalline and ‘single crystal’ multilayers. The model is based on the Hall-Petch theory applied to both the soft mode (in plane) and hard mode (cross plane) of deformation. In this theory the parameters to be evaluated are a Taylor factor M, the shear stress τ0 to move a dislocation within a multilayer and τ*, the shear stress needed to push a dislocation over a grain or interphase boundary. All three parameters are material- specific and attention is focussed on coherent multilayers of γ TiAl with micron thick layers and Cu-Ni with nanometer thick layers. M and some components of τ* are estimated classically. The remaining components of τ* and some components of τ0 are estimated from embedded atom simulations. The model captures the main experimental facts, that γTiAl is plastically very anisotropic with a rising yield stress as the lamellar thickness is refined and that Cu-Ni displays a peak in the yield stress at a layer thickness of approximately 10nm.
A Finite Element Study on Constrained Deformation in an Intermetallic / Metallic Microlaminate Composite
Authors: Heathcote J. , Odette G. R. , Lucas G. E.
Published: April 2011

The mechanical properties of intermetallic / metallic microlaminates were studied by determining the fundamental composite properties that control the fracture behavior: namely, the stress-displacement functions of the metal layers. Finite element methods were used to model the stress-displacement function of a constrained metal layer and to examine the effect of constituentproperties, residual stress, offset cracks in adjacent intermetallic layers, and debonding inclusions in the metal layer. Finally, FEM models representative of four specific microlaminates weredeveloped and the results were compared to experimentally determined σ(u)'s for those composites. Determining these fundamental composite properties and showing how they control the mechanical behavior gives insight into the optimum design of this composite system.
Impact Behavior of Extrinsically Toughened Discontinuously Reinforced Aluminum Composites
Authors: Irfan M. A. , Liou N. , Prakash V.
Published: April 2011

Discontinuously reinforced aluminum (DRA) composites with enhanced fracture toughness have recently been developed at ALCOA. The approach consists of producing a composite microstructure in which discrete ductile phases have been incorporated into the DRA through traditional powder processing routes. In the present paper, the high strain rate behavior of these toughened composites is investigated by obtaining (i) the dynamic flow characteristics at various levels of elevated strain rates using a split Hopkinson compression bar, and (ii) energy absorption during dynamic crack initiation and crack propagation using three-point bend specimens loaded on a modified Hopkinson bar configuration.
Microstructure and Thermal Conductivity of Thermal Barrier Coatings Processed by Plasma Spray and Physical Vapor Deposition Techniques
Authors: Ravichandran K. S. , Dutton R. E. , Semiatin S. L. , An K.
Published: April 2011

The temperature dependence of the thermal conductivity of multilayer coatings made by a plasma spray technique as well as some coatings made by physical vapor deposition (PVD) was investigated. The multilayer coatings consisted of a varying number of layers of Al2O3 and ZrO2 stabilized by 8%Y2O3. Plasma sprayed coatings exhibited a large reduction in thermal conductivity at all temperatures when compared to the bulk monolithic materials. This reduction was found to be due to porosity as well as thermal resistance brought about by interfaces in the coatings. A comparable reduction in thermal conductivity was achieved in monolithic ZrO2 as well as in a composite coating deposited by the PVD technique. Microstructural factors that may be responsible for this reduction are discussed.
Structural and Phase Transformations in Thin Film Ti-Aluminides and Ti/Al Multilayers
Authors: Banerjee R. , Swaminathan S. , Wheeler R. , Fraser H. L.
Published: April 2011

Multilayered Ti/Al thin films (with nominally equal layer thickness of Ti and Al) have been sputter deposited on oxidized silicon substrates at room temperature. Transmission electron microscopy (TEM) and high resolution electron microscopy have been used to characterize the structure of these multilayers as a function of the layer thickness. Ti changed from an hcp to an fcc and back to an hcp structure on reduction of the layer thickness. Al too changed from an fcc to an hcp structure at a layer thickness of 2.5 nm. The observed structural transitions have been explained on the basis of the Redfield-Zangwill model. Subsequently Ti-aluminide thin films were deposited using a γ-TiAl target. These films were found to be amorphous in the as-deposited condition with crystallites of α-Ti(Al) embedded in the amorphous matrix. On annealing under a protective Ar atmosphere at a temperature of 550 °C, the Ti-aluminide film crystallized into a nanocrystalline two phase microstructure consisting of γ-TiAl and α2-Ti3Al. The crystallization of the aluminide film has been investigated in detail by in-situ annealing experiments on a hot stage in the TEM. The results of this investigation have been discussed in this paper.
Measuring Interfacial Fracture Toughness With The Blister Test
Authors: Hohlfelder R. J. , Luo H. , Vlassak J. J. , Chidsey C. E. D , Nix W. D.
Published: April 2011

The adhesion of thin films to substrates can be quantified using the blister test, which measures the crack extension force (G) required to propagate a crack along the film/substrate interface. We summarize the derivation of crack extension force for the blister test, and discuss how blister tests can be conducted by measuring only the pressure and volume of liquid injected into the test system. We describe a way to calculate the velocity of the interface crack front.

Data from blister tests of acrylate films (14 μm thick) on nitride substrates are analyzed. The critical crack extension forces (GC) measured were 25 − 34 J/m2 for samples which had a commercial adhesion promoter at the interface, and 0.5 − 2.0 J/m2 without the adhesion promoter. GC was observed to increase with the velocity of the interface crack, and the dependence appears to obey a power-law.
Evolution of the Contact Area During an Indentation Process
Authors: Li Kangjie , Wu T. W. , Li J. C. M.
Published: April 2011

The evolution of the contact area during an indentation process has been examined by an a.c. technique and also by finite element analysis on five different bulk materials. The consistency of the results obtained by the two approaches not only show the validity and advantage of the a.c. technique but also corroborate the applicability of the elastic contact equation.
Micromechanical Tensile Testing
Authors: Greek S. , Ericson F. , Johansson S. , Schweitz J.-Å.
Published: April 2011

A method is described where tensile tests can be performedin situon micromachined structures. The testing equipment consists of a testing unit mounted on a micromanipulator in a Scanning Electron Microscope (SEM). The fracture loads of micromachined beam structures made from thick and thin film polysilicon as well as from electrodeposited nickel and nickeliron alloy were measured, and the fracture strengths then calculated via measurements of the test structures’ initial cross-sectional areas. The statistical scatter of the polysilicon fracture strength values were evaluated by Weibull statistics. The mean fracture strength and the Weibull modulus, a measure of the scatter, were obtained
Simulation of Mechanical Deformation and Tribology of Nano-Thin Amorphous Hydrogenated Carbon (a:Ch) Films Using Molecular Dynamics
Authors: Glosli J. N. , Philpott M. R. , Belak J.
Published: April 2011

Molecular dynamics computer simulations are used to study the effect of substrate temperature on the microstructure of deposited amorphous hydrogenated carbon (a:CH) films. A transition from dense diamond-like films to porous graphite-like films is observed between substrate temperatures of 400K and 600K for a deposition energy of 20 eV. The dense a:CH film grown at 300K and 20 eV has a hardness (˜50 GPa) about half that of a pure carbon (a:C) film grown under the same conditions.
Tribological Properties of Tetrahedral Carbon Films Deposited by Filtered Cathodic Vacuum Arc Technique
Authors: Shi X. , Tay B. K. , Flynn D. I. , Sun Z.
Published: April 2011

Ta-C films have been deposited using FCVA technique. The hardness and Young's modulus of the films on both silicon and sapphire substrates are determined by an ultra low load depth sensing nanoindenter to examine their dependence on the carbon ion energy. An optimum ion energy around 80 to 90 eV has been found, which coincides with the energy at which the sp3 content and film density reach maximum values. At this ion energy, the hardness, modulus and critical load of a 60 nm film on sapphire exhibit maximum values of 60 GPa, 580 GPa and 7 mN, respectively, whilst the frictional coefficient shows a minimum of 0.16.
Capillary Stress in Microporous Thin Films
Authors: Samuel J. , Hurd A. J. , Brinker C. J. , Frink L. J. Douglas , Swol F. Van
Published: April 2011

Development of capillary stress in porous xerogels, although ubiquitous, has not been systematically studied. We have used the beam bending technique to measure stress isotherms of microporous thin films prepared by a sol-gel route. The thin films were prepared on deformablesilicon substrates which were then placed in a vacuum system. The automated measurement was carried out by monitoring the deflection of a laser reflected off the substrate while changing the overlying relative pressure of various solvents. The magnitude of the macroscopic bending stress was found to reach a value of 180 MPa at a relative pressure of methanol, P/Po = 0.001. The observed stress is determined by the pore size distribution and is an order of magnitude smaller in mesoporous thin films. Density Functional Theory (DFT) indicates that for the microporous materials, the stress at saturation is compressive and drops as the relative pressure is reduced.
Anisotropic Behaviour of Surface Roughening in Lattice Mismatched Heteroepitaxial Thin Films
Authors: Ozkan Cengiz S. , Nix William D. , Gao Huajian
Published: April 2011

Heteroepitaxial Si1-xGex. thin films deposited on silicon substrates exhibit surface roughening via surface diffusion under the effect of a compressive stress which is caused by a lattice mismatch. In these films, surface roughening can take place in the form of ridges which can be aligned along <100> or <110> directions, depending on the film thickness. In this paper, we investigate this anisotropic dependence of surface roughening and present an analysis of it. We have studied the surface roughening behaviour of 18% Ge and 22% Ge thin films subjected to controlled annealing experiments. Transmission electron microscopy and atomic force microscopy have been used to study the morphology and microstructure of the surface ridges and the dislocations that form during annealing.
Anomalous X-Ray Scattering On Sr and Sr-Eu Metaphosphate Glasses
Authors: Bionducci M. , Meneghini C. , Navarra G. , Licheri G. , Balerna A. , Mobilio S.
Published: April 2011

The results of an Anomalous X-ray Scattering experiment performed on Sr(PO3)2 and Eu0.1Sr0.9(PO3)2.1 glasses are presented. These are the first measurements carried out on GILDA (General purpose Italian beamLine for Diffraction and Absorption) diffractometer, located at the European Synchrotron Radiation Facility (ESRF), Grenoble. To obtain detailed information about the local order on pure and Eu-doped Sr-metaphosphate glasses both samples were investigated near the Sr K-edge (16.107 KeV), while the latter was also studied near the Eu K-edge (48.517 KeV).
X-Ray Truncation Rod Analysis Of Cu Thin Films on C-Plane Sapphire
Authors: Chung K.S. , Hong Hawoong , Aburano R.D. , Roesler J.M. , Chiang T. C. , Chen Haydn
Published: April 2011

The interfacial structure of room-temperature MBE-grown Cu thin film on c-plane sapphire has been studied by measuring the substrate crystal truncation rod (CTR) using synchrotron radiation. One substrate was annealed in air at 1500°C for 3 hours followed by an anneal in UHV at 1200°C for 30 minutes prior to Cu deposition. CTR from a clean sapphire substrate without Cu coverage was measured as a reference. The annealed substrate showed higher diffracted intensity along the CTR due to changes in surface structure. The terminating sequence of the substrate surface layers have been obtained from intensity profile analysis.
Characterization of Diamond Thin Films by Core-Level Photoabsorption and UV Excitation Raman Spectroscopy
Authors: Zuiker C. D. , Krauss A. R. , Gruen D. M. , Carlisle J. A. , Terminello L. J. , Asher S. A. , Bormett R. W.
Published: April 2011

Near-edge x-ray absorption fine structure (NEXAFS) and Raman spectroscopies have been used to characterize both nanocrystalline and faceted, microcrystalline diamond thin films grown by microwave plasma chemical vapor deposition under a variety of conditions. Raman spectroscopy is perhaps the most commonly used method of characterizing diamond film quality, whereas photoabsorption requires a synchrotron radiation source and is much less commonly used. Both methods characterize the sp2 (graphitic) /sp3 (diamond) electronic bonding character of the films, but Raman spectroscopy is considerably more sensitive to sp2 than sp3 bonded carbon. For nanocrystalline diamond, the use of a visible excitation source for Raman spectroscopy also gives rise to an intense fluorescence band which may completely mask the sp3 Raman line, even in films with negligible (<1%) sp2 bonding character. Near-edge x-ray absorption fine structure (NEXAFS) is a more localized measurement of the electronic bonding character, and does not have as large a variation in sensitivity between sp2 and sp3 phases.

Raman spectra measured using 632.8 nm light exhibit a sharp diamond phonon peak at 1332 cm−1 for faceted, large grain diamond films, and no obvious diamond phonon peak for the nanocrystalline diamond films. However, Raman spectra excited by 228.9 nm light exhibit a sharp diamond phonon peak for both nanocrystalline and large grain, faceted diamond films. The UV Raman results are consistent with the C(ls) NEXAFS measurements which show clear bulk diamond excitonic and sp3 features, with little evidence of sp2 character for all of the tested films. We conclude that the use of visible excitation Raman spectroscopy as the sole criterion for the assessment of quality in nanocrystalline diamond films is misleading, but that UV Raman spectroscopy and NEXAFS provide a consistent and reliable characterization. Nanocrystalline films grown using a fullerene precursor in an Ar microwave plasma with very low levels of hydrogen (2%) are found by both of the latter methods to consist almost entirely of sp3-bonded carbon with ˜2% non-tetrahedral bonding.
XANES Studies at N and C K-Edge of Compounds in the Ternary System Si-C-N
Authors: Kroll P. , Greiner A. , Riedel R. , Bender S. , Franke R. , Hormes J. , Pavlychev A. A.
Published: April 2011

We report on XANES-investigations at the nitrogen and carbon K-edge of Si-C-N containing solid phases prepared by the reaction of silicon tetrachloride with bis(trimethylsilyl)carbodiimide and annealing the reaction product at temperatures between room temperature (RT) and 1600°C. From the spectra it is possible to evidence the evolution of four phase regions and their different structural increments. We can relate the observed changes of atomic excitations to chemical and structural effects. By that means proposed structural models for the different phases are testified.
Chemical Speciation by NEXAFS Spectromicroscopy: Insights from Molecular Modelling of Polymers
Authors: Urquhart S. G. , Hitchcock A. P. , Rightor E. G. , Smith A. P. , Ade H.
Published: April 2011

Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy of polymers performed in a scanning transmission X-ray microscope (STXM) can provide chemical speciation with <0.1 gm spatial resolution in imaging mode. The core excitation spectra of molecular compounds that are structural analogues of polymers help interpret the NEXAFS spectra of polymers. The effect of nt-delocalization on polymer NEXAFS is discussed and illustrated by comparison to molecular spectra. Extended Htickel calculations are particularly useful for providing insight into the relationship between chemical structure and the molecular and polymer spectra. We report the interpretation of experimental NEXAFS spectra of polyethylene terephthalate (PET). Molecular models indicate that NEXAFS will be sensitive to structural isomerization in polyester polymers. We demonstrate the capability of NEXAFS to distinguish hard-segment and soft-segment phase segregation in polyurethanes.
Evidence for a Structural Origin of Perpendicular Magnetic Anisotropy in PtxCo1−x Thin Film Alloys
Authors: Tyson T. A. , Conradson S. D. , Farrow R. F. C. , Jones B. A.
Published: April 2011

XAFS analysis of the local structure about Pt and Co in PtxCo1−x, for x ˜ 0,7 revealed that the local coordination of Co and Pt is similar to that found in cubic L12 Pt3Co. In the plane of the films, significant Co-Co bonding was found- a feature not present in ordered L12 Pt3Co. The presence of Co-Co bonds, preferentially in-plane, suggest that clustering of Co into “sheets” or “chains” is the source of PMA in these films.
Temperature Dependence of the Mcxd at the GD Lm Edge
Authors: Gofrono K. J. , Kimball C. W. , Lee P. L. , Jennings G. , Montano P. A.
Published: April 2011

An energy dispersive spectrometer is used to measure the temperature dependence of the Magnetic Circular X-ray Dichroism (MCXD) effect at the gadolinium (Gd metal) LIII absorption edge from 94 K to 335 K. In ferromagnetic Gd, the MCXD spectrum consists of the main positive peak with pre- and post-edge features. Only the main positive peak exhibits a temperature dependence similar to that of Gd magnetization. All other features decrease as the temperature increases and vanish slightly above the transition temperature (293 K). Well above the ordering temperature (paramagnetic Gd), the MCXD consists only of the positive peak, with a post-edge background that slowly decays away from it over a range of 90 eV.
In Situ Tem Analysis of TiSi2 C49-C54 Transformations During Annealing
Authors: Gignac L. M. , Svilan V. , Clevenger L. A. , Cabral C. , Lavoie C.
Published: April 2011

In situ transmission electron microscope (TEM) observations of TiSi2 C49-to-C54 phase transformations were recorded on video tape and photographic negatives, and transformation front velocities (vTF) were measured from the data. The samples studied in this work include: C49-TiSi2 blanket films and 0.2 μm wide, 7 mm long lines on undoped poly-Si and 0.13 μm wide, 10 μm long lines on either B- or As-doped poly-Si. The in situ TEM analysis showed that blanket TiSi2 films on undoped poly-Si fully transformed at 830°C and had an average vTF of 0.5 ± 0.2 μm/s. The transformation occurred from a sparse nucleation density of ˜0.1 site/μm2. The 0.2 μm wide lines transformed at temperatures greater than 885°C, and the average vTF was 1.1 ± 0.2 μm/sec. Agglomeration started for both the blanket film and the 0.2 μm wide lines at temperatures above 900°C. In situ x-ray diffraction (XRD) analyses of C49-TiSi2 on B- and As-doped poly-Si showed that blanket films completely transformed to C54-TiSi2 at T = 835–843°C, but 0.13 μm wide, varying length lines did not fully transform, even when rapid thermal annealed to 1025°C. From in situ TEM analysis of 0.13 μm wide, 10 μm long C49-TiSi2 lines on B-doped poly-Si, a distinct transformation was not observed. Instead, the lines slowly agglomerated, and electron diffraction of the agglomerated regions showed that the film had transformed to C54-TiSi2. An individual line either 1) completely transformed and agglomerated or 2) remained as C49-TiSi2 and did not agglomerate. Approximately 85% of all lines transformed. In situ TEM analysis of 0.13 μm wide, 10 μm long lines of C49-TiSi2 on As-doped poly-Si also showed an indistinct transformation to the C54 phase along with agglomeration, and 100% of the lines transformed.
Comparison of the Hafnium Diboride(0001) and Hafnium(0001) Surfaces
Authors: Belyansky M. , Trenary M. , Otani S. , Tanaka T.
Published: April 2011

The surface properties of the (0001) surfaces of single crystals of hafnium and hafnium diboride are compared with a boride film deposited on the Hf(0001) surface. The surfaces were characterized with X-ray photoelectron spectroscopy (XPS) and low energy electron diffraction (LEED). Boron deposition was achieved through the thermal decomposition of diborane. The deposited boron reacts with the hafnium substrate to form HfB2 as determined by XPS and the HfB2 films were found to be epitaxial as determined by LEED. The epitaxial nature of the thin films was confirmed with X-ray diffraction. The epitaxial thin films of HfB2 on Hf(0001) display properties identical to those of the HfB2(0001) single crystal surface.
Laser and Thermal Annealing Modification of Diamond-Like Atomic-Scale Composite Films Studied by Micro Raman Spectroscopy
Authors: Wan J. Z. , Pollak Fred H. , Dorfman Benjamin F.
Published: April 2011

We have modified the properties of diamond-like atomic-scale composite (DLASC) material of various thicknesses (5 μm – 70 μm) by means of (a) cw Ar-ion laser annealing using a focussed beam (˜ 2 μm spot size) and (b) thermal annealing (400°C≤ T ≤800°C for one hour). These DLASC films [amorphous “diamond-like/quartz-like” a-(C:H/Si:O)] constitute a novel class of diamond-related materials. The annealing effects were investigated by micro-Raman scattering. The laser annealing procedure shows that the structure of these films can be altered locally from amorphous to nano-crystallite depending not only on the parameters of the annealing process (annealing time, laser intensity) but also the mechanical properties (hardness and stress) of the DLASC films.
Effect of Non-Hydrostatic Stress on Kinetics and Interfacial Roughness During Solid Phase Epitaxial Growth in Si
Authors: Barvosa-Carter William , Aziz Michael J.
Published: April 2011

We report preliminary in-situ time-resolved measurements of the effect of uniaxial stress on solid phase epitaxial growth in pure Si (001) for the case of stress applied parallel to the amorphous-crystal interface. The growth rate is reduced by the application of uniaxial compression, in agreement with previous results. Additionally, the velocity continues to decrease with time. This is consistent with interfacial roughening during growth under stress, and is supported by both reflectivity measurements and cross-sectional TEM observations. We present a new kinetically-driven interfacial roughening mechanism which is consistent with our observations.
Interface Of Aluminum/Ceramic Power Substrates Manufactured By Casting-Bonding Process
Authors: Ning X. S. , Ogawa Y. , Suganuma K.
Published: April 2011

New processes for manufacturing Al/ceramic power substrates have been developed. These processes use a casting-bonding method to bond Al plates to the both sides of ceramic plates. The Al plates formed on the substrates are then chemically etched to be a desired shape using the conventional technology, followed by plating nickel on them. The power substrates manufactured by the process have both a perfect interface and an excellent thermal stress tolerance. Hence, these processes are especially suitable for assembling high reliability power devices such as IGBT power modules.
New Packaging Substrate Technology,Ibss (Interpenetrating Polymer Network Build Up Structure System)
Authors: Asai Motoo
Published: April 2011

We have developed a new type of printed circuit board which is called “IBSS” (Interpenetrating polymer network Build up Structure System) for the purpose of meeting the demand of high density routing, high reliability and low cost substrates in IC packages. The new technology achieves 50μm line / 50μm space and 100μm diameter photo‐via hole. Full additive method is applied for patterning, and the build‐up method is used to form the multi‐layer structure. The newly developed photo‐imagable dielectric resin, “IPN”, which has a glass transition of 200'C, a copper peel strength of 1.5kg/cm, and withstands 1000 cycles of temperature cycling (TCB), is used for IBSS. IPN is composed of high heat resistant photo‐sensitive epoxy and supper engineering plastic. This IBSS technology is suitable for direct chip attachment. This paper presents the characteristics IBSS.