bluuebunny/crossref_metadata_2025 huggingface dataset:
Spiral Cracking Around a Strained Cylindrical Inclusion in a Brittle Material and Implications for Vias in Integrated Circuits
Authors: Freund L. B. , Kim K. S.
Published: March 2011

The practice of forming electrical conduction paths in an insulating material by filling cylindrical holes with molten metal can result in high residual stresses when the metal cools. Residual stress is greatest near the metal-insulator interface, and stress relaxation by means of de-adhesion is possible. Another failure mode that poses greater practical difficulties is the growth of cracks along paths which spiral away from the interface into the brittle material. Such cracks may occur singly or in pairs, and their lengths can be sufficiently great to provide links with adjacent conduction paths. Such cracks are considered from the fracture mechanics point of view. The residual stress field is relaxed by the growth of spiral cracks which are modeled as continuous distributions of dislocations. It is assumed that these cracks grow so that the stress state on the prospective fracture plane just ahead of the crack tip is purely tensile. The paths are determined by means of an incremental numerical procedure.
Aging and Fracture Behavior of Polymers
Authors: Chudnovsky A. , Bosnyak C.P.
Published: March 2011

Significant changes in polymer materials and their subsequent mechanical performance can occur within an expected engineering service time. These changes can be further exacerbated with environmental effects such as with solvents and mechanical stresses. Examples are given of premature field failures which illustrate the inadequacy of existing understanding and design criteria. A new approach is outlined which is based on the coupling of two fundamental concepts; a geometrical representation of material morphology on various scales and thermodynamics of morphological transformation. These concepts allow one to bridge an existing understanding of aging on molecular and morphological levels with a phenomenological continuum mechanics approach.
Curvature Measurements of Tri-Material Structures Under Thermal Excursion
Authors: Lu Guo-Quan , Mogilevsky Boris , Gupta Tapan K.
Published: March 2011

The bending curvatures of tri-material plates have been measured using in situ laser reflection technique at temperatures ranging from 20°C to 160°C. The tri-material structures are formed by attaching silicon wafers to ceramic substrates with die-attach adhesives from solder-like (elastic modulus ≈ 24 GPa) to gel-like (elastic modulus ≈ 0.003 GPa) characteristics. The temperature dependence of curvature as a result of the thermal expansion mismatch is measured. The structure bonded by the gel-like adhesive has substantially lower, about a factor of ten less, bending than the structures attached by the other two types of adhesives. We found good agreements between the measurements and the theoretical derivations by Suhir[1] for the bending curvature of finite tri-material assembly.
Residual Stress Measurement in Silicon Substrate After Local Thermal Oxidation Using Microscopic Raman Spectroscopy
Authors: Miura Hideo , Sakata Hiroshi , Merl Shinji Sakata
Published: March 2011

The residual stress in silicon substrates after local thermal oxidation is discussed experimentally using microscopic Raman spectroscopy. The stress distribution in the silicon substrate is determined by three main factors: volume expansion of newly grown silicon–dioxide, deflection of the silicon–nitride film used as an oxidation barrier, and mismatch in thermal expansion coefficients between silicon and silicon dioxide.

Tensile stress increases with the increase of oxide film thickness near the surface of the silicon substrate under the oxide film without nitride film on it. The tensile stress is sometimes more than 100 MPa. On the other hand, a complicated stress change is observed near the surface of the silicon substrate under the nitride film. The tensile stress increases initially, as it does in the area without nitride film on it. However, it decreases with the increase of oxide film thickness, then the compressive stress increases in the area up to 170 MPa. This stress change is explained by considering the drastic structural change of the oxide film under the nitride film edge during oxidation.
Effects of Plastic Deformation on Charge Transport in Mercuric Iodide Radiation Detectors
Authors: Marschall J. , Milstein F. , Georgeson G. , Gerrish V.
Published: March 2011

The effects of bulk plastic deformation of mercuric iodide (HgI2), upon electronic properties which are relevant to the performance of HgI2 as a radiation detector, were examined experimentally. Hole lifetimes, as well as hole and electron mobilities, were measured at various stages of sample deformation. Hole lifetimes decreased by a factor of 2 under strains of several percent; carrier mobilities did not change significantly, except during creep loading where electron and hole mobilities decreased by about 65% and 25%, respectively. Additionally, dark current measurements were made on specimens with varying degrees of accumulated plastic strain; dark current values did not strongly reflect the extent of plastic damage in deformed specimens.
Creep-Fatigue Behavior of Microelectronic Solder Joints
Authors: Ross R.G. , Wen L.C. , Mon G.R. , Jetter E. , Winslow J.
Published: March 2011

Even at room temperature, solder joints exhibit both creep and fatigue behavior that is strongly dependent on solder joint configuration, the thermal environment, and the solder alloy properties. The microstructures of solder joints with up to 25 years of aging have been studied using SEM/EDS and metallographic techniques. Data are presented on grain growth and metallurgical composition versus aging time. A special non-linear finite element creep-fatigue simulation model has been developed, based on measured strain-rate hardness relationships, and used to analytically predict the effects of observed metallurgical changes and the effects of lead stiffness in solder joint creepfatigue interaction. To corroborate the analytical results, a special bi-metallic test fixture has been developed to accelerate the thermo-mechanical loading of solder joints in thermal cycling environments. Measured time-to-failure data for various electronicpackage lead configurations/stiffnesses, including gullwing and J-lead, are presented and shown to be in reasonable agreement with the analytical results.
Finite Element Simulation of Hillock Formation in Aluminum Interconnect
Authors: Burrell L. G. , Kapur S. , Shareef I.
Published: March 2011

A non-linear finite element model has been used to simulate hillock formation in an aluminum interconnect structure. The hillock formation is caused by the thermal expansion mismatch between aluminum and the surrounding SiO2 passivation. Using the ABAQUS software [1], a large strain elastic-plastic-creep analysis was done. The results showed there were stresses large enough to cause yield and permanent deformation of the aluminum interconnect.
A Methodology for Reliability Assessment of Non-Ductile Encapsulants
Authors: Wong Boon , Sandkulla David C.
Published: March 2011

This paper presents a probabilistic fracture-mechanics based methodology for the reliability assessment of non-ductile encapsulants. The study used an alumina-epoxy encapsulant as a working example and assessed the reliability in terms of (1) fast fracture and (2) delayed failure behavior of the material.

Applying the Weibull probabilistic model to flexural strength data, survival probabilities and strength requirements against fast fracture of the encapsulant under various stress states were quantified. Unifying the probabilistic concept and linear elastic fracture mechanics (LEFM), the probabilistic lifetime of the encapsulant was predicted as a function of stress magnitude, stress state, and material size. Merging the results obtained from this study with the mechanical response results independently acquired from finite element analysis (FEA) one may then establish conservative design margins for the encapsulant used in various electronic assemblies.
Effect Of Moisture On The Physical Properties Of Polyimide Films
Authors: Subramanian Rajeevi , Pottiger Michael T. , Morris Jacqueline H. , Curilla Joseph P.
Published: March 2011

Moisture absorption and its effect on electrical properties were measured for several polyimides. A Quartz Crystal Microbalance (QCM) was used to investigate the moisture absorption in BPDA/PPD, PMDA/ODA, and BTDA//ODA/MPD polyimides. The steady-state moisture uptake in polyimides as a function of relative humidity (RH) was determined by exposing film samples to successively higher RH values ranging from 10 to 85% at 25°C. The isothermal moisture absorption as a function of percent RH was found to be nearly linear for all of the polyimides studied. The effect of moisture on the electrical properties of a BPDA/PPD polyimide was also investigated. The relative dielectric constant at 25 °C was found to be a linear function of the moisture absorbed.
Stress measurement Of BPDA/PDA Polyimides From Poly(Amic Acid) And Photosensitive Polyimide Precursors On Silicon
Authors: Nomura Hideshi , Eguchi Masuichi , Niwa Katsuhiro , Asano Masaya
Published: March 2011

The intrazeolite chemistry of the two germylene complexes Cl2(THF)GeM(CO)5(M = Mo, W) was studied with x-ray absorption spectroscopy (Ge, Mo, W edge EXAFS) and in-situ FTIR/TPD-MS techniques. The slightly decarbonylated GeMo complex interacts with the framework of NaY zeolite at room temperature and retains the Ge-Mo bond up to about 100° C. In proton-loaded HY zeolite, framework interactions increase at elevated temperature, and the attached complex retains the Ge-Mo bond up to about 120° C. The Ge-Mo bond is cleaved at higher temperatures. MoC1x and Mo-Mo species are formed in NaY and HY zeolite, respectively, while GeClx fragments are anchored to the zeolite framework.

The complex Cl2 (THF)GeW(CO) 5 retains all five CO ligands up to about 100° C in both NaY and the proton form. Detectable anchoring occurs at room temperature in NaY and at about 80° C in the proton form. WC1x species are formed upon cleavage of the Ge-W bond at higher temperatures.
Thermal Expansion And Viscoelastic Properties Of A Semi-Rigid Polyimide
Authors: Smith Thor L. , Kim Churl S.
Published: March 2011

Studies were made of the physical properties of the commercially available polyimide Upilex-SGA, which is prepared from biphenyl dianhydride and p-phenylene diamine. Annealing the Upilex-SGA for 2 hr Linder N2 at 400°C gave a film that expanded continuously when heated at a fixed rate, in contrast to the as-received film. The linear expansion showed a change of slope at 84°C and also at 295°C, the later being Tg. The thermal coefficient of linear expansion at all temperatures was very small, even above 295°C it is 27.8 × 10−6. Its stress-strain curve did not exhibit a yield point, even though its ultimate elongation is ˜23%. Similar behavior is shown by the PMDA-ODA polyimide, except its ultimate elongation is ˜70%,. The unusual stress- strain curves exhibited by these polyimides is undoubtedly caused by their liquid-crystalline morphology. The stress-relaxation modulus was measured at 0.5% extension and 12 temperatures from 30 to 330°C. Derived isochrones showed that the 1-s tensile modulus at 20°C is 9.0 GPa, but at 330°C it is 2.0 GPa. Creep curves were also measured at a stress of 30 MPa and at 10 temperatures from 30 to 340° C. Master curves prepared from the relaxation and creep data are discussed briefly and evidence is given which, show that the superposition method is not truly valid for this polyimide, which actually is not surprising.
Polyimide Considerations In Thin-Film Electronic Packaging
Authors: Pawlowski W. P.
Published: March 2011

Free-standing polyimide film is used extensively in tape automated bonding (TAB) and flexible printed circuit (Flex) applications because of its excellent chemical, mechanical, and electrical properties. Kapton polyimide film has been the material of choice for many years. Recently, a new polyimide film, Upilex, has been introduced into the marketplace. The primary property differences between Kapton and Upilex result from differences in the chemical composition of each film. A review of property/product performance indicates that Upilex S is preferred with respect to dimensional stability, metal/polyimide and adhesive/polyimide adhesion, chemical inertness and glass transition temperature.
Liquid Crystalline Thermosets As Materials For Microelectronics
Authors: Ober C. K , Barclay G. G.
Published: March 2011

New liquid crystalline thermosets have been prepared from end-functional monomers and oligomers of varying molecular weight. Both triazine and epoxy networks were explored. Of primary interest was the exploitation of the mesophase properties of these networks for developing polymers with high thermal stability and low coefficients of thermal expansion (CTE). Curing was carried out either within the nematic mesophase or the isotropic phase of the prepolymers. Transition temperatures associated with the mesophase were observed to change after curing under these two sets of conditions. The networks with the highest crosslink density were found to exhibit the lowest CTE values. Crosslinking of these thermosets was also carried out in the presence of a 13.5 Tesla magnetic field to determine the effect of orienting fields on the curing of the LC network. Orientation parameters as measured by wide angle x-ray diffraction were as high as 0.6. Values of the coefficient of thermal expansion as low as 15 ppm were achieved in the aligned direction. Of the two resin types, those with the triazine crosslinks had the lowest thermal expansion coefficient. Other thermal properties of these networks will be discussed.
Phase Transitions In Blends Of Liquid Crystalline Polymer/Polyether Imide
Authors: Nam Joonhyun , Fukai Tomohiro , Kyu Thein
Published: March 2011

A thermotropic liquid crystalline copolymer consisting of bisphenol E diacetate, isophthalic acid and 2,6-naphthalene dicarboxylic acid was blended with polyether imide by dissolving in a mixed solvent of phenol/1,1,2,2-tetrachloroethane in a ratio of 60/40 w/w and co-precipitating the ternary solution in non-solvent (methanol). Wide-angle x-ray diffraction and differential scanning calorimetry studies revealed that the blends were completely amorphous with a single glass transition temperature. The single phase was probably entrapped during solvent removal, but these mixes were unstable and phase separated upon heating. Mesophase structure developed in the LCP rich region with continued annealing. The evolution of crystalline texture was monitored by time-resolved wide-angle x-ray diffraction following a temperature jump from ambient to 265 °C. The recrystallization process of LCP was found to slow down in the blend state relative to that of the neat LCP.
Surface Properties Of Photoablated Thermostable Polymers
Authors: Hiraoka Hiroyuki , Lazare Sylvain , Cros Alain , Gustiniani R.
Published: March 2011

Surface properties of photoablated thermostable polymers are considerably different from those of original, unexposed ones, and of mercury UV lamp exposed surfaces. They also depend on the laser exposure conditions. This paper reports such non-linear phenomena observed on polymer surfaces, caused by excimer laser exposures, like increased hydrophilicity of polymer surfaces, imagewise wetting and metallizations, and new metal compound formations on laser exposed polymer films. Because these features are limited to polymer films with high glass transition temperature, like polyimides and poly(phenylquinoxaline), photo-mechanical effects may be important. In some cases, new interfacial reactions appear between exposed polymer surfaces and deposited metal films. Swelling of polyimide in pre-photoablation irradiation is discussed.
A Calorimetric Evaluation Of The Peel Adhesion Test
Authors: Goldfarb J. L. , Farris R. J. , Chai Z. , Karasz F. E.
Published: March 2011

Simultaneous mechanical and calorimetric measurements of the work and the heat of peeling have been made for polyester films bonded to rigid metal substrates with a pressure sensitive adhesive. Most of the work expended in peeling is consumed by plastic deformation and viscous dissipation. 70% to 85% of the peel energy is dissipated as heat. The peeled polyester films were tightly curled. Energy stored in the peeled polyester films was measured using solution calorimetry and a significant fraction of the peel energy not dissipated as heat was found to be stored in the peeled films.
A Novel Photochemical Route For Modifying Surfaces: Prospects And Applications.
Authors: Harmer Mark A.
Published: March 2011

Potential applications of a very general route to photochemically modifying a range of surfaces will be described. Surfaces which have been modified vary considerably and include polyimide, polyethylene, fluoropolymers, polyester, glass, tin oxide and aluminum. Photoactivated azides, for example 3-azidopyridine, have been found to be very effective at modifying a range of surfaces. Using this method organic type functional groups, in this case pyridine type groups, can be photografted on to the surface. As a result of photomodification the surface properties change. In the case of polyethylene for example the surface becomes more hyrophilic and shows improved adhesion to metals. These modified surfaces also display acid-base character. In the protonated form anions can be exchanged into the film. This method has been used to modify a metal oxide electrode surface to develop chemically modified electrodes. The process may also be used in lithography.
Control Of Polyimide Surface Property By Changing The Surface Morphology
Authors: Lee Kang-Wook
Published: March 2011

The surface properties of polyimide can be changed without altering the bulk properties. The surface layer (around 200 Å) of fully cured PMDA-ODA polyimide is chemically modified to polyamic acid which is subsequently imidized at 230 °C for 30 min to give an unordered polyimide surface. This unordered layer seems amorphous since it swells well in NMP. The modified surfaces are analyzed by surface sensitive techniques such as contact angle measurement, XPS, ISS, and external reflectance infrared (ERIR) spectroscopy. Adhesion of polyimides and chromium on the amorphous polyimides is greatly enhanced. Interdiffusion and subsequent mechanical interlocking are the major contributions to the polyimide-polyimide adhesion.
Fluorinated Polyimide Block Copolymers
Authors: Labadic J. W. , Sanchcz M. I. , Cheng Y. Y. , Hedrick James L.
Published: March 2011

Block copolymers based on the poly(amic ester) of poly(4,4′-oxydiphenylene-pyromellitide) and perfluoroalkylene aryl ethers were synthesized from preformed amine terminated perfluoroalkylene aryl ether oligomers. Fluoropolymer structure, wt% incorporation, and molecular weight were varied. Reduction in the dielectric constant to 2.8–2.9 and reduced moisture sensitivity were observed for block copolymers with 55 wt.% poly(perfluoroalkylene aryl ether) content without significant compromise of mechanical or thermal properties.
Photochromic-Induced Photorefractive Changes in Barium Titanate
Authors: Garrett M. H. , Chang J. Y. , Jenssen H. P. , Warde C.
Published: March 2011

Photochromism in barium titanate was found to affect its deep and shallow trap properties. Argon ion laser illumination at 514.5 nm photo-induced semi-permanent (thermally reversible) changes in the visible absorption spectrum of barium titanate that were stable at room temperature. Increases in absorption at 514.5 nm, also the operating wavelength used to determine photorefractive properties, caused a decrease in the photorefractive response time but also a decrease in the sensitivity. When the photochromism was inactive the crystal shows light-induced absorption. With the photochromism saturated the crystal showed light-induced transparency. A model with two photoactive levels is used to characterize the photorefractive properties of this photochromic crystal.
The Effect of Copper Vacancies on the Optical Bowing of
Chalcopyrite Cu(In,Ga)Se2 Alloys
Authors: Albin D. S. , Carapella J. J. , Tuttle J. R. , Noufi R.
Published: March 2011

The optical bowing behavior of polycrystalline thin film
Culn1-yGaySe2 alloys is dependent upon
the Cu stoichiometry. The variation in optical band gap, Eg, for
alloys in which Cu is near stoichiometric (25 at.%) is parabolic and follows
the relationship: Eg(y) = 1.011 + 0.421 y + 0.244 y2
(eV), where y is the alloy parameter, [at.% Ga] / [at.%Ga + at.%In].
Contrary to this, films with Cu-poor stoichiometries (∼19 at.% Cu) exhibit
little alloy bowing: Eg(y) = 1.01 + 0.733 y - 0.046 y2 (eV). The
increase in Eg with Cu deficiency appears to be the result of both a
structural effect associated with tetragonal lattice shrinkage, ΔV =
Vstoichiometric - VCu-poor (resulting from the
presence of Cu vacancies) and a chemical effect, possibly associated with a
counterbalance between p-d repulsion and anion displacement effects.
Material Requirements For All-Optical Devices:Nonlinear Properties of Poly-4BCMU
Authors: Stegeman G. I. , Torruellas W. , Rochford K. B. , Zanoni R. , Krug W. , Miao E. , Beranek M. W.
Published: March 2011

The non-resonant third order nonlinearity of conjugated polymers appears to be potentially useful for all-optical devices in waveguide formats.[l,2] This nonlinearity manifests itself as an intensity-dependent refractive index which leads to a nonlinear phase shift over some propagation distance. Device research over the last few years has shown that there are certain minimum requirements for the nonlinear phase shift that need to be achieved over one absorption length of the material.[l,3] There are two principal sources of absorption, the usual linear absorption which is independent of fluence, and two photon absorption for which the absorption scales linearly with intensity. Thus the usefulness of a nonlinear material for all-optical switching devices can be evaluated from a limited number of material parameters, namely n2(in n = n0+ n2I where I is the local intensity), α0which is the low power absorption coefficient andβwhich is the two photon coefficient (in α = α0+βI). The problem for a given material is to identify spectral regions over which the minimum required phase shift can be achieved.
Preparation of Boron Nitride Films by Rf Reactive
Sputtering
Authors: Banerjee P. K. , Chaterjee B. , Kim J. S. , Mitra S. S.
Published: March 2011

Boron nitride films were deposited by rf reactive sputtering. The
composition of the film was determined by X-ray photo-electron
spectroscopy(XPS). Optical properties of boron nitride were studied by IR
spectroscopy. Resultant films showed optical characteristics similar to
those of hexagonal boron nitride. The ratio of boron to nitrogen was varied
from 3.11 to 1.45 by varying the amount of nitrogen. Resulting films have
refractive index in the range of 2.05 – 3.21.
Selectively Absorbing Properties of Sol Gel Dip Coated Indium
Tin Oxide Thin Films on A Glass Pane
Authors: Jung Hyung-Jin , Lee Hee-Hyung , Lee Dong-Heon , Lee Jeon-Kook
Published: March 2011

Selectively absorbing properties of indium tin oxide(ITO) thin film were
characterized in UV-VIS-NIR wavelength regions. Sodium diffusion from glass
pane had a bad influences on the properties of ITO layers. So
silica-zirconia barrier layers were formed by sol gel dip coating. ITO films
on buffer layered glass pane were formed by sol gel dip coating.
Transmittance and reflectivity dependence on the thickness of barrier layer
and ITO coating layers were studied by measuring sheet resistance and
UV-VIS-NIR spectroscopy.

Transparency at 550 nm wavelegth and selective reflectivities were important
to apply to passive solar collectors. In single barrier layer and six-fold
ITO coated films, good selectivities were obtained. Homogeneity of indium
tin precursor coating solution was important. Atmosphere condition
(humidity, temperature), dip and drawing conditions were also additional
factors for uniformity of films.
Influence of Structure on the Soft X-Ray Optical Properties of Metallic Multilayers
Authors: Slaughter J. M. , Kearney Patrick A. , Falco Charles M.
Published: March 2011

Multilayer thin film structures for reflecting soft x-rays are now being fabricated in a number of laboratories. However, understanding of. the optical properties of these structures is presently limited by lack of knowledge of the microstructure of the layers, as well as of the details of the interfaces. In this paper we present results from our studies of multilayers grown by molecular beam epitaxy (MBE), characterized in situ by reflection high energy electron diffraction (RHEED), low energy electron diffraction (LEED), Auger, and x-ray photoelectron spectroscopy (XPS), and characterized ex situ by scanning tunneling microscopy (STM), transmission electron microscopy (TEM), x-ray diffraction, and Rutherford back scattering (RBS). In the case of Mo/Si multilayers, we observe the formation of an amorphous interfacial silicide, which can have a positive effect on the performance of these evaporated multilayer mirrors. We observe a contraction in the period of these multilayers as the deposition temperature is raised from 50 °C to 250 °C, corresponding to an increase in the thickness of the interfacial silicide. This contraction indicates that the silicide is more dense than the average atomic density of its components. We also discuss Ag/B and Pd/B multilayers, which have very similar theoretical performance. However, due to differences in the multilayer structures formed, the actual performance of multilayers made from these materials is radically different. The structural differences originate from different growth modes for Ag and Pd on B.
Interfacial Mixing in Epitaxial Co/Pt Superlattices: a Source of Magnetocrystalline Anisotropy
Authors: Farrow R. F. C. , Hermsmeier B. D. , Lee C. H. , Marks R. F. , Marinero E. E. , Lin C. J. , Chien C. J. , Hagstrom S. B.
Published: March 2011

We report the results of photoelectron forward scattering studies of Co-Pt interfaces during the growth of epitaxial superlattices by MBE. These studies reveal that the interfaces are not atomically abrupt but exhibit limited interdiffusion. The dependence of magnetic anisotropy on growth axis and the strong 2-fold in-plane anisotropy for [110] oriented superlattices suggests that magnetocrystalline anisotropy is a major factor in determining the anisotropy in Co/Pt superlatticcs. The possibility that this anisotropy may arise from a combination of structural defects and local ordering is discussed.
The Effect of Grain Boundaries and Substrate Interactions with Hydrogen on the CVD Growth of Device-Quality Copper.
Authors: Kaloyeros A. E. , Dettelbacher C. , Eisenbraun E. T. , Lanford W. A. , Li H. , Olowolafe J. F. , Murarka S. , Pintchovski F. , Shy Y. -T. , Toscano P. J.
Published: March 2011

The effects of grain boundaries and substrate interactions with hydrogen on the CVD growth of device-quality copper were investigated by high-resolution x-ray photoelectron spectroscopy (HRXPS), Auger electron spectroscopy (AES), four-point resistivity probe, x-ray diffraction (XRD), and hydrogen profiling techniques. The films were deposited at 200° C in a stainless-steel cold-wall-type CVD reactor in an atmosphere of pure H2 from various β-diketonate precursors, including bis(6,6,7,7,8,8,8-heptafluoro-2,2- dimethyl-3,5-octanediono)copper(II), Cu(fod)2, and bis(2,2,6,6-tetramethyl- 3,5-heptanedionato)copper(II), Cu(tmhd)2. The results of these studies showed that films grown on in-situ plasma-cleaned metallic substrates were uniform, continuous, adherent, and highly pure. Films with grain size larger than 500Å exhibited very low resistivity, as low as 1.7 μΩcm. Preliminary investigations of the mechanisms of selective copper CVD showed that selectivity is independent of precursor chemistry and is a function of the nature and degree of substrate interactions with hydrogen.
The Real-Space Multiple-Scattering Theory and the Electronic Structure of Grain Boundaries.
Authors: Sowa Erik C. , Gonis A. , Zhang X. -G.
Published: March 2011

We describe the recently developed real-space multiple-scattering theory (RSMST), which is designed for performing first-principles electronic-structure calculations of extended defects, such as surfaces and interfaces including atomic relaxations and with or without impurities, without using artificial periodic boundary conditions. We present the results of non-charge-selfconsistent RSMST calculations of the local electronic densities of states at twist and tilt grain boundaries in fcc Cu and bcc Nb, and report on progress towards the implementation of charge self-consistency and total-energy capabilities.
Determination of Energy Minima for Dissimilar Metal Interfaces
Authors: Shewmon Paul , Dregia Suliman
Published: March 2011

Relative orientations which correspond to minimum energy can be found by particle rotation methods, both for particles on free surface and particles inside a solid. For common fcc metals (Ni,Ag,Cu,Ag) the minimum energy orientations predicted by Embedded Atom Method calculations correspond well with experimental observations. Epitaxial studies of growth on (001)Cu and (111)Cu show the observed orientation relationships of vapor deposited Ag and Au are consistent with EAM calculations and the limited particle rotation experiments available.
Tem Characterization of Grain Boundaries in Mazed Bicrystal Films of Aluminum
Authors: Dai-Men U. , Westmacott K. H.
Published: March 2011

The structure and faceting behavior of near-90° <110> tilt grain boundaries in thin films of aluminum with a unique mazed bicrystal geometry is characterized by conventional, highresolution and high-voltage electron microscopy. In this microstructure the absence of triple junctions allows grain boundaries to facet in optimum orientation (inclination) during annealing. The degree of anisotropy of the boundaries is expressed in the form of a rose plot. Small local deviations in misorientation are shown to be necessary to accommodate optimum boundary segments. The crystallographic symmetry inherent in this microstructure is apparent and utilizedthroughout the analysis.
A Preliminary Characterization of the Defect Structure of the Zeta Phase in the Interfacial Region of Fe-Zn Couples
Authors: Giannuzzi Lucille A. , Howell Paul R. , Pickering Howard W. , Bitler William R.
Published: March 2011

A preliminary investigation of the defect structure of the monoclinic zeta phase, within the interfacial region of Fe-Zn couples, has been performed using cross-section transmission electron microscopy (TEM). Twin boundaries and dislocations have been unambiguously identified, however, examples of defects which, as of yet are unknown, are also presented. The monoclinic zeta phase was found to twin by a rotation of 180° about the normal to the (110) plane.
Surface Wave Velocity of Silver/Chromium and Gold/Chromium Superlattices
Authors: Kaneko Takeo , Ogu Shinzo , Kyuno Kentaro , Inoue Yasushi , Yamamoto Ryoichi , Yoshihara Akira
Published: March 2011

Rayleigh surface wave velocities in Ag/Cr and Au/Cr metallic superlattices have been measured by Brillouin scattering spectroscopy. These metallic superlattices were prepared by the metal-MBE method. X-ray diffraction measurements indicated that the structures of Ag/Cr and Au/Cr superlattices were almost the same. In the Au/Cr superlattices a maximum in a plot of surface wave velocities as a function of the bilayer thickness was observed. On the contrary, a distinct dip was shown in Ag/Cr systems. This anomalous behavior of the sound velocity could not be attributed to the expansion and the contraction of the lattices. Differences in atomic scale structure in the interface seem to play a major role in these systems.
Interfacial Energy Reduction Analysis in Fibrous Structures
Authors: Sandlin A. C. , Schaefer R. J.
Published: March 2011

The morphology of directionally solidified CuAl-Pb monotectic alloys has been studied. The structure consisted of a hexagonal array of Pb rods in a Cu-based matrix. In addition, elongated grain boundaries in the Cu-based matrix with lens-shaped Pb fibers on the boundary and a “denuded zone”, depleted of Pb rods, were observed. Existence of these boundaries is shown to reduce the overall surface energy of the system leading to the formation of the elongated grain boundaries.
Reconstructions and Morphological Instabilities of FCC (110)Surfaces
Authors: Sun J. , Rottman Craig
Published: March 2011

We compare the ground state energy of the following structures of fcc (110) surfaces: the (1×1) flat surface, the (n×1) reconstruction (2 ≤ n < ∞), and the (∞ × 1) structure where the surface is faceted into macroscopic (111) surfaces. We map out the phase diagram using a lattice model with pair and triplet interactions. We argue that it is unlikely that any realist pair potential will give a reconstructed ground state. We also doubt that including, in addition, three body interactions will stabilize the reconstructed structure for interatomic interactions derived from the embedded atom method.
The Effect of S Segregation on the Grain Boundary Geometry of a Σ11 Nickel Bicrystal
Authors: Juhas Mary C. , Priester Louisette
Published: March 2011

Grain boundary (GB) solute segregation has long been associated with premature failure of engineering materials. Local changes in composition at the GBs can result in such phenomena as intergranular corrosion, temper embrittlement, intergranular fracture and fatigue as well as changes in electrical properties. The relationship between GB structure and solute segregation is not well understood.
Concentration-Dependent Surface-State Shifts: Au on Cu(001)
Authors: Hansen J. C. , Wagner M. K. , Tobin J. G.
Published: March 2011

High-resolution angle-resolved photoemission has been used to investigate the behavior of the Cu(001) surface state as a function of Au coverage and substrate temperature. Binding-energy shifts of this state are dependent on the concentration of Au atoms substituted into the top surface layer of the Cu(001) substrate. The results demonstrate the use of surfacelocalized Tamm states as a specific probe of the chemical environment in the surface plane.
Low Energy Electron Diffraction During Pulsed Laser Annealing: A Time Resolved Surface Structural Study
Authors: Becker R. S. , Higashi G. S. , Golovchenko J. A.
Published: March 2011

Nanosecond structural changes in a crystal lattice during pulsed laser annealing have been measured using time-resolved Low Energy Electron Diffraction (LEED). LEED is both structure and surface (∼ 10Å) sensitive. Lattice temperatures can be extracted from Debye-Waller like extinction coefficients. Combining these with nanosecond time resolution provides a surface probe for short-time dynamical processes. The technique is used to observe the time evolution of a Ge(l11) surface during pulsed laser annealing. The results demonstrate rapid formation of a liquid layer and subsequent surface recrystallization and cooling.
Optical Properties of Laser Induced Heavily Doped Silicon Layers
Authors: Slaoui A. , Fogarassy E. , Siffert P. , Morhange J.F. , Balkanski M.
Published: March 2011

The goal of this paper is to investigate optical properties of heavily doped silicon, performed by laser annealing of implanted layers.

The optical properties were investigated by using U.V. and visible light (between 200 and 500 nm)reflectance and Raman spectrometry measurements. The experimental observations have been correlated with the contribution of the supersaturated solid solution of arsenic in the silicon lattice. Furthermore,the absorption coefficent of these layers has been deduced from ellipsometry measurements.
CW Laser Annealed Small-Geometry NMOS Transistors
Authors: Naem A.A. , Boothroyd A.R. , Calder I.D.
Published: March 2011

Small geometry NMOS transistors were fabricated using junctions implanted with 1016; Asplus;/cm2; @ 180 keV and annealed through 1067 Å of SiO 2; with a cw argon laser. Phosphosilicate glass densification was the only other high temperature step. Channel lengths were varied from 1.3 to 50 μ. and channel widths from 1 to 50,μ. Physical characterization of these devices revealed a junction depth of 3000 Å with negligible lateral diffusion. The smallest transistor had approximately a square channel with WxL = 1×l.3μ2;. IDS;−VDS; characteristics of this device were similar to those of large geometry devices due to counteracting short and narrow channel effects. The threshold voltage was 0.61±0.013 V across an entire wafer, while there was no punch-through for VDS;<13 V and no avalanche breakdown for VDS; < 14 V. The junctions showed a forward-biased ideality factor of 1.17, and the contact resistance in an 8 × 8 μ2; area was 1.5Ω to the source/drain regions and 0.5Ω to laser-recrystallized polysilicon interconnects. It is concluded that cw laser annealing can be used to fabricate small-geometry devices with excellent performance and without any deleterious effects.
Some Results Concerning the Residual Stresses Distribution in Laser Treated Samples
Authors: Chabrol C. , Coquerelle G. , Gerbet D. , Nicolas G. , Vannes A.
Published: March 2011

Residual stress introduced in middle carbon steels by a solid-solid transformation following a laser heating are studied by two methods : a destructive one which consists in taking away layers of material, the other one, a non destructive method, based on the ferromagnetic noise analysis. The first method gives an average value of the stresses existing in the machined layers, the second one gives informations on localized variations.
Lattice Temperature of GaAs and Si During Nanosecond Laser Annealing
Authors: Pospieszczyk A. , Abdel Harith M. , Stritzker B.
Published: March 2011

Single crystals of GaAs (100) and Si (110) were laser annealed with a 20 ns ruby laser pulse. Both the velocity distribution and the density variation of evaporated Ga or As and Si atoms were determined by a time-of-flight measurement. In addition time-resolved measurements were made of the reflectivity of the surface during the laser annealing. The data consistently show that the molten phase occurs at energy densities of ≳ 0.35 J cm–2 for GaAs and ≳O.8 J cm for Si.
Taser Induced Bulk Defects in Single Crystal Silicon Below the Melting/Vaporization Thresholds
Authors: Parker Donald L.
Published: March 2011

Highly focused Q-switched Nd:VDG fundamental (1.05 micron wavelength IR) and second harmonic (0.53 micron wavelencth green) laser pulses have been shonm to produce bulk defects in single crystal silicon at peak power densities below the vaporization threshold for the IR and below the melting threshold for the green. The defects decrease the encess rinoritv carrier lifetime as measured by junction leakage, junction step recovery, the MOS CV method, bioolar transistor current qain, and pn junction photocurrent. Green pulses have no effect on the thermal oxide dielectric strength or pn junction breakdown voltage at power densities up to the melting threshold. IR pulses begin to lower the junction breakdown voltage below the vaporization threshold and oxide dielectric strength is drastically lowered at or slightly below this threshold. The defect density decreases exponentially into the crystal with effective ranges of 0.7 micron and 1.7 microns for the green and IR respectively. IR absorption is very nonlinear near the vaporization peak power density threshold. The defects are a point type; are unchanged by a subsequent 400°C anneal; and are completely removed by an 800°C anneal. The results suggest some detrimental effects of laser processing of silicon intergrated circuits as well as some new potential applications.
Device Applications of Rapid Thermal Processing
Authors: Gibbons J. F. , Dobkin D. M. , Greiner M. E. , Hoyt J. L. , Opyd W. G.
Published: March 2011

The potential of rapid thermal processing for applications in silicon integrated circuit technology, silicon microwave bipolar technology and GaAs FET technology is explored.In addition, two novel applications for GaAs processing are described.
Soi by CVD: An Overview of Material Aspects and Implications of Device Properties
Authors: Jastrzebski L. , Kokkas A. G.
Published: March 2011

Two CVD techniques producing monocrystalline SOI films, silicon-on sapphire (SOS) and Epitaxial Lateral Overgrowth (ELO), are described and the nature of the crystallographic defects in the films is discussed. The geometrical structure of SOI devices, device properties, dynamic characteristics, capacitance, and radiation hardness are then examined with emphasis on evaluating the potential of SOI technologies in future applications.
Grain Boundary Confinement in Soi Films Using Patterned Ar Coatings and Seeded Oscillatory Growth
Authors: Drowley C.I. , Zorabedian P. , Kamins T.I.
Published: March 2011

Regular arrays of grain-boundary-free silicon strips several hundred microns long have been produced in a silicon-on-insulator (SOI) structure by using a patterned anti-reflection (AR) coating in combination with seeded oscillatory growth techniques. The AR coating pattern consists of a series of parallel stripes (typically 10 μm wide, separated by 10 μm spaces) starting from a seeding window. A laser beam (typically a 50 μm × 250 μm elliptical beam) is scanned perpendicular to the stripes, with the long axis of the beam parallel to the scan direction. The beam is stepped 1–2 μm between successive scans to advance the single crystal along the direction of the AR stripes. Grain boundaries are confined to the region under the AR stripes. Stereographic analysis of KOH etch pits formed in the single crystal strips has shown that the orientation of the stripes gradually rotates from (001)[110] to (013)[331] as the crystal propagates away from the seed. MOS transistors formed in the single-crystal strips have mobilities comparable to devices formed in bulk films. These mobilities are approximately 20% higher than those found in devices formed in large-grain recrystallized polysilicon films.
The Role of Oxygen in Zone-Melting Recrystallization of Silicon-On-Insulator Films
Authors: Fan John C. C. , Tsaur B-Y. , Chen C. K. , Dick J. R. , Kazmerski L. L.
Published: March 2011

Using secondary-ion mass spectroscopy, we have found that oxygen is strongly concentrated at the sub-boundaries in zone-melting-recrystallized silicon-on-insulator films prepared by the graphite-strip-heater technique. This observation suggests that the formation of sub-boundaries during recrystallization may be caused by constitutional supercooling resulting from the presence of oxygen that is dissolved into the molten Si zone from the adjacent SiO2 layers. Since all zone-melting-recrystallized films to date have been bordered by SiO2 layers, regardless of the heating techniques employed, the sub-boundaries almost always present in these films may well have dissolved oxygen as their common origin.
Characteristics of Short-Channel Mosfet's in Laser Crystallized Si-on-Insulator
Authors: Ng K. K. , Celler G. K. , Povilonis E. I. , Trimble L. E. , Sze S. M.
Published: March 2011

Data are reported on short-channel MOSFET's fabricated in laser crystallized silicon-on-insulator (SOI) structures. In this experiment, special effort was made to minimize enhanced diffusion of dopants from the source and drain regions along grain boundaries. Instead of the standard anneal used for the implant activation, rapid thermal annealing and low temperature furnace annealing were used. These modified processes yielded functional MOSFET's with channel lengths as short as 1.5 μm, and ring oscillators of 2.0 μm. A speed of 115 ps per stage was obtained in these ring oscillators which is not only the fastest ever reported on any SOI structure, but also a factor of 2 faster than that from the same circuits in bulk Si. The results demonstrate quantitatively the speed improvement of SOI over bulk material due to reduced parasitic capacitance.
Thick Films for Dielectric Isolation by Lateral Epitaxy from the Melt
Authors: Celler G. K. , Trimble L. E.
Published: March 2011

Dielectric Isolation (DI) technology has been available for almost twenty years. It was first developed for low capacitance, high speed circuits, and was later adapted to radiation hardened devices and for high voltage isolation. We describe a new method of forming DI structures that simplifies wafer fabrication, reduces the density of process induced defects, and may lead to a more flexible device design. Our process is based on recrystallization from the melt of thick Si films deposited over oxidized Si wafers, with a regular array of seeding windows opened in the isolation oxide. The recrystallized films are free of grain boundaries and subboundaries.
Picosecond Time-Resolved Optical Studies of Plasma Formation and Lattice Heating in Silicon
Authors: Lompré L. A. , Liu J. M. , Kurz H. , Bloembergen N.
Published: March 2011

Time-resolved studies of reflectivity and transmission at 0.532 μm, 1.064 vm and 2.8 μm of thin silicon films following irradiation with ps pulses at 0.532 μm have been performed. The formation of the electron-hole plasma and the evolution of lattice temperature is investigated as a function of pump fluence and time delay. Quantitative determination of the plasma densities and lattice temperature up to the melting temperature shows that the maximum plasma density is limited to ∼ 1 × 1021 cm−3 by Auger recombination even on a time scale of picoseconds at fluences sufficient to cause the phase transition. The thermal nature of the phase transition is confirmed.
Beam-Recrystallized Device-Worthy Films of Si on SiO2 via Control of the Grain Boundary Location
Authors: Colinge J.P. , Bensahel D. , Alamome M. , Haond M. , Leguet C.
Published: March 2011

Device-worthy films of silicon on SiO2 have been produced using laser annealing and antireflection stripes. If no seeding is used, grain boundaries will be localized beneath the stripes; with seeding, large-area single crystals can be grown, of uniform <100> orientation. N-channel transistors show a mobility of 620 cm2/V.s and present leakage currents which can be reduced, however, down to a few pA/um when the substrate (back gate) is negatively biased to − 5 V. Ring oscillators have also been made, which oscillate with a delay per stage of 1 nsec.
Laser Annealing of GaP and GaAs in High-Pressure Argon Gas Ambients
Authors: Sato Fumio , Sunada Tadasu , Chikawa Jun-ichi
Published: March 2011

Pulsed laser annealing has been made for Te or Znimplanted GaP and Si-implanted GaAs in argon gas atmospheres in a pressure range of 1 to 1000 bar. Optical absorption measurement indicates that pulse annealing under pressures higher than 300 bar forms surface layers with a high crystallinity without appreciable evaporation of P or As. This pressure effect is discussed from the viewpoint of diffusion length of evaporated atoms during the annealing time.
Rapid Thermal Annealing of Si-Implanted GaAs
Authors: Rosenblatt D.H. , Hitchens W.R. , Shatas S. , Gat A. , Betts D.A.
Published: March 2011

Heatpulse rapid thermal annealing was used to activate Si implants of 3.5 × 1012cm−2 at 100 keV and 1.0 × 1013 and 1.0 × 1014cm−2 at 200 keV into semi-insulating GaAs. The effects of Si3N4 encapsulation, anneal temperature and time, and substrate Cr-doping level were investigated. The annealed samples were characterized with C-V, Van der Pauw, differential Hall, and SIMS measurements. Conventional furnace anneals were carried out for comparison, and in all cases, Heatpulse anneals produced sharper carrier concentration profiles. 84% electrical activation was obtained for the 200 keV, 1.0 × 1013 cm−2 implant after a 950°C, 5 sec. Heatpulse anneal. Capped Heatpulse anneals produced less Cr depletion from the implanted region than furnace anneals.