bluuebunny/crossref_metadata_2025 huggingface dataset:
Plastic Flow of L12Ordered Alloys
Authors: Pope D. P. , Vitek V.
Published: March 2011

The flow stress of many L12ordered alloys has a very unusual temperature dependence: the flow stress increases with increasing temperature. This unusual behavior is related to the nature of dislocation dissociation and core structure. The flow stress increase is the result of thermally activated cross slip of [101] screw dislocations to the (010) plane which is accompanied by a transformation of the dislocation core from a glissile to a sessile form. Thus dislocations which are mobile on (111) planes become immobile after cross-slip into (010) planes. The dependence of the flow stress on temperature, orientation and sense of the applied uniaxial stress will be discussed in the light of this cross slip model for Ni3Al, Ni3Ga and for γ/γ′ nickel base superalloys.

The response of Ni3Al to cyclic plastic strains (plastic strain controlled fatigue) will also be shown to be in accord with the cross slip model. The mean stress in such a test becomes compressive or tensile, depending on the orientation of the sample, even though the net plastic strain is zero after each cycle.

The strengthening of Ni3Al by ternary additions will also be discussed. It will be shown that ordinary solid solution strengthening models are not applicable but that the cross slip model can also be applied.

Finally, it will be shown that dislocation core simulation studies predict that there should also be a class of L12ordered alloys that show a “normal” flow stress-temperature behavior, i.e., the flow stress increases at low temperatures. The results of our studies on Pt3Al will be used to illustrate this behavior.
Wear Induced Deformation of Ni3Al, (Fe, Co)3V, and (Fe, Ni)3V
Authors: Marquardt B. J. , Werta J. J.
Published: March 2011

Several experimental techniques have been implemented in order to compare the tribological response of Ni3Al, (Fe, Co)3V, and (Fe, Ni)3V to commercial engineering alloys. Abrasive and adhesive macrowear behavior during sliding contact has been determined. Microstructural data obtained from transmission electron microscopy (TEM) and scanning electron microscopy (SEM) have been correlated with macrowear results. In this correlation, consideration was given to the effects of wear on long-range-order and the presence (or absence) of dislocation subcell structures. The formation of dislocation subcell structures is partially related to the material's stacking fault energy (SFE) which has been the basis of recent wear theory. An experimentally verified wear mechanism based on inhomogeneous slip is defined.
Characteristic Mechanical Properties and Phase Stability of L12Intermetallic Compounds
Authors: Mishima Yoshinao , Oya Yoshihiro , Suzuki Tomoo
Published: March 2011

The present paper deals with the occurence and magnitude of characteristic mechanical anomalies observed in many L12intermetallic compounds and their relation to the phase stability of the crystal structure against other geometrically closed packed(GCP) phases. The dislocation configurations in the crystal structure and resultant plastic behavior are in close relation with anti-phase boundary(APB) and stacking fault(SF) energies in the compounds, while the relative magnitude of these energies on various crystallographic planes actually determines the phase stability of the L12crystal structure. It is shown here, based on our series of investigations carried out over the past decade, that the general tendencies for particular deformation modes to occur can be systematically interpreted in terms of alloy chemistry of the compounds, including variables such as combination of component species, nonstoichiometry and ternary additions in the compounds, all of which affect the stability of the phase.
Damping and Modulus Measurements in B2 Transition Metal Aluminides
Authors: Harmouche M. R. , Wolfenden A.
Published: March 2011

The polycrystalline intermetallic alloys FeAl (50.9 to 58.2% Fe), NiAl (49.2 to 55.9% Ni) and CoAl (48.5 to 52.3% Co) have the B2 structure and are of interest for high temperature applications. We have used the PUCOT (piezoelectric ultrasonic composite oscillator technique) to measure mechanical damping or internal friction (Q−) and Young's modulus (E) as a function of temperature and composition for these materials. The modulus data for six CoAl alloys at temperatures up to 1300 K are presented. Examples are given of the strain amplitude dependence of Q−1 for four CoAl alloys. The curves showed the break away phenomenon and are interpreted in terms of a theory dealing with the pinning of dislocation lines and their eventual break away at large strain amplitudes. The dislocation density was calculated to be about 108 m−2. For all the compositions (Xl) of CoAl studied a single equation could be fitted to the data:

E (X1, T) = 210.8 + 2.2 (XI) -0.08T (1)

where T is in K and E in GPa.
Alloys based on NiAl for High Temperature Applications
Authors: Vedula K. , Pathare V. , Aslanidis I. , Titran R. H.
Published: March 2011

This paper presents some of the results obtained in an on-going study of NiAl alloys for potential high temperature applications. Alloys were prepared by powder metallurgy techniques. Flow stress values at slow strain rates and high temperatures were measured. Some promising ternary alloying additions (Hf, Ta and Nb) have been identified. The mechanism of strengthening in alloys containing these additions appears to be a form of particle dislocation interaction. Interesting effects of grain size and stoichiometry in binary alloys are also presented.
On the Feasibility of AB Initio Calculations of Ordering Alloy Phase Diagrams
Authors: Fontaine D. de
Published: March 2011

Many stable or metastable intermetallic phases useful to the alloy designer have crystal structures which are ordered superstructures of a parent disordered phase. A highly reliable statistical mechanical method (CVM) has now been developed for calculating such superstructure phase equilibria derived from say, the fcc parent lattice. To obtain phase diagrams, one needs certain physical parameters, such as effective pair interaction ratios. It is possible, in principle, to extract these parameters from band structure calculations in the coherent potential approximation (CPA), particularly from recently developed cluster-CPA techniques. If sufficient accuracy can be achieved, truly first-principles phase diagram calculations may soon become feasible.
Weldability of Ni3Al-Type Aluminide Alloys
Authors: Santella M. L. , David S. A. , White C. L.
Published: March 2011

If the ductile Ni3Al-based aluminides are to achieve their full potential as engineering materials, they must demonstrate a capability for being joined by conventional welding processes. The goal of this study was to identify some of the factors controllinq weldability of the ductile aluminides. The alloys selected for this initial study were boron-doped Ni3 Al and Ni3 Al containing 10 at. % Fe. Sheet stock was used to make full penetration autoqenous welds by the electron beam and gas tungsten arc processes. The main process variables were travel speed and preheat. The aswelded coupons were examined visually and by normal metalloqraphic methods. Although sound welds were made, initial results indicated weldments of these alloys are susceptible to cracking. Weldability of the ductile Ni3Al-based aluminides was found to be affected by alloy composition and welding speed.
Synchrotron X-Ray Study of the Structure of Silicon During Pulsed Laser Processing
Authors: Larson B. C. , White C. W. , Noggle T. S. , Barhorst J. F. , Mills D.
Published: March 2011

Synchrotron x-ray pulses have been used to make nanosecond resolution time-resolved x-ray diffraction measurements on silicon during pulsed laser annealing. Thermal expansion analysis of near-surface strains during annealing has provided depth dependent temperature profiles indicating >1100°C temperatures and diffraction from boron implanted silicon has shown evidence for near-surface melting. These results are in qualitative agreement with the thermal melting model of laser annealing.
Competition Between Solid Phase Epitaxy and Random Crystallization During cw Laser Annealing of Amorphous Si Films
Authors: Roth J.A. , Kokorowski S.A. , Olson G.L. , Hess L.D.
Published: March 2011

The kinetics of amorphous-to-polycrystalline conversion and solid phase epitaxy (SPE) in UHV-deposited Si films have been determined over a wide temperature range by the use of optical reflectivity measurements made during rapid heating by a cw Ar laser. Crystallization rates measured in UHV following film deposition are reported and compared to rates measured in air in order to elucidate the effects of contaminants on the processes. The effects of boron doping on nucleation and growth kinetics are also reported. The crystallization rates determined in these studies can be used to predict the volume fraction of polycrystalline material formed during laserinduced SPE growth of thick epitaxial layers.
Structural Modifications of Amorphized Silicon Surfaces Following Picosecond Laser Irradiation
Authors: ROZGONYI G.A. , Baumgart H. , Phillipp F. , Uebbing R. , Oppolzer H.
Published: March 2011

We have used cross-section TEM and Nomarski optical microscopy to examine the origin of halo patterns previously observed following picosecond irradiation of ion implantation amorphized Si. The importance of melt depth, quench rate and the incomplete nature of the initial amorphization step are emphasized. A search for a post annealing morphological or microstructural signature related to a plasma activated process proved negative.
Transient Conductance Measurements During Pulsed Laser Annealing
Authors: Thompson M. O. , Galvin G. J. , Mayer J. W. , Hammond R. B. , Paulter N. , Peercy P. S.
Published: March 2011

Measurements were made of the conductance of single crystal Au-doped Si and silicon-on-sapphire (SOS) during irradiation with 30 nsec ruby laser pulses. After the decay of the photoconductive response, the sample conductance is determined primarily by the thickness and conductivity of the molten layer. For the single crystal Au-doped Si, the solid-liquid interface velocity during recrystallization was determined from the current transient to be 2.5 m/sec for energy densities between 1.9 and 2.6 J/cm2, in close agreement with numerical simulations based on a thermal model of heat flow. SOS samples showed a strongly reduced photoconductive response, allowing the melt front to be observed also. For complete melting of a 0.4 μm Si layer, the regrowth velocity was 2.4 m/sec.
Pulsed X-Ray Annealing of Arsenic-Implanted Silicon
Authors: Sigmon T. W. , Osias D. E. , Schneider R. L. , Gilman C. , Dahlbacka G.
Published: March 2011

In this paper we report experiments on annealing of arsenic-implanted silicon using a pulsed imploding-plasma X-ray source. Silicon wafers of <100> orientation were implanted with arsenic ions at 50 keV to a dose of 3.5 ∼ 1015 cm−2 and exposed to a single 50 ns pulse of X-rays in the energy density range of 0.15 to 0.55 J/cm2 The characteristic X-ray absorptiog coeificient in silicon for these experiments was 1.6 ∼ 10 cm−1, resulting in most of the energy being absorbed in the first 100 nm of the wafer surface.

For wafers annealed in the energy density range of 0.3 to 0.4 J/cm2 backscattering and channeling measurements show recovery of the crystallinity of the damaged layer with incorporation of about 86% of the implanted arsenic onto substitutional lattice positions. Evidence of redistribution and flattening of the arsenic profile in the annealed wafer was observed in the backscattering data and confirmed by SIMS profiling. Detailed results on the electrical and structural properties of these annealed layers will be presented. High energy pulsed X-ray sources offer the unique capability of simultaneously exposing large numbers of wafers to an extremely uniform energy flux at much higher efficiencies than conventional lasers.
On the Influence of Laser Beam Homogenity on the Regrowth of Ion Implanted Si
Authors: Wielunski M. , Auleytner J. , Tjros A. , Wielunska D.
Published: March 2011

A simple method of improving laser beam homogenity has been developed. A cylindrical quartz pipe, acting as a lightguide, has been applied for dispersion of the components of the laser beam (microbeams), thus providing more uniform illumination of the sample's surface. The effects of such a homogenizer have been studied by means of X-ray transmission topography [4–5] and 2-MeV 4 He-ion channeling. The samples were ≤111≥ Si wafers implanted with 100 keV As and Bi ions to a dose of 1016 /cm2 . It has been observed that the shallow residual damage layer which exists in the directly irradiated samples is not present in the samples irradiatedthrough the homogenizer.
Divacancy Annealing in Crystalline Silicon Using E-Beam and Pulsed Ruby Laser Excitation
Authors: Stein H. J. , Knapp J. A. , Peercy P. S.
Published: March 2011

Annealing of divacancies which were produced by 11B ion implantation was investigated under furnace, pulsed e-beam and pulsed ruby laser exposures. Despite orders of magnitude shorter exposure times for annealing and the concomitant expected high levels of electronic excitation and layer stress, we find that the thermal annealing mechanism observed for furnace annealing is an adequate description for divacancy annealing under e-beam exposure. The observed need for melting to remove divacancies by Q-switched laser annealing is also consistent with predictions based upon extrapolations from furnace annealing.
Electronic Defects in Beam - Crystallized Silicon
Authors: Johnson N. M.
Published: March 2011

Directed energy sources have been used to recrystallize implanted amorphous layers in bulk single - crystal silicon and to crystallize silicon thin films on insulating amorphous substrates. All investigated forms of beam annealing leave residual electronic defects in and near the recrystallized layer on bulk silicon, with densities in excess of those obtained by conventional furnace annealing. This paper summarizes the general observations that may be drawn from numerous experimental investigations of electronic defects in CW beam - recrystallized bulk silicon and affirms the timeliness of similar comprehensive studies of residual defects in crystallized - silicon thin films.
Superconducting Effects in Rapidly Quenched Materials Formed by Ion and Laser Bombardment
Authors: Stritzker Bernd
Published: March 2011

The application of low temperature ion bombardment and pulsed laser or electron beam irradiation for the production of rapidly quenched superconducting alloys is described and compared with other more conventionally used non-equilibrium techniques. The comparison is based on the identification of the metastable phases produced by their specific electrical and superconducting properties. It is concluded that low temperature heavy ion bombardment is comparable with vapor quenching whereas laser quenching yields results similar to liquid quenching. Finally, the interesting superconducting properties of these rapidly quenched metastable alloys are discussed.
Space-Time Resolved Reflectivity Measurements of Picosecond Laser Induced Phase Transitions in <111> Silicon
Authors: Yen R. , Liu J. M. , Kurz H. , Bloembergen N.
Published: March 2011

The changes in reflectivity of a silicon surface, irradiated by a green picosecond pulse, are probed during and following that pulse with a spatial resolution of 10μm. The data indicate the development of a liquid phase, and a resolidification either into a single crystal or an amorphous phase. The latter has a characteristic ring-type pattern, and occurs only at locations where the incident picosecond laser fluence lies between 0.2 and 0.26 J/cm2. The reflectivity data appear to be in good quantitative agreement with a “simple heating” model, in which the electrons and phonons maintain a local thermodynamic equilibrium on a picosecond time scale.
Laser-Induced Liquid Zone Migration of Metal-Silicon Alloys in Si
Authors: Kluge-Weiss P. , Roggwiller P.
Published: March 2011

Patterns of sharp narrow vertical p-n junctions were produced by scanning a laser beam over the surface of a silicon wafer coated on the backsurface by either Au-Sb, Al or Ga. Formation of the junctions occurs by liquid zone migration along the thermal gradient induced by the laser beam. Nd-YAG as well as CO2 laser light was employed and the dependance of migration zone width, velocity, front stability and structure on the different laser wave lengths was studied. Structural investigations of the regrown layers included optical microscopy, SEM and TEM studies as well as spreading resistance measurements to ascertain the behaviour of the various p-n junctions produced. Annealing treatments of the migrated zones were performed to alleviate the stresses produced during the migration experiments.
CO2 Laser Crystallization of Silicon on Bulk Fused Silica
Authors: Hawkins William G. , Black Jerry G. , Griffiths Clifford H.
Published: March 2011

A CO2 laser beam was used to heat bulk fused silica which had previously defined Si3N4 and Si02 encapsulated LPCVD polysilicon islands (25,μm × 100μm) on its surface. The recrystallization process produces single crystal islands under a wide variety of laser treatment parameters. Under certain conditions, the recrystallized islands exhibit a (100) plane parallel to the substrate. These results are the first demonstration of oriented single crystal thin film growth using island predefinition, which eliminates thermal stress induced microcracking resulting from the mismatch in expansion between silicon and bulk fused silica.
Fast Scanned Energy Beam Induced Explosive Crystallization of Ion Implantation Amorphized Poly and Single Crystal Silicon Substrates
Authors: Lerme M. , Ternisien D'ouville T. , Vu Duy-Phach , Perio A. , Rozgonyi G.A. , Nguyen V. T.
Published: March 2011

Explosive crystallisation induced by an electron beam and by a CW Ar+ laser operating in fast scanning mode is observed for the first time on amorphized silicon layers created by implantation on either polycrystalline films deposited on Si02 or single crystal silicon substrates. The grain structure in the explosive crescents is studied by preferential chemical etching in conjunction with Nomarski optical microscopy, SEM and TEM. The results are similar to the so-called solid-phase explosive crystallization previously observed in a-Si films deposited on glass substrates.
Silicon-On-Insulator Mosfets Fabricated in Zone-Melting-Recrystallized Poly-Si Films on SiO2
Authors: Tsaur B­Y. , Gels M. W. , Fan John C. C. , Silversmith D. J. , Mountain R. W.
Published: March 2011

N- and p-channel enhancement-mode MOSFETs have been fabricated in Si films prepared by zone-melting recrystallization of poly-Si deposited on SiO2-coated Si substrates. The transistors exhibit high surface mobilities, in the range of 560–620 cm2/V−s for electrons and 200–240 cm2/V−s for holes, and low leakage currents of the order of 0.1 pA/μm (channel width). Uniform device performance with a yield exceeding 90% has been measured in tests of more than 100 devices. The interface between the Si film and the SiO2 layer on the substrate is characterized by an oxide charge density of 1–2 × 1011 cm−2 and a high surface carrier mobility. N-channel MOSFETs fabricated inSi films recrystallized on SiO2-coated fused quartz subtrates exhibit surface electron mobilities substantially higher than those of single-crystal Si devices because the films are under a large tensile stress.
P-Glass Reflow with a Tunable CO2 Laser
Authors: Jeuch P. , Joly J.P. , Hode J.M.
Published: March 2011

Phosphosilicate glass reflow to improve step coverage of metallizations in integrated circuits is usualy made by a high temperature heat treatment. A new technique is proposed to achieve this annealing by a transient localized heating with a tunable CW CO2 laser. A selective coupling of the laser power is obtained by choosing a 9.25 μm wavelength which matches the Si-O absorption band at 1100 cm−1. Focusing and scanning the laser beam makes the P-glass flow without excessive substrate heating.
Laser–Assisted Mos/Sos Transistor Fabrication
Authors: Hess L.D. , Kokorowski S.A. , Olson G.L. , Chi Y.M. , Gupta A. , Valdez J.B.
Published: March 2011

CW laser annealing techniques were incorporated into standard MOS/SOS transistor fabrication procedures and found to be advantageous as compared to conventional furnace methods for electrical activation of ion–implanted source/drain dopants for both N- and P–MOS transistors. Static electrical characteristics of 2.4 μm channel–length transistors are similar for both types of annealing, whereas the speed of devices with cw laser annealed source–drain regions is increased 10 to 40%, depending on the operating voltage.
Formation of p-n Junctions by Laser Processing Sb-Pt Thin Films on Si
Authors: Schutz R. J. , Celler G. K. , Chang C. C.
Published: March 2011

Planar p-n junctions with Pt silicide contacts have been formed by laser irradiating p-type Si/120Å Sb/400Å Pt composite thin film structures. The samples were prepared in a standard e-beam evaporation system. They were never ion implanted. Laser processing was performed with either a scanning cw Ar laser or a Q-switched Nd:YAG (λ = 0.53 μm) laser which provided 100 nsec long pulses. After the irradiations were performed, a p-type Si/n+Si/Pt-Si structure was present. The n+ region resulted from Sb incorporated in the Si lattice. When the same initial composite was furnace annealed, the Sb diffused to the surface and sublimated, leaving a p-type Si/PtSi near-ohmic contact. Depth profiles of the samples were determined with Auger electron spectroscopy. The structure of the Pt-Si layer was studied using wide film Debye X-ray diffraction. The electrical properties of the junctions were examined by measuring their I-V and C-V characteristics and minority carrier lifetimes. Differences in the structural and electrical properties that resulted from the two types of laser irradiation will be discussed.
Surface and Subsurface Morphology of Laser Bean Annealed Auge/Gaaa Ohmic Contacts
Authors: Aina O. , Norton J. , Katz W. , Smith G. , Rose K.
Published: March 2011

A study of the pulsed laser annealing of AuGe films on GaAs using a Nd:YAG laser has revealed differences between the surface and subsurface morfhologies. At laser energy densities lower than 1.1 J/cm2 , the surface retained the smooth, “golden” appearance of deposited AuGe films, while evidence of damage was observed below the surface. At higher energy densities, surface damage was observed. SIMS profiles of Ga and As in the AuGe layer and a laser heating model have been used to explain the presence or absence of damage in terms of the outdiffusion of As and Ga through the laser created melt which leads to the presence or absence of Ga and As at the surface and below the surface.
Laser Annealing of Selenium Implxnted InP
Authors: GILL Sukhdev , Topham Peter , Sealy Brian , Stephens Kenneth , Hales Michael
Published: March 2011

We have compared the electrical properties of laser and furnace annealed selenium implanted InP. Both annealing methods produce high activities, the best being for anneals in a phosphine ambient which also produces a better surface finish. Reasons for the poorer results from the laser annealed samples have been deduced from Rutherford backscattering experiments.
Transient Infrared Reflection and Transmission of Silicon During Pulsed Laser Annealing
Authors: Moss Steven C. , Marquardt Charles L.
Published: March 2011

We report measurements of reflectivity and transmission of probe beams at 0.633, 1.06, 1.34, and 3.39 μm during pulsed laser annealing of silicon. The transient infrared optical response of the silicon was monitored with several fast photodetectors. The diversity of detector response to transmitted light indicates that contradictory results obtained previously may be artifacts of photodetector response.
Discharge Annealing of Ion Implanted Silicon
Authors: Fleddermann C. B. , Ianno N. J. , Verdeyen J. T. , Streetman B. G.
Published: March 2011

A gas discharge system is used to produce a large area electron beam which can be used to angeal ion-implanted semiconductors. The sample temperature rise and amorphousto-single-crystal regrowth were monitored using the change in optical reflectivity.
Picosecond Dynamics of Laser Annealing
Authors: Kim Dae M. , Shah Rajiv R. , Von Der Linde D. , Crosthwait D.L.
Published: March 2011

We report simultaneous measurements of time resolved reflection and transmission of low intensity 1.06 μm, 35 ps pulses subsequent to excitation of 50 KeV, 1016 cm−2 boron implanted silicon by 0.53 μm 35 ps pulses of varying energy densities. The samples are examined by optical and scanning electron microscopy in conjunction with defect etching. These data are discussed from the point of view of both the thermal melting model and plasma model.
On the Mechanics of Failure in Ceramic/Metal Bonded Systems
Authors: Evans Anthony G. , Ruhle M.
Published: March 2011

Stress concentrations that develop in metal/ceramic bonded systems have been evaluated and shown to encourage crack propagation at, or near, the edge of bonded interfaces. Experimental indentation observations on Nb/Al2O3 confirm the existence of the predicted stress concentrations. In this system, failure was invariably observed to initiate in the ceramic, such that quasi-static cracks located at the interface exhibited crack blunting. However, substantial dynamic reductions in the crack growth resistance of the interface are inferred from fracture surface observations. Implications for the optimal strengths of ceramic/metal bonded systems are presented.
Thermal Expansion Mismatch in Electronic Packaging
Authors: Carlson R. O. , Glascock H. H. , Webster H. F. , Neugebauer C. A.
Published: March 2011

Thermal expansion mismatch causes serious problems in operating device reliability because of the various stresses imposed on the joint materials undergoing temperature changes. Silicon has a low expansion coefficient so strain buffers are often employed between the silicon and the outer metal covers with relatively high expansion coefficients. These buffers can be metals like molybdenum, ceramics like alumina, or a brush structure of copper, with soft solders at the joints. However, solders themselves have finite fatigue lives which can be estimated from material and dimensional data.
An Overview of Materials Science in Printed Circuit Packaging
Authors: Seraphim D. P. , Lee L. C. , Appelt B. K. , Marsh L. L.
Published: March 2011

A brief description of a set of processes and materials to make printed circuit panels will be given. Then we will discuss the multi-disciplines required for forming a scientific base and provide examples where the fundamentalist and often times specialist is providing the scientific data needed by the packaging engineer. Control techniques, characterization or otherwise basic information helpful in decision making is provided to the development and production groups. Specifically, the state of resin cure at critical steps in the process is used to demonstrate the inter-relation between cure, flow, and mechanical properties in affecting printed circuit board integrity. Finally, the complex role of moisture solubility and diffusion from the process environment in perturbing the chemical and mechanical state is discussed.
Chemical Interactions at Metal-Polymer Interfaces
Authors: Hahn P. O. , Rubloff G. W. , Bartha J. W. , Legoues F. , Tromp R. , Ho P. S.
Published: March 2011

This paper summarizes recent studies on metal-polymer interfaces for Cu, Ni and Cr on a high temperature polymer, polyimide. First some surface and bulk chemical properties of polyimide are described briefly, as measured with surface spectroscopies and verified by theoretical molecular orbital calculations. Then the chemical bonding and reactivity of the three interfaces are described and discussed in light of experimental observations of electronic structure, composition and interface morphology. The chemical trend of increasing reactivity of the interface is illustrated by comparing results from Cu to Cr.
Ion Beam Analysis of Diffusion in Polymer Melts
Authors: Green P. F. , Mills P. J. , Palmstrom C. J. , Mayer J. W. , Kramer E. J.
Published: March 2011

Two ion beam depth profiling methods have been used to measure the diffusion of polymer chains of molecular weight M into a matrix of polymer of molecular weight P. In the first the displacement xm of Au markers at the original interface of a diffusion couple between polystyrene with P=2×107 and a thin film of PS with M<P is measured using Rutherford backscattering spectrometry. From this modern version of the Kirkendall effect we find x=0.4t8(D*t) 0 5, where D* the tracer diffusion coefficient of the M chains at 174°C, is found to be D*=O.007M−2cm2/sec, in good agreement with the D*=DR expected for the reptation mechanism. Forward recoil spectrometry, a technique in which the energies of recoiling deuterons are detected, is used to obtain concentration profiles, and hence D*, of deuterated PS M-chains diffusing into a hydrogenated PS P-chain matrix. When P>>M, D*=0.008M−2, in good agreement with the marker data. When P<P*(M) however D*; increases greatly as P decreases; P* increases slowly with increasing M. The results are predicted quantitatively by D*=DR+DCR, where DCR=0.10Me2/(Mp 3 ) describes the diffusion of the M-chain by release of its topological constraints (by diffusion of the surrounding P-chains) and Me is an entanglement molecular weight. D* for self-diffusion (M=P) is dominated by reptation except for M's close to Me.
Electronic Structure and Properties of Oxide Surfaces and Interfaces
Authors: Stoneham A. M. , Tasker P. W.
Published: March 2011

Many technologically-important areas rely on properties of ceramic surfaces or interfaces. Some of these properties are simply stability, e.g. resistance to dimension change, to grain-size change, or to change in coverage by a metal layer. Other properties rely on well-defined electronic features, e.g. a suitable density of surface states, of surface defects, or of response to adsorbed species. Still further surface characteristics - the precise geometric structures, the near-surface electric fields, and especially impurity segregation - can strongly influence observed behaviour.

This survey emphasises the insights gained from atomistic modelling of ceramic surfaces and interfaces. The theoretical methods allow one to identify the features determining surface geometry, the degree of surface segregation by impurities, the role of the image charge and the influence of space-charge layers on intrinsic defect levels. The surface distortion affects defects like the surface Fs+ centre (electron trapped at an oxygen vacancy on an oxide) and similar colour centres. Whilst most of the results will be for oxides, parallels with semiconductor systems and the special features of metal-oxide interfaces are mentioned.
Materials Science and Processing, the Foundation of Packaging
Authors: Eastman D. E.
Published: March 2011

Electronic package systems for information processing include the functions of electrical interconnection, cooling and physical support for the sets of IC chips plus other components in electronic systems. There are several distinct packaging technology worlds, ranging from that of the large high performance mainframe systems to that of the supermini and to that of the small workstation or home computer. In all cases, the package system is a major cost factor; for high performance systems, it is also a major performance factor.
Characterization of Copper-Ceramic Interfaces
Authors: Kriven W. M. , Risbud S. H.
Published: March 2011

The interfacial zones in copper-magnesium aluminosilicate materials were characterized by several microscopic and microchemical techniques. Interfaces between copper-glass, copper-partially crystallized glass, and copper-fully crystallized glass were studied with the specific goal of determining the oxidation state of copper in various locations in the microstructure of the reaction zones. Optical microscopy, cathodoluminescence, electron probe microanalysis (EPMA), SEM, TEM, and other microtechniques were used. The presence of copper in various oxidation states can be attributed to the thermodynamics and kinetics of the system. Results correlating the observed interfacial microstructure and the thermochemistry of the system are presented.
Oxidation of Au/Si Films For Self-Confined Interconnects
Authors: Hewett C. A. , Scott D. M. , Lau S. S. , Bartur M.
Published: March 2011

We have explored the possibility of oxidizing a Au/Si composite layer or a Au-Si alloyed layer on SiO2 substrates to form a highly conductive narrow line with a protective SiO2 layer over it. A number of sample configurations and annealing ambients have been investigated. It was found that co-evaporated Au-Si alloys ( ∼30 at. % Au) showed no oxide formation for annealing temperatures between 200°C and 800°C in a flowing O2 ambient (annealing time ≃ 2.25hrs). Samples with a configuration of SiO2/Au/Si showed mixing of the Au and Si layers, but no appreciable oxide formation until after annealing at 800°C in a flowing O2. Samples with a configuration of SiO2/Si/Au, however, showed uniform and smooth oxide growth on top of the Au layer after annealing in air at 200°C. The structural and electrical properties of the self-confined Au lines will be discussed. This process may be potentially useful for narrow interconnects on VLSl chips.
Ceramic Substrates - Micro Circuits, a Partnership in Growth
Authors: Flock William M.
Published: March 2011

An increased understanding and utilization of suhstrate properties will he required to improve future performance and reliability of microelectronic devices. Previously, only the passive substrate/package properties were required for micro devices. Newer designs are utilizing both the active and passive properties of the ceramic materials. These new demands are being driven by end user circuit needs, and will generate major changes in the processing and fabrication of oxide materials.

The status of oxide raw material availability, and the characterization of these materials is reviewed. The processing, and fabrication of substrate materials and the interactions with end use properties are discussed. The future expectations and demand on the materials and processes are forecasted. Substrate properties and their impact on final circuit performance are emphasized.
Tape Casting of BaTiO3
Authors: Blum J. B. , Cannon W. R.
Published: March 2011

For the past two years we have been investigating the tape casting of BaTiO3 Specifically we have been interested in developing a useful tape casting formulation and procedure and in studying the effects of powder particle size distribution and dispersion processes on the forming of BaTiO3 tapes.

The formulation we have developed is non-aqueous. An MEKethanol mixture is the solvent and an acrylic binder is used. Two dispersants are being used, a phosphate ester and Menhaden fish oil. Ultrasonic dispersion was found to be effective in breaking up weak powder agglomerates. We have found it important to add the dispersant before adding other organic components to obtain the best dispersion and strongest tapes. The drying method is also important to tape strength. The strongest tapes resulted when the tape was removed from the glass plate soon after casting. We have also demonstrated that for forming purposes a wide particle size distribution is preferred.
Recent Applications of Neutron Small Angle Scattering
Authors: Kostorz G.
Published: March 2011

Recent results on the formation of voids and dislocation substructure in fatigued copper single crystals and on the early stages of decomposition in Ni base alloys are presented to illustrate some of the advances in the application of small-angle scattering techniques.
Adsorption and Ordering of Oxygen on Cu(110)
Authors: Gruzalski G. R. , Zehner D. M. , Wendelken J. F.
Published: March 2011

XPS and LEED were used to study the adsorption and ordering of oxygen on Cu(11O) at 83±1 K and between 300 and 320 K and to follow changes in the oxygen coverage and surface structure produced by 5-min anneals at temperatures up to 880 K. The relationship between oxygen coverage and surface structure, as well as their mutual dependence upon exposure, surface temperature at exposure, and subsequent annealing treatment, is discussed.
Studies of Planar Defects in Silver Plate-Like Crystals by CBED and Hrtem Techniques
Authors: Tanaka N. , Cowley J. M.
Published: March 2011

Electron diffraction patterns with <111> incidence of f.c.c. plate-like crystals prepared by gas evaporation technique show forbidden spots such as the 1/3.422 spot. The origin of the spots has been explained in terms of planar defects such as (i) fractional unit cells on (111) surfaces, (ii) repeated thin twins and (iii) stacking faults or hexagonal layers. In the present study, the defect structures are examined by CBED and HRTEM techniques. The <111> CBED pattern of the platelet shows three-fold symmetry for the whole pattern. The dark field patterns of ± 1/3. 422 discs show symmetry of. These features prove that the platelet ha-s no center of symmetry for the three dimensional crystal (3m) and irregular arrangements of twins parallel to (111) planes. The electron micrographs taken along the <110> and <211> directions can give “cross-section” images of the platelet. The images show a few repeated twins with a thickness of several nm. The dark field images taken with the forbidden spots with <111> incidence show weak step contrast. The contrast may be due to fractional unit cells. Consequently, the forbidden spots of the platelet are mostly due to the fractional unit cells.
Analysis of the Structure of Grain Boundaries Normal to the Boundary Plane Using Diffraction Techniques
Authors: Vaudin M. D. , Schmückle F. , Lamarre P. A. , Sass S. L.
Published: March 2011

By recording the intensity of electron scattering along the reciprocal lattice direction normal to the interface plane of a grain boundary, diffraction data is obtained which is sensitive to the boundary structure along this direction. Kinematical calculations of the diffracted intensity profile normal to the interface show that such diffraction data can provide information on the local expansion at the interface and the rigid body translation between the two grains. Electron diffraction data obtained from a variety of different boundaries are presented and analyzed by comparison with intensity profiles calculated for various model boundary structures.
Local Atomic Structure and Electrical Activity of Arsenic Implanted in Silicon
Authors: Erbil A. , Cargill G. S. , Boehme R. F.
Published: March 2011

We summarize the results of an extensive investigation on ion implanted arsenic in silicon after pulsed laser annealing and laser plus furnace annealing. The experiments are aimed at determining the structural and chemical environment around an arsenic impurity atom and relating that information to the electrical behavior of arsenic in silicon. We have implanted silicon with arsenic, 6×1016 As/cm2 at 100 KeV, followed by laser annealing, to obtain epitaxial regrowth with peak As concentrations of about 8 at.%. Subsequent furnace annealing at 800°C for 30 minutes reduces the apparent electrical activity of the arsenic atoms, increasing the electrical resistivity by a factor of three. We have used EXAFS, together with RBS and ion channeling, to investigate the structural and chemical origins of this deactivation. EXAFS measurements are consistent with As occupying tetrahedral sites in both laser ann-ealed and laser plus furnace annealed samples. Average As-As coordination numbers, found from fitting the EXAFS data, were 0.2 and 4.5 for nearest neighbors and for next nearest neighbors respectively. These coordination numbers suggest that there are regions with As concentrations much greater than the nominal maximum concentration mentioned above, and that the preferred local chemical order in regions of high As content resembles that in GaAs, with Si preferentially occupying Ga-sites. This short-range chemical order is unchanged by the furnace annealing. However, we find that furnace annealing does reduce the As-As second neighbor distance by approximately 0.1Å.
Instrumental Limitations and Current Prospects for Materials Research with the Latest Generation of High-Resolution Electron Microscopes
Authors: Smith David J.
Published: March 2011

The macroscopic properties of most materials depend directly on their microstructure and its local variability at the atomic level. Recent trends in high resolution electron microscopes (HREMs) have led to resolving powers on this scale, which in turn has made these instruments invaluable to many materials science investigations. The purposes of this short review are firstly to outline some of the fundamentals of high resolution image formation and interpretation and then to summarise some of the latest instrumental developments. Some recent applications are briefly described to provide some appreciation of the wide range of materials currently being investigated with the HREM. The impact of this work should be apparent from reference to other papers in this volume as well as several recent reviews [1–3] and special conference proceedings [4–5]. The likelihood of further developments in instrumentation and the necessity for complementary information from other techniques are also briefly considered.
Damage Nucleation in Si During Ion Irradiation
Authors: Holland O. W. , Fathy D. , Narayan J.
Published: March 2011

Damage nucleation in single crystals of silicon during ion irradiation is investigated. Experimental results and mechanisms for damage nucleation during both room and liquid nitrogen temperature irradiation with different mass ions are discussed. It is shown that the accumulation of damage during room temperature irradiation depends on the rate of implantation. These dose rate effects are found to decrease in magnitude as the mass of the ions is increased. The significance of dose rate effects and their mass dependence on nucleation mechanisms is discussed.
Characterization of Epitaxial CoSi2 Films Grown on <111> Si
Authors: Hamdi A. H. , Nicolet M-A. , Kao Y. C. , Tejwani M. , Wang K. L.
Published: March 2011

X-ray rocking curves and backscattering spectrometry with channeling have been employed to investigate epitaxial CoSi2 films grown on <111> Si substrates. Several preparation techniques were used: sputter cleaning, chemical cleaning, chemical cleaning with subsequent high temperature annealing, and e-gun evaporation on a cold or hot Si substrate, in situ annealing between 550–750°C for 30 min. Best results were obtained with chemical cleaning and pre-annealing at 925°C for 10 min, Co and Si codeposition on a 580'C hot substrate. For such samples, a typical x-ray perpendicular strain is -2.08%, and parallel strain is -0.11%. This parallel strain implies that the growth has been accommodated by dislocations with a spacing of ,∼ 2000 Å. The values of strain are consistent with the published lattice constants of Si and CoSi2 and Poisson's ratio of 0.28. The minimum yield in the channeling spectra of these films is. ∼ 3.6%, which is only slightly higher than that of <111> virgin Si.
The Gamma to Alpha Transformation in Thin Film Alumina
Authors: Clausen E. M. , Hren J. J.
Published: March 2011

Many forms of low temperature alumina have been identified [1]. These are collectively referred to as transitional forms. The particular form depends strongly on the starting material (e.g., hydrated, thermally oxidized, alkoxide, etc.), the impurities present, and on thermal history. Although different forms of transition alumina are sometimes referred to as phases, none can be considered a true polymorph of corundum, i.e., α-alumina. Transformations from one form to another which occur upon heating are not reversible, although they are quite reproducible [2]. These different transitional structures are therefore considered to comprise different states of reordering. Figure 1 is a compendium of powder x-ray diffraction patterns from all known transitional aluminas and several aluminum hydroxides [3]. It i.s obvious that there are several crystallographic spacings which are nearly common to all forms.
Applications of Neutron Scattering to Problems in Materials Science
Authors: Weertman J. R.
Published: March 2011

Neutrons possess a number of attributes which make neutron scattering a powerful technique for the investigation of problems in materials science. These properties are discussed with emphasis on their importance to materials characterization. A number of recent experiments using neutron scattering will be described. These studies include the areas of damage accumulation; residual stress; porosity in ceramics; polymer chain configurations; phase changes.
Investigation of the Homogeneity and Defect Structure in Semi-Insulating Lec GaAs Single Crystals by Synchrotron Radiation Double Crystal X-Ray Topography.
Authors: Barnett S J , Tanner B K , Brown G. T.
Published: March 2011

The high intensity and large beam size of a synchrotron radiation source have been exploited in order to obtain double crystal X-ray topographs of whole 2in. and 3in. slices of semi-insulating LEC GaAs single crystals. Exposure times, typically 30 minutes for high resolution topographs, are at least one order of magnitude down on those required when using a conventional source. Variations in relative lattice parameter and lattice tilt have been measured as a function of position on the slice. The defect structure has been imaged and dislocations are seen in cellular configurations, slip bands and linear arrays (lineage), the latter of which are shown to be associated with small lattice tilts, typically 30”. The defect structure revealed on the topographs has been correlated with 1μm infrared absorption micrographs which are believed to represent the concentration of the dominant deep level EL2.
Study of the Dynamic Behavior of Dislocations During the Melt Growth Process of Tin Crystal by Synchrotron X-Ray Topography
Authors: Nittono Osamu , Ogawa Taro , Gong Sheng Kai , Nagakura Sigemaro
Published: March 2011

The dynamic behavior of the melt growth process of Sn with low dislocation density has been investigated by means of synchrotron Laue topography using an X-ray sensing high resolution camera tube. No defect images are observed at the point where the melting begins. No dislocations are generated during the temperature rise to the melting point,although the dislocation configuration changes slightly. Most of dislocations which are contacting the melting interface do not propagate into a newly grown crystal part and the homogeneous solidification results in a nearly perfect crystal.Dislocations and slip bands are generated from a part where the solidification is completed. It was found that the growing interface appears atomically rough and extends through a considerably large number of layers.
Some Difficulties in the Assessment of Pore-Structure of High Performance Blended Cement Pastes
Authors: Marsh Bryan K. , Day Robert L.
Published: March 2011

Partial replacement of cement by fly-ash allows the production of concretes with high strength and low permeability. The correct analysis and prediction of engineering behaviour requires a knowledge of the development of pore-structure of these materials. However, a study of the relationships between engineering and microstructural characteristics has revealed problems in the accurate assessment of pore-structure.

Porosities of plain and blended pastes were analysed by both helium pycnometry and mercury porosimetry. Pastes showing pozzolanic reaction gave values of helium porosity whidh were different from the mercury porosity (measured on the same sample); pastes showing no pozzolanic reaction gave equal values for mercury and helium porosity. Also, significant differences in porosity and pore-size distribution were found for identical specimens when prepared by different techniques, namely direct oven-drying and solventreplacement; these differences occurred whether there was pozzolanic reaction or not.

It is suggested that as well as experimental difficulties, there may be fundamental differences in the way pore-structure develops in plain and blended cement pastes.