bluuebunny/crossref_metadata_2025_split huggingface dataset:
Grain Structure and Electromigration Testing of Deep Sub- Micrometer Cu Interconnects
Authors: Frankovic Richard , Bernstein Gary H. 
Published: April 2011

AbstractCopper interconnect test stripes were fabricated by electron-beam lithography, evaporation and lift-off to linewidths as small as 140 nm. Grain structure in the as-deposited films exhibited smaller standard deviation than long-term annealed films. Grain growth during the anneal step increased maximum grain size by 2.5 times. Electromigration lifetime testing indicated these interconnects have 2-4 orders-of-magnitude greater normal-use lifetimes than large cross-sectional area, large-grain Al-alloy interconnects.
Effect of Annealing and Passivation on the Electromigration and Linewidth Dependence
Authors: Carnes R.O. , Lee C.H. , Keating P.T. , Barrall II E.M. , York B.R. , Grivna G.M. , Bauguess S.W. , Dreyer M.L. , Edwards S.R. 
Published: April 2011

AbstractContinued miniaturization of conductor geometry below 0.5μm has by a concomitant decrease in Al deposition temperature, typically below 300°C. The degree of reliability exhibited by these films is strongly dependent on the grain size distribution and metallurgical configuration. This investigation focuses on the impact of post-deposition processing on changes in conductor microstructure and electromigration for films deposited at low temperature. AlCu(l%)Si(l%) was deposited at 300°C on PECVD phosphosilicate glass. The impact of post-deposition thermal budget on the as deposited grain size and distribution, preferred orientation and stress/strain states were analyzed using scanning electron microscopy, X-Ray diffraction and bending beam technique, respectively. These characteristics were also measured on unpassivated films subjected to the same thermal budget as SiO2 passivated films so that the geometric confinement and Al-SiO2 surface interaction could be quantified. Electromigration characteristics were measured for linewidths in the range W=1.0μm to W=10μm, for passivated and unpassivated films. A direct correlation between passivation and grain size was observed for both failure modes. This paper will also discuss the relationship between film stress and preferred orientation, the observed failure modes and their linewidth dependence.
Fast Thermal Cycling - Enhanced Electromigratton Failures in Si/TiSi2W-Ti/Al-Si-Cu Multilayer Contacts
Authors: Ivkin Victor V. , Baranov Valentin V. 
Published: April 2011

AbstractFailure mechanisms of TiSi2/W-Ti(15%)/Al-Si(l%)-Cu(2%) multilayer thin film contact to silicon shallow junction (0,25 μm) have been investigated. Both a fast temperature cycling (with 300 ms thermal cycle period) and a high constant temperature were used as means for the degradation processes acceleration. We have shown that stress time could be reduced by the factor of 10 or more if the temperature of adjacent contact region was cycled by a pulsed electrical current passed through the semiconductor region lying under the investigated contacts. Our data have also indicated that W-Ti barrier layer serves to reduce drastically the electromigration degradation of thin film contacts for failures caused by an increase in junction leakage on the one hand and on the other hand it serves to intensify the electromigration degradation caused by an increase in contact resistance. These distinctions have been explained through structural-morphological investigations of the contact layers surface morphology. They showed a reduction in size of crystallines of the sputter deposited Al-Si-Cu top layer with W-Ti barrier layer present.
Correlation of The Mechanical Properties of Silicon Oxynitride Films to Processing Parameters, Film Stoichiometry, and Hydride Bond Concentration
Authors: Moinpour Mansour , Moghadam Farhad , Williams Byron 
Published: April 2011

AbstractA selective range of hydrated silicon oxynitride thin films (SixOyNz:H) have been characterized in terms of their stress, hardness, and modulus in order to mechanically qualify them for use as an encapsulation layer for memory devices (e.g., Flash and EPROM memories). These films are analyzed by RBS and HFS for stoichiometry. The films exhibited stress values between 1.86 x 109 to -3.54 x 109 dyne/cm2 and showed a linear correlation with the hydride ratio (N-H/Si-H). An Ultra Micro-Indentation System (UMIS) measured hardness values between 10.5 GPa to 16.2 GPa while the elastic modulus varied between 119.1 to 141.2 GPa. The monatomic increase of modulus with hardness is attributed to increased amounts of nitrogen and nitrogen hydride bonding in the silicon oxynitride samples.
Dual-Mode Ion Switching Conducting Polymer Films as High Energy Supercapacitor Materials
Authors: Naoi Katsuhiko , Oura Yasushi 
Published: April 2011

ABSTRACTThe electropolymerized polypyrrole films formed from micellar solution of anionic surfactants, viz., Dodecylbenzene sulfonate(DBS), showed potential-dependent anion and cation ion switching behavior and the peculiar columnar structure. The formation process and the redox of the polypyrrole was studied with the in situ atomic force microscopy (AFM) and electrochemical quartz crystal microbalance(EQCM) methods. In-situ AFM observation clearly indicated that such a columnar structure started to form around critical charge densities of 60-100 mC cm−2. The cyclic voltammogram for the PPy doped with DBS− film showed two redox couples, each of which corresponds to a cation and an anion exchange process. Thus, the film behaves as a dual-mode ion doping/undoping exchanger. As the PPy film was prepared in higher concentration of the surfactant dopant, where the micelles are formed in solution, the resulting film showed a considerably higher(ca. three orders of magnitude) diffusion coefficient compared to ordinary PPy films so far reported. Such an enhanced diffusivity of ions could be attributed to a peculiar structure of the polymer formed. The feasibility of such polypyrrole in use of supercapacitor material was discussed.
Dual Intercalating Molten Electrolyte Batteries
Authors: Carlin R. T. , De Long H. C. , Fuller J. , Lauderdale W. J. , Naughton T. , Trulove P. C. , Bahn C. S. 
Published: April 2011

ABSTRACTDual Intercalating Molten Electrolyte (DIME) electrodes and cells have been examined using a number of low-melting and room-temperature molten salts. A cell with a chloroaluminate melt achieved a cycling efficiency of 85% with a discharge voltage of 2.92 V. Coke-elastomer composite electrodes underwent cation reductive intercalation without experiencing the exfoliation and degradation seen for graphite rods. Theoretical studies for an imidazolium-graphite intercalate predict the graphite layer spacing expands between 5.18 and 8.01 Å upon insertion of the imidazolium molecule into the graphite lattice.
High Surface Area Electrode Materials by Derect Metallization of Porous Substrates
Authors: Chyan Oliver , Chen Jin-Jian , Liu Min , Richmond Michael G. , Yang Kaiyuan 
Published: April 2011

ABSTRACTRecent advances in high surface area (HSA) electrode materials have played an important role in the development of high-performance batteries and fuel cells. HSA electrodes can significantly increase the power-density of batteries and fuel cells by enhancing the heterogeneous electrochemical reaction rate and concurrently reducing battery and fuel cell size and weight. The compactness of HSA electrodes can also reduce the ohmic potential drop, which has the clear advantage of reducing power losses. This paper reports results on utilizing direct metallization of porous substrates to prepare new HSA electrode materials. Specifically, Nickel HSA electrode materials, relevant to the Ni-Cd and metal-hydride rechargeable batteries, were prepared on porous carbon substrates by direct thermolysis of organometallic precursors and/or electroless Ni plating. SEM and XPS characterization results indicate a Ni metallic film was conformally coated over the porous carbon skeleton. The real electroactive areas were determined electrochemically in NaOH solution and results will be discussed in correlation with the metallization conditions.
Long Endurance Materials for Aluminum Fuel Cell Systems
Authors: Hall Susan E. , Carter Dennis L. , Weber Carl L. 
Published: April 2011

ABSTRACTAppropriate selection of long endurance materials is critical to the cost effective use of fuel cell technology for near-term commercial and defense applications. To effectively transition this technology from laboratory prototype to fielded system, the durability of all fuel cell subsystems must be addressed. Material selection based upon a thorough understanding of system performance requirements, operational environments, and user interfaces not only provides high reliability and enhanced safety, but also lowers life cycle costs.This paper discusses the development of an Aluminum Fuel Cell Power System (FCPS) for the Advanced Research Projects Agency (ARPA) Unmanned Underwater Vehicle (UUV) program, focusing on the operational endurance testing that was conducted to evaluate candidate materials for cell stack, electrolyte, and coolant subsystems.The FCPS is a 15 kW closed aluminum-oxygen fuel cell system that provides up to 1.1 MWh energy. Loral has completed small-scale bench tests and is currently fabricating a full-scale system to be demonstrated in 1995. Requirements that strongly influenced material selection included: chemical compatibility - 4M KOH electrolyte pumped at 50°C, with dissolved aluminum and hydrargillite; system operational objectives - time between refueling and maintenance ranging from daily startup / shutdown to three weeks continuous; ARPA program objectives - commercial components, rapid prototyping, low life cycle costs.A materials / component endurance test program was established and conducted early in the design phase of the FCPS program. To date, Loral has completed over 3000 operational test hours, with nearly 8000 hours of accumulated exposure to KOH. Results of these tests have been incorporated into the FCPS detailed design, and are expected to significantly enhance the performance of the fielded system. This program is sponsored by ARPA Maritime Systems Technology Office under NASA contract NAS3-26715.
Lithium Storage Mechanism in Nongraphitizable Carbon
Authors: Nagap Aisaku , Ishikawa Minoru , Masuko Jiro , Sonobe Naohiro , Chuman Hiroshi , Iwasaki Takao 
Published: April 2011

ABSTRACTA nongraphitizable carbon prepared from the cross-linked petroleum pitch and carbonized at 1473 K was found to have a unique structure and a charge capacity of more than 600 Ah/kg. A main peak of the 7Li Nuclear Magnetic Resonance spectra of the charged carbon shifted downfield with an increase of charge capacity. A Knight shift of lithium in the carbon charged to 600 Ah/kg reached 110 ppm when LiCl was used as the reference of 0 ppm. This shift was clearly distinguished from that of the lithium state in the first stage of the graphite intercalation compound, because the latter was observed at 45 ppm. A modified extended Hükel molecular orbital calculation showed that the average net electron density on lithium atoms drastically increased with increasing concentration of lithium atoms if the aromatic molecular planes are more than 0.5 nm apart. Both the experimental and theoretical results suggest that lithium atoms form clusters in this nongraphitizable carbon.
Thermal Stability of the Oxygen Ion Conductor Bicuvox.10 In Different Gaseous Atmospheres
Authors: W.Breiter Manfred , Reiselhuber Karl , Dorner Gertrude 
Published: April 2011

ABSTRACTA study of the thermal stability of the oxygen ion conductor BICUVOX.10 was carried out on small pieces of the polycrystalline material by combined TGA and DTA measurements in air, nitrogen, oxygen and helium. The TGA measurements demonstrated that the weight change was less than 0.1% in the different gases. The DTA curves were practically the same. There is evidence for the occurence of a phase change. TGA curves were also taken on BICUVOX.10, the parent compound Bi4V2O11, and the oxides CuO, B2o2, V2O5. under hydrogen. The comparison of the reduction curves shows that BICUVOX.10 is stable up to about 550C with respect to a direct reduction by molecular hydrogen.
Material Characteristics and the Performance of Electrochemical Capacitors for Electric/Hybrid Vehicle Applications
Authors: Burke A.F. , Murphy T.C. 
Published: April 2011

ABSTRACTElectrochemical capacitors (ultracapacitors) are one approach to meeting the high power requirements for the energy storage system in an electric vehicle. Energy is stored in an electrochemical capacitor by charge separation in the double layer formed in the micropores of a very high surface area electrode material, which does not undergo chemical change as in a battery. Consequently, the material requirements for capacitors are very different from those of batteries. In the last several years, a number of promising material technologies have been identified for use in electrochemical capacitors. These include activated carbon fibers, foams, and composites, doped conducting polymers, and mixed metal oxides. The most important material property is its specific capacitance (F/gm or F/cm3). Carbon materials with specific capacitances of 100 to 300 F/gm have been developed. Doped polymer materials having specific capacitances of 300 to 400 F/gm are also being studied. In addition to high specific capacitance, the electrode material must also have a low electronic resistivity ( < 0.1 Ω-cm) in order that charge can be distributed with minimum voltage drop in the electrode. Electrochemical capacitor cells have been fabricated using the various material technologies with both aqueous and organic electrolytes. Tests of the cells have shown near ideal charge/discharge characteristics — that is, the voltage versus time curves are nearly linear for constant current tests. The energy densities of 1 V cells, using aqueous electrolytes, are 1 to 1.5 W-h/kg and those of 3 V cells, using organic electrolytes are 7 to 10 W-h/kg. Most of the cells have high power densities of 1 to 3 kW/kg. Numerous new materials for electrochemical capacitors have been identified, processed, and tested in electrodes and cells in recent years and progress is rapid in this relatively new field of research.
Order-Disorder Transitions in Gadolinium Zirconate: A Potential Electrolyte Material in Solid Oxide Fuel Cells
Authors: Meilicke Scott , Haile Sossina 
Published: April 2011

ABSTRACTRare-earth, yttrium, and calcium doped zirconates are the materials of choice for electrolytes in solid oxide fuel cells. The dopant in these materials serves not only to stabilized the cubic phase of zirconia, but also to introduce anion defects that presumably increase the ionic conductivity. In order to understand the relationships between anion defect distribution, thermal history and ionic conductivity, the structural properties of gadolinium zirconate, Gd2Zr207, have been examined via high-temperature x-ray powder diffraction. Gadolinium zirconate is an ideal material for such a structure-property-processing study: it shows ordering of defects at low temperatures, taking on a pyrochlore structure, and disordering at elevated temperature, taking on a defect fluorite structure. Diffraction experiments, performed as functions of time and temperature, confirmed the transition temperature to lie between 1500 and 1550 °C. They also revealed that the transformation takes place most rapidly just below the transition temperature, indicating that the ordering process is kinetically constrained at low temperatures. Moreover, x-ray data collected at room temperature from quenched samples were found to be as useful, if not more so, than those collected in situ at high temperature. The latter are affected by thermal scattering, severely compromising data quality.
Irradiation Mixing of Al into U3Si
Authors: Birtcher R. C. , Ding F.-R. , Kestel B. J. , Baldo P. M. , Zaluzec N. J. 
Published: April 2011

AbstractThermal and irradiation induced intermixing of uranium suicide reactor fuels with the aluminum cladding is an important consideration in understanding their fission gas and fuel swelling behavior. We have used Rutherford backscattering to follow the behavior of an Al thin film on U3Si and U3Si2 during 1.5 MeV Kr ion irradiation at temperatures of 30 and 350°C. After an initial dose during which no intermixing occurs, the Al mixes quickly into U3Si. The threshold dose is believed to be associated with an oxide layer between the Al and the uranium suicide. At 300°C and doses greater than threshold, rates of mixing and aluminide phase growth are extracted.
Lateral Sputtering by Gas Cluster Ion Beams and its Applications to Atomic Level Surface Modification
Authors: Yamada Isao , Matsuo Jiro 
Published: April 2011

AbstractGas cluster ion beam equipment (max. voltage 30kV) for sputtering has been developed. Cluster ion beams from gaseous materials such as Ar, O2, N2 and compound materials such as SF6, N2O, CO2 can be generated by expanding them through a Laval nozzle into a high-vacuum region. With this equipment sputtering process fundamentals have been studied. One of the unique characteristics of gas cluster ion bombardment is lateral sputtering. This is shown experimentally by measuring the angular distribution of sputtered atoms and is predicted by molecular dynamics simulation. Dependencies of sputtering yield (10-1000 times higher than for the monomer ion case) on cluster ion size and on ion beam energy for different substrate surfaces have been obtained. Examples of surface smoothing (typically less than 1 nm average roughness) on metals, semiconductors and insulators and of surface cleaning are presented.
Enhanced Diffusion of High-Temperature Implanted Aluminum in Silicon Carbide
Authors: Suvorov A V. , Usov I.O. , Sokolov V.V. , Suvorova A.A. 
Published: April 2011

AbstractThe diffusion of aluminum in silicon carbide during high-temperature A1+ ion implantation was studied using secondary ion mass spectrometry (SIMS). Transmission electron microscopy (TEM) has been used to determine the microstructure of the implanted sample. A 6H-SiC wafer was implanted at a temperature of 1800 °C with 40 keV Al ions to a dose of 2 x 1016 cm-2. It was established that an Al step-like profile starts at the interface between the crystal region and the damaged layer. The radiation enhanced diffusion coefficient of Al at the interface was determined to be Di = 2.8 x 10-12 cm2/s, about two orders of magnitude higher than the thermally activated diffusion coefficient. The Si vacancy-rich near-surface layer formed by this implantation condition is believed to play a significant role in enhanced Al diffusion.
Carbon Nitride (Cnx) Films Formed by Ion Implantation into Thin Carbon Films
Authors: Husein Imad F. , Zhou Yuanzhong , Chan Chung , Kleiman Jacob I. , Gudimenko Yu , Leung Ka-Ngo 
Published: April 2011

AbstractCarbon nitride (CNX) films were prepared by nitrogen ion implantation into carbon films (a-C) deposited on Si substrates by the anodic vacuum arc. Plasma Immersion Ion Implantation (PIII) and Ion Beam (IB) implantation methods were used. X-ray Photoelectron Spectroscopy (XPS) C Is and N Is spectra of all CNX films indicate the formation of carbon-nitrogen bonds. The bonds are associated with the C 1s peaks at 286.6 eV and 285.6 eV , and the N 1s peaks at 399.1 eV and 400.6 eV. Raman spectra show that the structure of the implanted films (CNX) becomes more amorphous as the two broad peaks at 1577 cm-1 (G line) and 1350 cm-1 (D line) observed in the a-C films disappear and a broad asymmetric peak around 1500 cm-1 is formed. The interfacial tension between the a-C films and the substrate , obtained from the contact angle measurements, decreased by more than half after nitrogen implantation.
The Improvement of Mechanical Properties of Aluminum Nitride and Alumina by 1 Kev Ar+ Ion Irradiation in Reactive Gas Environment
Authors: Koh S.K. , Son Y.-B. , Gam J.-S. , Kim C.-J. , Choi W.K. , Jung H.-J. 
Published: April 2011

AbstractAr ions with 1 keV energy was irradiated on aluminum nitride in an O2 environment to increase the bonding strength with Cu and also on alumina in an N2 environment to increase the bending strength. Cu(1000 Å) films were deposited by ion-beam sputter on Ar+ irradiated/unirradiated A1N surfaces and the change of the bond strength was investigated by a scratch test. For the study of chemical structural change on the Ar+ irradiated A1N surface, Cu(50Å) were deposited on an A1N substrate and XPS depth profile analysis was performed. Cu films deposited on Ar+ irradiated A1N under an O2 environment showed the bond strength of 30 Newton by a scratch test. On the basis of Cu3p, A12p near core levels and OI s, N1 s core level spectra, it was found that the improvement of bond strength of Cu films on the AlN surface resulted from the formation of intermediate layers such as copper oxide and aluminum oxynitride. The bending strength of polycrystalline alumina irradiated by Ar ions in an N2 environment was also increased.
Modification of the Wettability of Plexiglas and Carbon by Means of Ion Beam Implantation: Application to Fluid Management and Materials Processing in Microgravity.
Authors: Pageau J.F. , Ross G.G. , Couture É. , Poirier A. , Quirion F. 
Published: April 2011

AbstractIn the absence of gravity, the behaviour of a liquid within a container will depend on its ability to wet the container. For instance, we evidenced that wetting property is involved in the propagation of perturbation, at the liquid-air interface. Because of perturbation in space, there is a strong interest in the modification of wetting properties for fluid management and materials processing in microgravity. The use of low energy (-500 eV) ion beams is attractive. Combining their low mean range (a few nm) and erosion rate, they are well suited for the modification at will of surface composition. Nitrogen, oxygen and neon ions of low energy were used to bombard the surface of plexiglas (polymethylmethacrylate or PMMA) and carbon samples at different fluences. Advancing and receding contact angles were measured before and after the implantation. A decrease of the contact angle as a function of the fluence of implanted ions was measured. A partial recovery of the contact angles as a function of time after the implantation was also observed. There was evidence that the long term value of the contact angles was influenced by the composition of the gas surrounding the samples. These results are discussed in terms of the development of a new technology for the modification at will of wetting properties of materials.
Tight-Binding Molecular Dynamics Simulations on Point Defects Diffusion and Interactions in Crystalline Silicon
Authors: tang M. , colombo L. , Diaz De La Rubia T. 
Published: April 2011

AbstractTight-binding molecular dynamics (TBMD) simulations are performed (i) to evaluate the formation and binding energies of point defects and defect clusters, (ii) to compute the diffusivity of self-interstitial and vacancy in crystalline silicon, and (iii) to characterize the diffusion path and mechanism at the atomistic level. In addition, the interaction between individual defects and their clustering is investigated.
Defect Creation by Electronic Processes in MgO Bombarded with GeV Heavy Ions
Authors: Beranger M. , Thevenard P. , Bremer R. , Balanzat E. 
Published: April 2011

AbstractTo study the defect creation induced by electronic processes in refractory oxides, MgO single crystals were irradiated with high energy tin, uranium and lead ions. Optical absorption measurements showed that F-type centers (oxygen vacancies with trapped electrons) were created during irradiation. The total number of centers per unit area of bombarded sample increases linearly with irradiating fluence. The main part of the point defects was found to arise from electronic processes. The concentration of F-type centers induced by ionization increases with the electronic energy losses. Assuming a saturation of point defect concentration at high fluences, F-type center creation cross sections could be estimated. The influence of irradiation temperature and of the velocity of the bombarding ions are discussed.