bluuebunny/crossref_metadata_2025 huggingface dataset:
NEUTRINO MASS AND COLD DARK MATTER PARTICLES IN BIG-BANG NUCLEOSYNTHESIS
Authors: KAJINO TOSHITAKA , KUSAKABE MOTOHIKO , KOJIMA KAZUHIKO , YOSHIDA TAKASHI , YAMAZAKI DAI G. , ICHIKI KIYOTOMO , MATHEWS GRANT J.
Published: October 2008

Neutrino is a tiny weakly interacting massive particle, but it has strong impacts on various cosmological and astrophysical phenomena. Neutrinos play a critical role in nucleosynthesis of light-to-heavy mass elements in core-collapse supernovae. The light element synthesis is particularly affected by neutrino oscillation (MSW) effect through the ν-process. We propose first that precise determination of sin 2 2θ13 and mass hierarchy can be made by a theoretical study of the observed 7 Li /11 B ratio in stars and presolar grains which are produced from SN ejecta. Theoretical sensitivity in our proposed method is shown to be superior to ongoing long-baseline neutrino experiments for the parameter region 10−4 ≤ sin22θ13 ≤ 10−2. We secondly discuss how to constrain the neutrino mass Σmν from precise analysis of cosmic microwave background anisotropies in the presence of primordial magnetic field. We obtain an upper limit Σmν < 1.3 eV (2σ). Thirdly, we discuss decaying dark-matter particle model in order to solve the primordial lithium problems that the standard Big-Bang nucleosynthesis theory predicts extremely different 6 Li and 7 Li abundances from observations.
EQUATION OF STATE OF DENSE MATTER FOR CORE-COLLAPSE SUPERNOVAE AND NEUTRINO BURSTS
Authors: SUMIYOSHI KOHSUKE
Published: October 2008

We report the recent developments on the tables of equation of state for dense matter and their influence on core-collapse supernovae and associated neutrino emissions. We study the gravitational collapse of massive stars by the numerical simulations with the tables of equation of state recently developed in relativistic many body frameworks. I discuss whether the equation of state of dense matter can be probed by the properties of neutrino signals from black hole forming supernovae, being different from ordinary neutrino bursts from supernova explosions.
VARIATIONAL CALCULATION FOR THE NUCLEAR EQUATION OF STATE TOWARD SUPERNOVA EXPLOSIONS
Authors: TAKANO MASATOSHI , KANZAWA HIROAKI , OYAMATSU KAZUHIRO , SUMIYOSHI KOHSUKE
Published: October 2008

The equation of state (EOS) is calculated for uniform nuclear matter at zero and finite temperatures with the variational method. Making use of uncertainty of the three-body nuclear force, adjustable parameters in the nuclear EOS are tuned so that the Thomas-Fermi calculations for β-stable nuclei with the EOS reproduce the empirical data. The calculated nuclear properties imply that larger symmetry energy of the EOS is preferable to reproduce the empirical β-stability line. The expectation value of the nuclear Hamiltonian caused by the 2π-exchange three-body nuclear force is uncertain and related to the symmetry energy.
BROWN-RHO SCALING IN THE STRONG COUPLING LATTICE QCD
Authors: OHNISHI A. , KAWAMOTO N. , MIURA K.
Published: October 2008

We examine the Brown-Rho scaling for meson masses in the strong coupling limit of lattice QCD with one species of staggered fermion. Analytical expression of meson masses is derived at finite temperature and chemical potential. We find that meson masses are approximately proportional to the equilibrium value of the chiral condensate, which evolves as a function of temperature and chemical potential.
NUCLEAR GROUND STATES AND EXCITATIONS IN RELATIVISTIC NUCLEAR MODELS
Authors: HAGA AKIHIRO , TOKI HIROSHI , TAMENAGA SETSUO , HORIKAWA YATARO
Published: October 2008

We study the role of the negative-energy nucleon states of relativistic nuclear models in nuclear ground states and excitations. The self-consistent calculation including the negative-energy states are performed by using the derivative expansion in terms of the meson field, which is known to provide a good description of the vacuum fluctuations in nuclear ground states quantitatively. A remarkable effect of the inclusion of the negative-energy contribution into the model is the increase of the nucleon effective mass. In particular, this produces the better description for the isoscalar quadrupole resonances, and essentially different results for the Gamow-Teller resonances.
SOLVING THE KAONIC-HELIUM PUZZLE
Authors:   KEK E570 collaboration, HAYANO RYUGO S. , BEER G. , BHANG H. , CARGNELLI M. , CHIBA J. , CHOI S. , CURCEANU C. , FUKUDA Y. , HANAKI T. , IIO M. , ISHIKAWA T. , ISHIMOTO S. , ISHIWATARI T. , ITAHASHI K. , IWAI M. , IWASAKI M. , JUHÁSZ B. , KIENLE P. , MARTON J. , MATSUDA Y. , OHNISHI H. , OKADA S. , OUTA H. , SATO M. , SCHMID P. , SUZUKI S. , SUZUKI T. , TATSUNO H. , TOMONO D. , WIDMANN E. , YAMAZAKI T. , YIM H. , ZMESKAL J.
Published: October 2008

We have measured the Balmer-series x-rays of kaonic 4 He atoms using large-area silicon drift x-ray detectors (SDDs) in order to study the low-energy [Formula: see text]-nucleus strong interaction. The energy of the 3d → 2p transition was determined to be 6467 ± 3( stat ) ± 2( syst ) eV . The resulting strong-interaction energy-level shift is in agreement with theoretical calculations, thus eliminating a long-standing discrepancy between theory and experiment.
KAONIC ATOMS/NUCLEI MEASUREMENTS AT DAΦNE: SIDDHARTA AND AMADEUS
Authors:   on behalf of the SIDDHARTA and AMADEUS Collaborations, CURCEANU PETRASCU C. , ZMESKAL J.
Published: October 2008

The DAΦNE electron-positron collider at the Laboratori Nazionali di Frascati dell'INFN has made available a unique quality negative kaons “beam”. Two experiments, SIDDHARTA and AMADEUS, will use this beam to perform unprecedented precision measurements on kaonic atoms and kaonic nuclei. The scientific cases, together with the experimental setups, are briefly presented in this paper.
FORMATION OF THE DEEPLY-BOUND K−pp STATE IN THE 3He(IN-FLIGHT K−, n) SPECTRUM
Authors: KOIKE TAKAHISA , HARADA TORU
Published: October 2008

The formation of a deeply-bound K−pp state by the 3 He (in-flight K−, n) reaction is investigated theoretically in a distorted-wave impulse approximation using the Green's function method. The expected inclusive and semi-exclusive spectra at pK− = 1.0 GeV / c and θn = 0° are calculated for the forthcoming J-PARC E15 experiment. We discuss these spectra with some K−-“pp” optical potentials, taking into account the energy-dependence of the imaginary part of the potentials by a phase space suppression factor.
CHIRAL SYMMETRY IN ATOMIC NUCLEI
Authors: MENG J. , QI B. , ZHANG S. Q. , WANG S. Y.
Published: October 2008

The significant progresses of the chirality in atomic nuclei are briefly reviewed for both experimental and theoretical sides. Chiral doublet bands beyond one-particle and one-hole coupled with a triaxial rotor as well as the possibilities of new phenomenon MχD are discussed.
THE ROLE OF PION ON NUCLEI WITH CHARGE AND PARITY PROJECTED CHIRAL MEAN FIELD MODEL
Authors: OGAWA YOKO , TOKI HIROSHI , TAMENAGA SETSUO , HAGA AKIHIRO
Published: October 2008

We construct a relativistic framework, charge and parity projected chiral mean field model, which takes into account explicitly a pion-exchange interaction. We take the chiral σ model Lagrangian for the construction of finite nuclei. We discuss several essential points of this framework with respect to explicit description of pionic-correlations, especially high-momentum component, in nuclear ground state wave function. We apply this framework to several even-even nuclei. We found that the pion contribution brings a significant change for nuclear ground state. We found that pion plays a role on the formation of jj-magic structure.
EFFECTIVE CHARGES OF E2 TRANSITIONS FOR CARBON ISOTOPES
Authors: UMEYA ATSUSHI , KANEKO GOUKI , MUTO KAZUO
Published: October 2008

In a shell-model calculation with traditional effective charges, theoretical B(E2) values are larger than experimental values for neutron-rich carbon isotopes 16 C and 18 C . Using the shell-model with 2ħw excitations in the first order perturbation theory, we investigate the B(E2) values and the effective charges for stable and neutron-rich carbon isotopes.
Uplift, compression and the Cenozoic Faroe–Shetland sediment budget
Authors: Smallwood John R.
Published: October 2008

Throughout the Cenozoic, the dominant sediment supply to the Faroe–Shetland Basin has been from the SE. However, the volume of sediment in the basin is greater than that supplied from the British Isles' provenance area alone. The British Isles and Faroes Platform experienced both epeirogenic and local uplift, caused by igneous underplating, mantle thermal variations and compression. A Cenozoic topographic model is presented for the British Isles' and Faroe Islands' provenance areas, from which sediment supply rates are calculated. The model includes permanent uplift from igneous underplating, which is estimated from gravity anomaly data, transient regional uplift and a simple elevation-dependent erosion term, under isostatic balance. Even using upside estimates of the British Isles' Cenozoic denudation and the documented post-Eocene contribution from the Faroe Islands, there is an apparent undersupply of sediment to the basin. The sediment volume balance suggests that around 30% of the Paleocene sediments currently in the basin were sourced from a westerly provenance area, the pre-basalt Faroes Platform terrane or East Greenland.
Palaeogene evolution of the Ymir and Wyville Thomson ridges, European North Atlantic margin
Authors: Ziska H. , Varming T.
Published: October 2008

The region to the SW of the Faroe Islands is an enigmatic area where the structural trends of the Faroe–Shetland and North Rockall basins meet. The Munkagrunnur, Wyville Thomson and Ymir ridges are major tectonic features within the area and arc approximately perpendicular to the primary Caledonian structural trend. Previous studies have suggested that these ridges formed as a result of compressive forces during the Eocene, Oligocene and Miocene. However, this study suggests that these ridges were initiated by a transient rifting event in the early Paleocene. This rifting event was accompanied by an igneous phase which emplaced large volumes of intrusive and extrusive igneous rocks. The igneous centres within the study area are located on older structural features, indicating exploitation of pre-existing structural weaknesses. The same structural weaknesses were later exploited by compressive events, which resulted in the generation of Ymir Ridge South, and also influenced the orientation and shape of the other segments of Ymir Ridge and the Wyville Thomson Ridge.
Approximating the true evolutionary distance between two genomes
Authors: Swenson Krister M. , Marron Mark , Earnest-Deyoung Joel V. , Moret Bernard M. E.
Published: October 2008

As more and more genomes are sequenced, evolutionary biologists are becoming increasingly interested in evolution at the level of whole genomes, in scenarios in which the genome evolves through insertions, duplications, deletions, and movements of genes along its chromosomes. In the mathematical model pioneered by Sankoff and others, a unichromosomal genome is represented by a signed permutation of a multiset of genes; Hannenhalli and Pevzner showed that the edit distance between two signed permutations of the same set can be computed in polynomial time when all operations are inversions. El-Mabrouk extended that result to allow deletions and a limited form of insertions (which forbids duplications); in turn we extended it to compute a nearly optimal edit sequence between an arbitrary genome and the identity permutation. In this paper we generalize our approach to compute distances between two arbitrary genomes, but focus on approximating the true evolutionary distance rather than the edit distance. We present experimental results showing that our algorithm produces excellent estimates of the true evolutionary distance up to a (high) threshold of saturation; indeed, the distances thus produced are good enough to enable the simple neighbor-joining procedure to reconstruct our test trees with high accuracy.
Exploring memory in email refinding
Authors: Elsweiler David , Baillie Mark , Ruthven Ian
Published: October 2008

Human memory plays an important role in personal information management (PIM). Several scholars have noted that people refind information based on what they remember and it has been shown that people adapt their management strategies to compensate for the limitations of memory. Nevertheless, little is known about what people tend to remember about their personal information and how they use their memories to refind. The aim of this article is to increase our understanding of the role that memory plays in the process of refinding personal information. Concentrating on email re-finding, we report on a user study that investigates what attributes of email messages participants remember when trying to refind. We look at how the attributes change in different scenarios and examine the factors which impact on what is remembered.
Up and coming SIGWEB supported conferences
Authors: Lunn Darren
Published: October 2008

SIGWEB supports several specialized conferences, short courses, and workshops, as well as the Annual Hypertext Conference. SIGWEB sponsored conferences focus on timely topics in applied and computational hypertext and Web disciplines and provide a place for members and the entire applied Hypermedia and Web community to exchange ideas and to meet with and expand their network of colleagues. In this article, we provide a brief overview of SIGWEB sponsored conferences, in addition to events that are in co-operation with SIGWEB.
Dscam-Mediated Cell Recognition Regulates Neural Circuit Formation
Authors: Hattori Daisuke , Millard S. Sean , Wojtowicz Woj M. , Zipursky S. Lawrence
Published: October 2008

The Dscam family of immunoglobulin cell surface proteins mediates recognition events between neurons that play an essential role in the establishment of neural circuits. The Drosophila Dscam1 locus encodes tens of thousands of cell surface proteins via alternative splicing. These isoforms exhibit exquisite isoform-specific binding in vitro that mediates homophilic repulsion in vivo. These properties provide the molecular basis for self-avoidance, an essential developmental mechanism that allows axonal and dendritic processes to uniformly cover their synaptic fields. In a mechanistically similar fashion, homophilic repulsion mediated by Drosophila Dscam2 prevents processes from the same class of cells from occupying overlapping synaptic fields through a process called tiling. Genetic studies in the mouse visual system support the view that vertebrate DSCAM also promotes both self-avoidance and tiling. By contrast, DSCAM and DSCAM-L promote layer-specific targeting in the chick visual system, presumably through promoting homophilic adhesion. The fly and mouse studies underscore the importance of homophilic repulsion in regulating neural circuit assembly, whereas the chick studies suggest that DSCAM proteins may mediate a variety of different recognition events during wiring in a context-dependent fashion.
Epigenetic Changes in Cancer
Authors: Iacobuzio-Donahue Christine A.
Published: October 2008

Cancer is as much an epigenetic disease as it is a genetic disease, and epigenetic alterations in cancer often serve as potent surrogates for genetic mutations. Normal epigenetic modifications of DNA encompass three types of changes: chromatin modifications, DNA methylation, and genomic imprinting, each of which is altered in cancer cells. This review addresses the various epigenetic modifications that are pervasive among human tumors and traces the history of cancer epigenetics from the first observations of altered global methylation content to the recently proposed epigenetic progenitor model, which provides a common unifying mechanism for cancer development.
Opportunities of ALD for Thin Film Solid Oxide Fuel Cells
Authors: Prinz Friedrich
Published: October 2008

In this paper I summarize several recent publications on thin film fuel cells performed at the Rapid Prototyping Laboratory at Stanford University. Reference is also made to the simulation of oxide ion conduction in yttria-stabilized zirconia. During the talk at the 214th ECS meeting, I plan on discussing previously unpublished data as well.
Fabrication of Self-aligned Enhancement-mode n-channel GaAs MOSFETs Employing a Wet Clean Process for GaAs Substrates
Authors: Shahrjerdi Davood , Garcia-Guteirrez Domingo , Kim Seyoung , Hasan Mohammad M. , Varahramyan Kamran , Tutuc Emanuel , Banerjee Sanjay
Published: October 2008

We report fabrication of self-aligned enhancement-mode GaAs MOSFETs employing a simple ex situ chemical clean. The role of precursor chemistry in removing GaAs native oxides as well as the impact of different ex situ chemical cleans on the properties of the interface between various atomic-layer-deposited high-k gate dielectrics and GaAs substrates were examined using x-ray photoelectron spectroscopy and Raman spectroscopy. The material characterization results indicate the effectiveness of ex situ sulfur passivation of GaAs surface prior to high-k deposition using ammonium sulfide solutions in improving the interface properties between high-k layers and GaAs substrates. Moreover, an appropriate choice of precursor chemistry for reduction of GaAs native oxides appears to play a crucial role in mitigating the Fermi level pinning at the interface. A maximum drive current of 4.5 uA/um at a gate overdrive of 2.5V was obtained for a MOSFET with a gate length of 20um.
Design and Development of ALD Precursors for Microelectronics
Authors: Kanjolia Ravi K. , Anthis J. , Odedra R. , Williams P. , Heys P. N.
Published: October 2008

Atomic Layer Deposition (ALD) has been identified as one of the primary technologies to fabricate devices with novel architecture. This requires design and development of advanced ALD precursors that can withstand the rigors of various integration steps while delivering the high quality layers essential to the new device design. The design criteria require these precursors to have suitable thermal stability, volatility, purity, reactivity, scalability, and economic viability. This brief review describes various elements of a precursor screening/development cycle from the materials company perspective. Specific examples will be presented for precursors of selected metals (such as ruthenium and cobalt) and high-k dielectrics (Hf, Zr, Ln) oxide materials.
Development of ALD Precursors for Semiconductor Devices
Authors: Wada Senji , Abe Tetsuji , Sakurai Atsushi , Higashino Takashi , Fujimoto Ryuusaku , Shimizu Masako
Published: October 2008

Two novel precursors, tetrakis(2-methyl-3-butene-2-oxy) hafnium (HMBO) and tetrakis(2-methyl-3-butene-2-oxy) zirconium (ZMBO), are synthesized for the deposition of hafnium dioxide (HfO2) and zirconium dioxide (ZrO2), respectively. HMBO and ZMBO have carbon-carbon double bond in their molecule, for ozone reactivity is added to themselves. Thermal stabilities of HMBO and ZMBO are more stabilized than those of TEMAH and TEMAZ. The effect of carbon-carbon double bond for the improvement of the O3 reactivity with HMBO and ZMBO is confirmed by thermogravimetric analysis (TG) under O3 atmosphere.
Ti Source Precursors for Atomic Layer Deposition of TiO2, STO and BST
Authors: Katamreddy Rajesh , Omarjee Vincent , Feist Benjamin , Dussarrat Christian
Published: October 2008

In this study we evaluated several precursors such as tetrakis(dimethylamino) titanium (TDMAT), tetrakis (diethylamino) titanium (TDEAT), tetrakis(ethylmethylamino) titanium (TEMAT) along with novel PrimeTiTM, StarTiTM and TyALDTM for TiO2 ALD application with both water and ozone as the oxidizer. Each precursor is evaluated with respect to some of the important characteristics like growth rate of TiO2 per ALD cycle, range and upper limit of process temperature window, volatility and stability of precursor, chemistry with desired oxidizer etc., that are critical for the selection of the precursor. All amino-compounds had a narrow process window. Precursor decomposition was observed for TDMAT, TDEAT and TEMAT at temperature higher than 225 oC limiting the deposition process at 225 {degree sign}C. On the other hand, TiO2 ALD using PrimeTiTM and StarTiTM is observed up to 325 and 400 {degree sign}C respectively. Finally, photoelectron spectroscopy analysis of some the films will be discussed.
Advances in ALD Equipment for sub-40nm Memory Capacitor Dielectrics: Precursor delivery, Materials and Processes
Authors: Karim Zia , Senzaki Yoshi , Ramanathan Sasangan , Lindner Johannes , Silva Hugo , Dauelsberg Martin
Published: October 2008

In DRAM, maintaining the cell capacitance more than 25 fF/cell with shrinking cell capacitance area has been accomplished with the introduction of higher k oxides as the capacitor dielectric. Higher k materials include Al2O3, HfO2, ZrO2 or a combination of HfO2/Al2O3/HfO2 and ZrO2/Al2O3/ZrO2. These materials can satisfy DRAM device requirements down to the 50 nm node. However, for sub 40nm DRAM technology nodes, precursor delivery challenges are far greater and require unique precursor delivery methodology to ensure >90% conformality in high aspect ratio DRAM capacitor structures, while maintaining higher productivity. The precursor delivery problem is due to the very low vapor pressures of the precursors for advanced high k dielectrics.. This paper highlights the progress made in ALD equipment development offering solutions for critical problems facing sub 40nm DRAM technology nodes. Particularly, this paper describes a unique pulsed vaporization technology (TriJet®) coupled with a high performance ALD reactor that offers solution for next generation high k film deposition without compromising productivity.
Atomic Layer Deposition as a Synthesis Method for Inorganic Membranes
Authors: Cassidy David , Higgins Scott , McCool Benjamin A. , DeSisto William J.
Published: October 2008

Atomic layer deposition has been used as a tool to modify mesoporous silica membranes. SiO2 has been deposited within mesoporous silica membranes using SiCl4 and H2O catalyzed with pyridine. Pore size reduction was self-limited and selectively reduced defective pores. Covalent attachment of silanes was also demonstrated by ALD. Both amino and alkyl groups were attached to mesoporous silica membranes. ALD is very effective for both pore size reduction and surface modification, yet is limited by the quality of the support material. ALD is a promising technique for membrane synthesis.
Synthesis of Zirconia and Hafnia Tubes by Atomic Layer Deposition (ALD) Template Method
Authors: Abdel-Fattah Tarek M. , Gu Diefeng , Baumgart H. , Namkoong Gon
Published: October 2008

Highly ordered zirconia and hafnia nanotubes are prepared by Atomic Layer Deposition (ALD) within the pores of an anodic alumina oxide (AAO) template. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) are used to characterize the morphology and elemental compositions of the different and EDS mapping of the entire sample cross-section. The diameters of the AAO channels are in the range of 200 nm and thickness of 60 μm. The length and diameter of the hafnia and zirconia nanotubes are dependent upon the pore diameter, the thickness of the applied AAO template and the ALD deposition time. The results indicate that the tubes are very uniformly assembled and parallel to each other in the pores of the AAO template.
Controlled Synthesis of 3D Nanostructures Using Proximity-Field Nanopatterning Lithography and Graded Temperature ALD
Authors: Grubbs Robert K. , Ellis A. R. , Sanchez A. M. , Wiwi M. , El-kady I. , Bogart Katherine , Su M. F. , Christodoulou C. , Taha M. , Shir D. L. , Rogers John
Published: October 2008

The combination of Proximity-field nanoPatterning (PnP) and graded temperature ALD has enabled the synthesis of robust three dimensional nanostructures. The PnP process uses a simple elastomeric optical phase mask to generate a complex three dimensional interference pattern in photopolymer1. Once the photopolymer structure has been obtained, it is subsequently used as a template for graded temperature ALD. The graded temperature ALD chemistry is used to coat and lock-in the designed nanostructure without melting the template. This process generates a thermally robust nanostructure for further, higher temperature, ALD surface treatments. The ALD chemistry is performed at various (increasing) temperatures to secure the nanostructure and to reduce the macroscopic stress of the structure as higher temperature depositions are performed. Three methods for nanostructure characterization have been useful in interrogating these structures: quartz crystal microbalance (QCM), optical interference, and focused ion beam scanning electron microscopy (FIB-SEM).
Oxidative Removal of Self-Assembled Monolayers for Selective Atomic Layer Deposition
Authors: Lee Wonyoung , Chao Cheng-Chieh , Jiang Xirong , Hwang Jaeeun , Bent Stacey , Prinz Friedrich
Published: October 2008

Using atomic force microscopy (AFM) lithography and self-assembled monolayer (SAM), selective atomic layer deposition (ALD) of ZrO2 was performed to fabricate nanostructures. SAM layer was used for a chemical mask for ZrO2 ALD process and AFM lithography for a nano-scale patterning method. AFM anodic oxidation process was applied to create oxide patterns on ODTS-coated silicon substrates. Subsequent HF etching locally removes oxide, exposing silicon layer underneath. After 100 cycles of ZrO2 ALD process and an oxygen plasma etching, ZrO2 ALD nanostructure of 4~7 nm in height and ~130 nm in line width were fabricated. A growth rate of 0.4~0.7 Aå per cycle is estimated from the AFM scanning at each step, which is slightly less than the typical ALD growth rates of ZrO2.
Formation of Metal-Semiconductor Core-shell Nanoparticles Using Electrochemical Atomic Layer Deposition
Authors: Gu Chaokang , Xu Hui , Park Minseo , Shannon Curtis
Published: October 2008

We report the synthesis of CuI coated and CdS coated Au core-shell nanoparticle films using electrochemical atomic layer deposition (EC-ALD). Au nanoparticle thin films were prepared on glassy carbon supports by depositing alternating layers of poly-(diallyl dimethylammonium)-stabilized Au nanoparticles and CoP2W17061 8- polyoxometallate interlayers. CuI was deposited onto the surface of Au nanoparticles using electrochemical atomic layer epitaxy, while CdS films were grown by an atom-by-atom co-deposition technique. The semiconductor coated nanoparticles were characterized by electrochemistry, photoluminescence spectroscopy, and Raman spectroscopy. Our results indicate that the semiconductors are deposited onto the Au nanoparticles surface by surface limited electrochemical reactions.
PEALD Ru Liner Conformality and Cu Trench Fill Characteristics
Authors: Van der Straten O. , Wynne J. , Vo Tuan , Maniscalco J. , Nogami Takeshi , Ali I. , Chiang Sunny , Ren J. , Ma P.
Published: October 2008

Conformality studies on trench structures in oxide and porous low-k dielectrics as well as Cu trench fill evaluations have been conducted employing a plasma enhanced atomic layer deposition (PEALD) Ru liner process in conjunction with conventional physical vapor deposited (PVD) Ta(N). The conformal growth of Ru by PEALD was demonstrated, while the benefits of a Ru layer underneath a conventional PVD Cu seed layer for Cu trench fill enhancement were shown. Poor PVD Cu seed layer coverage is considered to be the prime cause of the poor Cu/liner interface quality observed in the case of conventional Ta(N)/Cu liner/seed processes. Detailed EELS/EDX analysis has confirmed the presence of TaOx at the Ta(N)/Cu interface which is anticipated to be a key contributing factor impacting reliability performance.
Morphology of Electrodeposited Cu on 300 mm PEALD Ru Substrates
Authors: Kelly James , Vo Tuan , Van der Straten O. , Huang Qiang , Baker O'Neal Brett , Shao X I. , Chiang Sunny , Dukovic John
Published: October 2008

The morphology of thin layers of Cu electrodeposited on 300 mm Ru substrates (deposited by plasma enhanced atomic layer deposition or PEALD) is studied. To reduce the terminal effect, a layer of physical vapor deposited (PVD) Cu is employed beneath the Ru, allowing the characterization of the electrodeposited Cu on PEALD Ru across an entire 300 mm substrate. The morphology of the initially deposited Cu is studied for different current densities and entry biases using topdown scanning electron microscopy (SEM) and post-plating sheet resistance measurements. Electrodeposited Cu particle densities increase with deposition current density, while the particle size appears to change little. Despite the presence of the Cu underlayer, the morphology of the Cu deposited on Ru varies across the wafer, with higher deposited particle densities observed near the wafer edge as compared to the rest of the wafer.
Area Selective Atomic Layer Deposition of Cobalt Thin Films
Authors: Lee Han-Bo-Ram , Kim Hyungjun
Published: October 2008

Area selective atomic layer deposition (ALD) of Co thin films was investigated by using octadecyltrichlorosilane (OTS) self-assembled monolayer (SAM) as a blocking layer. Selective deposition was not observed in Co plasma enhanced ALD (PE-ALD) by CoCp2 and NH3 plasma, which was found to be due to the rapid degradation of OTS SAM. In contrast to PE-ALD, thermal ALD Co by Co(AMD)2 and H2 produced area selective deposition up to 1000 cycles.
Characteristics of Tantalum Carbo-nitride Thin Films Deposited with Atomic Layer Deposition Process
Authors: Song Moonkyun , Rhee Shiwoo
Published: October 2008

Tantalum carbo-nitride (TaCN) thin films were deposited on SiO2 surface with the plasma enhanced atomic layer deposition (PEALD) and thermal atomic layer deposition using tert-butylimido-tris (diethylamido)-tantalum (TBTDET) and reactive gas such as hydrogen and ammonia. It was confirmed that the film was a mixture of TaC, TaN, Ta3N5 and Ta2O5 with oxide phase formed from the post-deposition uptake of oxygen from the air. It was shown that electrical properties of TaCN film were affected by the phase composition in the film. Effect of the process parameters such as deposition temperature and plasma power was studied and their effect on phase composition and electronic properties was evaluated. The uptake of oxygen after deposition was about 10 atomic % with the PEALD process and about 30 atomic % with thermal ALD process and it is believed that denser film could be obtained with plasma.
Thermal Versus Plasma-Enhanced ALD: Growth Kinetics and Conformality
Authors: Detavernier Christophe , Dendooven Jolien , Deduytsche Davy , Musschoot Jan
Published: October 2008

Film purity, growth kinetics and conformality were compared for thermal and plasma-enhanced atomic layer deposition (PE-ALD) of Al2O3, AlN and TiN. The use of a plasma to enhance the activity of the reactant gas results in a significant improvement of the growth rate and film purity. However, based on experiments with an ammonia plasma for the growth AlN, the conformality of PE-ALD appears to be quite limited.
Plasma-Assisted ALD of Al2O3 at Low Temperatures: Reaction Mechanisms and Material Properties
Authors: Langereis Erik , Bouman Menno , Keijmel Jeroen , Heil Stephan , Van de Sanden M. C. , Kessels W. M.
Published: October 2008

Multiple in situ diagnostics have been employed to study the reaction mechanism of plasma-assisted ALD of Al2O3 and the influence of the substrate temperature on the material properties obtained. The results demonstrate that the ALD mechanism is governed by the formation of -CH3 surface groups and CH4 by-products upon Al(CH3)3 adsorption, while -OH surface groups and H2O, CO, and CO2 by-products are formed during the remote O2 plasma step. It has been observed that the amount of -OH involved in the ALD process increases with decreasing substrate temperatures which can account for the increase in growth per cycle at lower substrate temperatures. Moreover for substrate at 25 ºC, it has been found that a prolonged plasma exposure in the ALD cycle is effective in improving the film quality by a reduction of the impurity content and an increase in the mass density.
Comparison of Nanomechanical Behavior of the Amorphous and Crystalline Phases of ALD HfO2
Authors: Tapily Kandabara , Jakes Joseph , Shrestha Pragya R. , Gu Diefeng , Baumgart H. , Elmustafa Abdelmageed
Published: October 2008

HfO2 films were deposited using atomic layer deposition (ALD) at temperatures ranging from 100oC to 250oC. We report detailed nanoindentation measurements on the pure amorphous, mixed-phase and polycrystalline phase of HfO2. We use nanoindentation techniques for determining the important mechanical properties such as hardness and effective modulus. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and atomic force microscopy (AFM) to determine the structural properties of the various phases of these ALD HfO2 films. We measured the effective modulus to be 370 GPa for amorphous low temperature ALD HfO2 and 240 GPa after crystallization with rapid thermal annealing (RTA). Similarly, the hardness measurements revealed a value of 18 GPa for amorphous HfO2 and a lower value of 15 GPa following the transition temperature from amorphous to polycrystalline HfO2.
High-K Gate Dielectric Structures by Atomic Layer Deposition for the 32nm and Beyond Nodes
Authors: Clark Robert D. , Consiglio Steve , Wajda Cory , Leusink Gert , Sugawara Takuya , Nakabayashi Hajime , Jagannathan Hemanth , Edge Lisa F. , Jamison Paul , Paruchuri Vamsi , Iijima Ryosuke , Takayanagi Mariko , Linder Barry , Bruley J , Copel Matt , Narayanan Vijay
Published: October 2008

In this paper we will review some of our previous work on ALD deposited high-K dielectric stacks as well as present some of our more recent advances. We have shown that ALD can be used successfully to deposit high quality high-K gate dielectrics of Hf and Zr oxide. In addition, because of the inherent conformality of ALD processes, these dielectrics can be easily migrated to advanced device structures such as FINFETs. We have also been successful in developing ALD processes to deposit rare earth oxides (REOs), such as Y2O3 and La2O3. These processes are useful in creating layered dielectric structures where the REO functions as a threshold voltage adjustment layer. We use physical and electrical characterization of the films as deposited by ALD, including spectroscopic ellipsometry, corona oxide semiconductor charge measurement, TXRF, AES, angle resolved XPS, HRTEM, AFM, MEIS, and RBS, to provide information on the film growth mechanism and the primary parameters that influence the ALD growth of high-K oxides. We further correlate these findings with basic electrical results obtained from MOSFET and MOSCAP devices fabricated using our ALD processes to understand how process changes affect both the as-deposited films as well as the resulting devices.
Atomic Layer Deposited IrO2-TiO2 Thin Film Resistor for the Thermal Inkjet Printheads
Authors: Kwon Se-Hun , Kim Sung-Wook , Jeong Seong-Jun , Kim Kwang-Ho , Kang Sang-Won
Published: October 2008

IrO2-TiO2 thin films were prepared by atomic layer deposition using Ir(EtCp)(COD) and titanium isopropoxide (TTIP). The intermixing ratios between IrO2 and TiO2 in the IrO2-TiO2 thin films were controlled from (IrO2)0.33-(TiO2)0.67 to (IrO2)0.78-(TiO2)0.22. With the IrO2 intermixing ratio less than 0.55, both TCR values and resistivities were abruptly changed. The temperature coefficient of resistance (TCR) for IrO2-TiO2 thin films was controlled from -420 to -75.35 ppm/K by changing the IrO2 intermixing ratios from 0.55 to 0.78, while the resistivities was also controlled from 1500 to 356.7 μΩ•cm. Moreover, the change in the resistivity of IrO2-TiO2 thin films was below 10% even after O2 annealing process at 600{degree sign}C.
Photoluminescence of GaQ3-Al2O3 Core-Shell Nanowires
Authors: Wang Chih-Chieh , Kei Chi-Chung , Tao Ye , Perng Tsong-Pyng
Published: October 2008

Tris(8-hydroxyquinoline) gallium (III) (GaQ3)-Al2O3 core-shell nanowires with different shell thicknesses of Al2O3 were prepared by coating with atomic layer deposition (ALD) on GaQ3 nanowires. The photoluminescence (PL) and degradation with time of the core-shell nanowires were examined in the atmospheres of air, oxygen, argon, and water. Degradation of GaQ3 nanowires in PL intensity with time was observed in air, oxygen and water atmospheres, but not in argon. On the other hand, GaQ3-Al2O3 core-shell nanowires are only degraded in oxygen, but stable in other atmospheres. The degradation mechanism for both types of nanostructures is discussed.
Characteristics of TiSiO Films for Varistors
Authors: Lim Jung Wook , Yun Sun Jin , Kim Hyun-Tak
Published: October 2008

In this article, TixSi1-xO (TSO) thin film varistors were fabricated by plasma enhanced atomic layer deposition (PEALD) in order to lower the varistor voltage. The Ti content in TSO film was controlled by adjusting the cycle ratio of TiO2 and SiO2. In the measurement of current-voltage (I-V) characteristics, the nonlinear behavior was obtained. Asymmetric curves with both polarities were observed, which indicates that conduction is affected by the electrode. The nonlinear coefficient increases with the decrease of the Ti content and operating voltage is below 10 V in all samples. Relatively high nonlinear coefficient, 13.6, was obtained. Energy barriers between electrode and TSO film may dominate the carrier conduction of TSO varistor film.
Electromagnetic Pumping of a Silicon Melt
Authors: Korb Harold
Published: October 2008

This paper explores the potential for using transient magnetic fields produced using conventional magnet systems on commercial Cz crystal growers to create non-passive force fields in the bulk of a silicon melt. Sinusoidal currents superimposed on typical bias currents in two-coil axisymmetric magnet systems are considered, and the body force is calculated as a function of current amplitudes, frequencies, and relative phases. Both the magnitude and the direction of the time-averaged body force can be set by the appropriate choice of magnet current parameters. The magnitude of the force developed can be greater than the magnitude of buoyant forces in a typical Cz system, providing a practical means to modulate not only the magnitude but also the net direction of the combined buoyant and electromagnetically-generated force.
A Theoretical and Experimental Study of Stresses Responsible for the SOI Wafer Warpage
Authors: Dhumal Swapnil , Kommu Srikanth
Published: October 2008

Silicon-on-insulator (SOI) wafers are nowadays being prominently used for the manufacture of new generation semiconductor devices. In order to maximize the device yield, the device industry is seeking SOI wafers that meet very stringent wafer specifications such as very low wafer bow and warp. An SOI wafer can undergo severe process-induced stresses during its manufacture leading to significant wafer bow and warp. The objective of this study is to understand and control the process-induced stresses in SOI wafer in order to meet the stringent bow and warp specifications.
Solid Phase Crystallization (SPC) of a-Si Thin Film Induced by a Novel Approach for Photovoltaic Devices
Authors: Kim Taekon , Kumar Purushottam , Lee Jae Seok , Siebein Kerry , Singh Rajiv K.
Published: October 2008

The solid phase crystallization (SPC) of amorphous silicon thin films by a novel modification of nucleation step was investigated at low temperature. The thin film consists of polycrystalline nanoparticles embedded in an amorphous matrix which can act as nuclei, resulting in a lower thermal energy for the nucleation. Thus, this energy can shorten the transition time from amorphous to polycrystalline silicon and lower the processing temperature. The crystallinity and the crystallized volume fraction of silicon thin film annealed by the conventional furnace have been extensively studied by XRD and HRTEM. It was believed that high quality Si nanoparticles would act as nuclei for growth of crystalline Si, thus removing the high temperature requirement for nucleation. The crystalline films induced by nanoparticles can be used for the photovoltaic devices on glass substrates at a maximum temperature of 530oC.
Analysis of the Nucleation Kinetics of Oxide Precipitates in Czochralski Silicon
Authors: Kissinger Gudrun , Kot Dawid , Dabrowski Jaroslaw , Akhmetov Vladimir , Sattler Andreas , Von Ammon Wilfried
Published: October 2008

Vacancy dependent nucleation curves were measured. They exhibit four maxima which all increase with increasing vacancy concentration. Even at 1000 {degree sign}C considerable nucleation takes place for high vacancy concentrations. The analysis of nucleation based on classical nucleation theory has shown that nucleation of oxide precipitates takes place at heterogeneous nucleation sites. These sites contain oxygen atoms and vacancies and it is assumed that these sites are VOn complexes with 2<n<6. They are stable between 450{degree sign}C and 700{degree sign}C. As-grown silicon wafers contain a certain concentration of nucleation sites. This concentration increases or decreases during prolonged annealing and, as a result, the nucleation rate increases or decreases with annealing time, respectively. The grown-in concentration of nucleation sites can be markedly increased by appropriate rapid thermal anneal (RTA) pre-treatments. Supersaturated vacancies are assumed to be stored during RTA cooling mainly by reactions of vacancies with oxygen monomers, dimers, and trimers.
Formation and Annihilation of Hydrogen Related Donor States in Proton Implanted and Subsequently Plasma Hydrogenated N-Type Float Zone Silicon
Authors: Job Reinhart , Niedernostheide Franz-Josef , Schulze Hans-Joachim , Schulze Holger
Published: October 2008

The formation of hydrogen-related donor states was studied in proton-implanted and hydrogen plasma-treated Float-Zone silicon. H-implantations were executed at energies of 1 or 3 MeV, and fluences of 1x10E14 1/cm2. 13.56-MHz RF-plasma hydrogenations were done at 150 W for 15 min or 1 hour at substrate temperatures between 350 C and 500 C. Analysis was done by two-point-probe spreading-resistance measurements. H-plasma exposure for 15 min caused an enhanced donor concentration close to the projected ion range Rp. The donor states can be related to hydrogenated vacancy defects. Near the wafer surface n-type doping is also enhanced. Applying higher substrate temperatures (> 400 C) during plasma exposure, acceptor-like states overcompensate for the enhanced n-type doping near the surface. After 1-hour H-plasma exposure excessive donor states in the wafers subsurface region are completely annealed. At the surface n-type doping is still overcompensated for by acceptor-like defects attributed to hydrogenated vacancy defect clusters.
Extended Defects Created by Light Ion Implantation in Ge
Authors: David Marie-Laure , Barbot Jean François , Rousselet Sophie , Pailloux Frederic , Babonneau David , Beaufort Marie-France , Pizzagalli Laurent , Drouet Michel , Simoen Eddy R. , Claeys Cor
Published: October 2008

The effect of the implantation temperature in the range room temperature - 300oC has been studied in hydrogen and helium implanted germanium at high fluence and in the energy range of few tens of keV with either conventional implantation or plasma based ion implantation. The microstructure of the as-implanted Ge samples has been studied by Grazing Incidence Small-Angle X-ray Scattering and/or Transmission Electron Microscopy. For H-implanted Ge, small (001) and {111} platelets and {113} defects are nucleated at RT. With increasing the implantation temperature, microcracks, cavities and plate-like cavity clusters are created as well. The formation of these types of defects is ascribed to the interplay between dynamic and kinetic effects occurring during the implantation. As for He implanted Ge, a continuous cavity layer is formed whatever the implantation temperature in the range studied.
Metallic Impurities in Mono and Multi-crystalline Silicon and Their Gettering by Phosphorus Diffusion
Authors: Shabani Mohammad B. , Yamashita Takafumi , Morita Etsuoru
Published: October 2008

The concentrations of 42 metal impurities in mono-crystalline microelectronic grade (EG) and mono-crystalline solar cell grade (SOG) and cast multi-crystalline SOG silicon have been measured by ICP-MS. In mono-crystalline EG material, all 42 elements were found to be below the detection limit. In mono and multi SOG material we could measure Al, Ti, Cr, Mn, Fe, Ni, Co, Cu, Ga, Mo and Sn. No significant difference was observed between the metal content of the top, middle and bottom of cast multi-crystalline Si. In contrast, a significant difference was observed in top, middle and bottom of solar grade mono-crystalline Si. The outer part of cast multi-crystalline silicon contains higher metal impurities than the center part, likely caused by impurities from crucibles. In cast wafers, phosphorus diffusion gettering (PDG) at 900 C leads to complete gettering of Cu and Ni. Fe can be partially removed, effectively by ramp-down annealing to 700 C. In this case we found that the Fe segregation coefficient increases by a factor of 36 for lightly doped Si. In some cast material PDG could reduce metal impurities significantly without a strong improvement of lifetime. Depth profiling of metal impurities in PDG areas shows no Cr because it evaporates during PDG annealing. Also Fe is found to evaporate to some extent.
Nickel Contamination in Silicon: Electrical Activity Study and Microscopy Analysis
Authors: Polignano Maria-Luisa , Codegoni Davide , Grasso Salvatore , Riva Andrea , Sammiceli Francesca , Caputo Daniele , Privitera Vittoria
Published: October 2008

In this paper we show that nickel partially remains in the solid solution after Rapid Thermal Treatments (RTPs), so it can be detected by recombination lifetime techniques such as SPV and Elymat (based on photocurrent measurements). A quantification of nickel contamination based on lifetime measurements is provided. However, partial nickel segregation at wafer surface is observed even in RTPs by surface recombination velocity measurements. As a consequence, the near-surface region is depleted by nickel and a specific thermal treatment with very fast quenching is required to detect nickel in the volume by DLTS. Finally, the results about the electrical activity of nickel in carrier recombination and generation are compared to TOF-SIMS analyses at the oxide-silicon interface and to TEM analyses of nickel precipitates at wafer surface.
Copper Precipitation in Germanium-Doped Czochralski Silicon
Authors: Wang Weiyan , Yang Deren , Ma Xiangyang , Zeng Yuheng , Que Duanlin
Published: October 2008

Copper (Cu) precipitation behavior in p-type germanium-doped Czochralski (GCZ) silicon has been investigated by means of scanning infrared microscopy (SIRM) and optical microscopy (OM). It was revealed that compared with Cu precipitates in the form of etching pits (in OM image)/particles (in SIRM image) in conventional Czochralski (CZ) silicon, the Cu precipitates exhibited as the aggregated rods (in OM image)/star-like colonies (in SIRM image) within GCZ silicon. A mechanism of the effect of large grown-in oxygen precipitates on Cu precipitation is discussed. Moreover, it was found that the size or density of Cu precipitate colonies in GCZ silicon decreased with the decrease of annealing temperature or cooling rate, which is believed to be attributed to the reduced driving force for Cu precipitation.