bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stress-induced Void Formation in Passivated Cu Films
Authors: Gan Dongwen , Li Bin , Ho Paul S. 
Published: June 2019

AbstractIn this paper, we investigated void formation in passivated Cu films focusing on the kinetics of void formation under isothermal annealing as a function of temperature. Interestingly, we found that the kinetics of void formation in Cu films is consistent with that observed in Cu lines, which is driven by the combined effect of thermal stress and mass transport resulting in a peak growth rate at about 250°C. To analyze the observed results, we have calculated the stress state at the <111>/<200> Cu grain boundary to demonstrate the existence of a localized triaxial stress state as a result of elastic anisotropy. To account for void density, x-ray analysis was performed to measure the grain texture using inverse pole figure plot and the result can account for the void density observed. A kinetic model was used to analyze void growth under isothermal annealing. A threshold stress of about 40MPa was deduced for void growth in passivated Cu films with an activation energy of 0.75 eV.
Determination of Elastic Modulus and Yield Stress of Ultra-thin Cu and low-k Films Using Spherical Nanoindentation Measurement
Authors: Shimizu Satoshi , Kojima Nobuo , Ye Jiping 
Published: June 2019

AbstractA spherical nanoindentation method was developed to evaluate elastic and plastic deformation parameters. The experimental reliability was confirmed by examining fused silica in the elastic deformation range. Yield stress as a quantitative plastic parameter was estimated using the Hertz contact theory and Tresca yield criterion. A copper thin film and two types of low-k thin film were examined. Reduced modulus was almost the same as the value obtained for the Cu (100) plane and yield stress was found to be between single crystals Cu (111) and Cu (100). These mechanical properties were thought to be dependent on the crystal orientation of the copper thin film. The two types of MSQ low-k film exhibited a difference in yield stress, although hardness was estimated to be similar by using the conventional nanoindentation method. These results have never been seen on a micro-mater scale.
Advanced Al Damascene Process for Fine Trench Under 70nm Design Rule
Authors: Han Sung Ho , Choi Kyung-In , Yun Sera , Park Jeong Heon , Lee Won Sok , Lee Sang Woo , Choi Gil Heyun , Hong Change Kee , Kim Sung Tae , Chung Uin , Moon Joo Tae , Ryu Byung-Il 
Published: June 2019

AbstractDue to a rapid shrinkage in memory devices, backned of the line process experiences great difficulties, especially Al metallization. Furthermore, there is a continuous demands in low line resistance in order to promote device performances. In this article, Al damascene process is proposed as compared to Al patterning process, which suffers from inherent pattering issue at a fine pitch under 70nm. The most difficulties in the development of Al damascene process were to form a stable and void free Al in fine trench and to obtain scratch and corrosions free Al surface. In this study, 50nm beyond fill was successfully achieved by “bottom up growth” of CVD Al. For the process, CVD Al by using Methylpyrroridine Alane (MPA) precursor was deposited on a stacked film of CVD TiN and PVD TiN as a wetting layer, which was followed by PVD Al and reflow, then the Al surface was polished with colloidal silica based slurry.In addition, electrical property of Al scheme and W scheme was compared with damascene pattern, along with which we demonstrated that around 36% decrease in parasitic capacitance is achievable by decrease of metal line height from 3500A to 1000A on simulation test implying that device performance could be enhanced.
A Spin-on Dielectric Material for High Aspect Ratio Gap Fill
Authors: Chen Wei , Wang Sheng , Ashraf Ather , Somerville Edward , Nowaczyk Gerard , Hwang BK , Lee JK , Moyer Eric S. 
Published: June 2019

AbstractThis communication describes the results of a potential spin-on glass (SOG) solution for narrow and high aspect ratio trench fill in both shallow trench isolation (STI) and premetal dielectric (PMD) applications. We have focused our development work on a hydrogen silsesquioxane (HSQ, (HSiO3/2)n) material, which offers the advantage of a carbon free gap fill solution. The main challenge for carbon-free SOG materials is to achieve material densification in the nano-scale gaps during thermal processing that of the gap filled material during the wet cleaning steps. This paper reports some approaches and findings on material densification in the nano-scale gaps and the results of subsequent wet etch tests.
Synchrotron X-ray Micro-diffraction Analysis on Microstructure Evolution in Sn under Electromigration
Authors: Wu Albert T. , Tamura N. , Lloyd J. R. , Kao C. R. , Tu K. N. 
Published: June 2019

AbstractWhite Sn (β-Sn) thin film stripe shows a voltage drop about 10% when subjected to electromigration testing. Since β-Sn has anisotropic crystal structure, it possesses different resistivity along a-, b- and c axis. The direction of the axes determines the resistance in each grain. Under electromigration, low resistance grain tends to grow in the expense of the neighboring high resistance grains. The changes of grain orientation in the Sn stripe before and after electromigration was studied by synchrotron x-ray microdiffraction (∼1νm diameter) to achieve grain-by-grain analysis. Grain growth involves grain boundary migration and rotation of neighboring high resistance grains. A model different from normal grain growth is proposed to describe the condition and mechanism of microstructural evolution under electromigration.
Multi-Via Electromigration Test Structures for Identification and Characterization of Different Failure Mechanisms
Authors: Choi Z.S. , Chang C. W. , Lee J. H. , Gan C. L. , Thompson C. V. , Pey K. L. , Choi W. K. 
Published: June 2019

AbstractExperiments on three-terminal ‘dotted-I’ test structures (copper metal lines with vias at both ends and an additional via at the center) show that the mortality of a single segment not only depends on the values of its current density and length, but also on the stress conditions in the linked segment. The current density in one 25μm long segment was fixed at 0.5MA/cm2, with electron flow toward the central via. In the othersegment, the current magnitude and sign were varied for different test populations, with the current varied from 2.5MA/cm2 to -2.5MA/cm2 with intermediate values including zero. For all cases, some test structures survived for the full 780 hours of testing and some did not. The percent of the lines that failed increased monotonically with an effective jL product defined as the maximum of the sum of the jL products from all paths through the structure. However, some lines with smaller than expected effective jL products failed, and some lines with relatively large effective jL products did not. Simulations of electromigration and electromigration-induced failures for all test conditions have been carried out. We find that test conditions leading to extreme values of the effective jL product probe different failure mechanisms than those associated with intermediate effective jL products. It is also shown that the definition of the effective jL product must be modified to account for zero current (inactive) segments that act as reservoirs or sinks. Multi-via test structures in general, and dotted-I test structures specifically, are shown to be versatile tools for identification and characterization of different failure mechanisms and length effects through the use of different test conditions with a single fixed structure.
Microstructure Evolution During Electric Current Induced Thermomechanical Fatigue of Interconnects
Authors: Keller Robert R. , Geiss Roy H. , Cheng Yi-wen , Read David T. 
Published: June 2019

AbstractWe demonstrate the evolution of microstructure and deformation associated with the use of electrical methods for evaluating mechanical reliability of patterned interconnects on rigid substrates. Thermomechanical fatigue in aluminum and copper interconnects was induced by means of low frequency (100 Hz), high density (> 10 MA/cm2) alternating currents, which caused cyclic Joule heating and associated thermal expansion strains between the metal lines and oxidized silicon substrate. The failure mechanism involved formation of localized plasticity, which caused topography changes on the free surfaces of the metal, leading to open circuit eventually taking place by melting at a region of severely reduced cross-sectional area. Both aluminum and copper responded to power cycling by deforming in a manner highly dependent upon variations in grain size and orientation. Isolated patches of damage appeared early within individual grains or clusters of grains, as determined by a quasi in situ scanning electron microscopy and automated electron backscatter diffraction measurement. With increased cycling, the extent of damage became more severe and widespread. We document some examples of the types of damage that mechanically confined interconnects exhibited when subjected to thousands of thermal cycles, including growth and re-orientation of grains in a systematic manner. We observed in the case of Al-1Si certain grains increasing by nearly an order of magnitude in size, and reorienting by greater than 30°. The suitability of electrical methods for accelerated testing of mechanical reliability is also discussed.
Thin-Film Color Sensor Arrays
Authors: Knipp D. , Street R.A. , Stiebig H. , Krause M. , Lu J.-P , Ready S. , Ho J. 
Published: June 2019

AbstractColor information is commonly captured by silicon sensor arrays covered by a mosaic of color filters. However, the detection of the colors red, green and blue at different spatial positions of the sensor arrays leads to color aliasing or color moiré effects. This effect inherently limits conventional sensor arrays. In order to overcome this limitation we have realized color sensors based on vertically integrated thin-film structures. The complete color information can be detected at the same position of a sensor array without using optical filters. The sensors consist of a multilayer thin-film system based on amorphous silicon and its alloys. The spectral sensitivity of the sensors can be controlled by the optical and optoelectronic properties of the employed materials and the applied bias voltages. The working principle of the thin-film sensors and the sensor arrays will be presented. For the first time a large area three color sensor array was realized without using optical filters.
Integration of Zinc Oxide Thin Films with Polyimide-based Structures
Authors: Matsumura Masashi , Bandic Zvonimir , Camata Renato P. 
Published: June 2019

AbstractZinc oxide (ZnO) films were deposited on polyimide-based substrates by pulsed laser deposition. The ZnO films and the underlying polymer layers were studied using Fourier Transform Infrared (FTIR) and Photoluminescence (PL) spectroscopies. FTIR measurements in structurally well-characterized samples exhibiting all X-ray reflections of crystalline hexagonal ZnO show absorbance bands around 405 cm-1(Zn-O stretching vibration) and 1110 cm-1 (in-plane C-H vibrations on aromatic rings of polyimide). Observed shifts in both absorption features as a function of deposition temperatures can probably be attributed to thermal stress in the layers. PL measurements showed broad spectra centered around 3.35 eV from ZnO excitonic emission and a broader PL band from 2.7 to 3.1 eV defect complex emissions. The appearance of these peaks was consistent for depositions of ZnO on non-organic substrates, which indicates that the integration of ZnO thin films on polymer based substrate preserved the characteristic optical properties of ZnO.
Study of sputtered Hafnium oxide Films for Sensor Applications
Authors: Grüger H. , Kunath C. , Kurth E. , Sorge S. , Pufe W. 
Published: June 2019

AbstractIn this paper results of the deposition and annealing of hafnium oxide thin films are reported. Due to the sensor application in mind, thicknesses between 30 and 150 nm have been deposited by r.f. sputtering of a high purity oxide target. Annealing has an important influence on the layer structure, stress and application correlated properties. A detailed understanding of the layer preparation is necessary to adjust deposition and annealing. After deposition the layers are predominately amorphous, annealing leads to textured layers with monocline or orthorhombic phases.Besides gas sensor applications optimized layers may serve as protective coating or combined with a second material to multi layer stacks as high reflective dielectric mirror.
Perovskite Particles from Phytoplankton
Authors: Weatherspoon Michael R. , Allan Shawn M. , Gaddis Christopher S. , Cai Ye , Haluska Michael S. , Snyder Robert L. , Sandhage Kenneth H. 
Published: June 2019

AbstractControlled-shape BaTiO3-based microparticles were synthesized with the use of diatom microshells (frustules) as templates. The SiO2-based frustules of Aulacoseira diatoms were first converted into MgO-based replicas via a gas/solid displacement reaction at 900°C. A BaTiO3 coating was then applied to the MgO-bearing frustules by a sol-gel process. After firing at 700°C for 1.5 h, a conformal nanocrystalline coating of BaTiO3was generated on the surfaces of the MgO-bearing frustules. The underlying MgO scaffolds were then selectively dissolved away to yield freestanding 3-D BaTiO3-based replicas of the original Aulacoseira diatom frustules. This work demonstrates that microparticles with well-controlled 3-D morphologies and non-natural multicomponent ceramic compositions can be produced by merging the self-assembly ability of biomineralizing micro-organisms with synthetic chemical tailoring.
Laser Light Scattering Observations of Liquid–Liquid Phase Separation in a Polymer-Induced Liquid-Precursor (PILP) Mineralization Process
Authors: DiMasi Elaine , Liu Tianbo , Olszta Matthew J. , Gower Laurie B. 
Published: June 2019

AbstractA Polymer-Induced Liquid-Precursor (PILP) process for mineralization of calcium carbonate has been studied in-situ by laser light scattering. Static and dynamic light scattering data were obtained from CaCl2 solutions containing poly(aspartic acid). Under these conditions calcium carbonate mineralizes through a liquid droplet precursor phase when the solution is exposed to the decomposition products of ammonium carbonate. Our measurements probe the integrated scatterer mass and the apparent hydrodynamic radius Rh,app of the droplets as they nucleate and coalesce. The data reveal three stages in the formation of the PILP phase: an early stage of droplet growth to Rh,app ≈ 250 nm; a mid-time stage of fluctuations and polydispersity in particle size; and a final growth period where Rh,app increases from 350 nm to the micron scale. Aggregation of precursor droplets, rather than atom-by-atom growth, is the dominant mechanism of mineral formation under these conditions. With respect to biomineralization, this first observation of 100-nm-scale droplets is significant, implying a possibility to mineralize from the liquid phase within the nanoscale compartments in which many biominerals form.
Cell Biology, Biochemistry and Genomics of Coccolithophore Biomineralization.
Authors: González Elma L. , Read Betsy A. 
Published: June 2019

AbstractThe coccoliths that form the outer cell covering of the unicellular coccolithophores are assembled in a coccolith vesicle. The coccolith vesicle maintains the conditions and protein carriers sufficient to import the raw materials (Ca2+ and CO32-) for calcite formation and, furthermore, to initiate and sustain mineralization. We have isolated the coccolith vesicle membrane on which a proton-pumping, vacuolar ATPase has been localized. The V-ATPase has been characterized and its membrane-spanning subunit c has been cloned and sequenced. We used the highly conserved sequence for designing and constructing probes and primers that allowed us to analyze expression patterns to show a direct relationship between expression of the gene and calcification. Our collaborative work has now turned to a genomics approach that will lead us to additional calcification-specific genes.
Bio-inspired Design of Modular Multi-domain Polymers for Advanced Biomaterials
Authors: Roland Jason T. , Guzman Dora , Bai Jane , Guan Zhibin 
Published: June 2019

AbstractNative load-bearing proteins, such as the muscle protein titin, exhibit a remarkable degree of combined toughness, strength, and elasticity which have yet to be matched by synthetic materials.Single molecule nanomechanical studies on titin and other modular proteins suggest that these exceptional properties arise from a modular elongation mechanism. The sequential unfolding allows modular biopolymers to sustain a large force over the whole extension of the chain, which makes the polymer strong, along with a large area under the force-extension curve, making it tough as well. In addition, when the external force is removed, the unfolded domains of modular proteins will refold automatically, making them elastic. Inspired by nature, one research effort in my group is aimed at designing synthetic macromolecules that form high order structures by programming non-covalent interactions into polymer chain. The goal is to achieve synthetic biomaterials with combined strength, toughness and elasticity. Three classes of well-defined modular polymers have been synthesized in our laboratory: (1) using quadruple hydrogen-bonding motif 2-ureidon-4-pyrimidone (Upy) to direct the formation loops along a polymer chain (J. Am. Chem. Soc.2004, 126, 2058); (2) using a peptidomimetic beta-sheet based double-closed loop (DCL) as module (J. Am. Chem. Soc.2004, 126, 14328); and (3) an engineered protein G domain III as module. Single molecule force-extension experiments revealed the sequential unfolding of the loops or domains as these modular polymers are stretched, resulting in sawtooth-patterned curves similar to those seen in titin and other biopolymers. In this paper, we will discuss our designs, syntheses and single-molecule studies of polymers having modular domain structures.
Immobilization of Proteins on the Surface of Silanized Hydroxyapatite
Authors: Monkawa Akira , Ikoma Toshiyuki , Kumagai Yuri , Yunoki Syunji , Tanaka Junzo 
Published: June 2019

AbstractHydroxyapatite (HAp) is widely used as bioceramics for bone and dental tissue reconstructions due to its excellent biocompatibility with hard tissues and high osteoconductivity. Although it is well known that HAp has the high adsorbed ability, its ability is decreased in high ionic solution. To immobilize protein on the HAp surface, this study demonstrates that Collagen (Col) and fibronectin (Fnt) were immobilized on the surface of hydroxyapatite (HAp) sintered body with and without the silane coupling agent of aminopropyltriethoxysilane (APS). The proteins immobilized on the HAp and APS/HAp surfaces were investigated by atomic force microprobe (AFM, Simadzu; SPM 9500) analyses and Ζ potential measurements. The stability of protein/APS/HAp and protein/HAp composites was evaluated after immersion in phosphate buffer and NaCl solutions with various concentrations. AFM analyses and Ζ potential measurements revealed that proteins immobilized on the APS/HAp are more stable than those immobilized on the HAp in high ionic solutions.
Preparation and Characterization of Porous Material from Self-Organized Hydroxyapatite/Collagen Nanocomposite
Authors: Yunoki Shunji , Ikoma Toshiyuk , Monkawa Akira , Kikuchi Masanori , Tanaka Junzo 
Published: June 2019

AbstractSelf-organized hydroxyapatite /collagen (HAp/Col) nanocomposite was synthesized by a co-precipitated method. The porous HAp/Col nanocomposites with unidirectional and interconnected pores with approximately 20μm in size were prepared by a facile method. The ice crystals were grown up at a cooling brass bottom in the paste which kneaded the HAp/Col nanocomposite with a sodium phosphate buffer. The freeze-drying technique produced the replica of ice structures, and the porous composites showed the anisotropic compressive strengths. The nanostructure and micropore structure are of great importance for developing the novel artificial bone filling materials; attachment and migration of cells and blood vessels, and early regeneration of bone tissues.
Magnetic Rings: Influence of Asymmetry on Switching Mechanism
Authors: Mani Anand Subra , Geerpuram Dwarakanath , Baskaran Vidhya Shankar , Rodriguez Guadalupe , Metlushko Vitali 
Published: June 2019

AbstractWe found that the introduction of well-controlled asymmetry provides precise control of the switching mechanism and leads to improved switching characteristics in magnetic nano-rings.
Langmuir Layers of Magnetic Nanoparticles
Authors: Majetich Sara A. , Sachan Madhur , Kan Shihai , Cheng Yuhang , Gardener Julie 
Published: June 2019

AbstractMethods to form magnetic nanoparticle monolayers using non-aqueous Langmuir layers are reported. Following a discussion of the driving forces in various self-assembly techniques, we describe how aqueous Langmuir layers can be modified for use in conjunction with oxidationsensitive nanoparticles. Monolayers are formed using Fe and–Co nanoparticles, and transferred to carbon-coated transmission electron microscopy grids using the Langmuir-Schaefer method.
Magnetic Nanoparticle Aggregation States in Ag100-xFex Cosputtered Granular Films Investigated by Magnetic and Magnetotransport Measurements
Authors: Allia Paolo , Celegato Federica , Coisson Marco , Tiberto Paola , Vinai Franco , Spizzo Federico 
Published: June 2019

AbstractMagnetoresistance and.magnetization measurements have been performed on nanogranular, cosputtered Ag100-xFex films (x= 10 to 30) in the 4 K – 300 K temperature interval. The analysis reveals that the films with x ≤ 14 are interacting superparamagnets, characterized by a magnetic correlation length of the order of the electronic mean free path λ. Films with x ≥ 26 behave as concentrated magnets with strong competing interactions among magnetic moments (frustrated ferromagnets) and magnetic correlation length much larger than λ.
Self-Assembling Magnetic Nanostructures: Wires, Helices, Nanotubes Of Ni Nanoparticles
Authors: Kislov V.V. , Gulyaev Yu.V. , Taranov I.V. , Kashin V.V. , Kozhevin V.M. , Yavsin D.A. , Zabelin M.A. , Tret'yakov P.A. , Gurevich S.A. 
Published: June 2019

AbstractThe formation of organized structures of magnetic nanoparticles have been studied by scanning probe microscopy when depositing Ni nanoclusters on conducting (gold on HOPG) substrates. In this case magnetic Ni nanoparticles formed by laser electrodispersion technique based on laser ablation (size of particles ∼ 2.5 nm) form highly ordered superstructures, including helical (double helix with outer diameter ∼ 10 nm, distance between sequences ∼ 5 nm, length of such helix is typically hundreds of nm), linear (chains of clusters), etc. The structures discovered were investigated also by STS methods, with clear demonstration of Coulomb blockade effect over single nanoclusters. The results of calculations for dipole-dipole and exchange interaction of magnetic nanoparticles support such formation of helix-like structures.