bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adhesion of Triblock Copolymer-Based Thermoreversible Gels and Pressure Sensitive Adhesives
Authors: Shull Kenneth R. , Crosby Alfred J. , Flanigan Cynthia M. 
Published: June 2019

ABSTRACTTriblock copolymers with poly (methyl methacrylate) (PMMA) end blocks and a poly (n-butyl acrylate) (PnBA) midblock have been synthesized as model pressure sensitive adhesives and thermoreversible gels. These materials dissolve in a variety of alcohols at temperatures above 60 °C to form freely flowing liquids. At lower temperatures the PMMA end-blocks associate so that the solutions form ideally elastic solids. In our case the solvent is 2-ethylhexanol, polymer volume fractions vary from 0.05 to 0.3, and the elastic moduli are close to 10,000 Pa. We have conducted three types of experiments to elucidate the origins of adhesion and bulk mechanical properties of these materials: 1) Weakly adhering gels: The adhesive properties of the gels are dominated by the solvent. Very little adhesion hysteresis is observed in this case, although we do observe hysteresis associated with the frictional response of the layers. 2) Strongly adhering gels. By heating the gels in contact with a PMMA surface, it is possible to bond the gels to the surface. Development of adhesion as the PMMA blocks penetrate into the PMMA substrate can be probed in this case. The cohesive strengths of the gels are found to be substantially greater than their elastic moduli, so that these materials can be reversibly extended to very high strains. These properties have enabled us to probe the origins of elastic shape instabilities that play a very important role in the behavior of thin adhesive layers. 3) Dried gels – model pressure sensitive adhesives. By removing the solvent at low temperatures, the underlying structure of the gel is preserved, giving a thin elastic layer with excellent performance as a pressure sensitive adhesive. Resistance to adhesive failure, expressed as a velocity-dependent fracture energy, greatly exceeds the thermodynamic work of adhesion. This energy is further magnified by ‘bulk’ energy dissipation when the stress applied to the adhesive layer exceeds its yield stress.
Formation Mechanism of Molybdenum and Molybdenum Oxide Nanoparticles by Electron Irradiation
Authors: Jia Husheng , Xu Bingshe , Fan Yadi , Guo Ruiping , Tanaka Shun-ichiro 
Published: June 2019

ABSTRACTThe mechanism of molybdenum and molybdenum oxide nanoparticles formation from molybdenum oxide microparticles by electron beam irradiation using a high-resolution transmission electron microscope on a room-temperature stage have been investigated. It is found that, the microsized molybdenum oxide particles disintegrated to form nanosized molybdenum oxide particles by electron beam irradiation with an intensity of approximately 1021e/cm2 · sec. The molybdenum nanoparticles were formed from molybdenum oxide nanoparticles upon further electron irradiation. During the electron irradiation process, the surfaces and interfaces of molybdenum oxide nanoparticles suffered damage and defects, such as vacancy arrays showing hole like spots and a moire-like fringes in the lattice image due to oxygen loss, followed by a gradual change from molybdenum oxide to molybdenum nanoparticles. The phenomenon of molybdenum metal nanoparticle formation from nanosized molybdenum oxide is considered to be due to desorption of oxygen as a result of electron stimulation and atomic displacement via the knock-on effect. It is suggested that electron irradiation is a powerful technique to create nanostructured metal, ceramic and semiconductor materials by atomic-scale control.
Structure-Property Relationships in W Doped (Ba,Sr)TiO3 Thin Films Deposited by Pulsed Laser Deposition on (001) MgO
Authors: Navi N. , Horwitz J.S. , Wu H.-D. , Qadri S.B. 
Published: June 2019

AbstractBaxSr(1-x)TiO3 films (BST) with x=0.5, 0.6, 0.7, containing 1% W, were grown by pulsed laser deposition on MgO (001) substrates in an oxygen pressure from 3 to 500 mTorr, at a substrate temperature of 720 C. The crystal structure of the film, as determined from x-ray diffraction, was fit to a tetragonal distortion of a cubic lattice having two in-plane lattice parameters. The in and out-of-plane lattice parameters c, a, á, and lattice distortion (a/c and á/c) were calculated from the positions of the measured BST reflections ((004), (024) and (224)). The dielectric properties of the film at 2 GHz were measured using gap capacitors deposited on top of the dielectric film, at room temperature. For all compositions, as a function of the oxygen deposition pressure, a peak in the change in the dielectric constant, as a function of an applied electric field (0 – 80 kV/cm), was observed for films deposited in 50 mTorr of oxygen. Unlike the pure BST, the dielectric Q was insensitive to the oxygen deposition pressure. The largest Kfactor (K=(ε(0)-ε(V)/ε(0) x Q(0)) for films deposited from Ba0.6Sr0.4TiO3 target were observed in a film that had a minimum in-plane strain, where a~á.
Comparison of Microwave Dielectric Properties of between (001) and (011) Ferroelectric Ba1-xSrxTiO3 Thin Films grown by Pulsed Laser Deposition
Authors: Moon Seung Eon , Kim Eun-Kyoung , Lee Su-Jae , Han Seok-Kil , Kang Kwang-Yong , Kim Won-Jeong 
Published: June 2019

AbstractThe effects of anisotropic dielectric properties of ferroelectric Ba1-xSrxTiO3 (BST) films on the characteristics of phase shifter have been studied in microwave regions at room temperature. Ferroelectric BST films with (001) and (011) orientation were epitaxially grown on (001) and (011) MgO substrates, respectively, by pulsed laser deposition method. The structures of BST films were investigated using x-ray diffraction measurement. The microwave properties of orientation engineered BST films were investigated using coplanar waveguide transmission lines that were fabricated on BST films using a thick metal layer by photolithography and etching process. The measured differential phase shift and insertion loss (S21) for (011) BST films are larger than those for (001) BST films. Dielectric constants of the ferroelectric BST films are calculated from the measured S21 using a modified conformal-mapping model.
A Statistical Analysis of Laser Ablated Ba0.50Sr0.50TiO3/LaAlO3 Films for Microwave Applications
Authors: Romanofsky R.R. , Varaljay N.C. , Alterovitz S.A. , Miranda F.A. , Mueller C.M. , VanKeuls F.W. , Kim J. , Harshavardhan K.S. 
Published: June 2019

AbstractThe NASA Glenn Research Center is constructing a 616 element scanning phased array antenna using thin film BaxSr1-xTiO3 based phase shifters. A critical milestone is the production of 616 identical phase shifters at 19 GHz with ≈4 dB insertion loss and at least 337.5° phase shift with 3 percent bandwidth. It is well known that there is a direct relationship between dielectric tuning and loss due to the Kramers-Kronig relationship and that film crystallinity and strain, affected by the substrate template, play an important role. Ba0.50Sr0.50TiO3 films, nominally 400 nm thick, were deposited on 48 0.25 mm thick, 5 cm diameter LaAlO3 wafers. Although previous results suggested that Mn-doped films on MgO were intrinsically superior in terms of phase shift per unit loss, for this application phase shift per unit length was more important. The composition was selected as a compromise between tuning and loss for room temperature operation (e.g. crystallinity progressively degrades for Ba concentrations in excess of 30 percent). As a prelude to fabricating the array, it was necessary to process, screen, and inventory a large number of samples. Variable angle ellipsometry was used to characterize refractive index and film thickness across each wafer. Microstructural properties of the thin films were characterized using high resolution X-ray diffractometry. Finally, prototype phase shifters and resonators were patterned on each wafer and RF probed to measure tuning as a function of dc bias voltage as well as peak (0 field) permittivity and unloaded Q. The relationship among film quality and uniformity and performance is analyzed. This work presents the first statistically relevant study of film quality and microwave performance and represents a milestone towards commercialization of thin ferroelectric films for microwave applications.
The Effects of Charge Separation in Quaternary Ammonium, DABCO-Containing Polymers on In Vitro Toxicity and Gene Delivery
Authors: Reineke Theresa M. , Davis Mark E. 
Published: June 2019

AbstractPolycation materials have recently emerged as promising systems for the delivery of genetic material. In this study, several DABCO (1, 4-diazabicyclo[2.2.2]octane) polymers are investigated for their ability to bind and deliver plasmid DNA (pDNA) into mammalian cells. The DABCO polymers are synthesized by copolymerization of DABCO with 1, 3-dibromopropane (D3), 1, 4-dibromobutane (D4), 1, 6-dibromohexane (D6), 1, 8-dibromooctane (D8), and 1, 10-dibromodecane (D10) to form a series of quaternary ammonium polymers with increasing charge separation. Gel retardation experiments reveal that each polymer (D3-D10) binds pDNA above a charge ratio of 1.0 (polymer + / pDNA -). The polycations are examined for in vitro transfection efficiency and toxicity in BHK-21 cells. Results of the transfection experiments indicate that the D6 polymer had the highest transfection efficiency. Although all of the polymers are shown to have some toxicity, the D8 and D10 polymers are more toxic to BHK-21 cells; approximately 30% of the cells survive at a charge ratio of 5 +/- as compared to the D3, D4, and D6 polymers where survival rates are about 80%.
Oral Administration of Chemotherapeutic Agents Using Complexation Hydrogels
Authors: Blanchette James , Park Kinam , Peppas Nicholas A 
Published: June 2019

AbstractCarriers were synthesized to target delivery of a chemotherapeutic agent, bleomycin, to the upper small intestine in response to the pH shift when entering the upper small intestine from the stomach. Complexation hydrogels capable of pH-responsive swelling were used to form these carriers. Hydrogel nanospheres composed of methacrylic acid (MAA) and poly(ethylene glycol) (PEG) were loaded with bleomycin. Loading of bleomycin was performed by in situ polymerization and release of bleomycin from the nanospheres was measured by UV spectrophotometry. Results showed that bleomycin release from the nanospheres was responsive to the pH of the environment surrounding the nanospheres. In addition to pH-responsive release of bleomycin, the hydrogel nanospheres are also able to enhance the permeability of an in vitro model of the intestinal epithelium. Increasing the permeability of the intestinal epithelium could aid in transport of bleomycin from the lumen of the small intestine out into the bloodstream.
Nanocomposite Polyurethane Foams Via POSS Blends
Authors: McCabe Brock , Nutt Steven , Viers Brent , Haddad Tim 
Published: June 2019

AbstractPolyhedral Oligomeric Silsequioxane molecules have been incorporated into a commercial polyurethane formulation to produce nanocomposite polyurethane foam. This tiny POSS silica molecule has been used successfully to enhance the performance of polymer systems using co-polymerization and blend strategies. In our investigation, we chose a high-temperature MDI Polyurethane resin foam currently used in military development projects. For the nanofiller, or “blend”, Cp7T7(OH)3 POSS was chosen. Structural characterization was accomplished by TEM and SEM to determine POSS dispersion and cell morphology, respectively. Thermal behavior was investigated by TGA. Two methods of TEM sample preparation were employed, Focused Ion Beam and Ultramicrotomy (room temperature).
TEM Observations of Surface Graphitization and Interior Microstructural Changes in a Furan-Resin-Derived Carbon
Authors: Yamanaka Junji , Yasuda Eiichi , Weatherly George C. , Tanabe Yasuhiro 
Published: June 2019

AbstractFuran-resin-derived carbon structures have attracted interest as a component in carbon based composite materials. We have investigated the microstructures of furan-resin-derived carbon by transmission electron microscopy after high-temperature heat treatments. We observed that graphitization occurred at the surface even although furan-resin-derived carbon is believed to be a non-graphitizable carbon. On the other hand the interior of the specimens exhibited a cage-like structure. Specimens heat-treated at higher temperatures exhibited a well-developed cage structure, as evidenced by the number of stacked layers and their periodicity. Post-column type EELS was utilized to study the chemical state of the interior of the specimens. All of the EELS spectra had a characteristic edge structure showing the existence of π bonding. There were not significant differences between the spectra of early-stage and well-developed cage structures.
Nanocomposite Barrier Coatings for Elastomeric Applications
Authors: Goldberg H.A. , Feeney C.A. , Karim D.P. , Farrell M. 
Published: June 2019

AbstractInMat LLC has developed aqueous, non-hazardous nanocomposite dispersions with a unique combination of barrier properties and flexibility. Using butyl rubber as the matrix, and very high aspect ratio vermiculite filler, flexible coatings with gas permeability 30-300 times lower than butyl rubber have been produced.[1,2] These coatings have been shown to be undamaged by strains up to 20%. The first commercial application of this technology (sold under InMat's trademark Air D-FenseTM) is in Wilson's new, longer life, Double CoreTM tennis ball.
Filler Size Effect on the Structure of Polymer-Filler Interface in Polymer-Based Nanocomposites: Entropic and Energetic Effects
Authors: Picu R.C. , Ozmusul M.S. 
Published: June 2019

AbstractA study of the polymer structure in the vicinity of an interface with a rigid, curved wall is presented. The study is performed by means of lattice Monte Carlo simulations in melts of low and high density. Both purely entropic and energetic systems are considered. The configurational entropy of the chains as well as the cohesive interactions in the bulk polymer lead to the formation of a low-density layer in the close neighborhood of the wall. This layer is about one monomer thick in the purely entropic case, and has a thickness of about three radii of gyration in presence of energetic interactions. Increasing the wall curvature leads to an increase in density in the depleted layer, the effect being more pronounced in the energetic system. Chain end segregation at the wall is observed in all cases. This effect increases with increasing chain length and decreases with increasing wall curvature. The bonds are preferentially oriented in the direction tangential to the wall. The degree of orientation decreases with increasing wall curvature and is independent of chain length. Finally, the evolution of the density, of the segregation effect and of the bond preferential orientation with temperature is investigated. The density at the wall decreases with decreasing temperature in the melt state, while the segregation becomes more pronounced. The volume of polymer in which the structure is affected by the presence of the wall increases with decreasing temperature.
Interaction Between Ceria and Hydroxylamine
Authors: Tamilmani Subramanian , Shan Jilei , Huang Wayne , Raghavan Srini , Small Robert , Shang Cass , Scott Brandon 
Published: June 2019

AbstractCeria containing slurries are increasingly used in the chemical mechanical polishing of CVD silicon oxide films to obtain STI structures. Unlike silica or alumina, ceria has redox characteristics. Because of this characteristic, removal of ceria particles from planarized surfaces may be possible using chemical reagents that can participate in redox reactions. One such reagent is hydroxylamine, which is already being used in copper CMP. The objective of the work reported in this paper was to characterize the reaction between ceria and hydroxylamine, especially with respect to dissolution of ceria particles. A kinetic study of the dissolution of ceria in hydroxylamine solutions maintained at various pH values has been performed. The extent and kinetics of dissolution of ceria has been determined by ICPMS. Removal of ceria particles from oxide surfaces using hydroxylamine-based chemistries has been investigated.
Slurry Admittance and Its Effect on Polishing
Authors: Evans David R. 
Published: June 2019

AbstractConventional polishing process variables such as down force, platen speed, slurry flow rate, etc. tend to be both coupled together and indirect. Within this context, one might argue that the net rate of slurry admission or concomitantly, effective volume of slurry between the substrate and pad is a direct process parameter, which is affected by polishing pressure, substrate-pad relative velocity, pad wear and texture, etc. In this work, the role of slurry admittance is investigated by direct control of interference between the pad surface and the carrier retainer ring. Both fixed and dynamic implementations are investigated. Observed patterns of material removal on substrates polished with a fixed orientation are correlated and discussed.
CMP Revisited for the MEMS/Foundry Era
Authors: Camilletti Lawrence , Semiconductor Jazz 
Published: June 2019

AbstractBusiness/foundry driven requirements have necessitated the creation of modified ILD CMP processes for terminal metal-die planarization for BiCMOS SOC/MEMS applications. Therefore, despite much CMP process evolution, this paper ‘steps-back’ to test CMP assumptions first introduced within ILD process norms on these new applications at 10X typical process topographies. Evaluation of planarization targets, density effects, oxide budgets, as well as associated integration, throughput and metrology considerations within this expanded regime are discussed. ANOVA on inter- and intra-die (WIWNU and WIDNU) variation are used to quantify results throughout the work.
Polishing Behavior of the Various Interconnect Thin Films in Cu Damascene Process with Different Slurries
Authors: Zantye Parshuram B. , Sikder Arun K. , Kumar Ashok 
Published: June 2019

AbstractChemical Mechanical Polishing is a key technology for Cu damascene wiring process in integrated circuit (IC) manufacturing. It is important to understand the effects of mechanical and tribological properties of the coatings that form a part of Cu damascene structure on the CMP process in order to successfully evaluate and implement these materials. In this paper, we present tribological properties of different interlayer coatings (SiLKTM, Ta and Cu) during their CMP process using different Cu and barrier selective slurries. A micro CMP tester was used to study the fundamental aspects of the CMP process. The coefficient of friction (COF) and acoustic emission (AE) signals were acquired in situ to monitor the process and to see the difference in polishing behavior of these coatings. The issues of end point detection and slurry selectivity are discussed in detail.
Integrated Chip-Scale Prediction of Copper Interconnect Topography
Authors: Park Tae , Tugbawa Tamba , Cai Hong , Xie Xiaolin , Boning Duane 
Published: June 2019

AbstractIn this work, we present an integrated prediction of thickness variations in electroplating and chemical mechanical polishing (CMP) processes across an entire chip for random layouts. We achieve chip-scale prediction by first calibrating both electroplating and CMP models with experimental data using the same test mask. Using the calibrated plating model in conjunction with a discretized and binned layout extraction for a random chip layout, a prediction of plated copper topography is then performed. Finally, using the plated thickness prediction as the initial condition, the CMP model predicts the dishing and erosion across the chip. Layout geometry extraction for each discretized region of a chip as well as layout parameter manipulation and model output integration are all critical elements, in addition to the model development itself, enabling the integrated chip-scale prediction of final copper interconnect thickness variation.
Low Temperature a-Si:H Pixel Circuits for Mechanically Flexible AMOLED Displays
Authors: Nathan Arokia , Striakhilev Denis , Servati Peyman , Sakariya Kapil , Kumar Anil , Karim Karim S. , Sazonov Andrei 
Published: June 2019

AbstractThis paper presents the first demonstration of amorphous silicon (a-Si:H) thin film transistor (TFT) circuit integration on plastic substrates. The circuits compensate for material shortcomings such as metastable threshold voltage (VT) shift and high contact resistance, to supply stable and predictable currents to drive organic light emitting diode (OLED) displays on plastic. Various drive circuits were fabricated and tested. The simplest pixel driver circuit possible is the two TFT voltage-programmed circuit, which is very susceptible to any shift in VT of the drive TFT. To overcome this problem, we have developed current-programmed pixel circuits based on the current mirror circuit family, which include the simple and cascode current mirrors. The OLED current in these circuits is virtually independent of any VT shift or mobility variation in the drive TFT. Results show that the circuits provide higher linearity and dynamic range than currently available pixel circuits while minimizing the pixel area.
Curved Silicon Electronics
Authors: Wang Linlin , Ast Dieter G. , Bhargava Peeyush , Zehnder Alan T. 
Published: June 2019

AbstractAn electronic imaging system using a curved image sensor can use a faster lens, and cover a greater field of view, than an imaging system using a planar sensor. The simpler lens systems also weight less, a decisive advantage in portable applications.This paper describes a method to fabricate a curved silicon substrate from a flat wafer containing appropriate circuits. To curve the substrate, the processed wafer is diced, by dry-etching from the backside, into 1x1cm tiles. The tiles are separated by 0.5mm gaps, which are bridged, in turn, by a dense array of 45x100μm gold leads formed by electroplating using lithographically defined leads as seeds. Two methods were used to curve the wafer. In the first one, the wafer was bonded with epoxy to a PMMA disk, and then curved by heating the sandwich, under a load of ∼ 230gr, for 1.5 hrs at 130°C in a concave metal mold with a radius of curvature of 7.8cm. In the second method, the wafer was put into a curved metal mold, radius 14cm, loaded with 230gr, and heated to 290°C for 2 hrs. The normal and shear strains accommodated by the flexible interconnects were measured by analyzing their deformation. The experimentally measured strains are compared with a model that calculates the deformation required to deform a flat sheet into a spherical surface.
PMODTM-based Direct Thin Film Imaging, DTFITM, on Flexible Substrates
Authors: Roman Paul J. , Madsen Harold O. , Suh Seigi , Svendsen Leo G. , Mukherjee Shyama P. , Jamora Aleta , Fury Michael A. , Ip Katy 
Published: June 2019

AbstractPMOD (Photochemical Metal Organic Deposition)-based DTFI (Direct Thin Film Imaging) methodology is a demonstrated means for patterning organic materials on flexible (plastic) substrates. This process is used to pattern 1-micron features at an aspect ratio of 8:1 using contact lithography. Use of oxygen plasma RIE etch to transfer the hard mask pattern to the organic material allows for good sidewall angle control. High etch selectivity between the novolac polymer and PMOD TiOX hard mask (< 800:1) makes the use of very thin hard masks (∼ 200 angstroms) to pattern thick organic films (<10 microns) possible. Selective removal of the PMOD TiOX (TiO2) hard mask makes this process amenable to patterning of functional organic structures fabricated from materials chosen for their desired properties (e.g., glass transition temperature (Tg), etch resisitance, optical properties, mechanical properties, etc.) not their ability to be photopatterned (e.g., photoresist).