bluuebunny/crossref_metadata_2025_split huggingface dataset:
Supercritical Carbon Dioxide-based Fluids Used as a Recovery Tool for Low-k Materials
Authors: Orozco-Teran Rosa A. , Gorman Brian P. , Zhang Zhengping , Mueller Dennis W. , Reidy Richard F. 
Published: June 2019

AbstractConventional ash strippers can easily damage most porous low-k materials, causing increased dielectric constants and decreased film thicknesses. This effect is more prominent in carbon containing porous low-k materials such as methylsilsesquioxane (MSQ). Ashed MSQ films exhibit increased water adsorption and dielectric constants due to the removal of methyl groups and structural damage caused by interaction with plasma species. Supercritical carbon dioxide (SC-CO2), has attracted considerable attention due its low cost, low critical point temperatures and pressures, and environmentally benign nature. This work describes the effects of SC-CO2 in combination with silylating agents on O2 ash-damaged MSQ films. FTIR, sessiledrop goniometric contact angle measurements, and SEM were used to monitor changes in the films' chemical bonding, composition, and microstructure.
Mechanical Properties of Organosilicon Thin Films Deposited from Cyclic and Acyclic Precursors using Water as an Oxidant.
Authors: Burkey Daniel D. , Gleason Karen K. 
Published: June 2019

AbstractPulsed-plasma chemical vapor deposition was used to deposit thin films from four different organosilicon (OSG) precursors, using water as the oxidant. The OSG precursors varied in structure (cyclic or acyclic), chemical composition (siloxane or silane), and type of organic substituent. Significant differences in final film structure were observed based on precursor identity, with the primary result being that cyclic siloxane precursors yielded films with a greater degree of crosslinking. The identity of the organic substituents was shown to affect the crosslinking potential, in that more reactive side groups, such as vinyl groups, facilitated the formation of crosslinking groups. At low power (200 W), film structure was dictated by precursor identity, whereas at high power (400 W), film structure became more uniform and precursor identity was less important. Mechanical properties tracked with plasma power, with low power samples being relatively soft, with hardness values between 0.126 GPa and 0.536 GPa. Samples produced at higher powers are more extensively crosslinked, resulting in enhanced mechanical properties. Samples produced at high powers had hardness values between 0.679 and 3.22 GPa, depending upon precursor identity. Dielectric constants ranged between 2.3 and 4.0.
Nanoporous Silica Films Derived from Structural Controllable Poly(silsesquioxane) Oligomers by Templating
Authors: Liu Wei-Chih , Yu Yang-Yen , Chen Wen-Chang 
Published: June 2019

AbstractIn this study, nanoporous silica films were prepared from the poly(hydrogen silsesquioxane)(HSSQ) and a templating agent. Three different kinds of the HSSQ with different molecular weight and Si-OH end group content were prepared through the variation of the water/triethoxysilane ratio or pH. The templaing agent for generating nanopore was triphenylsilanol (TPS). The experimental results of refractive index, dielectric constant, and FE-SEM supported the formation of the nano-size pores in the prepared silica films. The dielectric constant of the prepared nanoporous thin films could be reduced form 2.89 (porosity: 12%) to 1.85 (porosity: 58%) by increasing the added TPS. The surface roughness of the prepared nanoporous silica film in comparison with the film thickness was less than 1%. For successful generating small and uniform nanopore in the film, low molecular weight or high Si-OH content of the prepared HSSQ would be required. The current approach is useful for preparing new kinds of low dielectric constant materials.
The characterization and preparation of porous low dielectric films using various cyclodextrins as template materials
Authors: Yim Jin-Heong , Kim Jung-Bae , Jeong Hyun-Dam , Lyu Yi-Yeoul , Mah Sang Kook , Hyeon-Lee Jingyu , Lee Kwang Hee , Chang Seok , Pu Lyong Sun , Hu Y. F. , Sun J.N. , Gidley D.W. 
Published: June 2019

AbstractPorous low dielectric films containing nano pores (∼20Å) with low dielectric constant (<2.2), have been prepared by using various kinds of cyclodextrin derivatives as porogenic materials. The pore structure such as pore size and interconnectivity can be controlled by changing functional groups of the cyclodextrin derivatives. We found that mechanical properties of porous low-k thin film prepared with mCSSQ (modified cyclic silsesquioxane) precursor and cyclodextrin derivatives were correlated with the pore interconnection length. The longer the interconnection length of nanopores in the thin film, the worse the mechanical properties of the thin film (such as hardness and modulus) even though the pore diameter of the films were microporous (∼2nm).
Effects of Supercritical CO2 Drying and Photoresist Strip on Low-k Films
Authors: Reidy R.F. , Zhang Zhengping , Orozco-Teran R.A. , Gorman B.P. , Mueller D.W. 
Published: June 2019

AbstractFuture interlayer dielectric (ILD) requirements necessitate reductions in dielectric constant to 2.1 within four years. Due to gaseous-like transport properties and near liquid-like densities, supercritical methods have been developed to dry and strip resist from these highly porous materials. Although a non-polar molecule, the solvating capability of supercritical CO2 (SCCO2) can be tailored by varying pressure, temperature, and co-solvents. This flexibility has been employed to remove photoresist and moisture from porous low-k films. The results of these experiments have been characterized using FTIR, ellipsometry, and SEM.
Development and Application of On-Wafer Small Angle X-Rayscattering for the Quantification of Pore Morphology in Low Kporous Silk Semiconductor Dielectrics
Authors: Landes Brian , Kern Brandon , Stokich Ted , Niu Jason , Yontz Dorie , Radler-Carol Mike , Ouellette Mohler Kacee , Lucero Sebring , Hahnfeld Jerry , King Danny , Quintana John , Weigand Steve 
Published: June 2019

AbstractThe continual drive for faster interconnects requires the development of new interlayer dielectricmaterials with k values less than 2.1. Porous SiLKTM semiconductor dielectric resin wasdeveloped to achieve these low dielectric constants by introducing nanometer-sized pores intothe dense SiLK resin matrix. A quantitative description of the nano-porous morphology in low-kinterlayer dielectrics can be difficult to achieve for many reasons, including: complexities in theporous structure (size range, geometry, pore/pore interaction), inadequate mathematicaldescriptors, limitations of existing metrology technology, and availability of “tailor-made” experimental samples with a wide range of pore morphologies. On-wafer quantification of poremorphology is even more difficult as data must be obtained from extremely limited samplevolumes (thin films of ∼100-500 nm) residing on thick silicon (Si) wafer substrates.This paper will focus on the design, development and successful application of on-wafer smallangle x-ray scattering (SAXS) technology to characterize the morphology of porous SiLK resin.It will be demonstrated, by example, that this technology is able to deliver rapid quantificationover the entire pore size range for these systems. Recently developed data acquisition, reductionand analysis tools will be described. Direct evaluation of the strengths and challenges of severalmodels used to generate average pore size and pore size distribution will be reviewed. Finally,additional capabilities offered by this technology (wafer mapping and detection of “killer” pores)will also be discussed.
Solvent diffusion in porous low-k dielectric films
Authors: Shamiryan Denis , Maex Karen 
Published: June 2019

AbstractPorous materials are being investigated as low dielectric constant (low-k) materials. While porosity decreases the k-value of a material by decreasing its density, it simultaneously allows unwanted adsorption and diffusion of chemicals inside the porous matrix. To investigate this, different porous low-k materials, specifically silicon oxycarbide (SiOCH), methylsilsesquioxane (MSQ), and a polymer, were exposed to polar (ethanol) and non-polar (toluene) solvents. A difference in diffusion of polar and non-polar solvents would be an indication of the density of polar centers which attract polar molecules (such as water) and increase the dielectric constant of a film. The diffusion coefficient for toluene at room temperature was found to be approximately 2×10-5 cm2/sec for MSQ (40% porosity), 10-7 cm2/sec for SiOCH (7% porosity), 2×10-8 cm2/sec for the polymer. The observed diffusion can be described by a model of a viscous flow in a porous medium. The toluene/ethanol diffusion coefficient ratios were 4.4, 1.3, 1 for MSQ, SiOCH, and the polymer, respectively. The difference in toluene/ethanol diffusion can potentially be used to screen a material's affinity for water adsorption.
Ferromagnetic Metal Nanoclusters Encapsulated in Carbon Nanotubes
Authors: Ma Xicheng , Cai Yuanhua , Lun Ning , Wen Shulin 
Published: June 2019

AbstractFerromagnetic nanoclusters are very useful for a magnetic recording. However, the application of ferromagnetic nanoclusters is limited due to air-oxidation. One way to solve air- oxidation is to encapsulate ferromagnetic nanoclusters with inert materials such as carbon when they are produced. This allows us to keep excellent magnetic properties for a long time. In this work, we report a very simple synthetic method of carbon nanotubes (CNTs) encapsulated ferromagnetic cobalt nanoclusters by catalytic decomposing benzene over Co/silica-gel nano- scale catalysts. Unlike previous reports, the catalysts do not need to be pre-reduced prior to the forming of CNTs encapsulated cobalt nanoclusters, thus, the advantage of this method is that CNTs encapsulated ferromagnetic nanoclusters can be produced in one step, at a relatively low cost. High-resolution Transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) patterns and energy dispersive X-ray spectroscopy (EDS) were used to characterize the microstructures and compositions of the products. Experimental results revealed that the encapsulated Co was always presented as high temperature alpha-Co phase with fee structure, which frequently consists of twinned boundaries and stacking faults. Based on the experimental results, a possible growth mechanism of the CNTs encapsulated Co nanoclusters was proposed. Magnetic property measurements showed that the CNTs encapsulated cobalt nanoclusters possessed excellent magnetic properties.
Elaboration of h-Bn Sheathed β-Sic Nanocables
Authors: Saulig-Wenger K. , Cornu D. , Chassagneux F. , Miele P. , Epicier T. 
Published: June 2019

Abstracth-BN sheathed β-SiC nanocables were synthesized under argon at 1200°C by the direct thermal treatment of a silicon powder mixed with turbostratic boron nitride. The structure and the chemical composition of these nanocables have been investigated by HRTEM, EDX and EELS. They have a diameter ranging from 10 to 80 nm. The core of these nanocomposites is composed of pure cubic silicon carbide and the outer layers have been shown to be hexagonal boron nitride planes, set in a parallel direction to the nanocables axis.
Fabrication of Field Emitter Arrays of Carbon Nanotubes Aligned on Patterned Substrates using Self-Assembly Monolayer
Authors: Lee Ok-Joo , Jeong Soo-Hwan , Lee Kun-Hong 
Published: June 2019

AbstractField emissions from the singlewalled carbon nanotubes (SWNTs) attached on various patterned substrates such as silicon wafer and polymer film, are reported. SWNTs were cut into sub-micron length by sonication in an acidic solution. The SWNT emitters were aligned on Au surface at room temperature by self-assembly monolayer technique. The field emission measurements in a silicon wafer and a polymer film showed that the turn-on fields were 2.8 V/ νm and 3.9 V/ νm at the emission current density of 10 μA/cm2, respectively. The current densities were 0.9 mA/cm2 and 1.6 mA/cm2 at 6.0 V/ νm. This room temperature process is suitable for the fabrication of flexible field emission devices with carbon nanotubes.
Field Emission Properties of Carbon Nanotubes Synthesized by High Temperature Arc Method and Low Temperature CVD Method
Authors: Lai Hong-Jen , Kung Sheng-Chin , Hsu Chih-Ming , Li Bean-Jon , Lin Ching-Cheng , Lin Chih. Jen. 
Published: June 2019

AbstractThe microstructure and field emission properties of multi walled carbon nanotubes (MWNTs) were investigated. The comparisons are made between MWNTs synthesized by high temperature arc methods and low temperature CVD methods. The results of the HRTEM image clearly exhibit characteristic features of a multi walled carbon nanotube. Raman spectrum shows a stronger peak at about 1580 cm-1 indicating the formation of a well-graphitized carbon nanotube. It also shows the high temperature arc process can produce MWNT that has perfect graphitic layer structure and high I(G)/I(D) ratio. The Ratio of G-line (sp2 bond) and D-line(sp3 bond) of these MWNTs are about 2.8 to 5.2. From the field emission measurement, the low onset field is about 1.4 to 2.4 V/ m, and can be attributed to highly sharp tips and high electric conductivity of MWNTs.
Yield of InxGa1-xAs Superlattices Under Bending and Nanoindentation
Authors: Lloyd Stephen J. , P'ng Ken M.Y. , Bushby Andy J. , Dunstan David J. , Clegg William J. 
Published: June 2019

AbstractA series of InxGa1-xAs superlattices grown on InP substrates with differing coherency strains have been deformed by bending at 500°C and by nanoindentation at room temperature. The deformation was characterised by transmission electron microscopy through examination of thin sections machined in a focused ion beam microscope. The bent samples sheared along {111} planes, and the most highly strained samples partially relaxed through the formation of misfit dislocations. Under indentation the majority of the plastic strain in the multilayers is accommodated by twinning whereas no twins were observed under indents in the InP substrate. The overall dimensions of the plastic zone increased linearly with indent load.
Continuum Analysis of Cooperative Pit/Island Formation and Stability in SiGe on Si(100)
Authors: Singh N. , Elzey D.M. 
Published: June 2019

AbstractRecent experimental work (J. Gray, R.Hull and J. Floro, App. Phys. Lett. Vol 81, No 13, 2002) has investigated the cooperative nucleation and growth of pits and islanding at pit edges in SiGe/Si(100) epitaxial films. The pits, which are observed to form under certain growth conditions, evolve along with the islands until a complete island wall is formed around the pit's periphery. Once formed the pit'island configuration exhibits a surprising stability, with no further lateral growth during continued deposition or annealing. The pits consists of low energy {501} facets (inverted {501} pyramid) and the islands surrounding the pit also exhibiting faceting. Elastic finite element analyses of these configurations were carried out to investigate the dependence of strain energy and surface stress on pit/island geometry. In particular, our results provide insight as to the mechanism responsible for the observed size stability of the pit/island structure once it has become fully developed. Surface stress gradients arising from the geometry are also found to be responsible for the observed initial island formation at the center of pit edges during growth.
Mechanical Properties Of P(S-co-Itana)/P(S-Co-Mana), P(S-co-Ssna)/P(S-co-Mana), And P(S-co-Itana)/P(S-co-Ssna) Ionomer Homoblends
Authors: Oh Sung-Hwa , Kim Joon-Seop , Yu Jeong-A , Shin Kwanwoo 
Published: June 2019

AbstractThree different sets of styrene-based ionomer homoblends containing ca. 5 mol% of ionic repeat units, i.e. poly(styrene-co-sodium itaconate) [P(S-co-ITANa)]/ poly(styrene-co-sodium methacrylate) [P(S-co-MANa)] ionomer blends, sodium sulfonated polystyrene [P(S-co-SSNa)]/P(S-co-MANa) ionomer blends, and P(S-co-ITANa)/P(S-co-SSNa) ionomer blends, were prepared and their dynamic mechanical properties were investigated. It was observed that with increasing itaconate content in the blend of P(S-co-ITANa)/P(S-co-MANa) ionomers the multiplet of the P(S-co-MANa) ionomer disrupted initially very rapidly, and ionic modulus of the blend increased drastically. In the case of P(S-co-ITANa)/P(S-co-SSNa) ionomer blends, again, the ionic modulus increased significantly with increasing itaconate content. In these two ionomer blend systems, the itaconate, having two ionic groups per ionic repeat unit, influenced the properties of the blends more noticeably than the other two ionic units, containing only one ionic group per ionic repeat unit. In the blend system of P(S-co-SSNa)/P(S-co-MANa), as expected, the cluster loss tangent peak shifted to higher temperature, ionic modulus decreased, but the ionic plateau extended more with increasing the ratio of the P(S-co-SSNa) content. However, it should be mentioned that when the ion contents of the methacrylate and sulfonate ionomers increased to over 6 mol%, at which the cluster phase of the P(S-co-MANa) ionomers is known to become dominant, compared to the matrix phase, the three loss tangent peaks were observed, which implies that methacrylate-rich and sulfonaterich phases exist together. This might be due to the fact that a copolymerization effect becomes stronger; that is, with increasing ion content the role of ionic units in random copolymer ionomers becomes more important, compared to the role of host non-ionic units. As a concluding remark, the properties of these three ionomer blend systems depend on the degree of clustering, type of ionic groups, and the number of ionic groups per repeat unit.
Dynamics of Nanoparticle Chain Aggregates of Carbon Under Tension
Authors: Bandyopadhyaya Rajdip , Rong Weizhi , Suh Yong J. , Friedlander Sheldon K. 
Published: June 2019

AbstractCarbon black in the form of nanoparticle chains is used as a reinforcing filler in elastomers. However, the dynamics of the filler particles under tension and their role in the improvement of the mechanical properties of rubber are not well understood. We have studied experimentally the dynamics of isolated nanoparticle chain aggregates (NCAs) of carbon made by laser ablation, and also that of carbon black embedded in a polymer film. In situ studies of stretching and contraction of such chains in the transmission electron microscope (TEM) were conducted under different maximum values of strain. Stretching causes initially folded NCA to reorganize into a straight, taut configuration. Further stretching leads to either plastic deformation and breakage (at 37.4% strain) or to a partial elastic behavior of the chain at small strains (e.g. 2.3% strain). For all cases the chains were very flexible under tension. Similar reorientation and stretching was observed for carbon black chains embedded in a polymer film. Such flexible and elastic nature of NCAs point towards a possible mechanism of reinforcement of rubber by carbon black fillers.
An in-situ TEM Nanoindenter System with 3-axis Inertial Positioner
Authors: Bobji M.S. , Ramanujan C.S. , Doole R.C. , Pethica J.B. , Inkson B.J. 
Published: June 2019

AbstractTo quantify the mechanical properties and deformation behaviour of sub-micron wires, an in-situ nanoindenter system is being developed for a TEM. The miniaturized displacement controlled nanoindenter fits inside a side entry specimen holder. For coarse positioning, a novel 3-axis inertial positioner has been developed. This positioner has a range of 5mm with a 300 nm resolution. The fine displacements are generated by means of a tube piezo and the force is measured using a fibre optic interferometer.
Nanomechanical Imaging Of Multi-Walled Carbon Nanotubes
Authors: Muthuswami Lata , Ajayan P. M. , Geer R. E. 
Published: June 2019

AbstractNanomechanical mapping of individual multi-walled carbon nanotubes (MWNTs) has been undertaken to investigate intra-tube variations of mechanical response. Ultrasonic force microscopy has been used to measure the relative axial and radial variations of contact stiffness of individual MWNTs synthesized using chemical vapor deposition (CVD) and arc-discharge (AD) techniques. For CVD-based MWNTs the contact stiffness of the tube was seen to vary strongly across volume defects (axial variation of the tube radius) and is assumed to result from the high crystalline defect density associated with such radial variations. These observations support recent experimental data of effective Young's modulus inferred from electrostatically-induced nanotube vibration amplitudes.
Silylation of Partially Aggregated Colloidal Silica Nanoparticles for Reinforcement in Silicone Elastomers
Authors: Chao Timothy C. , Bergstrom Debora F. 
Published: June 2019

AbstractAqueous suspensions of colloidal silicas are readily silylated with chlorosilanes in the presence of acid and isopropyl alcohol without aggregation of the silica particles. By using chlorosilanes, spherical nanoparticles with controlled functionality can be made and transferred to an organic phase to provide stable, water free suspensions. The hydrophobic colloidal silica particles readily disperse into silicone polymers. In order to provide mechanical reinforcement comparable to traditional fumed silicas, a high filler loading of ca. 60 wt % mono-dispersed colloidal silicas need to be used.Recently a unique pearl necklaced-shaped colloidal silicas become commercially available. These nanoparticles are successfully silylated and they maintain the original structures as evidenced by transmission electron microscopy (TEM). They are compounded into silicone polymers at ca. 30 wt % and they provide excellent viscosities and mechanical properties, especially the tear strengths. In this paper, we present the silylation, characterization and mechanical properties of these partially aggregated colloidal silica nanoparticles in silicone elastomers.
Texture and Nano Mechanical Properties of YSZ Electrolyte Thin Films Prepared by CCVD and PLD
Authors: Xu Z. , Waters C. , Wang X. , Sudhir N. , Yarmolenko S. , Sankar J. 
Published: June 2019

AbstractComposite thin films of yttria stabilized zirconia (YSZ) and alumina (Al2O3) have been synthesized using liquid fuel combustion chemical vapor deposition (CCVD) and pulsed laser deposition (PLD) in the NSF Center for Advanced Materials and Smart Structures (CAMSS) at North Carolina A&T State University. With the CCVD technique, addition of alumina was realized by adding the designated amount of aluminum-organic in the reagent solution; while with PLD, doping of alumina in YSZ was accomplished by alternative ablations of an YSZ target and an alumina target. Variations in morphology, surface roughness and nano-mechanical properties of the composite thin films of Al2O3/YSZ were characterized. Crystal size of the films processed by CCVD was much larger than that processed by PLD; surface roughness follows the similar tendency. Upon high-temperature annealing, crystals in the PLD processed thin films grew up to 300 nm. The effect of Al2O3 in YSZ thin films on their nano-mechanical properties was dependent on the film deposition techniques in our research. For the films deposited by CCVD, addition of Al2O3 improved the nano hardness and elastic modulus of YSZ thin films, while a decline was observed in the mechanical properties of the films deposited by PLD.