bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Study on the Properties of Different IMP Ta, Ta(N) and Multi-Layer Ta/Ta(N) as Diffusion Barriers for Cu Metallization
Authors: He L. , Li C.Y. , Zeng Z.Q. , Wu J.J. , Qian Y. , Zhang Y. , Liu H.D. , Xie Joseph 
Published: April 2011

ABSTRACTWe report a study on the properties of Ionized Metal Plasma (IMP) Ta, Ta(N) and multi-layer Ta/Ta(N) based on a comparative evaluation of their performance as diffusion barriers in Cu based metallization schemes. The film structures used in this study are: IMP Cu(2000Å)/IMP Ta(250Å)/Si; IMP Cu(2000Å)/IMP Ta(N)(250Å)/Si; and IMP Cu(2000Å)/IMP multi-layer Ta/Ta(N)(250Å)/Si. The samples were annealed in N2 ambient at 500 °C, 550°C, 600°C and 650°C, respectively, for 30 minutes. The failure behavior and film properties of different barriers were investigated using MetaPULSE, Film stress measurement (FSM), Four-point probe (FPP), X-ray diffractometry (XRD), Field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM). It has been observed clearly from the sheet resistance measurements that failures of Ta(N) and Ta barriers occurred at 550°C and 600°C respectively, whereas the multi-layer Ta/Ta(N) could still survive from the annealing up to 650°C. Evidence showing the formation of Cu3Si in the failed film stacks was found from XRD spectra. Based on our studies, it can be concluded that microstructures of the barriers has the major effects on preventing Cu from diffusing through them to react with Si and this makes the multi-layer Ta/Ta(N), in overall, superior to the other two Ta and Ta(N) barriers.
Deposition and Characterization of PECVD SiOC Films by Using Bistrimethylsilylmethane (BTMSM) Precursor
Authors: Kim Yoon-Hae , Hwang Moo Sung , Lee Young , Kim Hyeong Joon 
Published: April 2011

ABSTRACTCarbon-containing silicon oxide (SiOC) is regarded as a potential low dielectric constant (low-κ) material for an interlayer dielectric (ILD) in next generation interconnection. In this study, we present the fundamental film properties and integration process compatibility of the low-κ SiOC film deposited by using bistrimethylsilylmethane (BTMSM) precursor. As more carbon was incorporated into film, both film density and dielectric constant decreased. The lowest κ-value, which we have obtained in this study, was 2.3 and the hardness of SiOC film was 1.1GPa as well as showing the thermal stability up to 500°C. In case of using conventional gases, organic components in SiOC film restricted etch rate. However, O2 addition could make it possible to obtaine a reasonable etch rate. The post-treatment of SiOC film in hydrogen plasma improved the resistance to O2 plasma in ashing process. The compatibility of SiOC film to the CMP process was also examined.
Chemical Vapor Deposition (CVD) of Tungsten Nitride for Copper Diffusion Barriers
Authors: Gordon Roy G. , Barton Jeffrey , Suh Seigi 
Published: April 2011

ABSTRACTA new process was developed for deposition of the tungsten nitride at moderate substrate temperatures (350-400 °C). The tungsten source bis (tert-butylamido)bis(tertbutylimido) tungsten, (tBuNH)2(tBuN)2W, reacts with ammonia in a low-pressure CVD reactor. Growth rates ranged from about 0.6 to 4.1 nm per minute. The stoichiometry of the films varied from WN1.2O1.7 to WN1.6o0.25, depending mainly on deposition temperature. The films are amorphous by X-ray diffraction, and smooth by scanning electron microscopy. Step coverage is nearly 100% in vias with an aspect ratio of 6:1 for films deposited at 400 °C or lower. Barriers 45 nm thick resist diffusion of copper up to temperatures of 600 °C. Adhesion is strong to all substrates tested, including silicon, silicon dioxide, soda-lime glass, glassy carbon, aluminum and stainless steel. This new halogen-free process avoids halogen contamination of films and corrosion of equipment. Uniformity of thickness and stoichiometry are readily achieved. This process is a promising method for forming copper diffusion barriers in future generations of microelectronics.
Defect Nucleation and Annihilation in Sheared Polymeric Liquid Crystals
Authors: Grecov Dana , Rey Alejandro D. 
Published: April 2011

ABSTRACTShear–induced nucleation and annihilation of topological defects due to hydrodynamic instability in nematic liquid crystals is a phenomenon of both scientific interest and practical importance. We use a complete generalized non-linear second order tensor Landau-de Gennes model that takes into account short range order elasticity, long-range elasticity and viscous effects, to simulate the nucleation and annihilation of twist inversion walls in flow-aligning nematic polymers subjected to shear flow. Shearing a homogeneous nematic sample perpendicular to the director results in an linear instability that maybe symmetric at low shear rates, and antisymmetric at higher shear rates. At even higher shear rates the onset of nonlinearities results in the nucleation of a parallel array of twist inversion walls, such that asymmetry prevails. By increasing the shear rate the following director symmetry transition cascade is observed: symmetric → antisymmetric → asymmetric → symmetric. The nucleation of the parallel array of twist inversion walls in the asymmetric mode is due to the degeneracy in reorientation towards the shear plane. The annihilation of twist walls is mediated by twist waves along the velocity gradient direction. Twist walls annihilate by three mechanisms: wall-wall annihilations, wall-wall coalescence, and wall-bounding surface coalescence. The annihilation rate increases with increasing shear rate and at sufficiently high rates the layered structure is replaced by a homogeneously aligned system. The role of short range and long range elasticity on defect nucleation and annihilation is characterized in terms of the Deborah and Ericksen numbers. Close form solutions to approximated equations are used to explain the numerical results of the full Landau-de Gennes equations of nematodynamics.
Pulling Single Chains out of a Collapsed Polymer Monolayer in Bad-Solvent Conditions
Authors: Koutsos Vasileios , Haschke Heiko , Miles Mervyn J. , Madani Frédéric 
Published: April 2011

ABSTRACTIt has been theoretically predicted that a polymer chain in poor solvent conditions undergoes a phase transition from a collapsed globule to a stretched coil. In this paper, we present force-distance curves, obtained by atomic force microscopy (AFM), showing the characteristic forceplateau associated with this transition. We show that the magnitude of the force depends on the environment (interfacial energy) that the stretched coil experiences when it is pulled-out as it is predicted by the theory.
Biomimetic Dextran Coatings On Silicon Wafers: Thin Film Properties And Wetting
Authors: Ombelli Michela , Eckmann David M. , Composto Russell J. 
Published: April 2011

ABSTRACTThere has been much recent interest in polysaccharide coatings for biotechnology applications. We obtained highly wettable dextran coatings applied to flat silicon wafer surfaces through a two-step process: in the first step, the silicon is aminated by the deposition of a self-assembled monolayer of 3-aminopropyltriethoxysilane (APTES); in the second step, polydisperse and low dispersity dextrans with molecular weights ranging from 1 kDa to 100 kDa are covalently grafted along the backbone to the surface amino groups to achieve strong interfacial anchoring. The effect of dextran concentration on film thickness and contact angle is investigated. Atomic force microscopy (AFM) has been employed to characterize surface roughness and coverage of the dextrans as well as the APTES monolayers. The synthetic surfaces were also tested for gas bubble adhesion properties.
Hole injection and transport in a fluorene-containing copolymer
Authors: Khan Rizwan U. A. , Kreouzis Theo , Poplavskyy Dmytro , Bradley Donal D. C. 
Published: April 2011

ABSTRACTWe have studied the electrical properties of a fluorene-containing copolymer which is currently being developed for state-of-the-art blue polymer LEDs. This copolymer is made up of three functional groups which are nominally the hole-conducting, electron conducting and emissive regions. Using a combination of current/voltage, time-of-flight and dark injection transient versus temperature measurements, the injection and transport properties of the material have been investigated. Hole injection from polystyrene sulphonate doped polyethylenedioxythiophene (PEDOT:PSS) into the polymer is found to be consistent with an ohmic contact. Hole transport within the fluorene copolymer is found to possess a mobility that is two orders of magnitude lower than that for previously studied polymers containing the copolymer constituents. Using the equations for trap-free space-charge limited current, predicted J/V characteristics have been obtained from the mobility values derived using the time-of-flight technique. We discuss both the reduced hole mobility of the copolymer, and the discrepancies between the measured and predicted J/V characteristics, in terms of variations in both the trap and transport site densities and their energetic and spatial distributions.
Charge Carrier Injection Into A Disordered Organic Dielectric
Authors: Arkhipov Vladimir I. , Bässler Heinz , Emelianova Evgenia V. 
Published: April 2011

ABSTRACTBased upon the concept of charge carrier hopping within a disordered organic solid a formalism for the temperature and field assisted charge injection from an electrode into an organic dielectric has been developed. Both back flow of charges towards the injecting electrode and the dependence of the injection efficiency upon the charge carrier mobility has implicitly been taken care of. Experimental results for electrode limited injection are in good agreement with the theory.
Modification of Conducting Polymer Thin Film Interfaces Using Self-Assembled Monolayers Containing Transition Metal Complexes
Authors: Sarno David M. , Prasad Sudhindra , Jones Wayne E. , Matienzo Luis J. 
Published: April 2011

ABSTRACTThin films of polyaniline (PANi) have been in-situ deposited onto fused silica plates modified with ruthenium porphyrin and polypyridyl complexes coordinated to self-assembled monolayers of pyridyl-terminated alkylsilanes. Based on UV-vis and AFM studies, PANi exhibits a slower deposition rate and an earlier onset of secondary nucleation on the metal complex-modified interfaces. Electrical conductivity of the HCl-doped emeraldine salt form of PANi is increased to as high as 40 S/cm, relative to <1 S/cm on bare silica, measured under the same conditions and in the absence of any external modification to the polymer films. These changes are attributed to favorable π interactions between the aromatic surface species and the conjugated polymer that lead to a more expanded coil conformation for PANi.
Implant Surface Modification by Biological Multi-layer Systems
Authors: Willumeit Regine , Kamusewitz Helmut , Schossig Michael , Schröder Jens , Clemens Helmut 
Published: April 2011

ABSTRACTThe current design of implants or implant materials is under the pressure of an increasing demand. In our society we find more and more active older people with an increasing life time. On the other hand it can be observed that also for younger people implants become more and more necessary due to sport or accidents. As a consequence the development of new surgery strategies as well as new materials systems is needed. In this work we present the idea of creating a metal implant surface which mimics a cell membrane or at least parts of it. Scanning electron and atomic force microscopy investigations show that a multilamellar closed lipid layer can be prepared and that this layer resembles the same contact angle observed for the membrane of an osteoblast.
Current-Induced Degradation in Polythiophene
Authors: Goldberg Velda , Kaplan Michael , Soltzberg Leonard , Genevich Joseph , Coombs Emily , Giacomozzi Erica , Kwasnik Valarie , Naeem Samia , Pham Eleana , Malliaras George 
Published: April 2011

ABSTRACTThe three-year collaboration between Simmons College and the Cornell Center for Materials Research (CCMR) is focused on undergraduate student/faculty research in organic light emitting diodes (OLEDs). The physics of OLED devices is characterized by three major processes: charge injection, charge transfer, and light emission as a result of the electron-hole recombination. In the first year of the program our research has been related to the first two stages.OLEDs based on small molecule as well as polymeric layers have been investigated. The devices were prepared using mostly aluminum (also nickel and iron) as electrodes and PC:TPD or polythiophene as the organic layer. Electrodes of about 20 nm were formed by vacuum evaporation, and organic layers of approximately 100–200 nm were spin-coated. The current-voltage characteristics, measured under forward and reverse bias up to 10 volts, demonstrate typical semiconductor S-shape behavior, and show variations dependent on aging, thickness of the polymer layer, and type and combination of electrodes.The results presented here specifically track the degradation of devices using polythiophene sandwiched between aluminum electrodes. The I-V curves and successive current response as a function of time and under constant voltage drive are presented along with complementary mass spectra and UV-visible and infrared absorption spectra. These measurements along with preliminary computer modeling of HOMO and LUMO energies for a series of thiophene oligomers suggest a correlation between internal changes in the polymer and variations in the electrical characteristics of the devices.
Nanofiber Formation in Spider Dragline-Silk as Probed by Atomic Force Microscopy and Molecular Pulling
Authors: Oroudjev Emin , Hayashi Cheryl Y. , Soares Jason , Arcidiacono Steven , Fossey Stephen A. , Hansma Helen G. 
Published: April 2011

ABSTRACTDespite the extensive interest in its remarkable materials properties, the structure of spider dragline silk is not yet known. Indirect structural information is thus of particular interest. New data are presented here from two probe microscopy techniques – atomic force microscopy (AFM) and single-molecule force spectroscopy, or ‘molecular pulling.’ Using a soluble synthetic protein from dragline silk, segmented silk nanofibers have been observed by AFM. Molecular pulling (Force Spectroscopy) has revealed sawtooth-like rupture peaks, indicative of the sacrificial bonds and hidden lengths seen in molecules of other self-healing biomaterials. A model is presented for the folding of single dragline-silk molecules and the arrangement of these molecules into nanofibers. The relationship is discussed between these molecular / nanoscale results and the materials properties of natural and artificial dragline silks.
Confocal optoelectronic holography microscope for materials and structural characterization of MEMS
Authors: Furlong Cosme , Siegel Adam M. , Pryputniewicz Ryszard J. 
Published: April 2011

ABSTRACTIn this paper, we describe confocal optoelectronic holography microscopy (COEHM) technique specifically being developed for characterizing the shape of MEMS and microelectronics. This is particularly important because shape is directly related to the functionality, performance, and integrity of the microstructures of interest. A specific feature of COEHM is that it allows characterization of high aspect ratio MEMS and microelectronics. Representative applications demonstrating the capabilities of COEHM are presented. It is shown that measurement resolution is highly dependent on the numerical aperture (NA) of the optical components comprising COEHM and on the quality of image digitization. By utilizing optical components characterized by a magnification factor of 50x and a NA of 0.45, measurement resolution of 25 nm is achieved. The resolution is increased to 8 nm when utilizing optical components characterized by a magnification factor of 100x and a NA of 0.73.
Structure and Electronic Properties of Molecularly-capped Metal Nanoparticles: The effect of Nano-size, Metal Core and Capping Molecule Probed by X-ray Absorption Spectroscopy
Authors: Zhang Peng , Sham Tsun-Kong 
Published: April 2011

ABSTRACTWe have conducted an investigation using TEM, XRD and synchrotron based X-ray absorption fine structure (XAFS) to probe the structural and electronic characteristics of several molecularly capped metal nanoparticles (NPs). Three series of NPs were employed in the XAFS study to address the effect of nano-size, metal-core and capping molecules on the structure and properties of the NPs. They are (1) thiol-capped Au NPs from 1.6nm to 4.0nm, (2) thiol-capped Au and Pd NPs of ∼2nm and (3) Au NPs of ∼4nm capped by thiol and tetraoctylammonium bromide (TOAB). The results on their local structure, bonding and d-charge distribution are presented.
Strain relaxation of strained-Si layers on SiGe-on-insulator (SGOI) structures after mesa isolation
Authors: Usuda Koji , Mizuno Tomohisa , Tezuka Tsutomu , Sugiyama Naoharu , Moriyama Yoshihiko , Nakaharai Shu , Takagi Shin-ichi 
Published: April 2011

ABSTRACTStrained-Si-On-Insulator (Strained-SOI) MOSFETs are one of the most promising device structures for high speed and/or low power CMOS. In realizing strained-Si MOS LSI, fabrication of strained-Si MOSFETs with small sizes are indispensable and thus, the investigation of the strain relaxation is an important issue. Therefore, the strain relaxation of strained-SOI mesa islands with small active area was investigated in this study. Thin strained-Si films were grown on thin relaxed SiGe-on-insulator (SGOI) structures (x=0.28). The isolation process was carried out by using chemical-dry-etching (CDE) to fabricate samples with small active areas. Using Raman spectroscopy with resolution of > 1 micron meter, strained-Si islands on SGOI substrates with the size of 5 micron meter square were investigated. Rapid-thermal-annealing (RTA) in N2 atmosphere was performed to study the strain relaxation during heating processes. As a result, it was confirmed that the strained-Si layers grown on relaxed SiGe (x=0.28) before and after mesa isolation, down to 5 micron meter in size, had almost no relaxation after the RTA process at 1000°C. Furthermore, it was confirmed that the nano-beam electron diffraction (NBD) measurement showed similar tendency regarding the strain relaxation.
Triple-probe Atomic Force Microscope: Measuring a carbon nanotube/DNA MIS-FET
Authors: Shimotani Kei , Watanabe Hiroyuki , Manabe Chikara , Shigematsu Taishi , Shimizu Masaaki 
Published: April 2011

ABSTRACTWe have constructed an advanced electric probing system, which is a triple-probe atomic force microscope (T-AFM). The T-AFM consists of “Nanotweezers” and an AFM with a carbon nanotube probe. Using this system, we fabricated a single-walled carbon nanotubes (SWNTs)/deoxyribonucleic acid (DNA) three-terminal device and measured the current-voltage (I-V) curves of this device. In this three-terminal device, DNA strands were entangled with the SWNT bundle, and behaved as a gate-insulator-layer. This three-terminal device worked as a metal-insulator-semiconductor field effect transistor (MIS-FET) with depletion switching behavior.
The Role of Carbon Contamination in Suspended Gold Nanowires
Authors: Legoas Sergio B. , Galvão Douglas S. , Rodrigues Varlei , Ugarte Daniel 
Published: April 2011

ABSTRACTMetallic nanowires represent very interesting systems due to new phenomena such as quantum conductance and unexpected long interatomic distances attaining 0.3–0.5 nm. These large distances represent a challenge for physical interpretation. In this work we present experimental data from transmission electron microscopy and results from ab initio density functional calculations for suspended gold chains. We show that large distances as 0.5 nm can be easily explained by the presence of carbon atoms as contaminants, while distances ranging from 0.29 up to 0.36 nm might be explained as resulting of a mixture of clean stressed and contaminated linear chains.
Quantitative Morphology of Aluminum Silicate Nanoaggregates
Authors: F Crosta Giovanni , Sung Changmo , Kang Bongwoo , Ospina Carolina , J Stenhouse Peter 
Published: April 2011

ABSTRACTAluminum silicate nanoaggregates grown on organic multilayer templates were imaged by a transmission electron microscope. Images were processed by fractal and FOURIER analysis. The estimated mass fractal dimension suggested that aggregate formation was diffusion limited. Nonlinear filtering of FOURIER spectra, which included comparison with a model spectral density, yielded «enhanced power spectra». Some morphological descriptors were extracted from the latter. The main result, materials classification, was attained by a two-scale procedure. Some descriptors were related to the material properties such as nanoparticle size distribution and sharpness of aggregate boundaries.
Effect of Thermal and Mechanical Treatments on the Cathodoluminescence of Tin and Titanium Oxides
Authors: Maestre D. , Plugaru R. , Cremades A. , Piqueras J. 
Published: April 2011

ABSTRACTThe luminescence of titanium oxide and tin oxide has been investigated by cathodoluminescence in the SEM, as a function of the structural changes induced by thermal treatments. The evolution of the luminescence of TiO2 rutile, anatase and mixture phase with the annealing temperature is related to the process of thermal induced grain texture and to transition of metastables phases to the stable rutile. The emission band is peaked at 480 nm for the composite phase and at 580 nm for anatase and rutile phases respectively. A broad band in the 520–560 nm region is present in the spectra of both anatase and rutile phase. Thermal annealing leads to a red shift of the luminescence emission, with the emission band peaked at around 820 nm. In sintered tin oxide the main emission bands appear centered at about 480 nm and 630 nm. The intensity of these bands increases with annealing temperature up to 1200°, whereas for samples annealed at 1500° these emissions are quenched. Mechanical ball milling has been used to produce nanocrystalline SnO2 grains to investigate the influence of the presence of nanocrystals on the CL emission.
Nanoimpedance Microscopy and Spectroscopy
Authors: Shao Rui , Kalinin Sergei V. , Bonnell Dawn A. 
Published: April 2011

ABSTRACTOne of the key limiting factors in current-based scanning probe microscopies (SPM) is the quality of tip-sample contact and stray capacitance in the probe-surface junction. We conduct impedance spectroscopy over a broad frequency range (40Hz∼110MHz) through an AFM tip to quantify local electrical properties. Equivalent circuit for the tip-surface contact is constructed based on the impedance data and is used to study the mechanisms of relaxation in the near-tip region. Relative contributions of tip-surface contact and materials properties to the signal are discussed. This technique, referred to as Nanoimpedance Microscopy/Spectroscopy, is demonstrated in the imaging of an electronic ceramic: a ZnO varistor. Analysis of impedance spectra allows separation of tip-surface interactions and grain boundary behavior.