bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stress, Microstructure and Temperature Stability of Reactive Sputter Deposited WNx Thin Films
Authors: Leedy K. D. , O'Keefe M. J. , Wilson J. G. , Osterday R. , Grant J. T. 
Published: April 2011

AbstractTungsten nitride (WNx) thin films can be used as Schottky barriers in high power, high temperature semiconductor devices or as diffusion barriers between Cu, low-k dielectric and silicon because each application requires a thermally stable film. Therefore, it is important to understand the thin film properties of WNx as a function of deposition conditions and elevated temperature exposure. In this investigation, the influence of nitrogen content and post deposition annealing on the stress and microstructure of reactive dc magnetron sputter deposited WNx films was analyzed. With an increasing N2 to Ar flow ratio, the as-deposited crystal structure of the films changed from α-W to β-W to amorphous WNx and finally to W2N. Rapid thermal anneals up to 650°C resulted in large tensile stress increases and phase transformations to W2N in the nitrogen-containing films. Grain growth during annealing decreased as the concentration of nitrogen in the film increased. The nitrogen content in the films was determined using x-ray photoelectron spectroscopy (XPS).
Planarization of Copper Damascene Interconnects by Spin-Etch Process: A Chemical Approach
Authors: Mukherjee Shyama P. , Levert Joseph A. , Debear Donald S. 
Published: April 2011

ABSTRACTThe present work describes the process principles of “Spin-Etch Planarization” (SEP), an emerging method of planarization of dual damascene copper interconnects. The process involves a uniform removal of copper and the planarization of surface topography of copper interconnects by dispensing abrasive free etchants to a rotating wafer. The primary process parameters comprise of (a) Physics and chemistry of etchants, and (b) Nature of fluid flow on a spinning wafer. It is evident, that unlike conventional chemical-mechanical planarization, which has a large number of variables due to the presence of pads, normal load, and abrasives, SEP has a smaller number of process parameters and most of them are primary in nature. Based on our preliminary works, we have presented the basic technical parameters that contribute to the process and satisfy the basic requirements of planarization such as (a) Uniformity of removal (b) Removal rate (c) Degree of Planarization (d) Selectivity. The anticipated advantages and some inherent limitations are discussed in the context of process principles. We believe that when fully developed, SEP will be a simple, predictable and controllable process.
The Influence of Clusters on Vapor-Deposited thin Films: Atomistic Simulations
Authors: Torreg J. Dalla , Gilmer G. H. , Baumann F. H. , O'Sullivan P. , Rouhani M. Djafari 
Published: April 2011

AbstractWe investigate the morphology of films produced by cluster deposition using Monte Carlo atomistic simulations. Thin films of aluminum are considered as an example. The deposition of small Al clusters containing up to 5 atoms is simulated. Compared with monomer beams, Al cluster deposition increases the density of 3D islands nucleated on the substrate and tends to equalize the growth rate of the different crystal facets. We discuss the smoothening of the surface when the 3D islands merge. We find that there is an optimal size of the deposited clusters that produces the smoothest film.
Atomic Layer Deposition of TiN on Si (100) and (111) Substrates
Authors: Jeon Hyeongtag , Koo Jae-Hyoung , Lee June-Woo , Kim Young-Seok , Kang K. M. , Kim Yang Do , Kim Young Do 
Published: April 2011

AbstractTitanium nitride (TiN) films were successfully deposited on ρ-type Si (100) and (111) substrates by atomic layer deposition (ALD) method at 450°C. In this ALD system, the TiCl4 and NH3 gases were supplied, separately and Ar purge gas was added between the source and reactant gases to suppress the direct reaction. The main purpose of this study is to investigate the properties of TiN film grown by ALD method. To investigate the growth mechanism, the growth model of TiN was suggested for the calculation of growth rate per cycle with Cerius program. The results of calculation by the model were compared with experimental values of the TiN film deposited by ALD method. TiN films deposited on Si (100) and (111) substrates were examined by TEM and showed the randomly oriented columnar structure. The thickness of TIN film deposited on Si(111) substrate was slightly thicker than that of TiN film deposited on Si(100) substrate. Chlorine content in both TiN films was below the detection limit of AES (<lat%). And the densities of TIN films deposited on Si (100) and (111) substrates were 4.85g/cm3 and 4.98g/cm3. which are higher than that of the films deposited by other conventional CVD methods.
Microstructure and Nanomechanical Properties of Amorphous Carbon Thin Films Prepared by Pulsed Laser Deposition in Various Atmospheres
Authors: Wei Q. , Yamolenko S. , Sankar J. , Sharma A.K. , Yamagata Y. , Narayan J. 
Published: April 2011

AbstractWe have investigated the effect of chamber pressure and atmosphere on the microstructure and nanomechanical properties of amorphous diamondlike carbon (DLC) thin films prepared by pulsed laser deposition. The amorphous carbon films were deposited in various atmospheres such as nitrogen and argon at different pressures. We used Raman spectroscopy and optical microscopy to study the bonding characteristics and microstructures of the DLC films. Nanoindentation measurements were carried out on various samples prepared under different conditions to study the effect of chamber pressure and atmosphere on the elastic modulus and nano-hardness of the films. It was found that reduced vacuum leads to softer amorphous carbon films. Amorphous carbon films prepared in higher pressures exhibit increased density of particulates, and significantly rough surface. The results were understood in terms of thermalization of the laser plasma due to increased possibility of collision.
On the Challenges and Opportunities of Sensing Materials Growth Within Production Deposition Tools
Authors: Bean John C. , Kanakaraju S. , Lau Mark 
Published: April 2011

AbstractScanning probe microscopy has yielded extraordinary advances in our ability to characterize surfaces at the atomic scale. These advances are paralleled by improvements in computational methods and platforms that now yield realistically complex multi-scale models of deposition processes. Combining these developments, it might now be possible to sense the dynamic state of an atomic surface, consulting with models to analyze the path of a deposition process. This real-time information might allow us to tweak the growing materials towards particularly unique and desirable final configurations. What we are largely missing are sensors that can monitor atomic scale evolution without, themselves, compromising the commercial deposition process. In a manufacturing environment, sensors cannot shadow the deposition process or contaminate the material. They cannot add significantly to the complexity of the deposition tool nor require that tool's extensive redesign. Importantly (at least over the long term) the sensors cannot even require us, that is, highly trained (and paid) individuals to operate and interpret their data!
Low Pressure Photo-Assisted Mocvd for the Production of Homogeneous, Low-Strain, Amorphous Titanium Oxide Films
Authors: Haycock P.W. , Lopez M.G. , Auld J. , Bull J.W. , Williams E.W. 
Published: April 2011

AbstractThin films of titania have been grown by photo-assisted MOCVD which are amorphous and relatively strain free, with high refractive index, low optical loss and structural features all less than 100 nm in size. The stoichiometry is very close to TiO2 and the impurity content is negligible except for a small amount of calcium, thought to have been leached from the glass substrate. The optimum deposition conditions were found to involve a deposition temperature of around 200 °C, a cell pressure of 5.6 torr and the introduction of nitrous oxide, decomposed by UV irradiation to give oxygen free radicals which acted as an oxidant.
Recent Progress On The Modeling Of Laser Surface Cleaning
Authors: Lu Y.F. , Song W. D. , Lukyanchuk B.S. , Hong M.H. , Zheng W.Y. 
Published: April 2011

AbstractLaser cleaning has emerged to effectively remove contaminants from solid surfaces. In this paper, recent progress on laser cleaning has been studied. First, a cleaning model is established for removal of particles from substrate surfaces. The model not only explains the influence of fluence on cleaning efficiency, but also predicts the cleaning thresholds. Following that, the optical resonance and near field effect are discussed for transparent particles with a size of α ∼ λ (radiation wavelength) which strongly influences the intensity distribution in the contacted area (substrate surface). The characterization of ejected particles during laser cleaning is finally investigated. It is found that the particle distribution curves closely fit to Gaussian curve.
Surface Morphology Of PZT Thin Films Prepared By Pulsed Laser Deposition
Authors: Yamazato Masaaki , Nagano Masamitsu , Ikegami Tomoaki , Ebihara Kenji 
Published: April 2011

AbstractFerroelectric PbZr0.52Ti0.48O3(PZT)/YBa2 Cu3O7−x(YBCO) heterostructures on MgO substrate were fabricated by KrF pulsed laser deposition. The grid electrode was set between a substrate and target for improvement of surface morphology. The typical PZT layer had excellent ferroelectric properties; remnant polarization of 39 µC/cm2, coercive electric field of 41 kV/cm, loss tan δ=0.04, and dielectric constant of 950. X-ray diffraction results show that the films had highly c-axis and (a, b) plane orientation. The full widths at half-maximum (FWHM) of rocking curves was decreased with increasing the applied voltage of grid electrode. Atomic force microscopy (AFM) images of PZT layer showed that the film morphology was improved by using a grid electrode.
Properties of the magnetoresistive La0.8Sr0.2MnO3 film and integration with PbZr0.52 Ti0.48O3 ferroelectrics
Authors: Mitsugi Fumiaki , Ikegami Tomoaki , Ebihara Kenji , Narayan J. , Grishin A. M. 
Published: April 2011

AbstractThe colossal magnetoresistive La0.8Sr0.2MnO3 (LSMO) thin film was prepared on the MgO (100) single crystal substrate using KrF excimer pulsed laser deposition technique. The LSMO film deposited at the substrate temperature of 850 °C, oxygen pressure of 500 mTorr and laser energy density of 2 J/cm2(5 Hz) showed the resistivity peak temperature (Tp) of 330 K and the magnetoresi stance change of 15 %(H=0.7 T) at the room temperature. The large lattice mismatch with the substrate increased Tp and decreased the resistivity of the LSMO film.The X-ray diffraction measurement for the PbZr0.52Ti0.48O3 (PZT) / LSMO heterostructures indicated both c-axis and in- plane orientation, with the good PZT surface morphology.
Ablation-Induced Stresses in Fused Silica by 157-nm F2-Laser irradiation
Authors: Konovalov Igor A. , Herman Peter R. 
Published: April 2011

AbstractThe F2laser is a promising source for direct etching of microstructures and the precise shaping of optical-grade surfaces on wide bandgap materials such as fused silica. We report here on residual tensile stresses induced in fused silica (Coming 7940, UV grade) by 157-nm laser ablation. Plastic strain of 160-mm thick rectangular strips, monitored with an optical interferometric microscope, revealed the presence of residual tensile stresses in the near-ablated surface. HF chemical thinning of the sample showed the thickness of ablation-affected layer provoking strain was ∼275 nm, a value independent of laser fluence (1.9-4.7 J/cm2) and scanning speed (94 - 220 µm/s). A near-surface mean residual tensile stress of ∼80 MPa was inferred from a thin film-substrate approximation.
Optical Properties Of Tantalum Oxide Films Deposited On BK7 Substrates By Excimer Laser Ablation
Authors: Boughaba S. , Islam M. U. 
Published: April 2011

AbstractThin amorphous films of tantalum oxide were grown on borosilicate crown glass substrates by KrF excimer pulsed laser ablation of a Ta2O5 target, in an oxygen environment. The deposition was performed at a temperature of 250 or 400 °C, while the oxygen pressure was set in the range 5 to 30 mTorr. The optical properties of the tantalum oxide coatings, as evaluated by reflectance/transmittance spectrophotometry, were found to be dependent on the oxygen gas pressure. At a pressure of 5 mTorr, absorbing films were obtained, with extinction coefficients above 10−2 (at λ=633 nm), along with an optical energy band-gap as low as 0.7 eV. At a pressure of 10 mTorr and above, the coatings had refractive indices up to 2.25 (at λ=633 nm), extinction coefficients below 10−4 (for λ>390 nm), and an optical energy band-gap in the range 3.9 to 4.0 eV.
Process Modeling Of The Laser Induced Surface Modification Of Ceramic Substrates For Thermal And Electrical Lines In Microsystems
Authors: Gruhn Herbert , Heidinger Roland , Rohde Magnus , Rüdiger Sabine , Schneider Johannes , Gahr Karl-Heinz Zum 
Published: April 2011

AbstractLaser induced surface modification has been used to fabricate conducting paths in ceramic substrates. For the purpose of process simulation and prediction of process parameters a finite element model has been developed to simulate the thermal behaviour of the substrate during laser surface interaction. The results of the model calculation have been verified experimentally for alumina and Cordierite substrates. Using this model the width and the depth of the fabricated lines could be predicted as a function of the laser power and velocity. The stresses due to thermal mismatch are estimated and identified as the likely reason for crack formation which reduces the functionality of the conducting paths. Further developments will consider different ceramic substrates such as PZT.
Molecular multilayers: structure and templating effects
Authors: Heutz Sandrine , Bayliss Sallie M. , Cloots Rudi , Middleton Ruth L. , Rumbles Garry , Jones Tim S. 
Published: April 2011

ABSTRACTPowder X-Ray diffraction (XRD) has been used to study multilayered structures grown by, organic molecular beam deposition based on the molecular materials PTCDA and metal-free phthalocyanine (H2Pc). Double layers of different polymorphic forms (α, β1 and β2) of H2Pc indicate that the structure of the second layer is determined by the properties of the first layer. It is also shown that the first layer completely disrupts the crystallinity of the second layer in heterostructures containing PTCDA and H2Pc. The implication is that a strong templating effect occurs during the growth of multilayer molecular thin film structures.
Biogenic Inspiration for the Controlled Nucleation and Growth of Inorganic Materials
Authors: Heywood Brigid R , Hill Susan , Pitt Kate , Tibble Paul , Williams Stuart 
Published: April 2011

ABSTRACTThe development of effective protocols for the control of crystal structure, size and morphology attracts considerable interest given the requirement for particles of modal size and shape in many areas of particle processing and the importance of crystallochemical selectivity in determining the exploitable properties of crystalline solids. In biological systems there are many examples of advanced “crystal engineering” in which materials are deposited in a highly controlled manner to produce crystal phases that are unique with respect to their structure, habit, uniformity of size and texture. A review of biomineralisation will show that while a complex array of strategies have evolved for regulating crystal growth, one feature is common to the biological paradigm. Interactions between supramolecular organic structures and the nascent inorganic solids play a fundamental role in controlling the deposition of the biominerals and ordering the assembly of these units into hierarchical structures. In order to gain a better understanding of the molecular recognition events, which take place at the organic-inorganic interface, a bio-inspired crystal chemical approach has been adopted. For this work organised organic assemblies (e.g. surfactant aggregates, peptide mimics, dendrimers) of precise molecular design (head group identity, packing conformation, primary sequence etc.) are being assayed for their effectiveness in controlling the nucleation and growth of crystals. It is evident from these studies that the chemical organisation of the polymeric microenvironment operates at the molecular level to control certain aspects of the nucleation, growth and stabilisation of inorganic particles. By systematically changing the molecular motif of the organic template we have established that the size, crystallographic orientation, growth and assembly of the mineral phase can be tailored to function. These results have relevance not only to our understanding of biomineralisation but also suggest a multiplicity of exploitable opportunities for the engineering of crystals.
Surface Modification of Si Field Emitter Arrays for Vacuum Sealing
Authors: Nagao M. , Tanabe H. , Kobayashi T. , Matsukawa T. , Kanemaru S. , Itoh J. 
Published: April 2011

ABSTRACTVacuum packaging is a very important issue for vacuum microelectronics devices, especially for field emission displays. Emission current from the field emitter array (FEA), however, is known to decrease significantly after the vacuum packaging process. The current decrease is caused by heating treatment in the vacuum sealing process. In the present paper, the effect of the heating treatment on Si FEA was investigated and CHF3 plasma treatment was proposed for avoiding the problem. The Si FEA was exposed to plasma for 15sec and emission characteristics were measured before and after the vacuum sealing process using frit. It was confirmed that CHF3 plasma treatment was very effective for avoiding the emission degradation of the Si FEA. Details of the heating damage and CHF3 plasma treatment are described.
Experiment and Modeling of Conversion of Substrate-Waveguided Modes to Surface-Emitted Light by Substrate Patterning
Authors: Lu Min-Hao M. , Madigan Conor F. , Sturm J. C. 
Published: April 2011

ABSTRACTTo predict the optical power that could be harvested from light emission that is waveguided in the substrate of organic light emitting devices (OLEDs), a quantitative quantum mechanical model of the light emitted into the waveguided modes has been developed. The model was used to compute the exact distribution of energy in external, substrate and ITO/organic modes as a function of the distance of the emission zone from the cathode. The results are compared to the classical ray optics model and to experiments in two-layer OLED devices. Classical ray optics is found to substantially over-predict the light in waveguided modes.
High Voltage Effects in Top Gate Amorphous Silicon Thin Film Transistors
Authors: Tosic N. , Kuper F. G. , Mouthaan T. 
Published: April 2011

ABSTRACTIn this paper, an analysis of the high voltage induced degradation in top gate amorphous silicon Thin Film Transistors (TFT) will be shown, including the aspect of self-heating. It will be shown through experimental results that the degradation level under high voltages on drain and gate is different for TFT's with different channel lengths. In addition, the temperature distribution over the TFT area for devices with different channel length is simulated. Simulation shows that the peak of temperature distribution is located at the drain/channel edge and that level of thermal heating depends on the channel length.
Nd:YVO4 Laser Crystallization for Thin Film Transistors with a High Mobility
Authors: Dassow Ralf , Köhler Jürgen R. , Nerding Melanie , Strunk Horst P. , Helen Youri , Mourgues Karine , Bonnaud Olivier , Mohammed-Brahim Tayeb , Werner Jürgen H. 
Published: April 2011

ABSTRACTWe crystallize amorphous silicon films with a frequency doubled Nd:YVO4 laser operating at a repetition frequency of up to 50 kHz. A sequential lateral solidification process yields polycrystalline silicon with grains longer than 100 μm and a width between 0.27 and 1.7 μm depending on film thickness and laser repetition frequency. The average grain size is constant over the whole crystallized area of 25 cm2. Thin film transistors with n- type and p-type channels fabricated from the polycrystalline films have average field effect mobilities of μn = 467 cm2/Vs and μp = 217 cm2/Vs respectively. As a result of the homogeneous grain size distribution, the standard deviation of the mobility is only 5%.
13C NMR study of functionalized nanotubes
Authors: Goze-Bac C. , Holzinger M. , Jourdain V. , Latil S. , Aznar R. , Bernier P. , Hirsch A. 
Published: April 2011

Abstract13C nuclear magnetic resonance on functionalized single wall carbon nanoutubes is reported. We present a possible chemical modification of the nanotube in order to get soluble materials. NMR is used in order to study in details the chemical changes and their reversiblities. In particular, acid groups, inequivalent sp2 and sp3 carbons attributed to functionalized nanotubes are identified and characterized.
1D P-Block Halide Crystals Confined into Single Walled Carbon Nanotubes
Authors: Flahaut E. , Sloan J. , Coleman K.S. , Williams V.C. , Friedrichs S. , Hanson N. , Green M.L.H. 
Published: April 2011

AbstractThe synthesis and characterisation of one-dimensional (1D) crystals that have a well-specified chemistry, size and crystal structure have presented a formidable challenge for materials chemistry and analysis. We report here the filling of single (SWNTs) and double walled carbon nanotubes (DWNTs) by two different p-block halides, TlCl and PbI2. The nanotubes were produced either by the arc synthesis [1] or by a CVD method [2], based on the reduction of a Mg0.9Co0.1O solid solution by a hydrogen-methane mixture. In the case of TlCl, the structure of the crystals observed inside the tubes were all found to be derived from the rocksalt form and bilayer crystals were observed which exhibited reduced coordination relative to the fcc structure, as determined from high resolution transmission electron microscopy (HRTEM). In contrast, the crystal structure of bulk TlCl is a CsCl type structure. These results are consistent with the recently reported reduced coordination KI crystals formed within SWNTs [3]. In the case of PbI2 (i.e. with the CdCl2 structure), the use of HRTEM images combined with image simulations was used to confirm the partially reduced coordination of Pb atoms within the SWNT and DWNT confined 1D crystals.
Bromine Doped Single-walled Carbon Nanotubes
Authors: Liu Bingbing , Carlsten Jan , Sundqvist Bertil 
Published: April 2011

AbstractRaman spectra for three SWNT samples doped with Br2 were studied using different excitation energies, 2.41 eV and 1.58 eV. One sample was also studied under high pressure up to 2 GPa. The vibrations in the low frequency range behave similarly for all samples. With an excitation energy of 1.58 eV, additional peaks at ca 240 cm−1 and 209 cm−1 are observed. With increasing pressure, the peak at 209 cm−1 gradually softens by 2∼3 cm−1 and becomes very weak at 1.7 GPa, while a new broader peak at ca 250 cm−1 remains constant up to 2 GPa. A number of high intensity overtone modes are observed under high pressure. These results indicate that the vibrations are attributed to bromine, not to the breathing modes of SWNTs, and that bromine resides in the bundles, possibly also inside tubes as a form of polymer.