bluuebunny/crossref_metadata_2025_split huggingface dataset:
Growth and Metrology of Silicon Oxides on Silicon Carbide
Authors: Hoff Andrew M. 
Published: April 2011

AbstractThermal oxidation of SiC by the afterglow method has opened new pathways of opportunity to address both thin film growth and defects that hinder electronic device development with this important semiconductor material. Oxide growth, with rates up to 700Å per hour, on SiC has been demonstrated using this technique over a temperature range from 400°C to 1100°C at 1 Torr total pressure. Electrical and physical properties of oxide films grown by conventional means or by the afterglow method were obtained with a novel, non-contact charge-voltage (Q-V) metrology approach. This instrument employs a combination of incremental contact potential difference values obtained in response to applied corona charge generated from air. The slope of the Q-V characteristic within a bias range corresponding to accumulation of the semiconductor provides an effective dielectric permittivity value for the grown film. Effective permittivity values for afterglow oxides grown on SiC approach that of SiO2 grown on silicon substrates whereas the values for oxides grown on SiC in an atmospheric steam oxidation process are always depressed relative to SiO2 on silicon, indicating that the latter process always produces low-k oxides. A mechanistic discussion regarding these observed differences between the two oxidation methods is presented along with suggestions for an integrated process and metrology approach to reduce defects in oxide films on SiC.
Effect of Hydrogen Peroxide on Oxidation of Copper in CMP Slurries Containing Glycine and Cu Sulfate
Authors: Du Tianbao , Vijayakumar Arun , Desai Vimal 
Published: April 2011

AbstractThis study compares the oxidative dissolution, passivation, and polishing behavior of copper chemical mechanical polishing in the presence of hydrogen peroxide, glycine and copper sulfate. High purity discs were used to study the dissolution and oxidation kinetics under static and dynamic conditions at pH 4 with varying H2O2 concentrations. Changes in surface chemistry of the statically etched copper-disc were investigated using X-ray photoelectron spectroscopy (XPS). With the addition of glycine and copper sulfate to the slurry, the copper removal rates increased significantly and the maximum removal rate shifted to a H2O2 concentration of 3%. Electrochemical investigation indicates an enhanced dissolution of copper, which might be due to the strong catalytic activity of Cu(II)-glycine complexes in decomposing H2O2 to yield hydroxyl radicals. XPS results suggest that the passivation at higher H2O2 concentrations in the presence of glycine and copper sulfate is provided by the OH radicals adsorbed on Cu surface.
In-Situ Friction and Pad Topography Measurements During CMP
Authors: Gray Caprice , Apone Daniel , Barns Chris , Monsour Moinpour , +Anjur' Sriram , Manno Vincent , Rogers Chris 
Published: April 2011

AbstractDuel Emission Laser Induced Fluorescence (DELIF) and friction measurements are taken in-situ during CMP to observe slurry flow beneath a model of an integrated circuit (IC) wafer. Friction measurements average around 7.5 lb and multiple frequencies are observed. Slurry film thicknesses on the order of a 10±3μm were observed during CMP of a flat wafer. The film thickness seems uncorrelated to friction measurements except when the pad and wafer rotation speeds are significantly slowed. DELIF has also accurately measured a 9μm etched step, with noise in the image equal to ±3 μm.
Influence of Electrochemical Plating Process Parameters on Corrosion of Cu Damascene Interconnects
Authors: Ernur D. , Wu W. , Brongersma S. H. , Terzieva V. , Maex K. 
Published: April 2011

AbstractWe present the influence of the electrochemical plating recipe and the bath chemistry on Cu grain size evolution and its link to corrosion of Cu interconnects. Our results demonstrate the fact that Cu corrosion depends on the combination of (i) solution type and (ii) Cu quality. The latter is influenced by geometrical factors such as line width and pattern density as well as the electroplating parameters such as plating recipe and bath chemistry. Organic and inorganic acid based model-CMP solutions are used to make a comparison in terms of the interactions with the Cu surface. It is shown that an organic acid based solution etches Cu independent of the Cu quality. However, etching by an inorganic acid based solution reveals line width (0.2 μm <w<1.0 μm) and pattern density dependence (16%< pd< 72 %) with the narrow lines being etched more rapidly both for isolated and semi-dense structures. This kind of geometry dependent etch behavior by the inorganic acid based solution is also shown to be a function of the electroplating process parameters in contrast to an organic acid based one.
Analysis of Nanotopography in Silicon Generated by the Polishing Process
Authors: Isogai Hiromichi , Kojima Katsuyoshi 
Published: April 2011

AbstractThis paper describes a new model, which analyzes the effects of the polishing conditions on nanotopography after polishing silicon (Si) substrates. The thickness uniformity of dielectric oxide-films after Chemical Mechanical Polishing (CMP) is affected by nanotopography of the Si substrate. Therefore, reducing nanotopography in Si substrates is essential in order to obtain highly uniform dielectric film thickness after CMP. We have developed a model based on Preston's equation for estimating the change in nanotopography of Si substrates due to polishing. In this model, various conditions relating to the structure of the polishing apparatus, the polishing pad material and the motion of the substrate can be taken into consideration. To investigate the influence of the polishing conditions on nanotopography, we compared experimental polishing results with calculations using this model. Thus, it was clarified that the generation of nanotopography in the polishing process that determines the final shape of the substrate, depends on the history of the pressure and contact distance produced during the process.
Investigation and Control of Chemical and Surface Chemical Effects During Dielectric CMP
Authors: Abiade J. T. , Choi W. , Khosla V. , Singh R. K. 
Published: April 2011

AbstractDue to the ever-increasing popularity of STI in microelectronic device fabrication, designer slurries must be tailored to meet increasingly stringent planarity requirements. Although dielectric polishing is primarily mechanical in nature, the chemical and surface chemical effects can be tailored to enhance selectivity and planarity. Examples of chemical and surface chemical effects in dielectric CMP include; control of slurry pH, use of reactive particles such as cerium dioxide, and addition of surfactants to modulate the particle-substrate interactions. Cerium dioxide particles are utilized due to an increase in substrate dissolution through particle-substrate bonding, which accelerates the material removal of the dielectric surface. The increased efficiency of reactive particles is largely dependent on the area of contact between particle and substrate during polishing. The chemical nature of the interaction between the particles and silica substrates has been investigated using polishing experiments, AFM, and an in-situ friction force apparatus. Both the pH and cerium dioxide particles have been found to significantly affect the near surface region of the oxide film.
Hydrothermal Synthesis of Ce3+ and Tb3+ co-doped Ca3Al2(OH)12 Luminescent Material
Authors: Wen Fushan , Chen Jiesheng , Kim Jin Hyeok , Kim Taeun , Li Wenlian 
Published: April 2011

AbstractCe3+ and Tb3+co-doped calcium aluminates luminescent material (Ca3Al2(OH)12: Ce3+, Tb3+) was synthesized at 453 K in hydrothermal system without any protective atmospheres. All the reactants used in the system were simple inorganic salts. The crystallinity and luminescent property of as-synthesized compound were investigated using X-ray diffraction and luminescence spectrometer. The compound formula was confirmed to be Ca3Al2(OH)12. The emission spectrum showed that only typical Tb3+ emission was observed and the emission from Ce3+ was almost not observed, which should be attributed to the energy transfer from Ce3+ to Tb3+ in the compound. The emission peaks at about 486 nm, 498 nm, 540 nm, 549 nm, 582 nm, 595 nm and 623 nm should be assigned to 5D4-7F6, 5D4-7F5, 5D4-7F4, and 5D4-7F3 transitions of Tb3+ ions. The weak emission peak at about 380 nm should be assigned to the emission of Ce3+ ions in the compound.
Fabrication of Photonic Crystals in Microchannels
Authors: Kuo Chun-Wen , Hsieh Hui-Mei , Ting Jung-Chuan , Cho Yi-Hong , Wei Kung Hwa , Chen Peilin 
Published: April 2011

AbstractWe have developed a fabrication procedure for growing photonic crystals in the lithographic defined microchannels, which enables easy integration with other planar optical components. This technique is based on the directed evaporation induced self-assembly of nanoparticles in the microchannels. Substrates with pre-patterned microchannels (30-100 μm wide) were dipped into solution of nanoparticles for several days. By controlling the evaporation rate, the meniscus contacting the microchannels will undergo evaporation-induced self-assembly. The capillary forces cause nanospheres to crystallize within the microchannels forming colloidal photonic crystals in the microchannels. Two types of colloidal particles, polystyrene and silica, have been employed to fabricate colloidal photonic crystals in the microchannels. Both types of colloidal particles were found to form large-area well-ordered colloidal single crystals in the microchannels. The optical reflection spectra from the (111) surfaces of the colloidal crystals formed by various sizes of nanoparticles have been measured. And the measured reflection peaks agree with the photonic bandgap calculated by the plane wave expansion method.
Template-Assisted Growth of Nanowires Using Novel Nanoporous Films Fabricated by Inorganic Nano Phase Separation
Authors: Fukutani Kazuhiko , Motoi Taiko , Den Tohru 
Published: April 2011

AbstractUltrahigh pore density nanoporous films with a pore diameter of less than 10nm and a pore density exceeding 1016 pores/m2 were developed. Nano phase separation of a eutectic Al-Si system was used for the fabrication of these nanoporous films. Co-sputtered AlSi films form Al nano-cylinders, perpendicular to the substrate and parallel to each other, embedded in an amorphous Si matrix during film growth due to phase separation. Removal of the Al nano-cylinders from the co-sputtered AlSi films by chemical etching gives us ultrahigh pore density nanoporous films. The nanoporous films consist of mainly oxidized silicon. Depending on the film compositions and the film preparation conditions, such as RF power and the deposition temperature, the average pore diameter can be varied systematically from less than 5nm to 13nm with the pore density from 1015 to exceeding 1016 pores/m2. Furthermore we have demonstrated a template-assisted growth of ultrahigh-density Ni nanowire arrays with an aspect ratio of ∼100 in the nanoporous films by electrodeposition. The fabrication method for nanowire arrays using the nanoporous films is quite simple and promising for the fabrication of nanostructured devices.
Simple Fabrication of High Density Quantum Dot Arrays Using Anodic Aluminum Oxide Mask
Authors: Sung Joon-Ho , Moon Heesung , Bahng Jae Ho , Koo Ja-Yong , Kim Bongsoo 
Published: April 2011

AbstractWe fabricated quantum dot arrays using anodic alumina mask. We grew an alumina template on Si wafers by two-step anodization. The porous alumina template thus grown is used as a mask for metal deposition. After thermal evaporation and removal of the mask, we fabricated the quantum dot arrarys on a Si substrate. Using this template-assisted method we obtained a high density array of quantum dots in a large scale. These quantum dots have a narrow size distribution which can be easily controlled by a pore widening of templates from 20 to 60 nm.
Surface Oriented Self-Assembly of Carbon Nanotubes
Authors: Sivakumar Kousik , Panchapakesan Balaji 
Published: April 2011

AbstractIn this paper, we demonstrate the self assembled growth of nanotubes along the surface of (100), (110) and (111) silicon wafers using thermal CVD. Iron nanoparticles, 10 nm in diameter, were used as the catalyst. Carbon nanotubes were grown in a methane atmosphere at 1000°C. SEM and AFM characterization revealed single wall carbon nanotubes, about 10 nm in diameter and up to 10 νm in length, growing along the <111> direction of the silicon wafer. The mechanism of growth of nanotubes is similar to that of molecular epitaxy which occurs due to the lattice matching of the silicon and iron crystal lattices forming self aligned silicides at high temperature which help orient the nanotubes. This process may enable the integration of nanotubes with CMOS processing technology.
Analysis of the Three-Dimensional Nanoscale Relationship of Ge Quantum Dots in a Si Matrix Using Focused Ion Beam Tomography.
Authors: Kubis Alan J. , Vandervelde Thomas E. , Bean John C. , Dunn Derren N. , Hull Robert 
Published: April 2011

AbstractIt is well documented that buried layers in quantum dot (QD) superlattices influence the position of quantum dots in the subsequently grown layers through strain field interactions (e.g.1,2, 3,4). Using the Focused Ion Beam (FIB) tomographic technique we have reconstructed the 3D relationship of successive layers of coherent Ge QDs separated by epitaxial Si capping layers - a “QD superlattice”.Techniques such as Atomic Force Microscopy (AFM) and Scanning Tunneling Microscopy (STM) can only look at a single surface layer of QDs or, in the case of Transmission Electron Microscopy (TEM), look at a two-dimensional projection of a three-dimensional volume so that 3D relationships need to be inferred. Since the strain interactions are complex, an enhanced fundamental understanding of these self-organization mechanisms can more directly be obtained from full 3D reconstructions of these structures.By capping with Si at 300°C we were able to grow QD superlattices with QDs tens of nanometers in height. This places them within the resolution of the FIB tomographic technique to reconstruct. Using the FIB we performed in-situ serial sectioning of the QD superlattice and then reconstructed the QD superlattice. The reconstruction was then analyzed to investigate the ordering of the QDs.Results from a reconstruction of a superlattice matrix will be presented with analysis of the self-ordering of the QDs. Observations of a novel self-limiting (in height) morphology, the quantum mesa, associated with the capping technique used will also be discussed.
Templated Formation of Ordered Metallic Nano-Particle Arrays
Authors: Giermann Amanda L. , Thompson Carl V. , Smith Henry I. 
Published: April 2011

AbstractWe have used interference lithography to create surfaces with di-periodic topography with periods less than 400 nm and formed gold particle arrays on these substrates through the dewetting of thin solid films. Under appropriate conditions, we have found that dewetting of gold films on di-periodic arrays of {111} bound pits in silicon leads to periodic square arrays of particles with very narrow size distributions. In addition, we find that topography can significantly reduce the diameter of particles formed by the dewetting process. We present a mechanism for this self-organization process based on modulation of the local curvature of a conformal film on topography.
Biotemplate Synthesis of Ag Nanoparticles and Nanowires
Authors: Behrens S. , Unger E. , Wu J. , Habicht W. , Dinjus E. 
Published: April 2011

AbstractWe address the template-directed deposition of metals on microtubule supports for generating metal nanostructures with different morphologies. Microtubules are highly ordered protein assemblies of tubular structure with a high aspect ratio. In this approach, the biostructure serves as a functionalised scaffold where the metal is generated in situ and shaped into a nanostructure with its morphology complementary to that of the biotemplate. When the biotemplate is coupled to an appropriate chemical reaction, different Ag / protein structures are produced, ranging from microtubules densely covered by small Ag nanoparticles to continuous Ag nanowires.
Preparation and Characterization of Tin Oxide Nanowires for Gas Sensing
Authors: Zhang Daihua , Liu Zuqin , Li Chao , Zhou Chongwu 
Published: April 2011

AbstractEfficient and reliable laser-ablation approaches for large-scale synthesis of SnO2 nanowires are reported. Transmission electron microscopy (TEM) and x-ray diffraction (XRD) were used to confirm the crystal structure of the nanowires. The results show that these nanowires had uniform diameters around 20 nm and lengths in the order of 10 νm. In addition, field effect transistors have been constructed based on individual SnO2 nanowires. Excellent n-type transistor characteristics have been observed for SnO2 nanowire transistors. Detailed analysis revealed threshold voltages ∼ -50V with on/off ratios as high as 103 at room temperature. These nanowire transistors were further demonstrated to work as sensitive UV detectors and gas sensors.
The Strain-Assisted Nucleation and Growth Behavior of Co Islands: An Indirect Study of Nanopatterning Using the Remanent Magnetization Measurement (Δm)
Authors: Lee Yong-Won , Clemens Bruce M. 
Published: April 2011

AbstractNanopatterning through strain-assisted nucleation of metal adatom islands is experimentally studied using a magnetic remanence or Δm measurement. The strain field is generated by a square array of interfacial misfit dislocations with a spacing of 4.1 nm due to the lattice mismatch of the epitaxial Pt(002) film on MgO(002) substrates. The intensity of strain is controlled by changing the thickness of the Pt underlayer ranging from 2.0 to 10.0 nm. The amount of exchange coupling among the Co grains grown on Pt template is measured using the μm technique as an indirect indicator of magnetic grain distribution. From the measured μm values, the morphology of adatom islands is indirectly deduced. The Co islands on a 5.0 nm thick Pt underlayer show the overall negative behavior of Δm curve, i.e., the strongest nanopatterning effect. Strain driven nucleation is found to be achievable through a narrow selection of experimental growth conditions.
Covalent immobilization of DNA and hybridization on microchips by microsecond electric field pulses
Authors: Fixe F. , Branz H.M. , Prazeres D.M.F. , Chu V. , Conde J.P. 
Published: April 2011

AbstractSingle square voltage pulses were used to enhance by 7 and 9 orders of magnitude the rate of covalent immobilization and hybridization, respectively, of single stranded DNA probes on a chemically functionalized thin film surface (silicon dioxide) using 2 mm size electrodes. These electrodes were scaled down to 20 μm. Photolithography was used to define the electrode voltage line, ground line, and functionalized thin-film area on a plastic substrate (polyimide). At all electrode dimensions, electric field-assisted DNA immobilization and hybridization can be achieved in the microsecond time scale, far faster than the 2 hr or 16 hr needed for immobilization and hybridization, respectively, without the electric field. Pulse conditions optimized with the large-size electrodes (2 mm) were used in the microelectrodes.
Characterization of Alumina and Silica Sol-Gel Encapsulated Fe/Co/Ru Nanocatalysts in Microchannel Reactors for F-T Synthesis of Higher Alkanes
Authors: Kuila D. , Nagineni V.S. , Zhao S. , Indukuri H. , Liang Y. , Potluri A. , Siriwardane U. , Seetala N. , Fang J. 
Published: April 2011

AbstractWe have been investigating conversion of syngas (CO: H2) to higher alkanes [Fischer-Tropsch (F-T) Process] in 5 μm and 25 μm channel microreactors coated with sol-gel encapsulated Fe/Co-nanocatalysts. These nano-metal-catalysts were incorporated into the sol-gel matrix by two methods: 1) metal nitrate solutions; 2) metal oxide nanoparticles. Characterization of these catalysts containing Co and Fe in alumina and silica sol-gel has been carried out by several techniques. The surface area measurements by BET method show an average specific surface area of 285 m2/g for alumina and 300 m2/g for silica sol-gel encapsulated catalysts. In order to optimize the sol-gel preparation and deposition in the microchannels, the elemental composition of sol-gel encapsulated catalyst was examined by EDX. The SEM and AFM images of the reactors before and after deposition of the catalysts have also been studied. Hydrogenation-reduction efficiency of the activated Fe-Co catalysts and the level of poisoning after the reaction were estimated using a vibrating sample magnetometer (VSM). The result suggests more efficient reduction in the case of the nano-particle metal oxides compared to that derived from metal nitrate solutions. In overall, 85% of the catalyst is poisoned after 25 hrs of catalytic reaction. The surface area and the syngas conversion results indicate that silica sol-gel matrix may be a better catalyst support. For alumina sol-gel support, higher conversion of syn-gas is observed with 25 μm microreactor channels. For silica sol-gel, syngas conversion as high as 73% has been achieved by adding Ru as a promoter to the Fe/Co catalyst mixture.
Photophysical Properties of CdS Nanoparticles in Thin Films for Opto-Chemical Sensing
Authors: Guliants Elena A. , Haruff Barbara A. , Gord James R. , Bunker Christopher E. 
Published: April 2011

AbstractIn recent years, II-VI compound semiconductor nanoparticles synthesized in a liquid solution have been shown to possess unique optoelectronic properties which are highly attractive for the fabrication of various sensors based on the optical signal readout scheme. The challenge has been to immobilize these nanoparticles into films on solid surfaces, i.e. on a chip, so that they do not suffer any property deterioration as a sensing medium. In the presented work, synthesis of CdS nanoparticles in reverse micelle solution using AOT surfactant as a stabilizer has led to particles with relatively bright photoemission identified as originating from both shallow and deep traps inside the bandgap. Moreover, slightly altering the preparation procedure has produced samples with two distinctive crystal structures. Both types of CdS nanoparticles suspended in commonly utilized solvents such as chloroform and hexane were subject to chemical quenching when various organic compounds were introduced into the solution, demonstrating the sensitivity of trap states to their chemical environment. However, the two structures have shown very different optical properties. While post-synthesis treatment had no effect on one type of particle, the other type was able to undergo a photochemical reaction via prolonged UV irradiation, which resulted in an increased luminescence quantum yield ÖL from 2% to 14%. The same particle type was also responsive to thermal treatment, showing even higher values of ÖL (∼40%). The CdS/AOT particles have been cast into thin films by spin-coating on a Si wafer. Coating parameters have been investigated in order to achieve optimal control over the film thickness, uniformity, overall film durability, etc. These nanostructured films capped with various porous polymeric and sol-gel protective coatings were exposed to a series of organic compounds. Photoluminescence data collected for these samples served for identification of the compounds and their concentrations. This paper offers the discussion of photophysical response in CdS nanoparticle-based thin films with respect to development of novel nanostructured opto-chemical sensors.