bluuebunny/crossref_metadata_2025_split huggingface dataset:
Power and Radio Frequency Inductors Using a Hybrid Ferrite-Flex Foil Technology
Authors: Gijs Martin , Saidani Menouer 
Published: April 2011

AbstractWe present a hybrid technology for the realization of three-dimensional miniaturized power inductors and RF inductors on silicon. The power inductors consist of planar Cu coils on polyimide substrates, and mm-size ferrite magnetic cores, obtained by three-dimensional micro-patterning of ferrite wafers using powder blasting. The coils are realized using an in-house developed high-resolution polyimide spinning and Cu electroplating process. Winding widths down to 5 μm have been obtained and total device volumes are ranging between 1.5 and 10 mm3. Inductive and resistive properties are characterized as a function of frequency; inductance values in the 100 μH range have been obtained. We also have realized millimetre-size RF inductors on silicon using the same polyimide mould - Cu electroplating coil technology. Subsequently the coils are assembled with magnetic cover plates of commercially available bulk Ni-Zn ferrites of high resistivity. Using the magnetic flux-amplifying ferrite plates, we obtain a 40 % enhancement of the inductance and a 25 % enhancement of the quality factor (Q=10-20) for frequencies up to 0.2 GHz.
Towards the Integration of Barium Ferrite Sputtered Films for Coplanar Isolators and Circulators in the Millimeter Wave Range
Authors: Dehlinger A.-S. , Le Berre M. , Chatelon J.-P. , Benevent E. , Vincent D. , Givord D. , Larrey V. , Rousseau J.J. 
Published: April 2011

AbstractSignal processing in communication, instrumentation and radar detection requires low cost microwave and millimeter wave devices. The integration of millimeter wave passive components like isolators and circulators is thus a major issue. In these components, the nonreciprocal nature of wave propagation in ferrites plays an essential role. Hexagonal ferrites, such as barium ferrite (BaFe12O19 or BaM), which has a large resistivity and high permeability at high frequency, are of great interest for such applications. The present work deals with the characterization of barium hexaferrite sputtered films and with the device integration for the development of coplanar isolators and circulators working at frequencies around 40 GHz.The BaM films (in the thickness range of 10μm) were deposited on alumina substrate by RF magnetron sputtering at room temperature and were then crystallized using a 800°C thermal annealing. Structural properties were evaluated by X-ray diffraction and the magnetostatic properties of the film were determined using a Vibrating Sample Magnetometer (VSM) leading to assess a range of deposition conditions appropriate for device integration.Both coplanar isolators and circulators were implemented using standard lift-off technique. Coplanar circulators were designed by analytical calculation and 3D electromagnetic simulation (HFSS) supposing a saturated material and no losses. The microwave range characterization was performed using a network analyzer and a probing system with a prior OSTL calibration. The coplanar isolators were characterized both at the remanence and under a polarizing field. At the remanence, the gyroresonance occurred at 50 GHz and the nonreciprocal effect - difference between the transmission coefficient in the forward direction and in the reverse direction - was evaluated. When applying a polarizing field, the tunability of the isolator was verified experimentally. Finally first measurements on integrated coplanar circulators are currently under progress.
Development of 3D-Packaging Process Technology for Stacked Memory Chips
Authors: Mitsuhashi Toshiro , Egawa Yoshimi , Kato Osamu , Saeki Yoshihiro , Kikuchi Hidekazu , Uchiyama Shiro , Shibata Kayoko , Yamada Junji , Ishino Masakazu , Ikeda Hiroaki , Takahashi Nobuaki , Kurita Yoichiro , Komuro Masahiro , Matsui Satoshi , Kawano Masaya 
Published: April 2011

ABSTRACTA 3D packaging technology for 4 Gbit DRAM has been developed. It is targeting to realize 4Gb density DRAM by stacking 8-DRAM chips into one package. Interconnect between stacked chips will be done by through-silicon-via for the requirement of 3Gbps operation. Key process technologies for chip stacking are through-silicon-via formation, wafer back side process and micro-bump bonding. These chip-stacking processes have been developing using TEG, which can evaluate electrical characteristics.
High-Performance Temporary Adhesives for Wafer Bonding Applications
Authors: Puligadda Rama , Pillalamarri Sunil , Hong Wenbin , Brubaker Chad , Wimplinger Markus , Pargfrieder Stefan 
Published: April 2011

ABSTRACTMyriad structures for stacking chips, power devices, smart cards, and thin substrates for processors have one thing in common: thin silicon. Wafer thinning will soon be an essential process step for most of the devices fabricated and packaged henceforth. The key driving forces for thinned wafers are improved heat dissipation, three-dimensional stacking, reduced electrical resistance, and substrate flexibility. Handling of thin and ultrathin substrates however is not trivial because of their fragility and tendency to warp and fold. The thinned substrates need to be supported during the backside grinding process and through the subsequent processes such as lithography, deposition, etc. Using temporary adhesives to attach the processed device wafer to a rigid carrier wafer offers an efficient solution. The key requirements for such materials are ease of application, coating uniformity with minimal thickness variation across the wafer, good adhesion to a wide variety of surfaces, thermal stability in processes such as dielectric deposition and metallization, and ease of removal to allow high throughput. An additional requirement for these materials is stability in harsh chemical environments posed by processes such as etching and electroplating. Currently available materials meet only a subset of these requirements. None of them meet the requirement of high-temperature stability combined with ease of removal. We have developed adhesives that meet a wide range of post-thinning operating temperatures. Additionally, the materials are soluble in industry-accepted safe solvents and can be spin-applied to required thicknesses and uniformity. Above all, the coatings can be removed easily without leaving any residue. This paper reports on the development of a wide range of temporary adhesives that can be used in wafer thinning applications while applying both novel and conventional bonding and debonding methods.
Materials Aspects to Consider in the Fabrication of Through-Silicon Vias
Authors: Burkett Susan , Schaper L. , Rowbotham T. , Patel J. , Lam T. , Abhulimen I. U. , Boyt D. D. , Gordon M. , Cai L. 
Published: April 2011

ABSTRACTThe formation of vertical interconnects to create three-dimensional (3D) interconnects enables integration of dissimilar electronic material technologies. These vertical interconnects are metal filled blind vias etched in silicon and are formed by a series of processing steps that include: silicon etch; insulation/barrier/seed layer deposition; electroplating of Cu to fill the via; wafer grinding and thinning; and back side processing to form contacts. Deep reactive ion etching (DRIE) is used to etch silicon vias with attention given to process parameters that affect sidewall angle, sidewall roughness, and lateral etch growth at the top of the via. After etching, vias are insulated by depositing 0.5 μm of silicon dioxide by plasma enhanced chemical vapor deposition (PECVD) at 325°C. A barrier film of TaN is reactively sputtered after insulation deposition followed by a Cu sputtered seed film allowing electroplated Cu to fill the blind via. Reverse pulse plating is used to achieve bottom-up filling of the via. Once void-free electroplated vias are prepared, the process wafer is attached to a carrier wafer for silicon back grinding. Vias on the process wafer are “exposed” from the back side of the wafer with a combination of processes that include mechanical grinding, polishing, and reactive ion etching (RIE). Contact pads are then formed by conventional IC processes. Cu posts are used to connect the electronic devices and to address thermal management issues as well. This paper presents materials aspects to consider when fabricating through silicon vias (TSVs). Modeling of the Cu-filled vias to investigate thermal management schemes and Cu posts to investigate mechanical reliability is also presented.
Tailoring of Metal Borohydrides for Hydrogen Storage Applications
Authors: Nakamori Yuko , Miwa Kazutoshi , Li Hai Wen , Ohba Nobuko , Towata Shin-ichi , Orimo Shin-ichi 
Published: April 2011

ABSTRACTRecent investigations on thermodynamical stabilities of metal borohydrides were reviewed. The first-principles calculations indicated that the heat of formation normalized by the number of BH4 complexs, ΔHboro, show a good correlation with the Pauling electronegativitiese of M, χp, which is represented by the liner relation, ΔHboro = 252.8χp − 396.4 in the unit of kJ/mol BH4. In order to clarify the correlation between the stability of borohydrides and the electronegativity χp of M, M(BH4)n (M = Mg, Ca, Sc, Ti, V, Cr, Mn, Zn, Zr and Al; n = 2-4) were systematically synthesized by mechanical milling. The thermal desorption analyses indicated that Td correlate with χ p of M; Td decrease with increasing the values of χp, in M(BH4)n. Furthermore, the correlation can be reasonably extended to double cation ones, (ZrLin-4)(BH4)n. For single cation, M(BH4)n (M = Mn, Zn and Al; χp ≥ 1.5) desorb borane besides hydrogen, and M(BH4)n (M = Ti, V and Cr; χp ≥ 1.5) desorbe small amount of hydrogen provably due to desorption reaction during milling. Therefore χp is an indicator to approximately estimate the stability of M(BH4)n, and appropriateχp in M(BH4)n is expected to be smaller than 1.5. The enthalpy change for the desorption reaction, ΔHdes, is estimated using our predicted ΔHboro and the reported data for decomposition product, ΔHhyd/borideboro, which shows a good correlation with the observed Td. These results are useful for exploring M(BH4)n with appropriate stability for hydrogen storage applications
Molecular Simulation Study on Catenation Effects on Hydrogen Uptake Capacity of MOFs
Authors: Jung Dong Hyun , Lee Tae Bum , Kim Daejin , Park Kangsung , Kim Jaheon , Choi Seung-Hoon 
Published: April 2011

ABSTRACTIn order to investigate the reason for the higher capacity of the interpenetrating isoreticular metal-organic frameworks (IRMOFs) at lower temperatures, we performed grand canonical Monte Carlo (GCMC) simulations and molecular dynamics simulations at 77 K for a set of the interpenetrating IRMOF-11 and the non-interpenetrating counterpart IRMOF-12. From the GCMC simulations, we found universal force field (UFF) is better for describing the hydrogen adsorption behavior than DREIDING force field. The results from the molecular dynamics simulations showed the density of adsorbed hydrogen molecules was increased in the various pores created by the catenation of IRMOF comparing to that of the pores in IRMOF-12. Moreover, the adsorbed hydrogen molecules in IRMOF-11 have the smaller diffusion coefficients. It means that their dynamic behavior is more restricted because of the complexity of the interpenetrating network of IRMOF-11. These results of molecular simulations show the small pores created by the catenation are important for the increase of hydrogen adsorption on IRMOF-11 at lower temperatures.
Carbon Membranes: A Viable Technology for the Recovery and Purification of Hydrogen Gas
Authors: Merritt Anna , Rajagopalan Ramakrishnan , Foley Henry C 
Published: April 2011

ABSTRACTHigh throughput, asymmetric carbon membranes derived from pyrolysis of polyfurfuryl alcohol (PFA) have been fabricated on a novel support composed of porous stainless steel filled with nanoparticles. Variation of PFA molecular weight was found to have a significant impact on the single gas permeances of the resultant carbon membranes. High molecular weight precursor material yielded the best results; oxygen permeance values for membranes synthesized from high molecular weight resins were on the order of ∼1×10−8 mol m−2s−1Pa−1 with oxygen over nitrogen ideal selectivities greater than 7. Binary separations of hydrogen from nitrogen and hydrogen from carbon monoxide were carried out using a NPC membrane synthesized from high molecular weight precursor material. For both separations, hydrogen purities of better than 99% by volume were obtained in the permeate stream.
Complex Hydrides Studied by Raman Spectroscopy and Thermal Conductivity Measurements under High Pressure
Authors: Sundqvist Bertil , Talyzin Alexandr V. , Andersson Ove 
Published: April 2011

ABSTRACTThe pressure-temperature phase diagrams of alkali metal alanates and borohydrides are of large current interest, and we have recently studied phase transformations under pressure in several of these materials. We here report Raman studies of KBH4 under pressure at room temperature, showing a phase transition near 6 GPa. Although no structural information is yet available, the similarity between KBH4 and NaBH4 suggests the new structure is orthorhombic. We also report studies on LiBH4 showing that the high pressure phase of this material is metastable to zero pressure below 200 K.
Development of Environmental Cell and its Application to Hydrogen Storage Materials
Authors: Okudera Koya , Hamada Koichi , Suda Takanori , Hashimoto Naoyuki , Ohnuki Somei , Kawai Yasuaki , Kojima Yoshitsugu 
Published: April 2011

ABSTRACTHigh-resolution and “environmental cell” microscopy were applied for surveying the reaction of hydrides in Vanadium and Magnesium based alloys, which are candidate for hydrogen storage materials of advanced hydrogen energy systems. For clarify the hydrogenation process, in-situ experiment was carried out by using 200 kV TEM equipped with a newly developed environmental cell, which is enable to observe transmitted image and electron-diffraction under gas reaction under hydrogen environment of 0.1 MPa at room temperature. In case of Vanadium, bending fringe was created under hydrogen-gas of 0.1 MPa, which means that hydrogen reaction is not so quick in this case, and the local stress due to the hydrogen solution caused the fringes. In case of Magnesium, the gas reacted with the powders and showed the swelling, where the surface steps with several ten nm become to more straight, and also SADP showed the formation of MgH2. In-situ experiment for hydrogenation reaction by using the environmental cell has started recently, therefore the precise studies will be continued, as well as its improvement, especially in the transparence films.
Synthesis and Electrochemistry of Acicular Silver Vanadium Oxide Nanofibers
Authors: Takeuchi Kenneth J. , Marschilok Amy C. , Leising Randolph A. , Takeuchi Esther S. 
Published: April 2011

AbstractSilver vanadium oxide (SVO, Ag2V4O11) has demonstrated commercial success as a solid-state cathode material in power sources for implantable biomedical devices. This report describes the synthesis of SVO via a hydrothermal method. This novel synthetic approach allows low temperature production of acicular SVO nanofibers with a high surface area. This material was investigated as a cathode material in primary lithium batteries for high rate pulse applications.
Direct-Write Microfabrication of Single-Chamber Solid Oxide Fuel Cells with Interdigitated Electrodes
Authors: Kuhn Melanie , Napporn Teko , Meunier Michel , Therriault Daniel , Vengallatore Srikar 
Published: April 2011

AbstractMiniaturized single-chamber solid-oxide fuel cells (SC-SOFC) are a promising class of devices for portable power generation required in the operation of distributed networks of microelectromechanical systems (MEMS) in harsh environments. The single-face configuration, which consists of interdigitated (comb-like) array of electrodes on an yttria-stabilized zirconia (YSZ) electrolyte substrate, is of particular interest because of the ease of high-temperature microfluidic packaging and integration with MEMS. The primary design consideration for this configuration is the minimization of electrode widths and inter-electrode spacings to dimensions on the order of a few micrometers. This is necessary to minimize polarization resistance and increase fuel cell efficiency. Achieving these geometries using standard microfabrication methods is difficult because of the thickness, porosity, and complex chemistries of the electrodes. Here, we report the development of an innovative and rapid method for manufacturing SC-SOFCs with interdigitated electrodes using robot-controlled direct-writing. The main steps consist of: (i) formation of inks (or suspensions) using anode (NiO-YSZ) and cathode (lanthanum strontium manganite) powders, (ii) pressure-driven extrusion of inks through a micronozzle using a robot-controlled platform, and (iii) sequential sintering to form the fuel cell. The first-generation SC-SOFC device, with electrode widths of 130 μm and inter-electrode spacing of 300 μm, has been manufactured using direct-write microfabrication. The electrodes have been extensively characterized using electron microscopy and x-ray diffraction to assess porosity and to confirm phase identity. The primary process parameters in this approach are the particle size and size distribution, rheological properties of the suspension, extrusion pressure, nozzle size, stage velocity, and sintering conditions. As the first step in the development of detailed process-structure-performance correlations for the fuel cells, we have studied the effects of extrusion pressure (in the range 30-40 bar) and stage velocity (in the range 0.2-2.0 mm/s) on the geometry and size of electrodes, for fixed suspension viscosity and nozzle diameter. An optimal combination of speed and pressure has been identified and catalogued in the form of process maps. Similarly, the particle size distribution of the anode and cathode powders is found to have a significant effect on the microstructure, especially porosity, of the sintered electrodes. The implications of these results for the design of the next generation of SC-SOFC, with reduced electrode dimensions and improved electrochemical performance, will be discussed.
Merits of Bi3TiNbO9 for Humidity Sensors
Authors: Avila Ricardo , Castro A. , Serafini Daniel , Ulloa H. E. , Jiménez R. , Cabrera A. 
Published: April 2011

AbstractThe fast and reproducible electrical response of the new, metastable fluorite phase of Bi3TiNbO9 to ambient humidity is reported. Pellets were prepared by high energy mechanochemical activation of the precursor powders, pellet pressing, sintering, and sputter deposition of Pt electrodes. Thermal analysis shows exothermic peaks at 465 and 594 °C. X ray diffraction analysis identifies a metastable fluorite like phase, isomorphous to the δ phase of Bi2O3, between the first and the second peaks, and the stable Aurivillius phase after the second peak.Over a wide (-40 to 20 °C) dew point (DP) range, at 23 °C ambient temperature, the conductivity increases close to exponentially, from nearly 10−3 to 102 pS/cm. Upon removal of the bias, and under DP cycling, the relaxation current responds to humidity steps, on top of the long term current decay, in a manner similar as under bias. In addition, upon a step into humidity, after a dry spell, the current overshoots (before proceeding to the long term decay) to a maximum value (Im) which depends on the duration of the previous dry spell. If this is short, Im remains below the current value (Iph) at the end of the previous humidity stage. If the dry spell is long, Im overshoots above Iph. This behavior is unlike that of any discharge current through a leaky capacitor. A preliminary model for understanding it proposes the surface transport of a charge carrier, assisted by diffusion of some species from the interior of the ceramic grains.
Structural Characterization and Ionic Conductivity of Metastable Gd2(Ti0.65Zr0.35)2O7 Powders Prepared by Mechanical Milling
Authors: Fuentes Antonio F. , Moreno Karla J. , Santamaria Jacobo , Leon Carlos , Amador Ulises 
Published: April 2011

AbstractWe analyze in this work the influence of ordering on the oxygen ion dynamics in the ionic conductor Gd2(Ti0.65Zr0.35)2O7, prepared by mechanical milling. As-prepared powder phase presents a metastable anion deficient fluorite-type of structure below 800°C becoming a disordered pyrochlore above this temperature. Such phase transformation implies a significant increase in the ionic conductivity of this material as a result of a systematic decrease in the activation energy for the dc conductivity, from 1.23 to 0.78 eV. Electrical conductivity relaxation is well described by the Kohlrausch-Williams-Watts (KWW) stretched exponential function with the fractional exponent n decreasing systematically with increasing sintering temperature (increasing ordering) as a result of decreasing ion-ion interactions in better ordered samples.
Potentiometric Detection of VOCs using Non-Nernstian SmFeO3/Pt/YSZ/Pt Sensors
Authors: Chevallier Laure , Di Bartolomeo Elisabetta , Traversa Enrico , Mori Masami , Sadaoka Yoshihiko 
Published: April 2011

AbstractElectrochemical sensors for Volatile Organic Compound (VOCs) based on commercial YSZ layers were fabricated using Pt as reference electrode and SmFeO3 perovskite oxide as a sensing electrode, both exposed to the same gas environment. Pt was sputtered on YSZ layers while SmFeO3 p-type semiconducting oxide was deposited by electrophoretic deposition (EPD). Nanometric SmFeO3 oxide powders were selected because they have already shown good sensing performance in semiconducting sensors for oxidizing gases such as NO2 and ozone, and reducing gases, such as VOCs. Potentiometric measurements were performed under exposure to different concentrations of VOCs such as: methyl ethyl ketone (MEK), ethanol (EtOH) and acetic acid (AA). The best gas sensing response was obtained at 400°C.
Preparation of SrFeO3-X Thin Films by the Spin-Coating Method and its Gas Sensing Properties
Authors: Majid Abdul , Gollner Egmont , Matam Mahesh , Tunney Jim , Post Mike 
Published: April 2011

AbstractNanostructured coatings have recently attracted increasing interest because of the possibilities of synthesizing materials with unique physical-chemical properties. In this report we describe our efforts at developing a methodology for the fabrication of SrFeO3-X based thin films using a modified Pechini method. Thin films of SrFeO3-X were fabricated using a spin coating and PLD method on Al2O3. The films annealed at 600 °C for one hour show a perovskite phase. The sensors based on SrFeO3-X thin films on alumina were fabricated using spin coating and PLD techniques. The sensing properties were determined using propane and propene as the probing gases. Response characteristics and temperature dependency of spin coated and PLD fabricated samples were compared. The effect of the electrode material, Au and/or Pt, on the gas detection sensitivity of the SrFeO3-X thin films was also investigated.
The Hydrothermal Synthesis of Lithium Iron Phosphate
Authors: Chen Jiajun , Whittingham M. Stanley 
Published: April 2011

AbstractWell-crystalline LiFePO4 particles were successfully prepared in the temperature range between 120 and 220°C, and complete ion ordering was obtained above 175°C where the unit cell dimensions were identical to high temperature material. The use of a soluble reductant, such as sugar or ascorbic acid, was found to minimize the oxidation of the iron to ferric. The electronic conductivity was enhanced by the deposition of carbon from the sugar, or by the addition of carbon nanotubes to the hydrothermal reactor when over 90% of the lithium could be de-intercalated electrochemically. We have extended the hydrothermal synthesis method to the Mn, Co and Ni analogs as well as to the mixed phosphates, such as LiMnyFe1-yPO4.