bluuebunny/crossref_metadata_2025 huggingface dataset:
Cu Post-CMP Displacement Cleaning: A Mechanistic Product Development Approach Based on Selected Thermodynamic and Kinetic Data
Authors: Peters Darryl Wayne
Published: April 2011

A mechanistic product development approach will be presented that utilized selected thermodynamic and kinetic data for development of a Cu post-CMP cleaner for use after polishing with either high or low pH slurry. A Pourbaix diagram offers the thermodynamically stable Cu species vs. pH and open circuit potential (OCP) for an aqueous cleaner. Pourbaix diagrams do not provide any information on the kinetics for dissolution of water soluble species. Cu oxide dissolution rates were measured using an electrochemical cell. Deposition and removal rates for benzotriazole (BTA) and 1,2,4-triazole (TAZ) were measured using an electrochemical cell with a quartz crystal microbalance (QCM). Passivator film deposition was investigated to determine the film type and thickness resulting from a typical CMP process. BTA and TAZ films deposited near neutral pH were thicker than those deposited at high pH. TAZ films were significantly thinner (∼20Å) than BTA films deposited under similar conditions, approaching a self assembled monolayer (SAM). The BTA removal rate for a citrate solution with a pH of 4 was 20Å/min., an order of magnitude lower than that for TMAH-containing solutions. The TAZ removal rate for an oxalate solution with a pH of 4 was 240Å/min., which was twice the removal rate for BTA deposited under similar conditions. An appropriate TAZ solution was found to displace BTA on Cu and leave a hydrophilic, thin (∼20Å) passivating layer of TAZ. Other Cu passivators were also examined but only TAZ protected all Cu crystallographic orientations observed. BTA, 5-aminotetrazole (5-ATA) and 4-carboxybenzotriazole (CBTA) did not protect some Cu crystal orientations, leading to etching of entire grains and increased surface roughness. BTA and CBTA yielded hydrophobic Cu surfaces, leading to surface wetting issues and the potential for watermarks. A new alkaline Cu post-CMP cleaner was developed to remove residues resulting from slurries, regardless of their pH, which utilizes TAZ to displace BTA and protect Cu, significantly lower organic defects, reduce surface roughness, provide a hydrophilic Cu surface, and significantly extend the staging time allowed between the clean process and subsequent wafer processing.
New Particle Metrology for CMP Slurries
Authors: Williams Kim , Park Ilyong , Remsen Edward E. , Moinpour Mansour
Published: April 2011

A new particle sizing and counting method based on the coupling of flow field-flow fractionation (FFF) with dual-sensor, single particle optical sensing (SPOS) detection is reported. The integration of FFF and SPOS systems was accomplished by means of a dilution interface that preserved the resolution of FFF-separated particles. Analysis of a model mixture of polystyrene latex standards of different diameters established that the FFF-SPOS system can resolve particles into discrete peaks for subsequent particle counting. Application of this method for the analysis of a colloidal silica standard demonstrated its use for materials commonly employed as CMP abrasives. Further development and refinement of the technique will enable compositional and structural analyses of heterogeneous large particle populations constituting commercial CMP slurries.
Improved Defect Classification Techniques of a Laser Scattering Detection System for Post CMP Silicon Dioxide Wafers
Authors: Mateja Daniel , Kasai Toshi , Denham Michael , Siriwardane Haresh
Published: April 2011

A laser light scattering technique was used for the identification of defects on silicon dioxide (SiO2) wafers polished with a tungsten CMP slurry. Defects were then classified as scratches and particles using scanning electron microscopy (SEM). The effects of the incident beam illumination and scattering geometry on the defect detection are examined. Appropriate experimental conditions for selective detection of scratches and particles are discussed in conjunction with the estimated defect count and fractional ratio for specific defect types and sizes. The findings are qualitatively consistent with predicted light scattering distributions simulated from silicon bare substrates.
A Study in Selectivity Variations of WCMP Slurries Related to pH, ζ[zeta]-potential and Dilutions with De-ionized Water
Authors: Gianni Davide , Ardizzone Silvia , Cappelletti Giuseppe , Maspero Angelo , Monticelli Damiano , Spinolo Giulia , Masciocchi Norberto
Published: April 2011

Commercially-available WCMP slurries perform differently under diverse modifications: pH variations, dilutions, ageing, etc. In order to understand the physico-chemical basics of the mechanism and selectivity of these slurries, we have performed a number of measurements, including determination of effective CMP removal rates on blank and patterned wafers. The results of the performances of the different modifications have been compared, and a few optimized conditions and recipes derived. Our results surprisingly show that pH has a much greater influence on the removal rate of tungsten and silicon dioxide than the particles content, and that the way a certain pH is reached (or maintained) significantly affects the performances of the prepared slurries.

We propose that nitric acid can be used to dilute selective slurries in order to keep high removal rates. Indeed, diluting slurries with an acidic solution of the same pH maintains particle charges far from zero, and keeps oxidizing conditions stable. However, the effects of the acidic dilution of the slurries include a slight reduction of removal rate and a decrease in defect density
Enabling Damascene Solutions for 45 nm Beyond
Authors: Tsujimura Manabu
Published: April 2011

There are several technology developments, which should have been completed in CN 65 nm (Commercial node) device development, but passed over to CN 45 nm device development. Seven items relating with damascene process, especially connecting with planarization process, are nominated and introduced herein including new advent technologies as enabling solutions for CN 45 nm. First one is low-down-force planarization. Although there are several planarization technologies such as CMP (Chemical Mechanical Polisher), ECMP (Electrical Chemical Mechanical Polisher), ECP (Electrical Chemical Polisher), CE (Chemical Etching) and those combination technologies, it is not decided which is the best one and how low down force is optimized taking into account of CoC (Cost of Consumable) issues. In this report, all planarization technologies are explained using ‘General Principle governing all planarization technologies’, and allowable down force is suggested through stress analysis and fracture toughness analysis. Second one is direct polish on ULK. There may be two approaches. One is to adopt CMP hard mask which dielectric constant would not be changed by direct polish. In this case, non-uniformity of CMP in this hard mask is important. Second is to polish directly on ULK, which dielectric constant would be changed by CMP, then restoration technology should be discussed at a same time. Third one is Ru liner application. When is this technology required? Deposition for Ru seed and polishing of Ru integration are reported. Forth one is watermark free drying of ULK. Vacuum drying and IPA drying (Rotagoni) which is necessary for hydrophobic surfaces are reported. Fifth one is cleaning technologies for less than 45 nm FM. After CN 45 nm, it is difficult to distinguish several defects such as scratches or FM. In this case, soft cleaning methods such as non-contact cleaning would be required. Cavitation jet as one of non-contact type cleanings is reported with its cleaning results. Sixth one is Co-W cap process. Electro-less metal cap technology in order to enhance EM is reported. CMP after Co-W deposition may be useful in order to clean cap surfaces. Seventh one is starting material such as nanotopography and roll off which would affect on CMP performances.
Effects of Additives in KOH Based Electrolytes on Cu ECMP
Authors: Kwon Tae-Young , Kim In-Kwon , Park Jin-Goo
Published: April 2011

The purpose of this study was to characterize KOH based electrolytes and effects of additives on electro-chemical mechanical planarization. The electrochemical mechanical polisher was made to measure the potentiodynamic curve and removal rate of Cu. The potentiodynamic curves were measured in static and dynamic states in investigated electrolytes using a potentiostat. Cu disk of 2 inch was used as a working electrode and Pt electroplated platen was used as a counter electrode. KOH was used as the electrolyte. H2O2 and citric acid were used as additives for the ECMP of Cu. In static and dynamic potentiodynamic measurements, the corrosion potential decreased and corrosion current increased as a function of KOH concentration. In dynamic state, different potentiodynamic curve was obtained when compared to the static state. The current density did not decrease in passivation region by mechanical polishing effect. The static etch and removal rate were measured as function of KOH concentration and applied voltage. In ECMP system, polishing was performed at 30 rpm and 1 psi. The removal rate was about 60 nm/min at 0.3 V when 5 wt% KOH was used. Also, the effect of additive was investigated in KOH based electrolyte on removal rates. As a result, The removal rate was increased to 350 nm/min when 5wt% KOH, 5vol% H2O2, 0.3 M citric acid were used.
ECMP Enhances the Planarization Efficiency — a Phenomenon of Reverse Topography during Cu Removal
Authors: Liu Feng Q , Hsu Wei-Yung , Duboust Alain , Chen Liang
Published: April 2011

Planarization efficiency is a key parameter to evaluate the process effectiveness of CMP. When the Cu thickness was removed beyond the step height, under certain conditions, the recessed trenches become protruded, resulting in reverse topography. This reverse topography during bulk Cu removal can only be attributed to the low down force polishing, electrical driving Cu removal and Cu passivation mechanism in ECMP process. In this paper, the concept of reverse topography is introduced and the removal selectivity difference on the trench area and field area during bulk Cu removal is discussed. In ECMP, a “real” 100% planarization efficiency can be achieved when the Cu thickness removed is less than the trench step height. This new understanding in planarization efficiency sheds lights on ways to improve CMP productivity
Application of Scatterometry to BEOL Measurements: Post Cu CMP Measurements
Authors: Kulkarni Deepak , Ponoth Shom , Wu Li , Fang Rui , Liu Xiaoping , Elia Alex
Published: April 2011

With shrinking interconnect dimensions, as a result of scaling, resistance variations in percentage terms are increasing. Quick and reliable measurements on the interconnect structures are the first step to the detection and implementation of a process-control strategy in order to reduce process related variations. This paper discusses the application of Optical Digital Profilometry (ODP) to the measurement of BEOL parameters, specifically the measurement of post copper-CMP metal dimensions with the intention of understanding CMP related contribution to resistance variations. Traditionally a combination of electrical test, optical metrology and profilometry is needed to understand the contribution of CMP to the interconnect and inter-layer-dielectric (ILD) dimensions. This paper discusses the successful use of ODP to model and measure the dimensions of both the metal and the dielectric in nested patterned structures with different pattern densities for a single level patterned build. Hence this technique could potentially simplify and replace multiple measurement techniques and help in quickly providing relevant information for process monitoring and control.
Influence of Oxygen Annealing on Electrical Properties of ZnO:Cl Thin Films
Authors: Tchelidze Tamar , Chikoidze Ekaterine , Jomard Francois , Gorochov Ouri , Galtier Pierre
Published: April 2011

The influence of oxygen treatment on carrier transport properties of pure ZnO and ZnO:Cl thin films grown by MOCVD were studied. The experimentally obtained values of carrier concentrations after oxyden treatment at different temperatures, were compared with the the results obtained from thermodynemical analysis of the system: ZnO:Cl-Oxyen vapour pressure, using method of quasi-chemical reactions (QCR).
Evidence of the De-multiplication Interactions Between Threading Dislocations in GaN Films Grown on (0001) Sapphire Substrates
Authors: Wang Cheng-Liang , Gong Jyh-Rong
Published: April 2011

We report the observation of threading dislocation de-multiplication process by transmission electron microscopy (TEM). The GaN films used in this study were grown on (0001) sapphire substrates with LT-GaN buffer layers by reduced pressure organometallic vapor phase epitaxy. By using g · Db = 0 invisibility criterion, it was found that some of TDs were de-multiplicated by interactions among themselves. In particular, type a+c TDs were found to nucleate through the interactions between type a and type c TDs in GaN near the GaN/sapphire interface so that the de-multiplication of TDs in GaN films was achieved.
Characterization of Nanocavities in Silicon Using Small Angle X-Ray Scattering
Authors: Dunmont Myriam , Coulet Vanessa , Regula Gabrielle , Bley Françoise
Published: April 2011

The techniques of small angle X-ray scattering and transmission electron microscopy are applied to characterize the size distribution of nanocavities in a (111) Si wafer multi-implanted with He+ in the Mev range energy. The comparison between both methods shows that they all give access to the same structural information but small angle X-ray scattering additionally offers the possibility to monitor the cavity size distribution during a thermal treatment. Moreover, providing that the collected data are of good quality, the former method also allows the knowledge of the porosity of the implanted Si wafer.
Cathodoluminescence Study of V-defects in AlGaAs-based High-power Laser Bars
Authors: Pommies Matthieu , Avella Manuel , Martin Alonso , Jimenez Juan , Oudart Myriam , Nagle Julien
Published: April 2011

High-power semiconductor lasers are required to be more and more powerful, efficient and reliable for applications such as solid-state lasers pumping, materials processing, and thermal printing among others. The understanding of the degradation mechanisms is essential to improve the high power laser reliability. The highest power emission is achieved with multi-emitter laser cm-bars, which present problems related to packaging induced stress. A very harmful defect in this type of devices is the so-called V defect. We present herein a study of these defects using cathodoluminescence imaging, the role of packaging is discussed.
DLTS: A Promising Technique for Understanding the Physics and Engineering of the Point Defects in Si and III-V Alloys
Authors: Khan Aurangzeb , Yamaguchi Masafumi
Published: April 2011

Deep level transient spectroscopy (DLTS) is the best technique for monitoring and characterizing deep levels introduced intentionally or occurring naturally in semiconductor materials and complete devices. DLTS has the advantage over all the techniques used to-date in that it fulfils almost all the requirements for a complete characterization of a deep centre and their correlation with the device properties. In particular the method can determine the activation energy of a deep level, its capture cross-section and concentration and can distinguish between traps and recombination centers.

In this invited paper we provide an overview of the extensive R & D work that has been carrier out by the authors on the identification of the recombination and compensator centers in Si and III-V compound materials for space solar cells. In addition, we present an overview of key problems that remain in the understanding of the role of the point defects and their correlation with the solar cell parameters.
Schottky Barrier Height Engineering in NiGe/n-Ge(001) Contacts by Germanidation Induced Dopant Segregation
Authors: Liew S. L. , Chua C. T. , Seng D. H. L , Chi D. Z.
Published: April 2011

Schottky barrier height (ÖB) engineering of NiGe/n-Ge(001) diodes was achieved through germanidation induced dopant segregation on As implanted-Ge substrates. was reduced from 0.55 eV to 0.16 eV with increasing As dose on n-Ge(001) while on p-Ge(001), the diodes exhibited increasing ÖB.
Defect Reduction and Its Mechanism of Selective Ge Epitaxy in Trenches on Si(001) Substrates Using Aspect Ratio Trapping
Authors: Park Ji-Soo , Bai J. , Curtin M. , Adekore B. , Cheng Z. , Carroll M. , Dudley M. , Lochtefeld A.
Published: April 2011

Defect-free germanium has been demonstrated in SiO2 trenches on silicon via aspect ratio trapping, whereby defects arising from lattice mismatch are trapped by laterally confining sidewalls. Results were achieved through a combination of conventional photolithography, reactive ion etching of SiO2, and selective growth of Ge as thin as 450 nm. It was revealed that facets, when formed early on in the growth process, play a dominant role in determining the configurations of threading dislocations in the films. This approach shows great promise for the integration of Ge and/or III-V materials, sufficiently large for key device applications, onto silicon substrates.
Hydrostatic Pressure Studies of GaN/AlGaN/GaN Heterostructure Devices with Varying AlGaN Thickness and Composition
Authors: Steinke Isaiah , Kauser M. Z. , Ruden P. Paul , Ni Xianfeng , Morkoc Hadis , Son Kyung-ah
Published: April 2011

GaN-based heterostructure devices are of interest for pressure and stress sensing applications due to their potential for use at high temperatures and in caustic environments. We have grown n-GaN/u-AlGaN/n-GaN heterostructure devices on sapphire substrates by organometallic vapor phase epitaxy (OMVPE) using the epitaxial layer overgrowth (ELO) method. The devices were fabricated with varying AlGaN layer thickness and composition. Current-voltage (I-V) characteristics were obtained to characterize the performance of these devices under hydrostatic pressures up to 500 MPa. For a fixed bias, the current was observed to decrease in magnitude with increasing hydrostatic pressure for all devices tested. The current modulation is attributed to piezoelectric effects. Specifically, the polarization charge densities at both GaN/AlGaN interfaces are sensitive to changes in the hydrostatic pressure, and these charges affect the shape of the potential barrier and the current. Changes in the AlGaN layer thickness and composition modify the interfacial polarization, with thicker AlGaN layers and higher Al content increasing the effect of pressure on the observed I-V characteristics. The decreases in current magnitude with increasing pressure are linear over the pressure range tested. In order to quantify the performance of these devices, we calculate a pressure gauge factor based on a normalized change in current divided by the change in pressure. Values obtained range from 0.1–1.0 GPa−1, consistent with our previously published results for a single device. In addition, the turn-on voltages under both forward and reverse bias conditions are observed to increase with increasing AlGaN layer thickness and composition, a result that agrees with our device model. These turn-on voltages are governed by different mechanisms in the forward and reverse bias directions. Under forward bias, the mechanism is a transition from a thermionic to a tunneling process. However, under reverse bias, the turn-on occurs when the total electric field changes sign in the AlGaN layer.
Radiation-Induced Deep-Level Traps in CCD Image Sensors
Authors: Tivarus Cristian , McColgin William C.
Published: April 2011

Dark current spectroscopy (DCS) is used to study deep level traps corresponding to the bright pixels that form the histogram “tails” of irradiated charge-coupled devices (CCD). We found four distinct traps, among which the double vacancy (V2) and the vacancy-phosphorous (VP) have the highest concentrations and generation rates. We show that DCS can be used to examine the annealing mechanisms of silicon defects to concentrations as low as 5 × 107 cm−3.
Electronic Structure of Si/InAs Composite Channels
Authors: Prada Marta , Kharche Neerav , Klimeck Gerhard
Published: April 2011

Electronic structure calculations on composite channels, consisting of indium arsenide grown on the technologically relevant (001), (011) and (112)-orientated silicon surfaces are reported. The calculations are performed with NEMO 3-D, where atoms are represented explicitly in the sp3d5s* tight-binding model. The Valence Force Field (VFF) method is employed to minimize the strain. NEMO 3-D enables the calculation of localized states in the quantum well (QW) and their dispersion in the quantum well plane. From this dispersion, the bandgap, its direct or indirect in character, and the associated effective masses of the valence and conduction band can be determined. Such composite bandstructure calculations are demonstrated here for the first time. The numerical results presented here can then be included in empirical device models to estimate device performance. Pure InAs QWs create a direct bandgap material, with a relatively small gap and effective masses of about one order of magnitude smaller than for pure Si QW of equivalent thickness. Si, on the other hand, has a larger bandgap, superior thermal and mechanical properties, and a heavily invested industry. Thus heteroepitaxy of both components is expected to yield a highly optimized overall system. For samples grown along the (001) direction, Si is a direct bandgap material, and deposition of an InAs 3nm layer reduces substantially the hole effective mass and slightly the electronic mass, decreasing the magnitude of the gap. Along the (011) and (112)-growth direction, Si QWs are indirect bandgap material, and deposition of a few InAs layers suffies to make the new material a direct-bandgap heterostructure, decreasing significantly the electronic effective mass. (011) and (112) are the experimentally most relevant growth directions since they prevent heterointerface dipoles.
Comparative Study of Electronic Properties of Point Defects in Monoclinic Hafnium Dioxide
Authors: Cuny Valerie , Richard Nicolas
Published: April 2011

Continuous downscaling of transistor leads silicon dioxide constituting the gate in typical metal oxide semiconductor field effect (MOSFET) to its limits. One possibility is to replace SiO2 by a material of higher dielectric constant (high-k). Hafnium dioxide seems to be the most promising one. However, high-k transistor performances are often affected by the presence of defects creating charge traps or diffusion centers. In this paper, using a pseudopotential plane wave code in the density-functional total theory framework, we calculate in a monoclinic HfO2 supercell the structure, formation and ionization energies, electron affinities of intrinsic defects (oxygen vacancy and interstitial, and hafnium vacancy). We consider different charge states of these defects. The positions of defect levels with respect to the bottom of silicon conduction band are determined. Our results will be discussed and compared to literature data.
The Electrical Characterization of Molecular-Beam-Deposited LaAlO3 on GaAs and its Annealing Effects
Authors: Choi Donghun , Warusawithana Maitri , Chui Chi On , Chen Joseph , Tsai Wilman , Schlom Darrell G. , Harris James S.
Published: April 2011

The electrical properties of Al/LaAlO3/GaAs metal-oxide-semiconductor capacitors were investigated. A thick arsenic (As2) capping layer was used to protect the GaAs from oxidation and contamination during the air exposure that occurred between the deposition of the GaAs and LaAlO3 layers in different molecular-beam epitaxy systems. Amorphous LaAlO3 was deposited on c(4×4)- and (2×4)-reconstructed (100) GaAs surfaces. Post dielectric deposition annealing was found to improve the capacitance-voltage (C-V) characteristics by eliminating frequency dispersion in the depletion and weak inversion regimes and diminished the bi-directional C-V hysteresis to 210 mV. Reasonably low gate leakage current was maintained after annealing.
Atomic-scale Characterization of HF-treated 4H-SiC(0001)1×1 Surfaces by Scanning Tunneling Microscopy
Authors: Arima Kenta , Hara Hideyuki , Sano Yasuhisa , Yagi Keita , Okamoto Ryota , Murata Junji , Mimura Hidekazu , Yamauchi Kazuto
Published: April 2011

Scanning tunneling microscopy (STM) observations are performed on 4H-SiC(0001) surfaces after wet-chemical preparation steps including HF treatments.1×1 structures are formed on a terrace together with other local structures. Their atomic images are investigated in conjunction with low-energy electron diffraction and electron spectroscopy for chemical analysis. It is suggested that each bright dot forming the 1×1 phase corresponds to an OH-terminated Si atom.
Effects of Annealing on Structural and Magnetic Properties of Cobalt Implanted TiO2 Thin Films
Authors: Luk W. Y. , Li Q. , Wong S. P. , Ho H. P. , Ke N. , Lindner J. K. N.
Published: April 2011

Since the observation of room-temperature ferromagnetism (RTFM) in Co-doped anatase TiO2 [1], there have been many reports on the study of the magnetic properties of Co-doped TiO2 prepared by various methods with diversified results. The origin of the RTFM in these systems is still a topic of controversy today. In this work, TiO2 thin films were prepared by RF sputtering onto thermally grown oxide layers on Si substrates. Cobalt implantation was performed using a metal vapor vacuum arc (MEVVA) ion source to various doses ranging from 3×1015 cm-2 to 4×1016 cm-2. Post-implantation annealing was performed in a vacuum chamber at various temperatures ranging from 400°C to 700°C for 2 hours and 4 hours. Characterization of these films as-implanted and after thermal annealing under various conditions was performed using Rutherford backscattering spectrometry, energy filtered and high-resolution transmission electron microscopy, x-ray diffractometry, x-ray photoelectron spectroscopy, and vibrating sample magnetometry. The dependence of the magnetic properties on the implantation and annealing conditions were studied in detail. Clear RTFM properties were observed. The saturation magnetic moment per implanted Co atom (MS) seems to increase with increasing dose within the implantation dose range in this study. At a fixed dose, the MS value also shows a generally increasing trend with increasing annealing temperature and annealing time. Quite a number of samples showed MS values exceeding the bulk Co value of 1.69 ìB/Co significantly and the maximum MS value observed is about 3.16 µB/Co. Such high MS values indicate that the RTFM must not come from Co clusters alone. Possible origins of the RTFM properties will be discussed in conjunction with the structural properties.
Functionalizingλ-AlOOH Surface with Silanol -- an Ab-initio Study
Authors: Lehtinen Petri , Grundmeier Guido , Blumenau Alexander
Published: April 2011

On HDG-steel, zinc coatings are used for corrosion protection. Part of that coating is composed of aluminum and this leads to the creation of aluminum oxide film on the coating with thicknesses of 2-3 nanometers. This layer is an amorphous boehmite film.

Boehmite, or λ-AlOOH, has several application areas, but for us the interesting ones are related to an area where the surface is functionalized, for example in a way that the organic and inorganic films can be “glued” together. A good candidate for the interface is the silanol molecule. The idea is that the OH-groups of the molecule attach on the inorganic film and the methyl groups on the organic film and hence promote adhesion between the two.

We present theoretical ab-initio results of adsorption of water and silanol molecules on the λ AlOOH (0001)-surface. Since the experimental adsorption of the silanol on the boehmite surface is done in water environment, the adsorption process is therefore a competing process. We will present some result of adsorption of silanol in the presence of water molecules to get an insight into this process.
Sm-doped YBCO Coated Conductor on the IBAD MgO Template Fabricated by MOD Process
Authors: Shin Geo-Myung , Ko Rock-Kil , Song Kyu-Jung , Yoo Jae-Moo , Park Chan , Moon Seung-Hyun , Yoo Sang-Im
Published: April 2011

Metal organic deposition (MOD) is one of the attractive processes for coated conductor applications because it is a non-vacuum cost-effective process. Many research groups have successfully fabricated high-JC YBCO coated conductor on the RABiTS and IBAD-YSZ or GZO template with the MOD process. Reports on MOD-processed YBCO coated conductors prepared on the IBAD-MgO template, however, are hardly found. The precursor solution was coated on the CeO2 capped IBAD-MgO template using the slot-die coating method, calcined at a temperature of 550oC, and fired at high temperatures for 2 h 30 min in a reduced oxygen atmosphere. Optimal processing resulted in YBCO coated conductors exhibiting JC value of 0.75 MA/cm2 at 77 K in self-field. The JC values of YBCO coated conductors were found very sensitive to their microstructure, critical temperature, and in-plane texture.
Flux Pinning Enhancement of YBCO Films by Y and Ba Site Doping at Minute Concentrations
Authors: Kell Joseph W. , Barnes Paul N.
Published: April 2011

YBa2Cu3O7-x (Y123) superconducting thin films can maintain high critical current densities in applied magnetic fields up to a few Tesla at 77 K. Even so, this does not preclude the intentional addition of alternate flux pinning centers in the Y123 films to further optimize their in-field Jc. Unfortunately, many methods to incorporate flux pinning centers into Y123 thin films introduce additional steps and/or re-optimization of the deposition parameters for a given addition. Identifying potential additions that can optimize the performance of YBCO films without changing the deposition conditions would be ideal. The work presented here is an extension of earlier work and demonstrates new dopants and possibilities for introducing pinning centers by the route of minute doping or nanodoping. Preliminary results of a study to determine if minute doping can be performed with smaller lanthanide atoms (Tm, Lu), non-lanthanide atoms (Sc) and Ba-site substitution (Sr) are presented. All samples were deposited under identical conditions as pure YBCO. The new dopants will be discussed in addition to those previously presented (Tb, Pr, Ce, Nd, and La). Critical current density data will be presented for 65 K and 77 K in fields up to 9T in addition to new structural data obtained by cross-sectional TEM.
High Resolution Electron Beam Lithographic Deposition of Metal and Metal Oxide Films from Metal Complexes
Authors: Zhang Xin , Hill Ross H.
Published: April 2011

In this paper, a method of direct electron beam lithographic deposition of metal and metal oxide films is demonstrated using metal organic complexes. In this method, a solution of a metal complex is used to spin coat a substrate to obtain a precursor film. The precursor film is then directly patterned by electron beam writing. A solvent is then used to develop the latent image. Using examples of titanium, tantalum, zirconium, and gold, we illustrate patterning of metal and metal oxide films and both positive and negative deposition. The feature size demonstrated is as low as 14 nm while the demonstrated aspect ratio is as high as 11.
Using Tubular Millifluidics as a Versatile Tool Box for The Generation of New Complex Architectures: Some Integrative Chemistry Synthetic Pathways
Authors: HANY Cindy , TACHIBANA Masatoshi , ENGL Wilfried , PANIZZA Pascal , BACKOV Ré;nal
Published: April 2011

We present a continuous flow scheme to produce hierarchically organized large emulsions and particles with very good control over size, shape and internal structure. By assembling together elementary co-axial flow modules and integrating their corresponding functions, modular set-ups can be designed “on demand” to engineer complex architectures in characteristic sizes ranging from 50 micrometers up to a few mm. The high potentiality of this approach stems from the continuous production of drops and the ability to manipulate and functionalize each one independently “on line”. Its great versatility is limited only by the number of combinations possible using the modular tool box and one's imagination. We illustrate this through the encapsulation of droplets or solid particles of various shapes, composition and size,in liquid or solidified drops as well as the formation of large organic or inorganic cylindrical particles.
Fabrication and Characterization of Electrowetting on the flexible substrate
Authors: Kim Jin-Young , Seo JungHo , Lee JungHwan , Kim KyuChae , Lim Hyun Woo , Park JinGoo , Jeon SungChae , Jin SeoungOh , Huh Young
Published: April 2011

This paper reports the fabrication of and characterization on EWOD(electrowetting-on-dielectric) devices on flexible substrates of interest to the flexible displays and devices. The EWOD devices were fabricated on PET (poly ethylene terephthalate) and PMMA (polymethylmethacrylate) substrates. Au and ITO(indium tin oxide) were used as electrode materials. The wet etching process was developed not to attack plastic flexible substrates. The photo resist was used as an insulator materials in EWOD devices due to the deformation of substrate when oxide layer was deposited on plastic substrate. As a hydrophobic layer, cytop was spin-coated on the photo resist. Wetting tests were done with DI water in air environment. In sessile droplet test, the contact angle of droplet changed from 116◦ to 80◦ under DC power. Threshold voltage was 20 Vdc. The droplet was oscillated under AC power because of the frequency. But the contact angle of droplet was began to change at 30Vac and decrease with the increase of AC power. In droplet transporting test, a droplet(0.2§¡) was started transporting at 20Vac and the transporting speed increased with the increase of AC power. But the droplet transporting was not occurred under DC power because of slower contact angle recovery rate under DC power.
Nanostructured Coatings Obtained Via Cationic UV-Curing
Authors: Sangermano Marco , Bongiovanni Roberta , Malucelli Giulio , Priola Aldo , Amerio Ezio , Pospiech Doris , Voit Brigitte
Published: April 2011

Polymeric nanocoatings have drawn considerable attention, in recent years, due to improvements in various properties including scratch resistance, abrasion resistance, heat stability as well as other mechanical properties [1-3].Different meal oxide nanoparticles have been employed s filler, in particular SiO2, TiO2 and ZnO were deeply investigated in literature [4].The use of inorganic particles in the nanoscale range is particularly attractive with the aim of improving the polymer properties by controlling the degree of interaction between the polymer and the nanofiller [5]. As inorganic fillers a range of different metal-oxide particles can be dispersed in the polymeric matrix [6-8]. Particularly attractive is the use of inorganic particles in the nanoscale range with the aim of improving the properties of the polymers by controlling the degree of interaction between the polymer and the nanofillers [9] via a top-down approach.One major problem with nanosized particles is their homogeneous dispersion within the organic matrix avoiding macroscopic phase separation. An in-situ approach of preparing nanoparticles using sol-gel precursors is appealing for this reason; it involves a series of hydrolysis and condensation reactions starting from a hydrolyzable multifunctional metal-alcoxide as precursor for the inorganic domain formation [10] (bottom-up approach).The use of suitable coupling agent permits to obtain a strictly interconnected network preventing macroscopic phase separation. The coupling agent provides bonding between the organic and the inorganic phases, therefore well-dispersed nanostructured phases may result [11] and hybrid organic-inorganic materials are achieved.
Synthesis of Nickel-Coated Carbon Nanopaper Sheets by Pulse Laser Deposition
Authors: Gou Jihua , Blanco Roy , Zhao Zhongfu , Khan Aurangzeb , Appalla Aditya
Published: April 2011

Surface coating of carbon nanotubes and carbon nanofibers can significantly improve their properties such as electrical, thermal, magnetic, acoustic, vibration, catalytic, optical properties. This paper presents a novel method to coat carbon nanotubes and carbon nanofibers by using as-prepared carbon nanopaper sheets. The carbon nanopaper sheet consisted of randomly oriented single-walled nanotubes and vapor grown carbon nanofibers, which formed into a highly uniform non-woven material. This flexible and lightweight material was coated with nickel by laser pulse deposition. The effects of deposition parameters on the morphology of the nanotubes and nanofibers will be studied using scanning electron microscopy. The electrical conductivities of carbon nanopaper sheets associated with deposition parameters will be characterized using four-point probe method. The deposition parameters will be optimized to achieve a highly conductive carbon nanopaper sheet.
Hierarchically Porous Oxides, Hybrids and Polymers via Sol-gel Accompanied by Phase Separation
Authors: Nakanishi Kazuki
Published: April 2011

In various crosslinking systems containing metal oxides, organo-siloxane polymers and pure hydrocarbons, monolithic materials with hierarchical well-defined macropores and controlled mesopores have been synthesized. Synthetic progress in alkoxy-derived macroporous silica lead to the preparation of long-range ordered mesoporous skeletons in well-defined macroporous framework. Alkylene-bridged silicon alkoxides can also be prepared into similarly hierarchical porous structures with broadened variations in framework morphology. Macro-mesoporous alkoxy-derived pure titania and zirconia have been prepared using hydrochloric acid – mediated processes. Compared with those prepared from colloidal dispersions, alkoxy-derived macroporous titania exhibited much higher mechanical strength. Titania monolith is a promising candidate as a separation medium to discriminate phosphorylated compounds in a liquid chromatography mode. Pure alumina macroporous monolith has been first synthesized from aluminum salt using propylene glycol as a proton scavenger to thrust the solution pH from acidic into neutral conditions. Alumina-based complex oxides such as garnets and spinels can also be prepared in pure phases. Polymerization and phase separation in organic crosslinker system was also controlled to obtain well-defined co-continuous macro-frameworks instead of those composed of aggregated particles. These examples demonstrate the versatility of using phase-separation in gelling systems to obtain well-defined macroporous structures.
Low Temperature Deposition of Metal Oxide Thin Films in Supercritical Carbon Dioxide Using Metal-organic Precursors
Authors: Gougousi Theodosia , Chen Zhiying
Published: April 2011

A novel chemical route in thin film formation that includes the use of inorganic and organic peroxides and metal organic complexes soluble in supercritical carbon dioxide has been investigated for the deposition of alumina, titania and zirconia thin films at low temperatures (<150°C). The metal organic precursors used include: Al(acac)3, OTi(tmhd)2, and Zr(acac)4. Tert-butyl peroxide, and a 30% aqueous solution of hydrogen peroxide were used as oxidants. Depositions were carried out in a 25 ml hot wall reactor at pressures ranging from 2100 to 3900 psi at 80-140°C. The deposited thin films were investigated by using X-ray photoelectron spectroscopy (XPS) and transmission Fourier transform infrared spectroscopy (FTIR). XPS and FTIR results indicate the formation of metal oxides thin films with some bonded carbon. The deposition temperatures achieved in this process are substantially lower than those used in conventional vacuum deposition techniques making feasible the deposition on temperature sensitive substrates and organic materials required for the development of hybrid organic/inorganic devices. Processing at low temperatures in supercritical carbon dioxide may provide the basis for the development of an alternative, environmentally friendly, thin film deposition technique for the processing of nanostructures.
Evaluation of Cationic Biopolymers for the Design of Silica-coated Alginate Capsules
Authors: Bruyant Aurelie , Coradin Thibaud
Published: April 2011

Lysozyme and chitosan were evaluated as cationic polymers for the design of silica-coated alginate capsules. No direct relationship was found between the strength of the bio-organic poly-electrolyte membrane and the stability of capsules after the silica coating, which depends mainly on the nature of poly-cation/silicate interactions.
Study of the Architecture of Inorganic-Organic Matrix in the Ventral Segmental Concretion of Porcellius Chilensis Nicolet, 1849 (Crustacea, Isopoda)
Authors: Pai Ranjith Krishna , Neira-Carrillo Andrónico , Fernandez Maria Soledad , Arias José Luis
Published: April 2011

Mineralized biological concretions have attracted increasing interest because of their outstanding properties. The mineralized concretion of terrestrial isopods is an excellent model for acellular natural composite material. Before the molt terrestrial isopods resorb calcium from the posterior cuticle and store it in concretion within the cranial (head) and caudal (tail) ventral segments. This paper present for the first time an analysis of ultrastructural changes occurring in the caudal ventral segmental (CaVS) concretion of a terrestrial isopod Porcellius chilensis during their formation and degradation. The CaVS concretion of the woodlice Porcellius chilensis was analyzed with respect to their content of inorganic material. It was found that the concretion consists of amorphous calcium carbonate (ACC), and amorphous calcium phosphate (ACP), besides small amounts of water and an organic matrix. The CaVS concretion consists of structurally distinct stratum due to inhomogeneous solubility of ACC within the organic matrix that consists of calcareous knob with reticules elements. The organic matrix plays a role in the structural organization of the concretion and in the stabilization of ACC, which is unstable in vitro. We present an analysis of the distribution of minerals, elements, and organic matrix with in the CaVS concretion by using SEM, XRD, IR and EDS. The decalcification experiments exactly imitated the natural demineralization of the CaVS concretion of the Porcellius chilensis and it is thought that an inhomogeneous solubility of ACC and ACP within the CaVS concretion probably caused by variations in the stabilizing properties of matrix components.
Interfaces Involving Biomolecules and Inorganic Materials: a Solid State NMR Approach
Authors: Bonhomme Christian , Hartmeyer Geoffrey , Babonneau Florence , Wong Chi Man Michel , Arrachart Guilhem , Carcel Carole , Moreau Joel , Alonso Bruno
Published: April 2011

Materials based on ureidopyrimidinone (UPY) dimers and Adenine (A) / Thymine (T) derivatives were synthesized and characterized by advanced solid state NMR (Nuclear Magnetic Resonance) techniques. Silylated UPY molecules were used as model compounds, leading to structured organic-inorganic materials after hydrolysis and condensation processes (sol-gel reactions). High resolution 1H solid state NMR has been extensively used for the in-depth description of the H-bond networks, including very fast MAS (Magic Angle Spinning) experiments at very high field and DQ (double quantum) recoupling experiments. The chemical nature of the organic-inorganic interface has been illuminated by such techniques. In, particular, it has been demonstrated that H-bond networks were preserved during sol-gel reactions and were comparable to those observed in the UPY crystalline precursors.
Advances in Encapsulating Elastically Stretchable Microelectrode Arrays
Authors: Graudejus Oliver , Tsay Candice , Wagner Sigurd , Yu Zhe , Morrison Barclay , Lacour Stephanie
Published: April 2011

Stretchable microelectrode arrays (SMEAs) that are fabricated on the compliant silicone poly dimethyl siloxane (PDMS) have potential applications for research on traumatic brain injury (TBI). Increasing the number of electrodes in the array improves the accuracy in assessing the effects of traumatic injury to cell tissue cultures. The currently available encapsulation process with a photopatternable silicone limits the electrode density on the array. The present research examines four factors in the encapsulation process: exposure dose, scattered and reflected light as well as hard bake time. Careful optimization of these four factors leads to a significant reduction of the minimum feature size of a contact via patterned into the encapsulation layer, thus enabling an increase of the electrode density on the array.
Neuro-Technical Interfaces Based on Biocompatible Polymeric Substrates
Authors: Stieglitz Thomas
Published: April 2011

Multielectrode arrays create the interfaces between nerves and technical systems in neuroprosthetic devices. MEMS (microelectromechanical systems) technologies offer opportunities to develop high density arrays with large numbers of electrodes and smallest dimensions of electrode site area and pitch. Polymers are promising candidates for flexible substrates of these electrode arrays to meet the requirements of structural biocompatibility. In addition, these substrates must be biostable and should be non-toxic. From an engineering point of view, material processing should be feasible with standard MEMS process technology. Fail-safe integration of electronic circuitry, encapsulation of the systems with substrate-integrated electrodes and connection to cables and connectors is of great importance for reliable (micro-) implants.

A comprehensive overview of the application of polymers like silicone rubber, polyimide, and parylene C as substrate, insulation and encapsulation material for multielectrode arrays will be given. Assembling techniques for system integration and encapsulation concepts will be discussed with a special attention on the adhesion properties between substrate, interconnects and insulation and possible failure mechanisms. Application scenarios include peripheral nerve interfaces like cuff and sieve electrodes as well as multielectrode arrays for retinal vision prostheses and shaft and grid arrays for the central nervous system interfaces.
Metallization Process for Polydimethylsiloxane (PDMS) Rubber
Authors: Béfahy Stéphane , Yunus Sami , Burguet Véronique , Heine Jean-Sébastien , Dague Etienne , Trooters Michel , Bertrand Patrick
Published: April 2011

A process to fabricate stretchable and adherent gold tracks on flat silicone rubber substrates is studied by X-ray photoelectron spectroscopy (XPS), static water contact angle measurement, atomic force microscopy (AFM) and scanning electron microscopy (SEM). The process involves several steps: curing flat silicone substrate; removing uncured oligomers by hexane Soxhlet extraction; pre-stretching the substrate; activating the strained silicone surface by an oxygen plasma treatment; coating the strained substrate with 5nm titanium and 80nm gold layers by e-beam evaporation; and finally releasing the sample. The plasma treatment creates a thin brittle silica-like layer that temporarily increases the substrate's surface energy. Indeed the plasma treatment is followed by a hydrophobic recovery. As a consequence, the delay between plasma treatment and metal deposition has to be reduced as much as possible. The silica-like layer can be nicely observed after release. Its thickness is estimated to be around 20nm to 50nm. The entire process allows us to obtain stretchable metallized samples that remain conductive even after an excessive deformation leading to electrical failure.