bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical Vapor Deposition of Tantalum Nitride Films Using Pentakis(Diethylamido)Tantalum and Ammonia
Authors: Cho Sung-Lae , Kim Ki-Bum , Min Seok-Hong , Shin Hyun-Kook
Published: April 2011

Tantalum nitride (TaN) films were deposited by using pentakis(diethylamido)tantalum and ammonia. The activation energies of the surface reaction were obtained with the NH3 flow rate. In addition, the resistivity, composition, crystal structure, and microstructure were systematically studied with the NH3 flow rate from 0 to 25 sccm. The resistivity of the asdeposited film was decreased as the NH3 flow rate was increased, but it was increased at the NH3 flow rate of 25 sccm. The minimum value of resistivity is about 7000 μΩ-cm at the NH3 flow rate of 20 sccm. The carbon content in the film was decreased down to 1 at.% as the NH3 flow rate was increased up to 25 sccm by Auger electron spectroscopy. Rutherford backscattering spectrometry showed that the N/Ta ratio is about 1.75, which is not considerably changed with the NH3 flow rate. In spite of this high nitrogen content in the film, it was revealed that the fcc TaN was formed by x-ray diffractometry and transmission electron microscopy. The etch-pits test showed that 50-nm-thick TaN films deposited at the NH3 flow rate of 0 and 25 sccm prevented the diffusion of Cu into the Si substrate at the annealing condition of 500 °C and 550 °C for 1 hour, respectively. The step coverage was estimated as over 80 % at the NH3 flow rate of 0 sccm and below 10 % with the addition of NH3 in 0.5 μm × 1.5 μm contacts by cross-section scanning electron microscopy.
Copper Metallization Layers on Bismuth-Telluride Substrates: Effectiveness of Cr, Pt, and Ta40Si14 N46 Thin Films as Diffusion Barriers
Authors: Kacsich T. , Nicolet M.-A. , Kolawa E. , Fleurial J.-P.
Published: April 2011

For power-chip cooling devices based on Bi2Te3 thick films, copper is a desirable choice as metallic conductor, because it has high thermal conductivity and low electrical resistivity. On the other hand, Cu shows donor activity in Bi2Te3, and is known for its high diffusivity in bismuth-telluride and the rapid formation of Cu2Te. Therefore, the deployment of a chemically inert, low resistivity diffusion barrier between the Cu metallization layer and the thermoelectric base material is indispensable. In this paper we report on the effectiveness of films of Cr, Pt, and Ta40Si14N46 as diffusion barriers at temperatures up to 350°C for Cu overlayers on Bi2Te3 bulk substrates. The films, each about 100 nm thick, were magnetron-deposited on the Bi2 Te3 followed by about 300 nm thick copper overlayers without breaking vacuum. The samples were annealed in vacuum at temperatures of 200 and 350°C for up to 50 h. The performance of the metals and the tantalum-silicon-nitride films as diffusion barriers for Cu inward and Bi and Te toward diffusion was evaluated by 2.0 MeV4 He backscattering spectrometer and x-ray diffraction. While the Cr and Pt films fail already after hours of annealing at 200°C, the Ta40Si14N46 film remains intact at this temperature after vacuum heat treatment for 50 h, and even at 350°C for 1 h as well. Ta-Si-N, and related ternary materials of this type, have already shown to be highly effective barriers in Cu/Si contacts. This study demonstrates that their field in application extends quite beyond Si-based technology.
Texture and Grain Boundary Structure Dependence of Hillock Formation in Thin Metal Films
Authors: Nowell Matithew M. , Field David P.
Published: April 2011

The development of hillocks on metal films during annealing is detrimental to downstream processing of integrated circuit structures. This work focuses upon the local character of texture and grain boundary structure near hillocks in metal films. It is apparent from the results that local grain boundary structure and texture strength are important parameters in identifying locations in the films that are preferentially susceptible to failure under given conditions. Results in aluminum and platinum films indicate that non-(111) oriented grains preferentially contain hillocks. In addition, (111) oriented grains with boundaries characterized by high angle rotations about random axes are prone to hillock formation.
Electromigration Failure Kinetics in Al Alloy Lines: A Microstructure-Based Constitutive Equation
Authors: Kang S. H. , Morris J. W. , Kim C.-U.
Published: April 2011

In previous work we proposed a simple constitutive equation that describes the electromigration failure kinetics in naturally passivated Al(Cu) quasi-bamboo lines. The time to failure, tf obeys the relation, tf = t0 exp (−l/t0), where t0 and l0 are characteristic constants and l is the length of the polygranular segment that causes failure (which is ordinarily the longest polygranular segment in the line). The present paper gathers the data supporting this relation, which includes tests on lines as-patterned and annealed at low and high temperature, and examines the dependence of the factors t0 and l0 on current density, test temperature, line geometry, and Al2Cu precipitate distribution. The experimental data suggest that to varies geometrically with j, with exponent n ≈ 2.8, and exponentially with T−1, with activation energy of ∼0.69 eV. It also varies with the line width and the distribution of Al2Cu precipitates. On the other hand, l0 is only weakly dependent on current density and temperature, but may vary with the ratio of line width to grain size (w/G).
Modelling of Heat Conduction and Thermal Stresses in Multilevel Interconnects
Authors: Shen Y. -L.
Published: April 2011

The effects of metal Joule heating in interconnects were studied numerically. Particular attention is devoted to the multilevel nature of interconnects in modem microelectronic devices. Heat conduction analyses were carried out to quantify the temperature rise in structures composed of various levels of metal lines under different electric current densities. Two types of metallization (aluminum and copper) and two types of interlevel dielectric (silicon dioxide and polyimide) were considered. It was found that increasing the total number of metal level and/or switching the dielectric from silicon dioxide to polymer-based low-k dielectrics can cause substantial temperature increases, pointing out that interconnect Joule heating can become a major reliability threat in future applications. Thermal stresses induced by the nonuniform temperature field were also analyzed.
Dependence of Stress-Related Reliability of Metallic Power Line on Physical Properties of Its Overlayer, Chip Location and Package Structure in Memory Devices
Authors: Lee Seong-Min
Published: April 2011

This work shows that shear failure in the metallic power line on the IC chip, which mainly takes place after plastic packaging, is always followed by mechanical damage in its overlayer. Thus, the topological feature of the metallic overlayer is important in defining shear damage in the metal line. On the other hand, since open failure in the metal line associated with stress migration is caused by tensile stress resulting from thermal mismatch with its overlayer, the physical properties of the overlayer plays an important role in determining open failure in the metal line. The FEM simulation shows how the tensile stress distribution along a metal line varies with the physical properties of its overlayer. The metallic overlayer with an initial coating of a ductile oxide layer was estimated to be a very effective way of minimizing tensile stress induced to the metal line. On the other side, shear damage of the metal line was found to be highly sensitive to the chip location or the package structure. The numerical calculation also indicates that shear stress applied to the passivated metal line, which reveals a maximum value at the chip comer, can be considerably reduced by chip premolding overcoating with ductile photosensitive polyimide.
Measuring Local Strain Variations Full-Field in Photoresist Thin Films Using Photolithographic Dot Arrays
Authors: Lin P.P. , Rowlands R. E.
Published: April 2011

Photoresist (such as PMMA) thin films are among the most important materials in semiconductor fabrication processes. Photolithography exclusively uses photoresist to construct the circuit pattern. The quality of a pattern relies on the uniformity of a photoresist layer. However, thermal expansion mismatch between the photoresist and silicon substrate during the subsequent thermal cycling process inevitably produces undesirable residual strains/stresses in the resist layer. Such residual fields can deteriorate the desired quality of the final pattern. A recently developed method is used here to record full-field strain information in the thin resist film.

Traditional methods such as wafer curvature measurement or x-ray diffraction (for crystalline films) have not been effective for measuring the full-field strains. However, using a deposited dot array in the interface between the film and substrate, one can measure the strains in the thin film, full-field, by analyzing the displacements of individual dots. A biquadratic surface model is employed to fit these dot pattern displacements. An IDL (Interactive Data Language, Research Systems Inc.) program is utilized repeatedly to accurately locate the positions of the individual dots and transform that information into displacement and strain data by differentiating the biquadratic surface. This study successfully demonstrates a straightforward approach to determine the residual strains, full-field, in photoresist thin films.
Investigations of Electromigration Failure by Electrical Measurement and Scanning Probe Microscopy With Additional Simulation
Authors: Fabricius Alexander , Breternitz Volkmar , Knedlik Christian , Henning Andreas , Liebscher Eckhard , Vogel Silvia
Published: April 2011

A set of 10, 5 and 2 µm wide, 500 µm long and 0.7 µm thick Al/Si/Cu-lines (1% Si, 0.5% Cu) was investigated under different stress conditions. Typical stress conditions were current densities of 2 to 6 MA/cm2and ambient temperatures of 125 to 225°C. For additional mathematical simulation it was important to observe the complete history of the resistance development from the beginning until the break down of the samples. Depending on the line width a number of different resistance developments and times to failure occured. Especially at smaller line widths, i. e. near to bamboo structures, the differences of the resistance development and times to failure are wide-ranging. This fact must be taken into acount for the simulation. Furthermore unpassivated samples were used to enable investigations of the structures by SEM and SPM. Measurements of the size of hillocks and voids has been carried out by AFM. Thereby twin-crystals were observed. This fact indicates that there are special strains, which could be estimated.

Another aspect of investigations was the exact measurement of the temperature in the break down area. For that purpose a special test structure with diodes underneath the stressed line was developed. These diodes are used to deduce local temperatures.
Effect of Thermal Treatment on the Hardness and Fracture Toughness of Sputter Deposited Bi-Layered Thin Films on Silicon
Authors: Manoharan M. , Narayanan B. , Muralidharan G.
Published: April 2011

Microhardness testing is widely used for characterizing the mechanical properties of both bulk materials and thin films. Although this technique is usually associated with hardness measurements, fracture properties of brittle materials can also be studied with cracking associated with microhardness indentations. It is well known that the length of radial cracks emanating from the comers of indents made with Vickers and Berkovich indenters is related to the fracture toughness of the material. In the present study, microhardness testing has been used to follow the evolution of the mechanical properties of a 10 nm.Cu/200 nm. Ni(V)/300 nm. Al(Cu) thin film deposited on a Si substrate. Composite hardness and fracture toughness have been followed as a function of heat treatment temperatures and times and were found to be dependent on both variables. The roles of residual stresses, interdiffusion, and intermediate phase formation in the observed variation in hardness and fracture toughness are discussed.
Segregation of Cu on Etched and Non-Etched Al(Cu) Surface
Authors: Li Hua , Maex Karen , Brijs Bert , Conard Thierry , Vandervorst Wilfried , Baklanov Michael , Boullart Werner , Froyen Ludo
Published: April 2011

In this paper, we have studied the segregation phenomenon of Cu on the surfaces of patterned lines, dry-etched films and non-etched films, by using X-ray photoelectron spectroscopy and lower energy Rutherford Backscattering Spectrometry. Significant enrichment of Cu is found on the sidewall of the lines. Annealing at 350°C and above cause the disappearance of this enrichment. Origin and evolution of this Cu enrichment have been investigated on films taken out from different steps of the etching process. It has been found that most of the Cu products induced by the plasma etching are CuCl and CuCl2 and they are removed mostly from the top Al oxide layer by the strip process. On the interface area between Al and the native oxide, considerable quantities of etched induced Cu are retained. This Cu is identified to be mainly metallic Cu. Different from the mechanism explained above, thermal annealing can also cause Cu segregation. We have found that Cu atoms diffuse into the native Al oxide where they form Cu2O.
Multilayer Microelectromechanical Structures for Material Property Characterization
Authors: Pratt R. I. , Johnson G. C.
Published: April 2011

A new class of micro-electro-mechanical systems (MEMS) for material characterization is presented. These multilayered structures are lateral resonators which allow the determination of material properties of the different materials making up the system. Of particular significance is the ability to characterize many new materials previously untestable by resonant techniques. The basic lateral resonant structures are made of a single material, usually doped polycrystalline silicon, with beams anchored to the substrate at one end and supporting a rigid mass at the other. The rigid mass has a comb-shaped region on each side for electrostatically actuating and sensing the motion. The use of this electrostatic comb drive requires that the structure be made of a material that is electrically conductive. Thus, the class of materials which is amenable to characterization by resonance techniques has been somewhat limited. Multilayer structures, tested in conjunction with these basic monolithic structures, permit properties of both the base material and the subsequent layers to be determined. Stiffness and mass density of many new materials can be obtained by comparing the behavior of multilayer structures with their single-layer counterparts. Experimental designs and the associated analytical techniques for obtaining various properties are presented.
Polysilicon Tensile Testing With Electrostatic Gripping
Authors: Sharpe W. N. , Turner K. , Edwards R. L.
Published: April 2011

Techniques and procedures are described for tensile testing of polysilicon specimens that are 1.5 or 3.5 νm thick and have various widths and lengths. The specimens are fixed to the wafer at one end and have a large free end that can be gripped by electrostatic forces. This enables easy handling and testing and permits the deposition of 18 specimens on a one-centimeter square portion of a wafer. The displacement of the free end is monitored, which allows one to extract Young's modulus from the force-displacement record. Some of the wider specimens have two gold lines applied so that strain can be measured interferometrically directly on the specimen to record a stress-strain curve.

The specimens were produced at the Microelectronics Center of North Carolina (MCNC). When compared with earlier results of wider MCNC specimens that were 3.5 μm thick, the Young's modulus is smaller and the strength is slightly larger.
The Effects of Texture and Doping on The Young's Modulus of Polysilicon
Authors: Lee Sangwoo , Cho Changho , Kim Jongpal , Park Sangjun , Yi Sangwoo , Kim Jongjun , Cho Dong-Il Dan
Published: April 2011

Polysilicon films deposited by low pressure chemical deposition (LPCVD) are the most widely used structural material for microelectromechanical systems (MEMS). However, the structural properties of LPCVD polysilicon films are known to vary significantly, depending on deposition conditions as well as post-deposition processes. This paper investigates the effects of phosphorus doping and texture on Young's modulus of polysilicon films. Polysilicon films are depostied at 585°C, 605"C, and 625°C to a thickness of 2µm. Specimens with varying phosphorus doping levels are prepared by diffusion doping at various temperatures and times using both POCl3 and phosphorsilicate glass (PSG) as the source. Texture is measured using an X-ray diffractometer. Young's modulus is calculated by taking the average of the values calculated from the resonant frequencies of four-different size lateral resonators. Our results show that Young's modulus of diffusion doped polysilicon films decreases with increasing doping concentration, and increases with increasing <111> texture.
Finite Element Simulations of the Mechanical Stress in and Around Narrow Tisl2Lines
Authors: Steegen A. , De Wolf I. , Maex K. , Ignat M.
Published: April 2011

The primary objective of this work is to carry out a combined experimental and numerical investigation of the mechanical stress induced during the Ti-silicidation of narrow lines spaced by a Poly Buffered Local field oxide. Therefore micro-Raman spectroscopy (μRS) measurements of local mechanical stress are combined with simulations by Finite Element Modeling (FEM). Numerical determination of the local stress in the Si-substrate by means of FEM becomes more and more important when scaling down the device dimensions because the spatial resolution of μRS is limited at about 1μm and because the stress in the Si-substrate underneath silicided lines can not be detected using pRS unless the silicide is very thin. The Finite Element analysis was done using SYSTUS and involves a two dimensional plane strain thermo-elastic formulation. A good agreement was obtained between the FEM simulations and the μRS data for line widths above 1Bm making the extrapolation of the FEM to line widths smaller than I1m an attractive alternative for μRS.
Dopant Mapping and Strain Analysis in B Doped Silicon Structures Using Micro-Raman Spectroscopy
Authors: Bowden M. , Gardiner D. J. , Lourengo M. A. , Hedley J. , Wood D. , Burdess J. S. , Harris A. J.
Published: April 2011

Raman microscopy, using a novel line focus configuration, has been used here to study boron concentration distributions and depth profiles in silicon for two different sources of dopant. Changes in the Raman phonon peak frequency for boron doped silicon have been calibrated against concentration by comparison with SIMS data and a relationship between Raman shift and lattice strain has been obtained.
Measurement of Mechanical Properties in Small Dimensions by Microbeam Deflection
Authors: Kraft O. , Schwaiger R. , Nix W.D.
Published: April 2011

In this paper, we describe a technique for measuring elastic and plastic properties of thin films by microbeam deflection. The test procedure is similar to a macroscopic bending test where an external load is applied to a beam and its bending measured. Silicon oxide microbeams were made by different growth, lithography and etching techniques. The beams were then deflected with a nanoindenter, while the applied load and the displacement of the beam were recorded. Young's modulus was determined from the initial linear load-displacement behavior. Some beams were notched using a focused ion beam technique and loaded until brittle fracture occurred. These measurements permit the determination of the fracture toughness of the beam materials. In order to study plastic deformation in thin Ag films, the method was extended by depositing films onto the beams and measuring the behavior of the beam/film composite. Yielding of the Ag film was seen as a deviation from the linear-elastic behavior of the beam.
Amine Templated Zinc Phosphates Phases for Membrane Separations
Authors: Nenoff Tina M. , Chavez Alejandra V. , Thoma Steven G. , Provencio Paula , Harrison William T. A. , Phillips Mark L. F.
Published: April 2011

Our research is focused on developing inorganic molecular sieve membranes for light gas separations such as hydrogen recovery and natural gas purification, and organic molecular separations, such as chiral enantiomers. We focus on zinc phosphates because of the ease in crystallization of new phases and the wide range of pore sizes and shapes obtained. With our hybrid systems of zinc phosphate crystalline phases templated by amine molecules, we are interested in better understanding the association of the template molecules to the inorganic phase, and how the organic transfers its size, shape, and (in some cases) chirality to the bulk. Furthermore, the new porous phases can also be synthesized as thin films on metal oxide substrates. These films allow us to make membranes from our organic/inorganic hybrid systems, suitable for diffusion experiments. Characterization techniques for both the bulk phases and the thin films include powder X-ray diffraction, TGA, Scanning Electron Micrograph (SEM) and Electron Dispersive Spectrometry (EDS).
On-Line Spectroscopic Studies of Group iv Alkoxides and their Interactions with Polymerizable Organic Additives During the Sol-Gel Process
Authors: Cinier R. , Guilment J. , Poncelet O. , Truchet S. , Wettling D.
Published: April 2011

The monitoring of different reactions such as the stabilization of the alkoxides with polymerizable organic additives, the building of the inorganic network during the hydrolysis process, and in a same manner, the polymerization of the organic additives, can be of great importance for the development of hybrid materials with improved processability.

NIR spectroscopy is a very versatile technique but lacks of specificity. IR and Raman give more interpretative results but are not always easy to run on a process. We used both techniques along with chemometric tools to extract relevant information from our processes. Then 2D correlation allowed to benefit from the specificity of IR and Raman to develop robust NIR methods able to be used on line to control the different steps of the sol-gel process.

The hydrolysis of mixed species of titanium containing chloro, isopropoxo and methacrylato ligands will be discussed in terms of mechanism occuring during the sol-gel process.
Characterization of Dendrimer-Based Nanocomposites by Saxs and Sans
Authors: Tan N. C. Beck , Balogh L. , Trevino S. F. , Tomalia D. A. , Lin J. S.
Published: April 2011

Dendritic polymers have been used as soluble templates/unimolecular reactors from which nano-clusters of inorganic compounds were synthesized. These organic/inorganic, dendrimerbased hybrid species or “nanocomposites” display unusual properties, i.e., their solubility is deterrnined by the properties of the dendrimer molecules. Since it has been established that there is no covalent bond between the dendrimer host and the inorganic guest, these observations suggest that the guests are physically and spatially restricted by the dendrimer shell. However, this structure has not been verified. In this investigation a preliminary understanding of the physical structure of these dendrimer-based nanocomposites was sought. A model system of PAMAM dendrimer-copper sulfide nanocomposites was studied in various stages of its formation using a combination of small angle X-ray and neutron scattering experiments. The results suggest that little perturbation of the dendritic species occurs on complexation, but indicate that a secondary supermolecular aggregation phenomena occurs within nanocomposite solutions.
Hybrid Materials : Intricate Structures Guiding Complex Dynamics
Authors: Judeinstein P.
Published: April 2011

The structure and certain properties of Class {I} and Class {II} nanocomposites based on silica-poly(ethylene)oxide blends are described herein. The detailed structure of the silica framework of Class {I} materials is depicted by combining 29Si NMR and X-Ray diffractometry, while the properties of the polymer phase are obtained from 13C NMR and thermal analysis (DSC). These experiments demonstrate the significant influence of the catalyst on the silica structure (compositional and positional disordering). Moreover, the dynamic properties of the polymer phase are greatly effected by the silica morphologies (silica surface area and degree of phase interpenetration). Class {II} materials were also studied. They have rubbery properties and can be used as a matrix to absorb large quantities of solvents. Hence, combining uniaxial anisotropy (through unidirectionnal strain) with deuterated molecules enabled the study of these materials by quadrupolar NMR. This technique is very sensitive to the local anisotropy of the samples used and leads to a better understanding of supramolecular interactions between probe and host polymer.
Organic Dye-Doped Hybrid Sol-Gel Coatings and Pigments – Synthesis, Structural Elucidation and Application
Authors: Schottner G. , Hofacker S. , Sandrock J.
Published: April 2011

The chemistry of sol-gel processing of dye-doped, hybrid coatings for glass surfaces has been studied via FT-Raman-, NIR- and NMR-spectroscopy both in the liquid and solid state. Based on these results further investigations are presented aiming at the development of new hybrid pigments by spray drying of two-component sols. The properties of the resulting powders are discussed with respect to their morphology, migration behaviour and photostability.
Photoluminescence of Eu3+:Y2O3 Nanoclusters Embedded in SiO2 Glass
Authors: Jia Weiyi , Wang Yanyun , Santiago Miguel , Castro Limari , Liu Huimin , Claflin B. , Lucovsky G.
Published: April 2011

Eu3+(1at%) doped and Eu3+"(1at%), Y3+(10at%) codoped SiO2 glasses were prepared by sol-gel technology. Dominant red emission at 615 nm from 5D0to 7F2of Eu3+ was observed from both samples annealed above 800 °C. The intensity of luminescence of Eu, Y codoped samples is three times stronger than that of Eu doped samples. The lifetime of the former is two times longer than the latter. An analysis indicates that in the sample of Eu, Y codoped SiO2 glass, Eu3+ ions stay in the Y2O3 nanoclusters, which were formed during the annealing process and embedded in SiO2.
Hybrid Materials Made by Polymerization of the Nanobuilding Blocks {(BuSn)12O14,(OH)6,}2+(AAMPS−)2 (AAMPS = 2-acrylamido-2-methyl-l-propanesulfonate)
Authors: Ribot F. , Eychenne-Baron C. , Sanchez C.
Published: April 2011

The reaction of {(BuSn)12014(OH)6}(OH)2 and 2-acrylamido-2-methyl-1-propanesulfonic acid yields bifunctional nanobuilding blocks, {(BuSn)12,014(OH)6)(AAMPS)2, which carry highly polymerizable acrylamido groups. In such species, the functionalization with polymerizable groups is achieved through electrostatic interaction; the charge compensating anions AAMPS− being located at both poles of the {(BuSn)12O14(OH)6}2+ macrocation. Free radical polymerization of these nanobuilding blocks in THF yields an insoluble material. Solid state 13C CP-MAS NMR of the insoluble fraction (∼70%) indicates that the polymerization of the acrylamido groups is complete. Solid state 119Sn MAS NMR shows that the oxo-hydroxo butyltin core of the nanobuilding blocks is fully preserved in the final material.
The Cubeoctameric Silicate Anion: Formation and Application to Porous Material Synthesis
Authors: Hasegawa Isao
Published: April 2011

The cubeoctameric silicate anion is one of compounds which can be used as a building block for constructing nanostructures of materials. This paper deals with the synthesis and reactivity of the silicate anion and organic-inorganic hybrid and inorganic multi-component porous materials produced from the anion.
Novel Uv-Curable Low-Shrinking Silanes as Precursors for the Sol-Gel-Process
Authors: Stein S. , Moszner N. , Voelkel Th. , Rheinberger V.
Published: April 2011

The increasing interest in inorganic-organic nanocomposites which offer the possibility to build up both an inorganic and organic network by hydrolysis and condensation and by polymerization reactions, respectively, leads to the development of a new class of double bond functionalized silanes. These 2-vinylcyclopropyl silanes were synthesized e.g. by reaction of 1-methoxycarbonyl-2-vinylcyclopropane-l-carboxylic acid with 3-isocyanatopropyltriethoxysilane. Hydrolysis and condensation of the alkoxy groups as well as cocondensation with tetraalkoxysilanes lead to solvent-free liquid resins that can be cured by UV-light-induced radical polymerization of the vinylcyclopropane group. The synthesis and characterization of different 2-vinylcyclopropyl silanes, hydrolysation and condensation behavior and first results of the radical polymerization will be discussed.
Microwave Assisted Blending-Intercalation of Ion-Conductor Polymers into Layered Silicates
Authors: Aranda P. , Galván J.C. , Ruiz-Hitzky E.
Published: April 2011

Organo-inorganic hybrid nancomposites derived from poly(ethylene oxide) and montmorillonite silicate are prepared by an alternative procedure to classical polymer intercalation either from solutions or by polymer melt-intercalation. XRD, FTIR, DSC, elemental microanalysis and SEM techniques are applied for structural characterization of the resulting materials. The electrical properties of these nanocomposites are studied by means of the electrical impedance spectroscopy (EIS) showing enhanced ionic conductivity compared to similar samples prepared by intercalation from solution.
Systematic Approach to the Synthesis of Organic-Inorganic Nanocomposites Based on Dmta Measurements and Ir Spectroscopy
Authors: Müller Peter , Becker Carsten , Schmidt Helmut
Published: April 2011

Sol-gel derived organic-inorganic hybrid materials with potential fields of application as refractive optical components for example laser diode bars and ophthalmic lenses are presented. The main components of the hybrid materials under investigation are precondensed methacryloxypropyltrimethoxysilane (MPTS, denoted: M) with an organically polymerisable methacrylic functionality and tetraethyleneglycoldimethacrylate (TEGDMA, denoted: T) as crosslinking organic monomer with two polymerisable double bonds. The molar ratios of the components ranged from M/T 10/90 up to M/T 70/30. The polymer derived from pure TEGDMA (M/T 0/100) served as a reference material. In addition to this nanoscaled TiO2 particles (5 wt.% and 10 wt.%) were incorporated in the organic-inorganic M/T 30/70 matrix to increase the refractive index of the resulting nanocomposites. For the preparation of the different systems, precondensed MPTS was mixed with TEGDMA, the nanoparticulate titania sol (when used), an appropriate photoinitiator and a thermoinitiator. The reaction mixtures were polymerised photochemically and/or thermally. The propagation of the free radical polymerisation reaction after photopolymerisation and subsequent thermal curing was followed by IR-spectroscopy, showing that the degree of double bond conversion is strongly increased by the thermal curing step. Incorporation of increasing amounts of TiO2 nanoparticles resulted in reduction of the double bond conversion compared to the corresponding unfilled system. The homogeneous dispersion of the titania particles in the completely cured M/T 30/70 matrix could be manifested by high resolution transmission electron microscopy (HTEM). The thermomechanical properties of the completely cured nanocomposites were monitored by dynamic mechanical thermal analysis (DMTA) showing a strong dependence on composition.
Investigation of Transition Metal-Xanthate Complexes for Nonlinear Optical Applications
Authors: Zelmon David E. , Gebeyehu Zewdu , Tomlin David , Cooper Thomas M.
Published: April 2011

We have synthesized several metal xanthate complexes from metal salts and xanthate potassium salts. Powders of several of the materials were sorted and tested for their nonlinear optical properties. Cadmium xanthate demonstrated phase matchability for frequency doubling of 1.06 micron light and generated a very strong second harmonic signal.
Incorporation of Siloxane And Cyclophosphazene Units Into Metal Oxides by a Nonhydrolytic Sol-Gel Route
Authors: Crouzet L. , Leclercq D. , Mutin P. H. , Corriu R. J. P. , Vioux A.
Published: April 2011

A nonhydrolytic sol-gel method was used to incorporate siloxane and cyclotriphosphazene units within metal oxides. The degree of mixing of the components was investigated by EDX, XPS, and 29Si and 31P solid-state NMR. The NMR data confirmed the presence of Si-O-M and PO- M bonds.
Self-Assembly of Organic-Inorganic Nanocomposite Coatings that Mimic the Structure of Shell
Authors: Sellinger Alan , Weiss Pilar M. , Nguyen Anh , Lu Yunfeng , Assink Roger A. , Brinker C. Jeffrey
Published: April 2011

After over a decade of research, the efficient synthesis and processing of layered organic/inorganic nanocomposites that mimic bone and shell structures remains an elusive goal of the materials chemist. We report on a rapid, efficient, continuous method to form layered nanocomposites via evaporation induced supramolecular self-assembly (SSA). During dip coating of a homogeneous sol containing alcohol or ether solvents, silica precursors, organic monomers, initiators and surfactant (at an initial concentration below cmc), solvent evaporation induces the formation of micellar structures that co-organize with silica to form cubic, hexagonal or lamellar mesophases. The organic monomers and initiators are solvated within the hydrophobic micellar interiors. Subsequent photo or thermal polymerization and washing results in a silica/polymer thin film nanocomposite. The microstructural and physical characteristics of these materials will be discussed in the context of potential applications as abrasion resistant coatings and optical hosts.
Preparation of Tem Plan View Sections on Specific Devices Using the Tripod Polisher
Authors: Benedict J. P. , Anderson R. M. , Klepeis S. J.
Published: April 2011

Plan view or “top down” sections of specific sites for TEM analysis can be prepared by mechanically polishing the specimen with the Tripod Polisher. This technique produces plan view sections with a large area available for TEM analysis that encompasses the specific site. Because the sample is mechanically polished, the problem of surface topography due to non uniform thinning is minimized.
Dislocations in InAs Epilayers Grown by MBE on GaAs Substrates Under Various Conditions
Authors: Wang Hongmei , Zeng Yiping , Pan Liang , Zhou Hongwei , Zhu Zhanping , Kong Meiying
Published: April 2011

Using Transmission Electron Microscopy, we studied the misfit and threading dislocations in InAs epilayers. All the samples, with thickness around 0.5μm, were grown on GaAs(001) substrates by molecular beam epitaxy under As-rich or In-rich conditions. The As-rich growth undergoes 2D-3D mode transition process, which was inhibited under In-rich surface. High step formation energy under As-deficient reconstruction inhibits the formation of 3D islands and leads to 2D growth. The mechanism of misfit dislocations formation was different under different growth condition which caused the variation of threading dislocation density in the epilayers.
Ordering in Compound Semiconductors: The Role of Transmission Electron Microscopy
Authors: Su D. S. , Tham A. T. , Schubert-Bischoff P. , Hähnert I. , Neumann W. , Giersig M. , Zeitler E.
Published: April 2011

In this paper, the ordering of ternary semiconductor compounds is briefly reviewed by means of a coordination polyhedron model. Long-range ordering of chalcopyrite and CuAu-type structures can be represented as an array of repeating A2B2 tetrahedra. A CuAu-type ordered phase in a chalcopyrite AIBIIICVI2 compound is surrounded by an A3B+ AB3 boundary, whereas a CuPt-type ordered phase in a zinc-blende (A, B)IIICV compound is surrounded mainly by A2B2 type tetrahedra and thus restricted in size. Following the description of the ordered structure model, the detection of the asymmetry in ordering directions in (A, B)IIICV compounds is discussed. Some examples that employ transmission electron microscopy are presented.
In Situ Monitoring of the Electrochemical Absorption of Deuterium into Palladium by X-Ray Diffraction using Synchrotron-Wiggler Radiation
Authors: Dominguez D. D. , Hagans P. L. , Skelton E. F. , Qadri S. B. , Nagel D. J.
Published: April 2011

With low energy x-rays, such as those from a Cu x-ray tube, only the outer few microns of a metallic sample can be probed. This low penetrating power prohibits structural studies from being carried out on the interior of an electrode in an electrochemical cell because of absorption by the cell material, electrodes and the electrolyte. The work described in this paper circumvents this problem by utilizing high energy, high brightness x-rays produced on the superconducting wiggler beam line, X-17C, at the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory. The penetrating power of the higher energy x-rays allowed Pd diffraction spectra to be obtained in-situ on a 1 mm diameter Pd wire cathode during electrolysis of heavy water. Moreover, the beam (28 × 28 μm in cross-section) allowed diffraction spectra to be acquired as a function of distance across the sample. Spectra were recorded in 50 μm steps from the edge of the Pd wire to its core. This was done at 2 minute intervals as a function of electrolysis time. The α-β phase transition induced in the Pd while deuterium was electrochemically absorbed was observed by monitoring the Pd-(422) diffraction peaks. Results allowed the diffusion rate and the diffusivity of deuterium atoms in the Pd wire to be determined. Other features of the structural changes associated with the absorption of deuterium into Pd are reported.
High Pressure Synchrotron Diffraction of KCa2Nb3O10, a Layered Perovskite Compound
Authors: Steiner K. A. , Petuskey W. T.
Published: April 2011

High pressure synchrotron x-ray diffraction experiments were conducted on KCa2Nb3O10, to determine lattice constants as a function of pressure. A diamond anvil cell was used to produce pressures up to 66 GPa. A phase transition occurred at 13.5 GPa. From the lattice constants, linear compressibilities of 8.55 × 10-4 GPa-1 in the a direction, -9.40 × 10-4 GPa-1 in the b direction, and 142 × 10-4 GPa-1 in the c direction, and a bulk modulus of 68.5 GPa were found for the lower pressure orthorhombic phase.
Comparison Of A Mosaic-Crystal Spectrometer To Ahigh-Performance Solid-State Detector For X-Ray Microfluorescence Analysis
Authors: Chung J.-S. , Isa S. , Sparks C. J. , Ice G. E. , Mchugo S. , Thompson A.
Published: April 2011

The minimum-detectable-limit of a compact double-focusing graphite mosaic-crystal spectrometer is compared to the minimum-detectable-limit from a high-performance Ge solidstate detector. The solid angle and efficiency of the solid-state detector is much greater than for the crystal spectrometer. However, the better signal-to-noise of the spectrometer and its insensitivity to matrix fluorescence and scattering can give it a better minimum-detectable-limit for trace element analysis. The relative advantages of the two detectors are illustrated for some simple test samples. The performance of the crystal spectrometer compared to the solid-state detector increases as the flux in the x-ray probe increases. This makes crystal spectrometers especially interesting for use with new high intensity 3rd generation synchrotron microprobes. An estimate is made of the source and sample conditions favored for each detector.
Spectroscopic Studies of Low Dielectric Constant Fluorinated Amorphous Carbon Films for Ulsi Integrated Circuits
Authors: Ma Yanjun , Yang Hongning , Guo J. , Sathe C. , Agui A. , Nordgren J.
Published: April 2011

Performance of future generations of integrated circuits will be limited by the RC delay caused by on-chip interconnections. Overcoming this limitation requires the deployment of new high conductivity metals such as copper and low dielectric constant intermetal dielectrics (IMD). Fluorinated amorphous carbon (a-CFx) is a promising candidate for replacing SiO2 as the IMD. In this paper we investigated the structure and electronic properties of a-CFx thin films using high-resolution x-ray absorption, emission, and photoelectron spectroscopy. The composition and local bonding information were obtained and correlated with deposition conditions. The data suggest that the structure of the a-CFx is mostly of carbon rings and CF2 chains cross-linked with C atoms. The effects of growth temperature on the structure and the thermal stability of the film are discussed.
The Spin Polarized Band Structure of Strained Thin Films of Gadolinium
Authors: Waldfried C. , Dowben P.a , Vescovo E.
Published: April 2011

The magnetic properties of strained thin films of gadolinium are characterized by a wave vector and thickness dependence of the exchange splitting. The spin-resolved band structure has been mapped by spin polarized photoemission, and provides considerable insight into the relationship between magnetism of local moment systems, and band structure.
Chemical Analysis of Particles and Semiconductor Microstructures by Synchrotron Radiation Soft X-Rays Photoemission Spectromicroscopy
Authors: Gozzo F. , Triplett B. , Fujimoto H. , Ynzunza R. , Coon P. , Ayre C. , Kinney P. D. , Uritsky Y. S. , Ackermann G. , Johnsono A. , Padmore H. , Renner T. , Sheridan B. , Steele W. , Hussain Z.
Published: April 2011

Chemical analysis on a microscopic scale was performed on a TiN particle sample on silicon and on two patterned samples using a synchrotron source scanning photoemission microscope. For all the experiments, we exploit the ability, developed in our experimental system, to reach specific locations on the wafer and analyze the local chemical state.
Characterizing Trace Metal Impurities in Optical Waveguide Materials Using X-Ray Absorption
Authors: Citrin P. H. , Northrup P. A. , Atkins R. M. , Glodis P. F. , Niu L. , Marcus M. A. , Jacobson D. C.
Published: April 2011

X-ray absorption measurements are described for identifying metal impurities in
silica preforms, the rod-like starting materials from which hair-like optical fibers are drawn.
The results demonstrate the effectiveness of this approach as a non-destructive,
quantitative, element-selective, position-sensitive, and chemical-state-specific means for
characterizing transition metals in the concentration regime of parts per billion.
Surfaces of Semi-Fluorinated Block Copolymers Studied Using Nexafs
Authors: Genzer J. , Sivaniah J. E. , Kramer E. J. , Wang J. , Körner H. , Xiang M.-L. , Yang S. , Ober C. K. , Char K. , Chaudhury M. K. , Dekoven B. M. , Bubeck R. A. , Fischer D. A. , Sambasivan S.
Published: April 2011

The molecular orientation within a surface liquid crystalline layer made up of semifluorinated side-groups [-CO-(CH2)x−x-(CF2)yF] (SF groups) attached to the isoprene block of a styrene-isoprene diblock copolymer was determined by analyzing the partial electron yield Cedge NEXAFS signal. The results show that in contrast to the bulk, where the SF groups lie parallel to the diblock copolymer lamellae and thus parallel to the surface, the surface SF groups make an average angle with the surface normal of between 29 and 46° depending on x and y.
UV-Laser Ablation of HFO2 Dielectric Layers on SiO2 for Mask Preparation
Authors: Rubahn K. , Ihlemann J.
Published: April 2011

The thickness dependence of ablation rates following 193nm UV-laser irradiation of single HfO2 layers on fused silica (SiO2) is investigated using scanning electron microscopy and stylus profilometry to determine quantitatively substrate roughness and ablation depth. Thin dielectric films of the investigated kind build up dielectric mirrors, which are patterned to prepare masks for excimer-laser micromachining. The single pulse ablation thresholds are found to increase approximately linearly with increasing HfO2 thickness and consequently the threshold fluence for obtaining clean ablation of the total HfO2 coating increases exponentially with its thickness. At elevated fluences both ablation of the coating as well as ablation of the substrate are observed. The results provide important quantitative values for a future treatment of more complicated multilayer systems of HfO2/SiO2 bilayers.
Synthesis and Characterization of Ferroelectric Thin Films by KrF Excimer Laser Ablation for Memory Applications
Authors: Kumar Ashok , Alam M.R.
Published: April 2011

Pb(ZrxTi1-x)O3 (lead zirconate titanate or PZT) ferroelectric thin film capacitors are of considerable interest for the realization of memory devices such as nonvolatile random access memories (NVRAMs). The PZT capacitors were prepared on platinized silicon Pt/(100)Si using conducting oxide LaxSr1-xCoO3 (lanthanum strontium cobalt oxide or LSCO) as electrodes. The PZT and LSCO thin films were deposited by the KrF excimer laser ablation technique. The optimum preparation conditions such as oxygen pressure, laser energy influence and substrate temperature were investigated. The PZT and LSCO films grown on Pt/(100)Si are polycrystalline. The crystallographic properties of the films were determined using X-ray diffractometer (XRD) method. The electrical characterizations of the films including hysteresis loop, fatigue, and retention properties were determined by the RT66A Standardized Ferroelectric Test System.
Laser Deposited Iron Garnet Films for Magneto-Optic Applications
Authors: Kim H. , Duan M. , Grishin A.M. , Rao K.V.
Published: April 2011

Submicron thick Bi, Ga substituted dysprosium iron garnet films were laser deposited on Gd3Ga5O12(GGG) and ceramic glass substrates at room temperature and then post annealed by rapid thermal annealing (RTA). From Faraday rotation studies, the films deposited on glass substrates are found to exhibit perpendicular magnetic anisotropy, Faraday rotation of 0.88 deg / μm, and coercive field Hc of 0.88 kOe. On the other hand, films deposited on GGG substrates with the same processing parameters are found to exhibit perpendicular anisotropy, but with much smaller values for Faraday rotation(0.03 deg; μm) and coercive field Hc(0.018 kOe). The uniaxial magnetic anisotropy with easy magnetization axis perpendicular to the film surface is caused by the stress induced on the polycrystalline film / substrate interface. The effect of changing the oxygen pressures, in the range of 20 to 100 mTorr during the deposition process, on the crystalline structure as well as coercive field and Faraday rotation angle are also presented.
The Effect of Gas-Surface Interactions on Laser-Generated BaTiO3Plumes
Authors: Paul Albert J. , Hastie John W. , Bonnell David W. , Schenck Peter K. , Vaudin Mark D.
Published: April 2011

Two models, based on hydrodynamic and Direct Simulation Monte Carlo approaches, have been investigated for the simulation of species fluxes arriving at substrates during pulsed laser deposition of thin films. The models are assessed in light of the results of mass spectrometric and optical imaging observations of the plume. Model predictions of film composition are compared with the results of microscopic compositional analysis across a deposited BaTiO3film. The spatial distributions of the relative abundance of total Ba and Ti were a particular focus of this study, with the latter model giving the best agreement with experiment. The Monte Carlo simulation results indicate that the incoming concentration ratio of total Ba to Ti, across the substrate surface, is strongly modified by gas collisions within a compressed region that forms between the infalling plume and the substrate surface, and also by momentum exchange (scattering) between the lighter plume species and the added background gas.