bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laser Induced Metal and Alloy Plating with Simultaneous Silicide Compound Formation
Authors: Zahavi J. , Tamir S. , Halliwell M. 
Published: March 2011

AbstractHighly selective metal and alloy deposition with simultaneous silicide formation - on semiconductor substrates immersed in commercial electroplating solutions has been investigated via pulse laser irradiation without masking procedures and external electric current.Specimens of 5i and GaAs substrates, immersed in gold and in palladiumnickel electroplating solutions, were irradiated by a Qswitch YAG pulse laser perpendicular to their surfaces at predesired local zones. The gold, palladium and nickel deposits thus obtained were subsequently examined and characterised by SEM, TEM, AES, ESCA and RBS.Deposit thickness ranged from a few hundred angstroms to several micrometers, depending primarily on the laser irradiation energy. The elemental Gold deposit exhibited Schottky barrier contacts with the GaAs and Si substrates. Palladium and nickel silicides obtained on n-type silicon substrates likewise exhibited Schottky behavior contracts.
Rapid Thermal Processing and The Quest for Ultra Shallow Boron Junctions
Authors: Sedgwick Tom 
Published: March 2011

AbstractRapid Thermal Processing (RTP) can minimize processing time and therefore minimize dopant motion during annealing of ion implanted junctions. In spite of the advantage of short time annealing using RTP, the formation of shallow B junctions is thwarted by channeling, transient enhanced diffusion and concentration enhanced diffusion effects all of which lead to deeper B profiles. Channeling and transient enhanced diffusion can be avoided by preamorphizing the silicon before the B implant. However, defects at the original amorphous/crystal boundary persist after annealing. Very low energy B implantation can lead to very shallow dopant profiles and in spite of channeling effects, offers an attractive potential shallow junction technology. In all of the shallow junction formation techniques RTP is required to achieve both high activation of the implanted species and minimal diffusion of the implanted dopant.
Using Rapid Thermal Processing to Induce Epitaxial Alignment of Polycrystalline Silicon Films on (100) Silicon
Authors: Harrison H.B. , Johnson S.T. , Komem Y. , Wong C. , Cohen S. 
Published: March 2011

AbstractUndoped polycrystalline silicon (poly-Si) films obtained by low pressure chemical vapour deposition (LPCVD) techniques have previously been demonstrated to align epitaxially with respect to the underlying (100) silicon substrate in the 1000-1100°C temperature regime. However the alignment rate at temperatures in excess of 1100°C is too rapid to be obtained by conventional furnace processing. Rapid Thermal Processing (RTP) offers an excellent technique of attaining this temperature in the requisite time and in this paper we report on the results of a study in which RTP has been used. Our results show an activation energy of ∼4.5eV, and that the growth rate constant is dramatically enhanced, without any alignment delay in the initial heat treatment phase, which is contrary to previous findings.
Effects of Pre-Gate Oxidation Cleaning and Gettering Upon The Very Thin Oxide Integrity
Authors: Lee J. , Tung C. Y. , Hahn S. , Chiao P. 
Published: March 2011

AbstractVarious pre-gate oxide cleaning and gettering techniques on the integrity of thin gate oxide were investigated. A 100 Å thick oxide capacitor was used to study its time-dependent breakdown characteristics and minority carrier lifetime. It has been shown that the oxide integrity as measured by time-dependent breakdown and the minority carrier lifetime are very sensitive to the cleaning technique. On the other hand, given adequate cleaning process, different intrinsic gettering schemes may only influence the oxygen precipitation, as well as the minority carrier lifetime, but not the oxide integrity.
The Influence of Point Defects on Two Dimensional Diffusion Kinetics
Authors: Griffin P.B. , Plummer J.D. 
Published: March 2011

AbstractThe problems associated with two-dimensional diffusion of impurities coupled with point defects are outlined. The relative importance of the generation, diffusion and surface recombination rates are examined and the implications for 2-D modelling are discussed. Experimental results for the diffusion coefficient of interstitials indicate that the point defects can have orders of magnitude faster diffusivity than dopants. For accurate 2-Dprofiles, a large simulation space is needed to solve for the defects even though the impurity diffusion of interest occurs in the near surface region. The lateral extent of the diffusion profile is determined by the surface recombination rates of the defects. Results indicate that different technologically important interfaces, such as nitride and pad oxide have different recombination rates. The time dependence of the lateral decay isexperimentally investigated and indicates a steady state condition being reached. Parameters are extracted for the 2-D process simulator SUPREM-IV and the computer simulations are compared with experiment.
Synthesis and Sintering Comparison of Cordierite Powders
Authors: Bernier J. C. , Rehspringer J. L. , Vilminot S. , Poix P. 
Published: March 2011

ABSTRACTCordierite and cordierite based glass ceramics are promising materials for electronic packaging. Preparations by organic and inorganic precursors along sol-gel processing are reported. Compared with conventional methods, they show a drastic decrease of the sintering temperatures. A process able to giving better than 95% theoretical density ceramic below 1000°C, with good electronic properties is described.
Synthesis and Processing of the Sol-Gel Derived β-Quartz Lithium Aluminum Silicates
Authors: Covino J. , Laat F. G. A. De , Welsbie R. A. 
Published: March 2011

ABSTRACTLithium Aluminum Silicate (LAS) glass-ceramic compositions with and without phosphorous have been synthesized by Sol-Gel techniques. Resulting LAStype powders are herein designated as NZ and NZP. X-Ray analysis, thermogravimetric analysis (TGA), particle size measurements, and thermal dilatometric shrinkage measurements have been performed on these samples. The NZ and NZP powders in calcined form, as well as commercially-available LAS glass-ceramic produce x-ray diffraction pattern very similar to the pattern of Virgilite LixAlxSi3−xO6 (x=0.5–1.0). There is little difference between powders with and without phosphorous in the diffuse reflectance spectra (DRS). Preliminary results show that the material can be easily processed into glass ceramics.
A Solid State Multinuclear Magnetic Resonance Study of the Sol-Gel Process using Polysilicate Precursors
Authors: Klemperer W. G. , Mainz V. V. , Millar D. M. 
Published: March 2011

ABSTRACTA solid state multinuclear NMR study of the sol-gel process was performed using the molecular building blocks tetramethoxysilane, hexamethoxydisiloxane, octamethoxytrisiloxane and octamethoxyoctasilsesquioxane as precursor monomers. Water content, solvent content, and hydrolysis/condensation processes were monitored using 17O, 13C, and 29Si FT, FTMAS and CPMAS NMR techniques.
High field 1H NMR Studies of Sol-Gel Kinetics
Authors: Kay Bruce D. , Assink Roger A. 
Published: March 2011

ABSTRACTHigh resolution 1H NMR spectroscopy at high magnetic fields is employed to study the reaction kinetics of the Si(OCH3)4:CH3OH:H2O sol-gel system. Both the overall extent of reaction as a function of time and the equilibrium distribution of species are measured. In acid catalyzed solution, condensation is the rate limiting step while in base catalyzed solution, hydrolysis becomes rate limiting. A kinetic model in which the rate of hydrolysis is assumed to be independent of the adjacent functional groups is presented. This model correctly predicts the distribution of product species during the initial stages of the sol-gel reaction.
Stereo-Tem Imaging of Sol-Gel Glass Surfaces
Authors: Ruben George C. , Shafer Merrill W. 
Published: March 2011

ABSTRACTSol-gel top and cross-fractured surfaces have been Pt-C replicated (9.7–11.3 Å thick) and carbon film backed (100–145 Å thick) and separated from the gel with an HF solution. Samples made from both base catalyzed LUDOX/Kasil mixtures and acid catalyzed alkoxides were studied with tilt series of 104 to 105 magnification TEM mlcrographs of the surface replicas. The LUDOX/Kasil gels contained spherical particles with a raspberry-like morphology and the acid catalyzed alkoxIdes are composed of densely packed filaments and no apparent particles. The smallest structural entity in both gels are Pt/C coated filaments (12–14Å) estimated to be 1.5–2.7 Å in width. The pore sizes were characterized in both gel types, though TEM pore measurements were only made on the LUDOX/Kasil gels.
Drying Mechanics of Gels
Authors: Scherer George W. 
Published: March 2011

ABSTRACTA model is presented for the stresses and strains that develop in a gel during drying. The driving force for shrinkage is assumed to be the interfacial energy, and the gel is considered to be viscoelastic. The liquid seeks to flow into the dry region of a gel in order to replace the solid-vapor interface with a solid-liquid interface having lower specific energy. This creates a “redistribution pressure” that causes the wet region to contract. The free contraction rate can be calculated by equating the decrease in surface energy with the energy dissipated in viscous flow as the gel contracts. The permeability of the gel to the liquid in the pores is especially important in the early stages of drying, and may control the contraction rate. The model allows quantitative predictions of contraction rate and stress during drying. In this paper, the model is applied to a plate drying from both sides.
Calculated Vs Measured Viscosities of Sol-Gel Processed Silica
Authors: Gallo T. A. , Klein L. C. 
Published: March 2011

ABSTRACTThe densification of sol-gel processed silica was studied by comparing calculated and measured viscosities between 700 and 850°C. Linear shrinkage was measured in a dilatometer. From shrinkage data, relative bulk densities were determined. The densities were used in a model for viscous sintering to calculate viscosities. Beam-bending viscosimetry was used to determine viscosities directly. The deflection rate of a centrally loaded beam was measured. Both the calculated and measured viscosities had the same time dependence. The temperature dependence was also determined.
Fluorine In Silica Gels
Authors: Rabinovich E. M. , Wood D. L. 
Published: March 2011

ABSTRACTFluorine has a remarkable and diverse action in silica sols, gels and gel-derived glasses. Introduced in ionic form, it causes more rapid gelation, it reduces surface area and water adsorption of dry gels, and it helps to eliminate bubble formation during sintering and reheating of gel-derived glasses. The mechanisms for these actions of the fluoride ion are reviewed, with a more detailed discussion of the rate of gelation. Several previously held views of the way fluoride accelerates gel formation are compared with a new suggestion that it is caused by an electrostatic attraction between the proton of the OH of silicic acid and F− present as Si-F groups.
Studies of the Initial Steps in Sol-Gel Processing of Si(OR)4:29Si NMR of Alkoxysilane and Alkoxysiloxane Solutions
Authors: Balfe Carol A. , Martinez Sheryl L. 
Published: March 2011

ABSTRACTSilicon-29 NMR has been used to investigate the initial steps of hydrolysis and condensation of tetramethoxysilane (TMOS), hexamethoxydisiloxane, and octamethoxytrisiloxane in both basic and acidic methanol solutions. Comparisons of the spectra obtained from the various starting solutions and literature reports of mono-, di-, and tri-silicic acids in aqueous solution were used to identify and assign chemical shifts to condensation intermediates in the TMOS system. The observation of cyclic intermediates in the acid catalysis of TMOS in methanol and the chemical shifts of several products of its hydrolysis and condensation are reported.
General Scaling Phenomena in Porous Silica Gels as Probed by Saxs and Molecular Adsorption (Tiling)
Authors: Drake J. M. , Levitz P. , Sinha S. 
Published: March 2011

ABSTRACTUsing N2 adsorption (B.E.T.), small angle X-ray scattering and molecular adsorption (tiling) we attempt to describe the internal pore morphology and surface structure of three porous silica gels. The results are analyzed from both a classical euclidian and a fractal scaling viewpoint. The applicability of both viewpoints are shown to be limited but important in describing the structure of porous silicas.
Studies of Organometallic Precursors to Aluminum Nitride
Authors: Interrante Leonard V. , Carpenter Leslie E. , Whitmarsh Christopher , Lee Wei , Garbauskas Mary , Slack Glen A. 
Published: March 2011

ABSTRACTThe reaction of trialkylaluminum compounds with ammonia has been examined as a potential route to high purity AlN powder and to AlN thin films. This reaction proceeds in stages in which the initially formed Lewis acid/base adduct undergoes thermal decomposition to a series of intermediate alkylaluminum-amide and -imide species with increasing Al-N bonding, i.e.,The structure and properties of several of these species have been studied using various physical and chemical methods, leading to a better understanding of the chemistry of this novel AlN precursor system. The structure of the intermediate organoaluminum amide, (CH3)2AlNH2, has been determined by single crystal X-ray diffraction methods and found to contain molecular trimer units with a six-membered Al-N ring structure similar to those which make up the wurzite structure of AlN. This compound is readily volatile and has been used to deposit AIN thin films on Si surfaces by a low-pressure CVD process. This approach has also been used to prepare AlN as a high surface area, high purity powder.
A Low Temperature Chemical Route to Precursors of Boride and Carbide Ceramic Powders
Authors: Ritter Joseph J. 
Published: March 2011

ABSTRACTThe controlled reductive dehalogenation of elemental halides has been studied as a low temperature approach to boride and carbide precursors. We have shown that SiCl4 and CCl4 can be reacted with metallic sodium at 130° in a non-polar solvent to give the precursor to SiC. Similar type reactions with TiCl4 and BCl3 or with BCl3 and CC14 have produced the precursors to TiB2 and B4C respectively. This procedure has also been used to generate the precursors to the two-phase composites SiC/TiC and SiC/TiN. The method is generally applicable to any combination of elemental halides which can be reduced by alkali metals or alkali metal alloys.
A New Catalytic Method for Producing Preceramic Polysilazanes
Authors: Blum Yigal D. , Laine Richard M. , Schwartz Kenneth B. , Rowcliffe David J. , Bening Robert C. , Cotts David B. 
Published: March 2011

ABSTRACTA transition metal (e.g., Ru3 (CO)12, Pt/C) catalyzed process for Si-N bond formation is discussed that provides a new route to mono-, oligo-, and polysilazanes. The catalysts function by activating Si-H bonds in the pres-ence of ammonia. Polymeric silazanes can also be produced from oligomers in the presence of ammonia at low temperatures. This method allows us to control or modify the composition of the polysilazane during or after the polymeriza-tion. A variety of polysilazanes were prepared and converted to Si3 N4 with ceramic yields ranging from 55%-85%. By varying the monomers and reaction conditions, we can control the nitrogen and carbon content in the preceramic polymers, which enables us to obtain ceramic products that are primarily Si3N4and simultaneously minimizes the coproduction of SiC and C.
A Comparison of Structures and Crystallization Behavior of Gels, Gel-Derived Classes and Conventional Glasses
Authors: Mukherjee Shyama P. 
Published: March 2011

ABSTRACTStudies on the structures and crystallization behavior of gels in TiO2, GeO2, SiO2-GeO2 and PbO-GeO2 systems are presented to analyze the differences in structures and crystallization behavior of gel-derived glasses and conventional glasses. The kinetic parameters for crystallization such as activation energies and frequency factors of gels, gel-derived glasses and conventional glasses in the GeO2-PbO system are presented to elucidate their difference in nucleation and crystallization behaviors. The influence of gel processing parameters such as pH and water concentration on the crystallization behavior of gels are discussed.
Synthesis and Characterization of Aluminum Propionate Sol-Gel Derived Al2O 3
Authors: Covino J. , Nissan R. A. 
Published: March 2011

ABSTRACTAl2O3 has been synthesized from aluminum propionate [A1(CO2CH2CH3)3] bySol-Gel techniques. Methods of characterization include: x-ray powder diffraction, scanning electron microscopy (SEM) and nuclear magnetic resonance(NMR). Solution and solid state 13C and 27Al NMR data is coupled with bothx-ray diffraction powder data and SEM in order to understand the transitionfrom sol + gel + amorphous powder + crystalline powder In the sonicated andunsonicated aluminum propionate precursor, and A12O3 powders. Resultsindicate that the sonicated dried powder is crystalline, having the γA12O3structure while the unsonicated dried powder is amorphous and crystallizesat 800°C with the a A12O3 structure. These differences in crystallinity arefurther substantiated by solid state 27AL NMR chemical shifts and linewidths at half height.
Polymeric Precursor Synthesis of Ceramic Materials
Authors: Eror Nicholas G. , Anderson Harlan U. 
Published: March 2011

ABSTRACTFor the past twenty years we have successfully synthesized a wide range of ceramic materials by using organic precursors. The organic precursors are formulated into a glass before pyrolysis. Synthesized compounds include, for example, titanates, zirconates, silicates, chromites, niobates, tantalates, ferrites and molybdates.This preparation technique is based upon having individual cations complexed in separate weak organic acid solutions. The individual solutions are gravimetrically analyzed for the respective cation concentration to a precision of 10–100 ppm. In this way it is possible to precisely control all of the cation concentrations, and to mix the ions on an atomic scale in the liquid state. There is no precipitation in the mixed solution as it is evaporated to the rigid polymeric statein the form of a uniformly colored transparent glass. The glass retains homogeneity on the atomic scale, and may be calcined at a relatively low temperature of only a few hundred degrees Celsius to the homogeneous single phase of precise cationic stoichiometry and particle size of a few hundred Å.The advantage of having such well characterized, thermodynamically defined compounds is illustrated by the resulting understanding of the solid state chemistry of multicomponent compounds that has occurred.
Dispersion of Ceramic Particles in Organic Liquids
Authors: Calvert P. D. , Lalanandham R. R. , Parish M. V. , Fox J. , Lee H. , Pober R. L. , Tormey E. S. , Bowen H. K. 
Published: March 2011

ABSTRACTGood dispersion of oxide ceramics in organic solvents can be achieved using many different dispersants. Several types of dispersants, including fatty acids, coupling agents, polar aromatic compounds and polymers, are discussed to illustrate the important phenomena. Many new problems arise in actual slips during ceramics processing; these are briefly discussed.
The Gel Route to TiO2 Photoanodes
Authors: Doeuff S. , Henry M. , Sanchez C. 
Published: March 2011

ABSTRACTCr3+ and Al3+ doped TiO2 can be easily made via the sol-gel process. Mixing the metal-organic solutions give rise to a random dispersion of the doping ions into the TiO2 network. Amorphous and crystalline phases have been characterized all the way from the gel to the crystalline products by thermal analysis, X-ray diffraction, vibrational spectroscopy and E.S.R. Organic groups appear to be involved in the formation of the gel network and could lead to a better control of the morphology of the xerogel. A thermal stabilization of the anatase phase, up to 900°C, is observed when Cr3+ is introduced as a dopant. This would lead to the preparation of anatase TiO2 photoanodes.
Dielectric Properties Of Sol - Gel Silica Glasses
Authors: Chandrashekhar G. V. , Shafer M. W. 
Published: March 2011

ABSTRACTDielectric properties have been measured for a series of porous and fully densified silica glasses, prepared by the sol-gel technique starting from Si-methoxide or Si-fume. The results for the partially densified glasses do not show any preferred orientation for porosity. When fully densified (∼2.25 gms/cc) without any prior treatment of the gels, they have dielectric constants of ≥ 6.5 and loss factors of 0.002 at 1 MHz, compared to values of 3.8 and <0.001 for commercial fused silica. There is no corresponding anomaly in the d.c. resistivity. Elemental carbon present to the extent of 400–500 ppm is likely to be the main cause for this enhanced dielectric constant. Extensive cleaning of the gels prior to densification to remove this carbon were not completely successful pointing to the difficulty in preparing high purity, low dielectric constant glasses via the organic sol-gel route at least in the bulk form.
Crystallization Of Oxide Films Derived From Metallo-Organic Precursors
Authors: Chen K. C. , Janah A. , Mackenzie J. D. 
Published: March 2011

ABSTRACTFerroelectric lead zirconate titanate and ferrimagnetic nickel ferrite films were prepared by dip-coating of metal organic solutions. In the amorphous state, both films were porous, with specific porous surface areas on the order of tens of square meters. Crystallization temperatures were in the range of 400–500°C. The crystallization kinetics of the porous films and powders of both compounds have been studied by using non-isothermal DSC and isothermal XRD. The kinetic parameters were empirically described by the Johnson-Mehl-Avrami transformation equation α = 1- exp(−Ktn). The order of reaction (n) of PZT film is approximately 1 but that of the powder is 2, and their activation energies are 80 and 70 kcal/mole, respectively. It was found that the PZT film crystallizes more easily than the powder at the same temperature. The nickel ferrite film and powder, on the other hand, have similar n values ranging from 0.6 to 0.7, with activation energies of 20 and 35 kcal/mole, respectively. The possible mechanisms were also briefly discussed.
Preparation of A12O3-ZrO2 Composites by Adjustment of Surface Chemical Behavior
Authors: Baik S. , Bleier A. , Becher P. F. 
Published: March 2011

ABSTRACTAqueous colloidal routes for processing binary suspensions containing Al 2 O 3 and ZrO2 were designed and tested in order to achieve homogeneous microstructures. Effects of particle size and size ratio of each component, pH, and electrolyte concentration of composite suspensions on sedimentation, green density, and ZrO2 distribution in sintered microstructures were examined. The pH conditions for inhibiting differential sedimentation without impairing green density were optimized. Overall suspension and coagulation behavior for these composite systems were explained using the DLVO approach. Optimum balance of colloidal and gravitational forces occurred when the secondary minimum heterocoagulation was maximized.
Silicon Carbide From Organosilanes and Application in Silica Gel Glass Composites
Authors: Lee Butrand I. , Hench L. L. 
Published: March 2011

ABSTRACTSeveral organosilanes were crosslinked and pyrolyzed to produce silicon carbide (SiC). Use of chemical crosslinking agents required lower temperatures and shorter times for curing and increased SiC char yields. Impregnating the silanes into sol-gel derived silica monoliths followed by crosslinking and pyrolysis resulted in hard and tough SiC/SiO2 composite bodies.