bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Comparative Study Between high and low Temperature Thermally Controlled Crystallization of thin films
Authors: Robinson Richard D. , Miaoulis Ioannis N. 
Published: March 2011

ABSTRACTNumerical simulation of zone-Melting recrystallization (ZMR) was conducted to determine the heat transfer dynamics over a wide range of temperatures. ZMR is a thermal processing technique used to recrystallize Materials. Therefore, the thermal effects induced by the ZMR process critically affect the crystallization dynamics. Parametric studies indicated that the conductive heat flux from the heat source through the gas accounted for at least 15% of the total energy heating the film for materials with melting points less than 800°C. The influence of this conductive heating has been neglected in past analyses. Also, Materials with higher melting points are less sensitive to changes in the heat flux from the heat source. Slight variations of thermal gradients in the film can lead to different qualities of crystal, so care must be taken when processing materials with lower melting points, since they are more sensitive to temperature variation. This paper analyzes the dominant modes of heat transfer in ZMR over a wide range of temperatures that influence the recrystallization dynamics.
Au0.80Cu0.10Y0.10, A Gold-Rich Ternary Alloy Glass with Tc > 400°C and its Crystallization Kinetics
Authors: Gokhale Sunil V. , Marchev Krassimir G. , Nowak Welville B. , Giessen Bill C. 
Published: March 2011

ABSTRACTThere are no reported gold-rich alloys that are both readily glass forming (RGF) upon rapid solidification processing (RSP) and, in the glassy state, have crystallization temperatures Tc sufficiently high to insure long metastable life times at room temperature. A representative of a new family of ternary gold-based glasses is described that contain Cu and a rare earth (RE) Metal (or Y), with total addition element concentrations as low as 15 at. pet., and its crystallization characteristics are reported. Under RSP processing by arc furnace hammer-and-anvil quenching, the alloy Au0.80Cu0.10Y0.10 readily forms a ductile glass, with Tc = 685 K, ΔHc = 1.25 kJ/g-Mole and an activation energy of crystallization ΔE3 (cryst.) = 190 kJ/g-Mole.
Atomic Motion in Amorphous Ni81B19 Studied by Reverse Monte Carlo and Molecular Dynamics Simulation
Authors: Thijsse Barend J. , Van Ee Leon , Sietsma Jilt 
Published: March 2011

ABSTRACTMolecular dynamics simulations of glassy Ni81B19, starting with a configuration obtained by the Reverse Monte Carlo Method, indicate a calorimetrie glass transition at 960 K and point to a significant change in the atomic dynamics between 960 and 1200 K. Above this range, normal liquid-like behavior is found; at lower temperatures, we find a residual diffusivity and cooperative atomic Motion. Atomic jumps are processes smeared out in time and space over continuous rather than discrete scales.
Atomistic Details Of Disordering Processes in Superheated Polymethylene Crystals II. Effects of Surface Constraints
Authors: Wunderlich B. , Liang G. L. , Sumpter B. G. , Noid D. W. 
Published: March 2011

ABSTRACTAtomistic details of disordering in superheated polymethylene crystals have been studied using full molecular dynamics simulations of crystals containing 9600 CH2-groups. The crystal size was about 227 nm3 Simulations were carried out for up to 100 ps, starting at temperatures about 100 K above the melting temperature. Typically 1.5 h of CPU time on a Cray X-MP were necessary per ps simulation. Superheating causes a quick development of large-scale disorder throughout the crystal, including reorientation, translation, and the destruction of crystal symmetry. This is followed ultimately by surface Melting. Crystallization centers with hexagonal packing are found in superheated, unconstrained crystals. On cooling during the simulation, recrystallization processes compete with the disordering, resulting in a reorientation of the molecular chains and reorganization of the crystal. Neither the fully amorphous phase nor the ordered crystal are reached during these short-time simulations using an instantaneous temperature increase to above the melting temperature, followed by a slow cooling into the crystallization temperature region.
Film Softening Effects of ZrO2 on MoSi2
Authors: Czarnik C. M. , Gibala R. , Nastasi M. , Garrett J. D. 
Published: March 2011

AbstractWe have investigated the effect of thin films of ZrO2 on the mechanical behavior of [001] single-crystalline MoSi2. Previous work in our laboratories has shown there to be a 20-40% reduction in hardness in coated samples relative to the corresponding uncoated samples. We now compare fracture around the indentations as a function of thickness. Thicker ZrO2 coatings reduce radial crack length around the indentation through the intrinsic compressive stress at the film/substrate interface. In addition, ZrO2-coated materials tested in compression at 1250°C exhibit approximately twice the plastic strain of uncoated materials, indicating that reduction in hardness is associated with enhanced plasticity from dislocation activity associated with the film/substrate interface.
Strength and Toughness of Silicide Matrix Materials Consolidated by Hot Isostatic Pressing
Authors: Suryanarayanan R. , Sastry S. M. L. , Jerina K. L. 
Published: March 2011

AbstractSubstantial improvements have been reported in high temperature strength and creep resistance, and room temperature fracture toughness of molybdenum disilicide (MoSi2) reinforced with ductile or brittle reinforcements. The influence of Hot Isostatic Pressing (HIP) process parameters on the mechanical properties of MoSi2 based alloys was studied. Monolithic MoSi2 powder and MoSi2 powder blended with either niobium powder or silicon carbide whisker reinforcements were consolidated by HIP at 1200 − 1400°C, 207 MPa, and 1 - 4 hrs. The HIP'ed compacts were characterized for compression strength and creep resistance at 1100-1300°C. Fracture toughness was measured on single edge notched rectangular specimens at room temperature. Mechanical properties were correlated with post-HIP microstructural features.
Powder Processing of Refractory Metals and Alloys
Authors: German Randall M. 
Published: March 2011

AbstractFor the past century the processing of refractory metals and alloys has been linked to powder metallurgy (P/M). A firm understanding of processing has been critical to attaining the desired performance levels. Although the consolidation science is in good shape, the availability of tailored powders with appropriate attributes is a limitation. This presentation reviews the key issues related to refractory metal and alloy processing, with particular emphasis on tungsten and its alloys. An exciting growth area is in liquid phase sintering microelectronic systems where the concern is with thermal properties, specifically for W-Cu and Mo-Cu.
Microstructures, Defects and Deformation Mechanisms in Vanadium Modified Nb3Al
Authors: Smith L.S. , Aindow M. , Loretto M.H. 
Published: March 2011

AbstractA transmission electron microscope study of the microstructure and defect structure in vanadium modified Nb3Al and its deformation mechanisms is presented. Two alloys are examined in which 20 and 40 atomic % V is substituted for Nb. The former alloy exhibits a microstructure containing a stable A15 phase and a metastable B2 phase which transforms to A15 upon heat treatment. The A15 grains contain defects similar to those observed previously in binary Nb3Al: i.e. large growth faults with R=1/4<012> and dissociated dislocations with a separation of =15nm and b=1/2<001> bounding a stacking fault with R=1/2<001>. The alloy containing 40 atomic % V consists only of an equilibrium B2 phase and exhibits greatly enhanced ductility. Slip occurs by the glide of dislocations with b=<111> on {011}.
Photodefinable Benzocyclobutene Formulations for Thin Film Microelectronic Applications. III. 1 to 20 Micron Patterned Films
Authors: Moyer E. S. , Becker G. S. , Rutter E. W. , Radler M. , Bremmer J. N. , Bernius M. T. , Castillo D. , Strandjord A. J. G. , Heistand R. , Foster P. , Harris R. F. 
Published: March 2011

AbstractNegative working photodefinable benzocyclobutene formulations capable of obtaining patterned dielectric films from 1 to 20 microns thick are being developed using bisaryl azides as photocrosslinkers. Three different formulations are used to cover this range of film thicknesses. The formulations are very sensitive to the 365 nm and 405 nm wavelengths of light (i-line and h-line) of the high pressure mercury spectrum and require low exposure doses to produce resolved patterns. Twenty five micron round and square vias with sloping sidewalls (geometry good for metallization) have been successfully patterned in 10 micron thick films. The photodefined patterns can be obtained with good film retention using several developing solvents including: Stoddard solvent, ProglydeTM DMM, and n-butyl butyrate.
The Effect of Curing on the Thermomechanical Properties of BPDA-PDA Polyimide Thin Films
Authors: Leu J. , Kang Y. S. , Liou H. C. , Ho P. S. 
Published: March 2011

AbstractThe effect of the heating rate during curing on the thermal expansivity and mechanical properties of poly(p-phenylene biphenyltetracarboximide) (BPDA-PDA) polyimide thin films has been investigated in the range from 3 to 40 μm, which is commonly used for packaging application. Structural characterization was carried out using birefringence and wide-angle x-ray diffraction (WAXD) techniques. The morphology and packing order are found to be strongly influenced by the heating rate and, to a lesser extent, by the film thickness. The themomechanical properties of the polyimide films show an overall variation consistent with the changes in the molecular packing, thus demonstrating a close structure-property correlation. For slow-cure films, the variation of the molecular order is almost independent of film thickness. In contrast, the molecular order for the fast-cured films strongly depends on the thickness. The in-plane chain orientation decreases, but crystallinity increases with increasing film thickness. The heating rate gives rise to an opposite effect on the morphology for thin (∼ 5 μm) and thick films (∼ 38 μm). For thin films, high heating rate yields a high degree of crystallinity and in-plane chain orientation of the polymeric chains, leading to low thermal expansion coefficient (TEC) and high mechanical strength. In contrast, high heating rate for the thicker film gives a low in-plane chain orientation, leading to high TEC and low mechanical strength. The close correlation between morphology and the thermomechanical properties such as Young's modulus, stress-strain relationship, and lateral TEC is demonstrated.
Morphological Effects on the Materials Properties of Polyimides
Authors: Poon T. W. , Leu J. , Kang Y. S. , Liou H. C. , Ho P. S. 
Published: March 2011

AbstractWe have carried out a comparative study on the thermomechanical properties and interfacial fracture for two polyimides, a rigid-rod like BPDA-PDA and a flexible-chain PMDA-ODA. This study is focused on the correlation between material strength and polymeric chain morphology. A strong correlation was observed, with high chain packing order giving rise to strong material strength. Quantitatively, the mechanical strength of PMDA-ODA thin films along the direction tangential to the film plane is about 1/3 of that of BPDA-PDA, and its thermal expansivity 1.5 to 5 times larger. For fracture, the mechanical strength of the polyimide plays a different role. A softer polyimide such as PMDA-ODA will strengthen the confinement exerted by the metal lines with smaller interfacial strain, thereby decreasing the amount of deformation transmitted through the interface into the metal, and shifting the onset of delamination to a higher strain on the entire structure. However, the same softer polyimide layer also induces a larger amount of plastic deformation, leading to fracture of the film at a smaller strain. For a strong metal/polymer interface, the strength of the interfacial bonds is sufficient to hold the interface intact while the polymer near the interface deforms plastically because it is much softer mechanically than the metal. This continues until the deformation energy accumulated in the polymer is sufficient to delaminate the interface. Under this condition, the locus of failure will be determined by the relative fracture toughness of the polymer compared with the interface, which may very well occur in the polymer very close to the interface.
Adhesion of Cyclotene™ (BCB) Coatings on Silicon Substrates
Authors: Townsend P. H. , Schmidt D. , Stokich T. M. , Kisting S. , Burdeaux D. C. , Frye D. , Bernius M. , Lanka M. , Berry K. 
Published: March 2011

AbstractThis work examines the adhesion of coatings derived from divinylsiloxane bisbenzocyclobutene, mixed stereo and positional isomers of 1,3-bis(2-bicyclo[4.2.0]octa-1,3,5-trien-3-ylethenyl)-1,1,3,3-tetramethyl disiloxane (CAS 117732–87–3), on oxidized silicon substrates treated with silane coupling agents.This material, commercially available as Cyclotene™ 3022, can be used in the construction of high performance electronic circuits, such as multichip modules. Silane coupling agents examined in this study were 3-aminopropyltriethoxysilane (CAS 01760-24-3)(APTES)(, vinyltriethoxysilane (CAS 00078–08–0)(VTES), and 3-methacryloxypropyl trimethoxysilane (CAS 02530–85–0) (MOP-TMS).Measurement of the interfacial adhesion was performed using microindentation. Bond strengths obtained by this method exceed 200 MPa for the most effective coupling agents. However, these high bond strengths were not found to correlate with acceptable adhesive performance in all cases. In addition to the choice and preparation of the coupling agent, process related chemical exposure has been found to be a key element in the observed adhesive performance. The effect of the cure schedule for the thermoset coating has also been found to be a controlling factor. A short cycle test vehicle was developed consisting of a single 20 gIm polymer layer etched with anisotropic sidewalls. This test vehicle was used to evaluate the efficacy of the coupling agents during process exposures and subsequent thermal shock testing. A solution of MOP-TMS pre-hydrolyzed in methanol was found to produce the most reliable interface with high bond strength.
New Techniques for Measuring Strain at Fracture of Thin Film Materials
Authors: Goforth R. C. , Chandran B. , Nasrazadani S. , Salamo G. J. 
Published: March 2011

AbstractThe High Density Electronics Center (HiDEC) at the University of Arkansas is developing advanced electronic packaging methods including multi-chip modules which utilize high temperature superconductor interconnects. A wide variety of materials have been proposed and investigated for these applications. Good knowledge of the mechanical properties of the candidate thin film materials is important for reliable device design.Two new techniques have been developed to measure strain at fracture of thin film materials. The first is an acoustic technique in which an accelerometer is attached to the film. The film is then gradually strained. When the film fractures, an acoustic wave propagates through the film thereby creating a transient signal from the accelerometer. This signal is used to trigger an oscilloscope. The second technique is similar except that it utilizes a laser probe to detect the acoustic wave. In this photo-acoustic technique, the laser is reflected from the film onto a bi-sectional photodetector while the film is gradually strained. Upon film fracture, the acoustic wave modulates the laser beam and a transient voltage pulse is produced by the photodetector. Both techniques are capable of detecting extremely small cracks.
Effect of Microstructure on the Dissolution Kinetics of Copper Thin Films in Dilute Aqueous Solutions of Cupric Chloride
Authors: Walsh L. Harper , Feilchenfeld N. B. , Schwarz J. A. 
Published: March 2011

ABSTRACTMicrostructural differences in copper deposited by four techniques commonly used in the microelectronics industry were previously reported. [1] The reaction rates were predicted using either grain size or grain orientation as the dominant microstructure characteristic. A practical method to monitor copper speciation was developed.[2] This technique was used to measure the reaction rates for the different copper films under two different etching conditions. The results are explained using grain size, grain orientation and near surface region composition.
High-Density, High-Speed Connectors Based on Flexible Etched Circuits
Authors: Wrisley David B. 
Published: March 2011

AbstractWith advances in semiconductor technology straining the ability of packaging to keep pace, conventional electrical connectors cannot always meet emerging requirements in interconnection density and signal transmission speeds.Connectors using flexible etched circuits (FEC) can provide interconnection densities of up to 200 lines per inch and high transmission quality for signals with 250-picosecond risetimes. A practical connector design meeting these density and speed goals depends on careful consideration of connector and system tolerances, ease of application, manufacturability, and material properties.This paper discusses a practical approach to an FEC-based connector and the influence of material properties on connector performance.
Real Time Process Monitoring with Multiwave-Length Pyrometric Interferometry (Pi)
Authors: BÖbel F.G. , Wowchak A. , Chow P.P. , Hove J. Van , Chow L.A. 
Published: March 2011

AbstractPyrometry Interferometry (PI) is a powerful technique for in-situ sensing of the wafer temperature and growth rate. Evaluation of the two parameters would allow exact process control required for sophisticated device fabrication and material processing. The PI technique analyzes the interference patterns of the thermal radiation from the growing layer with a changing thickness d at growth temperature T. Since it is non-contact, applicable to all semiconductor materials and insensitive to wafer motion, the method is an ideal candidate for real time process control. We use a reflection assisted method to aid real time computation of these parameters. One could select the wavlength of interest to optimize the temperature and layer thickness resolution. We present data on MBE grown quarter wavelength stacks of GaAs and AlAs, and silicon oxidation to show P1 is extremely useful for growth of surface emitting laser and for silicon processing.
Characterization of Quantum well Structures Using Microscope-Spectrophotometry
Authors: Geatches Rachel M , Reeson Karen J , Criddle Alan J , Webb Roger P 
Published: March 2011

AbstractIn this paper the application of microscope-spectrophotometry to the nondestructive characterization of a variety of multi-layer GaAs/A1GaAs structures, is described. Spectral reflectance results are used to indirectly determine variations in aluminium content, and the interdependency of aluminium content with layer thicknesses. The penetration depth of light from the visible spectrum is assessed from the correlation between spectral reflectance measurements and fitted optical models. Finally, a series of single quantum wells are investigated, and it is concluded that a significant improvement in the characterization of these materials will be achieved with an extension of the spectral measurement range into the ultra violet.
Photoluminescence Characterization of Inp-Based Hemt Structures
Authors: Hendriks Henry T. , Brierley Steven K. , Hoke William E. , Pan Noren 
Published: March 2011

AbstractInP-based lattice matched high electron mobility transistor (HEMT) structures have been characterized by liquid nitrogen temperature photoluminescence. A phenomenological line shape model has been utilized to fit photoluminescence spectra in order to obtain key parameters, such as the subband energies and transition amplitudes. From transition amplitude ratios and subband energies, fundamental quantum well characteristics are inferred. Changes in these parameters are linked to variations in the growth conditions of the epitaxial layer structures.
Fiber Optics-Based Fourier Transform Infrared Spectroscopy for in-Situ Concentration Monitoring in OMCVD
Authors: Salim Sateria , Jensen K.F. , Driver R.D. 
Published: March 2011

AbstractFiber-based Fourier transform infrared spectroscopy for remote in-situ monitoring of organometallic delivery in organometallic chemical vapor deposition (OMCVD) is presented. The measurement is based on infrared absorbance of the organometallic reagent in a short single pass gas cell placed in the gas delivery line of an OMCVD system. The performance of the set-up is demonstrated for monitoring concentration transients during the delivery of two common OMCVD precursors, trimethylgallium (TMG) and trimethylindium (TMI). The time to reach saturation is shown to be faster for a TMG bubbler than for a TMI bubbler. This difference in delivery behavior is interpreted through a mathematical model of the gas handling lines and the monitoring gas cell. The utility of the system in monitoring temporal variations in TMI delivery is also demonstrated. Finally, the ability of the system to detect the chemical species unintentionally present in the feed lines is illustrated with the observation of methane gas from TMG and TMI bubblers that have been dormant for a period time. The methane gas is shown to quickly disappear with repeated used of the bubblers.
Photoluminescence Study of Hydrogen-Related Defects in Silicon
Authors: Henry A. , Monemar B. , LindstrÖm J.L. , Zhang Y. , Corbett J.W. 
Published: March 2011

AbstractThe effect of ion-implantation followed by a rapid thermal annealing was investigated in borondoped silicon using photoluminescence (PL) spectroscopy. The radiation induced defects giving rise to the G, W and C PL lines are completely passivated by a hydrogen plasma treatment. However this hydrogen exposure also introduces broad and deep luminescence structure as well as new sharp PL lines very near the silicon band gap. Up to twelve new lines are observed at low temperature (< 20K). One of them exhibits a very low exciton localisation energy (≈ 2 meV) compared to the value measured for classical shallow donors or acceptors, and is observed only at very low temperature (≈4K). A broad deep PL band with a halfwidth of 30 meV is observed at around 925 meV. The excitation power dependence and the temperature dependence of the PL intensity of these sharp lines and the broad band are presented. Tentative correlations with the data currently available in the literature are presented for the understanding of the formation of the defects associated to the broad band as well as the sharp near band gap PL lines.