bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calculation of Electrical Conductivity and Giant Magnetoresistance within the Free Electron Model
Authors: Zhang X.-G. , Butler W. H. 
Published: April 2011

ABSTRACTWe use the model of free electrons with random point scatterers (FERPS) to calculate the electrical conductivity and giant magnetoresistance (GMR) for FeCr multilayer systems and compare our results with the experimental values. Our analysis suggests that the primary cause of the GMR in FeCr systems is regions of interdiffusion near the interfaces. We find that in the samples analyzed, these regions of interdiffusion occupy about 8.5Å of the magnetic layer near each interface.
Colossal Magnetoresistance in Thick La0.7Ca0.3MnO3 Films
Authors: Treece Randolph E. , Dorsey P. , Rubinstein M. , Byers J. M. , Horwitz J. S. , Donovan E. , Chrisey D. B. 
Published: April 2011

ABSTRACTThick films (0.6 and 2.0 μm) of the colossal magnetoresistance (CMR) material, La0.7Ca0.3MnO3 (LCMO), have been grown by pulsed laser deposition (PLD). The films were grown from single-phase LCMO targets in 100 mTorr 02 pressures and the material deposited on (100) LaAlO3 substrates at deposition temperatures of 800°C. The deposited films were characterized by X-ray diffraction (XRD), magnetic field-dependent resistivity, and Rutherford backscattering spectroscopy (RBS). The LCMO films were shown by XRD to adopt an orthorhombic structure. Brief post-deposition annealing led to ~50,000% and ~12,000% MR effect in the 0.6 μm and 2.0 μm films, respectively.
A New Magnetooptical Effect Discovered on Magnetic Multilayers: The Magnetorefractive Effect
Authors: Jacquet J. C. , Valet T. 
Published: April 2011

ABSTRACTWe show theoretically that the change in the magnetization structure of magnetic metallic multilayers under the application of a magnetic field shall be generally associated with a significant change of the refractive index. This constitutes a new magnetooptical effect: the magnetorefractive effect.Optical transmission measurements under an applied magnetic field through [Ni80Fe20/Cu/Co/Cu] multilayers, in the light wavelength region between 2 μm and 20 μm, clearly demonstrate the existence of the predicted effect and are found in reasonnable agreement with the theoretical calculations.
Evolution of Nanoscale Ferromagnetic Particles in Co-Cr and Cr-Fe Alloys Observed by Atom Probe Field Ion Microscopy
Authors: Hono K. , Okano R. , Takanashi K. , Fujimori H. , Maeda Y. , Sakurai T. 
Published: April 2011

ABSTRACTWith appropriate processing conditions, nanoscale ferromagnetic particles precipitate from nonmagnetic matrix phase in the Co-Cr and Cr-Fe systems. In these heterogeneous alloys, unique magnetic properties are observed. In order to correlate such magnetic properties with the microstructures, we have employed an atom probe field ion microscope (APFIM) and a three dimensional atom probe (3DAP). In the Co-22Cr thin film sputter-deposited at elevated temperatures (~500 K), both APFIM and 3DAP data convincingly showed that the film was composed of lamellae-like ferromagnetic and paramagnetic phases of approximately 8 nm in thickness. On the other hand, it was shown that the films sputter-deposited at ambient temperature was composed of s-Co single phase without significant compositional heterogeneity. Based on these observations, we conclude that phase separation progresses during the growth of the film on a heated substrate. In the Cr-Fe alloy, large negative MR was observed in the as-quenched alloy at liquid helium temperature. However, the MR behavior changes as the phase decomposition progresses by annealing. The change in the MR behavior observed in this alloy with various heat treatment conditions will be discussed based on the microstructural characterization results by APFIM and 3DAP.
Magnetic Properties of Embedded Rh Clusters in Ni Matrix
Authors: Li Zhi-Qiang , Hashi Yuichi , Yu Jing-Zhi , Ohno Kaoru , Kawazoe Yoshiyuki 
Published: April 2011

ABSTRACTThe electronic structure and magnetic properties of rhodium clusters with sizes of 1 - 43 atoms embedded in the nickel host are studied by the first-principles spin-polarized calculations within the local density functional formalism. Single Rh atom in Ni matrix is found to have magnetic moment of 0.45μB. Rh13 and Rhl 9 clusters in Ni matrix have lower magnetic moments compared with the free ones. The most interesting finding is tha.t Rh43 cluster, which is bulk-like nonmagnetic in vacuum, becomes ferromagnetic when embedded in the nickel host.
Removal of Poly(Dimethylsiloxane) Contamination from Silicon Surfaces with UV/Ozone Treatment
Authors: Egitto F. D. , Matienzo L. J. , Spalik J. , Fuerniss S. J. 
Published: April 2011

ABSTRACTUV/ozone cleaning is known to be effective for removing thin organic contaminants, but removal of silicon containing contaminants is questionable. Organo-silicon contaminants, e.g., silicones, can result from a variety of integrated circuit chip and electronic packaging fabrication processes. In this investigation, films of poly(dimethylsiloxane) (PDMS) on silicon substrates, with and without a gold coating, have been used to simulate such contamination up to a thickness of 50 nm. Although treatment consistently reduced the advancing DI water contact angle, in some cases from a value greater than 100° to a value less than 5°, the hydrophilic nature of the treated surfaces was not due to complete contaminant removal, i.e., a significant amount of modified contaminant remained on the surface. High resolution x-ray photoelectron spectroscopy (XPS) in the Si 2p region suggest that O-Si-C bonds in the siloxane, observed prior to treatment, are converted to SiOx, where x is between 1.6 and 2. The time required to reduce the contact angle to a minimum value was greater for the thicker PDMS film samples. Deflection testing was used to evaluate the adhesion of an epoxybased adhesive to intentionally-contaminated silicon chips, before and after UV/ozone treatment. Although PDMS contamination induced loss of adhesion between the chip and the adhesive, complete conversion to silicon oxides by UV/ozone treatment of contaminants having a thickness of 5.0 nm has been demonstrated to restore adhesion to a value equivalent to that of uncontaminated silicon chip surfaces.
Nondestructive Characterization of Fiber-Matrix Adhesion in Composites by Vibration Damping
Authors: Gu Weiqun , Lu Guo-Quan , Wu H. Felix , Kampe Stephen L. , Lichtenstein P. Ross , Dwight David W. 
Published: April 2011

ABSTRACTAdhesion at fiber-matrix interface in fiber-reinforced composites plays an important role in controlling the mechanical properties and overall performance of composites. Among the many available tests applicable to the composite interfaces, vibration damping technique has the advantages of being nondestructive as well as highly sensitive. We set up an optical system to measure the damping tangent delta of a cantilever beam, and correlated the damping data in glass-fiber reinforced epoxy-resin composites with transverse tensile strength which is also a qualitative measurement of adhesion at fiber-matrix interface. Four different composite systems containing three different glass-fiber surface treatments were tested and compared. Our experimental results showed an inverse relationship between damping contributed by the interface and composite transverse tensile strength.
Deposition of Ca+, Na+, Al+, K+ on Single-Crystal Si From DIH20: NH40H: H202 and DIH20: HCL: H202 as Analyzed by ToF-SIMS and SPV
Authors: Debusk Damon , Lowell John , Reich Fraser 
Published: April 2011

ABSTRACTThe solutions DIH20: NH40H: H202 and DIH20: HCL: H202 have been used extensively in the semiconductor industry for the removal of transition and alkali metals from wafer surfaces. The former, when used in a ratio of approximately 5:1: 1 effects the wet oxidation removal of organic surface films and trace metals (Cu, Au, Ag, Ni, etc.) while the latter, in an approximate 6:1:1 ratio dissolves alkali ions and hydroxides of Al+3, Fe+3, and Mg+2 desorbing by complexing residual metals. Of concern is that these mixtures are known to plate out charged ionic species, particularly Fe, which remains on the Si surface after exposure to these solution. This effect adds an enhanced surface potential barrier which can be negative or positive depending on the concentrations of species deposited.While the effects of Fe as deposited by the NH40H solution is well-known, we are concerned in this study with the deposition of Ca, K, and the lighter ions, Na and Al. Conventional analytical methods such as ICP-MS or AAS or TXRF have been used to detect these ions but are problematic since each has a limited range of detectable species or is destructive to the surface when used with VPD to increase resolution. In this study, we have verified the deposition of these species by a ToF-SIMS (Time-of-Flight Secondary Ion Mass Spectrometry) analysis since it has the ability to detect the complete range of the desired ions. In addition, we have applied high-injection surface photovoltage (SPV) to obtain an average surface charge on each sample. To illustrate the use of these methods, we have applied them to the analysis of various closed acid processing systems. Our interest here is the amount of these selected ions being deposited from these solutions and the influence of using a standard canister or bulk acid supply system. Comparisons were also made to standard and megasonic RCA cleans and hot phosphoric nitride strips. We will discuss ToF-SIMS and how it was applied to analyze the addition of these charged trace ions. This work suggests that the problem of trace ion detection on Si must include the entire range of transition and alkali metals, and that ToF-SIMS is a promising analytical tool for this purpose.
Extremely Low Temperature Silicon Liquid Phase Epitaxy
Authors: Konuma M. , Silier I. , Gutjahr A. , Bauser E. , Banhart F. , Frey H. , Nagel N. 
Published: April 2011

ABSTRACTBy liquid phase epitaxy (LPE) we have grown silicon layers on silicon and partially masked silicon at temperatures below 450 °C from Ga and Ga-In solutions. Oxidation of the cleaned silicon substrate surfaces before epitaxial growth has been prevented by a buffered hydrofluoric acid treatment. The epitaxial layers reached a thickness of 7 jim and were free of extended defects.Low growth temperatures make it possible to grow silicon layers also on pre-treated glass substrates. The amorphous glass is first coated with a thin nano-crystalline silicon layer which is deposited by plasma processes from a mixture of SiH4/H2 gas. The grains in the silicon layers grown from Ga solution on glass have reached sizes up to 100 μm.
Computational Fluid Dynamic Modeling and Flow Visualization of an Enclosed Wet Processing System
Authors: Bay Steven T. , McConnell Christopher F. , Thomas Huw K. , Izenson Michael G. , Murthi Jayathi 
Published: April 2011

ABSTRACTWith the goal of optimizing point-to-point etch uniformity in a continuous flow wet processing system, a comprehensive fluid dynamics study was undertaken. Aspects of this work included developing a computational, finite-element, fluid dynamic model; performing a series of empirical studies based on dye-injection with photo detection and video analysis; and observing platinumwire bubble generation with transparent wafers.Various flow modification designs were tested including the base case of no inserted device, a stationary “spinner” insert, and a stationary “showerhead” insert. Unsteady, non-uniform, flow distribution and zones of substantial flow recirculation were observed in the case of using no flow modification device. These observations were confirmed with the computational fluid dynamic model.Used in conjunction with the two different types of flow inserts, a new supplementary Teflon screen was designed and tested. The combined optimum configuration using this screen with an insert was then identified. Significantly enhanced point-to-point etch uniformity, with minimal recirculation and prompt fluid displacement, resulted from this design.
Monitoring Of HF/H2O Treated Silicon Surfaces Using Noncontact Surface Charge Measurements
Authors: Roman P. , Hwang D. , Torek K. , Ruzyllo J. , Kamieniecki E. 
Published: April 2011

ABSTRACTIn this work, a new commercial system allowing non-contact measurement of the surface charge is used to monitor the condition of the silicon surface following HF/water etch. Results obtained demonstrate that by monitoring changes of surface charge using this system, a truly non-invasive, instant and easy to carry out characterization of Si surfaces after HF/water etch can be accomplished. The results show that HF/water exposure adds positive charge to the silicon surface. Change in the surface charge, considered to be indicative of the change in the electro-chemical condition of the surface, appears to precede initiation of the oxide etching process, and is proposed to be a factor in initiating etching reactions that involve mainly negatively charged species.
Electrochemical Aspects of Etching and Passivation of Silicon in Alkaline Solutions
Authors: Jeon Joong S. , Raghavan Srini 
Published: April 2011

ABSTRACTElectrochemical polarization experiments were performed on Si wafers in ammoniacal solutions maintained at a pH in the range of 9.5 to 11.5. Anodic polarization of silicon yielded curves which are typical for materials that undergo passivation. The values of open circuit potential and passivation potential for p-type Si wafers were more anodic than for the n-type Si wafers. Corrosion current density of p-type Si wafers of low resistivity was lower than that of wafers of high resistivity. Corrosion current densities correlated well with surface roughness induced in alkaline solutions. Addition of surfactant or H2O2 to alkaline solutions reduced critical current density for passivation and corrosion current density.
Advanced Properties of Silicon Oxynitride (SiOxNy) Thin Films Prepared by Pulsed Laser Deposition
Authors: Xiao R.-F. , Ng L.C. , Liao H.B. 
Published: April 2011

AbstractA pulsed laser deposition technique has been used to grow silicon oxynitride (SiOxNy) thin films at low deposition temperatures (25°C - 300°C). the thin films were found to be quite smooth in surface morphology, extremely inert in chemical solution and highly transparent in the optical range of 0.3 μm to 5 μm. the refractive index was tunable between 1.4 - 2.1 by the addition of oxygen in substitution of nitrogen in the film, and the dielectric constant is much larger than the similar films grown by conventional chemical vapor deposition. the high quality of the SiOxNy films deposited at such low temperatures was resulted from the large kinetic energy carried by the impinging particles created by the ablation of a high-power pulsed excimer laser. the kinetic energy of the impinged particles on the substrate provides thermal energy for surface diffusion and relaxation.
Mechanism of ArF Laser induced Photolytic Deposition of W From WF6 on Etched Si and Unetched Si
Authors: Zhang Xiafang , Leary Herbert J. , Allen Susan D. 
Published: April 2011

AbstractArF excimer laser-induced photolytic chemical vapor deposition of W on etched Si substrates using tungsten hexafluoride has been studied. Our experimental results show that tungsten film thickness is proportional to the laser irradiation time and fluence, and that the deposition rate initially increases, then decreases with increasing WF6 pressure. the activation energy obtained from an arrhenius plot is much less than that for conventional CVD. a deposition mechanism has been proposed which yields results in good agreement with the experimental dat A. the absorption cross section of WF6 is determined to be 2.75xl0-18 cm2/molecule.
Solid Phase Epitaxy of Implanted Si-Ge-C Alloys
Authors: Lu Xiang , Cheung Nathan W. 
Published: April 2011

AbstractSi1-x-yGexCy/Si heterostuctures were formed on Si (100) surface by Ge and C implantation with a high dose rate MEtal - Vapor Vacuum arc (MEVVA) ion source and subsequent Solid Phase Epitaxy (SPE). after thermal annealing in the temperature range from 600 °C to 1200 °C, the implanted layer was studied using Rutherford Back-scattering Spectrometry (RBS), cross-sectional High Resolution Transmission Electron Microscopy (HRTEM) and fourbounce X-ray Diffraction (XRD) measurement. Due to the small lattice constant and wide bandgap of SiC, the incorporation of C into Si-Ge can provide a complementary material to Si-Ge for bandgap engineering of Si-based heterojunction structure. Polycrystals are formed at temperature at and below 1000 °C thermal growth, while single crystal epitaxial layer is formed at 1100 °C and beyond. XRD measurements near Si (004) peak confirm the compensation of the Si1-x Gex lattice mismatch strain by substitutional C. C implantation is also found to suppress the End of Range (EOR) defect growth.
The Role of Ions for the Deposition of Hydrocarbon Films, investigated by In-Situ Ellipsometry
Authors: Von Keudell A. 
Published: April 2011

AbstractThe growth mechanisms for the deposition of hydrocarbon films (C:H-films) from a methane electron cyclotron resonance (ECR) plasma are investigated by means of in-situ ellipsometry. Ion bombardment during plasma-enhanced chemical vapor deposition of hydrocarbon films mainly governs the properties of the films and the total growth rate. the role of ions for the growth rate and the film properties is discussed in this paper. Films were deposited with varying RF-bias, resulting in a DC self-bias ranging from floating potential up to 100 V. the ion-induced modification of the film properties was investigated by a new technique using a double layer consisting of a polymer-like film with low optical absorption and a hard carbon film with high absorption on top. the interface between these layers was analysed after deposition by a layer-by-layer etching in an oxygen plasma at floating potential. From these data it is possible to determine with high accuracy the range of the ion-induced modification of the optical properties in the underlying polymer-like film. the thickness of this modified layer ranges from 6 Å at 30 V self-bias to 40 Å at 100 V self-bias, which is consistent with the range of hydrogen ions in polymerlike films as calculated by the computer code TRIM.SP.Based on the presented results, the growth of C:H-films and the resulting film properties can be modelled by the growth at activated sites at the film surface. these activated sites are represented by dangling bonds, induced by the ion bombardment. they also show up in the ellipsometric results during the deposition of C:H-films by a change of the optical response of the film surface.
AFM Study of Surface Morphology of Aluminum Nitride Thin Films
Authors: Watanabe Yoshihisa , Nakamura Yoshikazu , Hirayama Shigekazu , Naota Yuusaku 
Published: April 2011

AbstractAluminum nitride (AlN) thin films have been synthesized by ion-beam assisted deposition method. Film deposition has been performed on the substrates of silicon single crystal, soda-lime glass and alumin A. the influence of the substrate roughness on the film roughness is studied. the substrate temperature has been kept at room temperature and 473K and the kinetic energy of the incident nitrogen ion beam and the deposition rate have been fixed to 0.5 keV and 0.07 nm/s, respectively. the microstructure of the synthesized films has been examined by X-ray diffraction (XRD) and the surface morphology has been observed by atomic force microscopy(AFM). IN the XRD patterns of films synthesized at both room temperature and 473K, the diffraction line indicating the alN (10*0) can be discerned and the broad peak composed of two lines indicating the a1N (00*2) and a1N (10*1) planes is also observed. aFM observations for 100 nm films reveal that (1) the surface of the films synthesized on the silicon single crystal and soda-lime glass substrates is uniform and smooth on the nanometer scale, (2) the average roughness of the films synthesized on the alumina substrate is similar to that of the substrate, suggesting the evaluation of the average roughness of the film itself is difficult in the case of the rough substrate, and (3) the average roughness increases with increasing the substrate temperature.
Mechanical Behaviour of Two Sorts of MCM Structures
Authors: Pozza G. , Parat G. , Ignat M. , Dupeux M. , Terriez J. M. 
Published: April 2011

ABSTRACTWe analysed the mechanical response of samples, representing Flip-Chip bonded type structures. Two sort of distributions of the PbSn solder bumps, interconecting a chip to a substrate were investigated. The mechanical response was established from macroscopic shear and tensile tests. The microstructural evolution to complete mechanical failure, was observed during similar tests, but performed in a Scanning Electron Microscope. These in-situ tests revealed a preferential crack nucleation site in the samples, specific to one of the interfaces. A complementary numerical analysis was developed, for trying to explain the preferential crack opening site.
Failure Analysis of Aluminum Wire Bonds in High Power Igbt Modules
Authors: Dittmer Klaus J. , Poech Max H. , Wulff Frank W. , Krumm Martin 
Published: April 2011

ABSTRACTThe reliability of high power Insulated Gate Bipolar Transistor (IGBT) modules is mainly limited by the aluminum wire bonds. Bond failure occurs due to fatigue fracture close to the welded interface inside the large bonding wire caused by thermal cycling at extreme operating conditions. This paper presents the results of the metallographic and electron microscopic examinations of the welded interface as well as fracture morphology investigations of failed parts after power cycling. Infrared thermal imaging and investigations of the stress/strain relationship analyze the differential expansion caused by temperature distribution and thermal expansion mismatch between large bonding wire and semiconductor.
Design of Epoxy Encapsulating Compounds for Highly Reliable Surface Mounting Semiconductor Devices
Authors: Ishii Toshiaki , Moteki R. , Nagai A. , Eguchi S. , Ogata M. 
Published: April 2011

ABSTRACTOne of the most important subjects for semiconductor packages is preventing cracks which occur when the entire package is exposed to a soldering temperature of 215 to 260°C in the surface mounting technology. Cracking, as seen during temperature cycling tests is also a problem to be addressed. This paper reports the design of epoxy encapsulating compounds for highly reliable semiconductor devices which require the following properties: (1) toughness of matrix resin, (2) low moisture absorption, (3) high adhesion to insertions, and (4) reduction of thermal stress. The moisture absorption was lowered and the toughness was improved by using hydrophobic epoxy resins and high filler loading. The latter reduced the thermal stress, and it was effective for lowering the moisture absorption and increasing the fracture toughness of molding compounds. The reliability tests results were also considered in terms of physical properties of molding compounds.