bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural and Electrical Characterization of TiB2/TiSi2 Bilayer Barrier Structure
Authors: Sade G. , Pelleg J. , Grisaru A. 
Published: April 2011

AbstractThe TiB2/TiSi2 bilayer is considered as a diffusion barrier in metallization system with Cu. The TiSi2 sublayer serves as a contact and also as an additional diffusion barrier against boron, which outdiffuses from TiB2 at high temperature annealing. The attempts to form TiSi2 by vacuum annealing of TiB2/Ti film, which was obtained by co-sputtering from elemental targets are described. The composition and the structure of the films were analyzed by Auger electron spectroscopy (AES), X-ray diffraction (XRD) and high-resolution cross-sectional TEM (HRXTEM). The Cu/TiB2/(Ti-Si)/n-Si contacts were investigated using current-voltage (I–V) on Schottky diode structures, which were prepared on n-type Si (100). The thermal stability of the TiB2/(Ti-Si) barrier was studied by structural and electrical analysis.It was observed that the lowest sheet resistance of 5.1 Ω/‪ was obtained after 850 °C annealing for 30 min, however the resulting Ti-Si layer is practically still amorphous and contains only a very small fraction of C54 TiSis in the form of microcrystallites. This layer also contained Ti5Si3 as indicated by XRD. The barrier height of Cu/TiB2/(Ti-Si)/n-Si Schottky diodes is ˜0.6 V and it does not show significant changes in the range 400–700 °C. Electrical monitoring is a very effective tool to detect deterioration of the barrier. No penetration is observed by AES at 700 °C, while the I–V curve shows changes in properties.
Initial Buffer Layers on the Growth of InGaP on Si by MBE
Authors: Kawanami H. , Ghosh S. , Sakata I. , Sekigawa T. 
Published: April 2011

AbstractSingle domain InxGa(1-x)P (x=0.3) films were successfully grown on Si(001) misoriented substrates by molecular beam epitaxy with a solid phosphorous source. The effects of interfacial buffer layers such as InGaP (i.e. direct growth without buffer layer), GaP, AlP, and GaAs were examined. Also a Si epitaxial buffer layer was tried to control the Si surface structure. Mirror like surfaces were obtained for all films with RHEED patterns of (2×1) single domain surface structure. PL intensities for all films indicated almost the same values except for the films with a Si epitaxial buffer layer. The films with a Si epitaxial buffer layer had almost three times larger PL intensities than the films without Si epitaxial buffer layer. The results suggest incomplete cleaning of the Si surface by the high temperature (1000 °C) treatment and possibility of surface structure control for Si substrates by a Si epitaxial buffer layer.
Microraman Spectroscopy and X-Ray Diffraction Studies of Ti-W-O Thin Films
Authors: Sangaletti Luigi , Bontempi Elza , Depero Laura E. , Galinetto P. , Groppelli Silvio , Salari Roberto , Sberveglieri Giorgio 
Published: April 2011

AbstractThin films of the Ti-W-O system grown by r.f. reactive sputtering from a Ti-W (10%–90% weight) target have been studied by Raman and microraman spectroscopy, X-ray diffraction and scanning electron microscopy with the aim to investigate their microstructural and morphological properties. To this purpose, the kinetics of structural transformations at different temperatures (600 °C, and 800 °C) have been studied, and the effect of Ti on the WO3 lattice has been singled out. The results show that annealing at different temperatures induces a microstructural evolution from the amorphous phase of the as-deposited thin film to WO3 crystalline phases via an intermediate cubic disordered phase of WO3. The effect of Ti on this cubic phase and on the thin film morphology is also investigated with the aid of microraman and scanning electron microscopy analysis. The results show that two distinct phases arise upon long annealing treatments; namely, small crystallites belonging to the WO3 monoclinic phase are dispersed on a layer composed of a disordered cubic WO3 phase with a high Ti content.
Stress and Temperature Dependence of Misfit Dislocation Nucleation Rate in SiGe Alloys: Evidence of Homogeneous Nucleation
Authors: Labovitz S. M. , Xie Y. H. , Pope D. P. 
Published: April 2011

AbstractA recent theory on the brittle-to-ductile transition (BDT) sheds new light on the issue of the generation of misfit dislocations- in strained epitaxial layers. The Khantha-Pope-Vitek model of the BDT states that thermal fluctuations in the lattice, assisted by an applied stress, can result in the spontaneous generation of dislocations. Application of the KPV model to the problem of epitaxial layers predicts that at a critical temperature and stress, a sudden onset of homogeneous islocation generation will occur.In this paper the dislocation nucleation rate in SiGe strained layers of varying isfit stress is investigated as a function of temperature. Using the wafer curvature echnique, real-time strain relaxation curves are generated. These measurements how a sudden onset of relaxation of up to 22% of the epitaxial strain upon reaching emperatures in the range of 500 to 550C. The strong temperature dependence of his initial relaxation event is indicative of a BDT as predicted by the KPV model.
Plasma Etching and Patterning of CVD Diamond at <100° for Microelectronics Application
Authors: Ramesham R. , Welch W. , Neely W. C. , Rose M. F. , Askew R. F. 
Published: April 2011

AbstractOxidation resistance of diamond is an important characteristic to be considered in many high temperature microelectronics and other applications. We have tested the stability of CVD diamong by exposing to Ground State Atomic Oxygen (GSAO) at a temperature of 70°C. Polycrystalline diamond is quite stable at this temperature using GSAO. We have tested the stability of diamond using Excited State Atomic Oxygen (ESAO). Initially, CVD diamond was exposed to ESAO for 15 mind at 63°C and noted that the diamond was etched. We have also carried out the experiments at different time intervals such as 30 and mine. Etching rate of the diamond using ESAO is ≈ 0.2 – 0.25 μm/min at 63°C. We have successfully patterned the diamond using a Ni mask by exposing the sample to ESAO for longer time. ESAO has etched the diamond uniformly in all the directions of the diamond crystal as opposed to the molecular oxygen. Stability of the single crystal diamond has been tested using ESAO by using Ni mask material. We were able to etch the single crystal diamond (type Iia, 100 orientation) quite uniformly. An etching rate of single crystal diamond using ESAO was observed to be 0.3 μm/min.
A Study on the Residual Stress of Diamond-Like Carbon Films Deposited by Magnetically Enhanced RF PECVD
Authors: Choi Woon , Shin Dong-Hoon , Nam Seoung-Eui , Kim Hyoung-June 
Published: April 2011

AbstractHydrogenated DLC films were synthesized by RF plasma deposition with and without magnetic enhancement, and their film stresses were investigated as a function of process parameters. Under investigated process conditions, Vb/P1/2 (where Vb is the self-bias voltage and P is the working pressure) is the appropriate scaling factor representing impinging ion energy. Film stress is influenced by not only ion impinging energy but also by ion to adspecies flux ratios. As ion energy increases, film stresses increase to a maximum value corresponding to the highest number of sp3 carbon bonds. As ion/adspecies flux ratio increases, the maximum stress value decreases and the corresponding ion energy increases. Induction of a magnetic field promotes film stresses as high as 15.2 GPa, which is one of the highest value reported in hydrogenated DLC films. The magnetic-induced increase of stress can be explained by increased ion/adspecies flux ratio, thus, enhanced sp3 formation. Rapid reduction of stresses observed at high ion energies may stem from the formation of graphite (sp2 bond) phases. Inclusion of hydrogen in the films is not directly responsible for the stress generation.
Observation of Film Growth Phenomena Using Micromachined Structures
Authors: DiMeo F. , Cavicchi R. E. , Sernancik S. , Suchle J. S. , Tea N. H. , Kelliher J. T. 
Published: April 2011

AbstractA method of studying thin film growth and materials processing using micromachined Si-based structures is presented. The microsubstrate platforms (called “microhotplates”) allow temperature control during deposition, andin situmonitoring of the electrical properties of connected coatings. The efficiency of the approach is amplified when multiple. Independentlyoperated elements are used in array configurations. Illustrations here involve chemical vapor deposition of semiconducting oxides, but the methodology can be employed to investigate the growth of other classes of materials as well.
Growth of SiCN Crystals Consisting of a Predominantly Carbon Nitride Network
Authors: Bhusari D. M. , Chen C. K. , Chen K. H. , Chen L. C. , Chuang T. J. 
Published: April 2011

AbstractWe report here growth of thin films of Si-containing crystalline carbon-nitride by microwave plasma assisted CVD. The chemical composition of these films has been observed to be a strong function of the substrate temperature. A significant incorporation of Si into the CN network occurs for substrate temperatures exceeding 1000C. XPS analyses of these films indicate a multiple bonding structure between carbon and nitrogen and also indicate that a majority of the carbon atoms are tetrahedrally coordinated and covalently bonded with nitrogen. Investigations of the growth rate as a function of various deposition parameters revealed that Si substrates exhibit weight loss rather than deposition, suggesting that abstraction of Si atoms from the substrate surface by the chemically active radicals from the plasma is a dominant process. The species thus formed, i.e., the active radicals bonded with Si, appear to facilitate the subsequent reactions in the gas phase. A major achievement of this study is that there is no obvious deposition of any amorphous CN material.
Synthesis of Crystalline C3N4 films and the new C-N Phases
Authors: Chen Yan , Johnson D. J. , Prince R. H. , Guo Liping , Wang E. G. 
Published: April 2011

AbstractCrystalline C-N films composed of α- and β-C3N4, as well as other C-N phases, have been synthesized via bias-assisted hot-filament chemical vapor deposition using a gas mixture of nitrogen and methane. Scanning electron microscopy(SEM), energy dispersive X-ray (EDX) analysis, X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the films. Lattice constants of the α- and β-C3N4 phases obtained coincide very well with the theoretical values. In addition to these phases, two new C-N phases in the films have been identified by TEM and XRD; one having a tetragonal structure with a = 5.65 Å, c = 2.75Å, and the second having a monoclinic structure with a = 5.065 Å, b= 11.5 Å, c = 2.801 Å and β = 96°. Their stoichiometric values and atomic arrangements have not yet been identified. Furthermore, variation in growth parameters, for example methane concentration, bias voltage, etc., can yield preferred growth of different C-N phases.
Structural and Optical Properties of Electro-Chromic Nickel Oxide Films
Authors: Murai Kensuke , Sato Yoshiyuki , Tamura Shigeharu 
Published: April 2011

AbstractThe electro-chromic behavior of nickel oxide (NiOx) films, prepared by spin-coating, were analyzed for their structual and optical properties before and after cycling procedure in electrolyte. It was found that the chemical composition, refractive index, and thickness of the film changes significantly on hydration.
Strain Effects in Heteroepitaxial Growth: Island and Dot Formation Kinetics
Authors: Williams D. R. M. , Sander L. M. 
Published: April 2011

AbstractIn many situations where islands and quantum dots are formed on a growing surface strain effects are believed to play an important role. Here we present some preliminary results from a computer simulation study of a one-dimensional model system. Our system consists of an A material upon which grows a B material with a different lattice constant. We only consider the case where less than one monolayer of B has grown on the surface. At any given time the surface consists of a series of “islands” of B bounded by up and downsteps. Dispersed between these islands are mobile B atoms. In general, because of the lattice mismatch between A and B the mobile B atoms are repelled from the islands. This repulsion has an effect on the island size distribution and more particularly on the number of islands per unit length. Here we show that for a moderate repulsion there is a large effect on the number of islands per unit length. However, as the repulsion is increased the effect grows only gradually.
Analysis And Characterization Of Electrically Conductive Adhesives
Authors: Gaynes Michael A. , Matienzo Luis J. , Zimmerman Jeffrey A. , Vanhart Daniel 
Published: April 2011

AbstractElectrically conductive adhesives (ECAs) are considered an alternative to solder interconnection in microelectronic circuit packaging. In an effort to understand the performance of this class of materials, several chemical analytical techniques have been employed to characterize polymer chemistry, filler morphology and surface chemistry. These techniques include fourier transform mass spectroscopy pyrolysis (FTMS), optical microscopy, confocal laser scanning microscopy (CLSM), scanning electron microscopy with energy dispersive x‐ray analysis (SEM/EDX), auger electron spectroscopy (AES) and photo‐electron spectroscopy (XPS). Samples studied were conductive adhesive layers and deposits, plated metal surfaces, cross‐sections of bonded joints and fractured bonds. Electrical contact resistance data were also taken on bonded joints. Three commercial adhesives were studied. It was found that thermal stability varied among the three adhesives with one adhesive showing degradation at as low as 200 °C. Differences were also noted in silver flake size, morphology and apparent contact area. Excellent contact resistance stability is achieved with two formulations on a palladium‐nickel alloy surface. In contrast, a hard gold surface yielded unstable contact resistance. Fractured bond surfaces were studied for both stable and unstable joints to understand mechanisms for contact resistance degradation. The increase in contact resistance is most likely caused by oxygen ingress along an interfacial bond where the adherend surface is smooth. The matrix polymer oxidized at the interface when exposed to temperatures above the glass transition temperature. Tin surfaces cause increasing contact resistance and nickel surfaces give an initial contact resistance that is more than two orders of magnitude higher than noble metal surfaces. Oxide formation in both cases is the likely cause for the unstable and high resistances. Various analytical techniques have been used to characterize and differentiate electrically conductive adhesives. Differences among three adhesives are noted and correlated to contact resistance performance.
In‐Situ Mapping and Modeling Verification of Thermomechanical Deformation in Underfilled Flip‐Chip Packaging Using Moiré Interferometry
Authors: Dai Xiang , Kim Connie , Willecke Ralf , Ho Paul S. 
Published: April 2011

AbstractAn experimental technique of environmental moiré interferometry has been developed for in‐situ monitoring and analysis of thermomechanical deformation of microelectronics packages subjected to thermal loading under a controlled atmosphere. Coupled with fractional fringe analysis and digital image processing, the environmental moiré interferometry technique achieves accurate and realistic deformation monitoring with high sensitivity and excellent spatial resolution. It has been applied to investigate the thermomechanical deformations induced by thermal loading in an underfilled flip‐chip‐on‐board packaging. The effects of temperature change in the range of 102 °C to 22 °C are analyzed for underfill and solder bumps. In addition, shear deformation and shear strains across the solder bumps are determined as a function of temperature. The experimental results are compared with the results of a finite element analysis for modeling verification. Good agreement between the modeling results and experimental measurements has been found in the overall displacement fields. Through this study, the role of underfill in the thermomechanical deformation of the underfilled flip‐chip package is determined.
In‐Situ Measurements of Thermal Properties of Dielectric Films on Metal‐Dielectric‐Substrate Structures
Authors: Bloss P. , De Reggi A.S. , Schäfer H. 
Published: April 2011

AbstractWe show that the thermal diffusivity of a dielectric film and the heat‐transfer coefficient between the film and the substrate to which it is adhesively bonded can be determined from the electret‐like response stimulated by laser pulses applied to the voltage‐biased dielectric. The temperature profile is calculated as a function of time from the heat‐conduction equation with boundary conditions appropriate for the model structure representing the metallic electrode/ dielectric film/ glue layer/ substrate structure. The electrode, acting as a thermal mass, and the substrate, acting as a thermal sink, affect the temperature profile in different time ranges.The response is a convolution of the temperature and the electric‐field profiles across the dielectric. For nonideal dielectrics that acquire bulk charge under bias, deconvolution is necesssary to determine the field profile and the thermal properties. Deconvolution is accomplished using the Tikhonov‐regularization technique with a self‐consistent regularization parameter. This procedure yields information about the thermal properties of both the dielectric and the glue joint, as shown by actual measurements.
Interfacial Delamination in Plastic Encapsulated Integrated Circuits (Pics)
Authors: Strifas Nickolaos , Christou Aris 
Published: April 2011

AbstractThe reliability of plastic packaged integrated circuits was assessed from the point of view of interfacial mechanical integrity. It is shown that the effect of structural weaknesses caused by poor bonding, voids, microcracks or delamination may not be evident in the electrical performance characteristics, but may cause premature failure. Acoustic microscopy (C-SAM) was selected for nondestructive failure analysis of the plastic integrated circuit (IC) packages. Integrated circuits in plastic dual in line packages were initially subjected to temperature (25 °C to 85 °C) and humidity cycling (50 to 85 %) where each cycle was of one hour duration and for over 100 cycles and then analyzed. Delamination at the interfaces between the different materials within the package, which is a major cause of moisture ingress and subsequent premature package failure, was measured. The principal areas of delamination were found along the leads extending from the chip to the edge of the molded body and along the die surface itself. Images of the 3-D internal structure were produced that were used to determine the mechanism for a package failure. The evidence of corrosion and stress corrosion cracks in the regions of delamination was identified.
On Relating Thermodynamic Work of Adhesion to Interfacial Fracture Toughness
Authors: Pearson Raymond A. , Lloyd Thomas B. 
Published: April 2011

AbstractOrganic adhesives are commonly used in the microelectronics industry to bond silicon chips to a wide variety of substrates. The substrates include copper, silver, nickel / palladium, polyimide, and glass‐filled epoxies. The surfaces of these substrates are affected by the processing steps used in the manufacturing process used to produce the final package. The most common adhesives used in the assembly of microelectronic packages are epoxy‐based and there are numerous grades and types to chose from. Therefore, the packaging engineer is faced with the dilemma of what criterion to use to select the best adhesive for a particular package design.At the crux of the problem is how does one predict adhesion and how does one measure it? It is proposed that the surfaces play an important role in forming the interfacial bond and that strength of the mating surfaces can be characterized in terms of the thermodynamic work of adhesion. Roughness is also a factor but will not be dealt with here. The thermodynamic work of adhesion describes the energy to reversibly separate two surfaces (elastic). Interfacial fracture mechanics may be used to quantify the strain energy release rate for separating two surfaces and contains both elastic and inelastic contributions. This talk will contain a discussion of our studies on the use of a three liquid probe method to determine the thermodynamic work of adhesion and a mixed‐mode bending method to measure interfacial fracture toughness. Moreover, we will comment on the perils of relating the thermodynamic work of adhesion to the interfacial fracture toughness.
Low Temperature Oxidation of Cu-Base Leadframe and Cu/Emc Interface Adhesion
Authors: Cho Soon-Jin , Paik Kyung-Wook 
Published: April 2011

AbstractLow temperature oxidation of a Cu-base leadframe has been investigated to understand the effect of Cu oxidation on the adhesion between Cu-base leadframes (Cu L/F) and epoxy molding compounds (EMC). From the kinetic studies on the oxidation, oxide growth was found to follow the parabolic rate law in the temperature range of 150 °C to 300 °C and the activation energy for the oxidation was 17.0 kcal/mol. X-ray photoelectron spectroscopy (XPS) studies confirmed that the oxide film consisted of Cu2O, CuO, and NiO. It was shown that the early stage of oxidation improved the adhesion strength. Furthermore the optimum copper oxide thickness required for the maximum pull strength ranged between 20 nm and 30 nm. The high pull strength was presumably due to the increase of surface wettability and mechanical interlocking effects resulting from copper oxidation.
A Study of the Surface Morphological Features of the Polar Faces of ZnO by Atomic Force Microscopy (AFM) Methods and AlN Thin Films Deposited on ZnO Polar Faces by PLD
Authors: Suscavage M. J. , Ryder D. F. , Yip P. W. 
Published: April 2011

ABSTRACTThe effects of both temperature and atmosphere on the resulting morphological features of the polar faces of single crystal ZnO were investigated and characterized by atomic force microscopy (AFM). In studies where ZnO was thermally processed in flowing oxygen at atmospheric conditions within the temperature range of 500°C to 900°C for 30 minutes, the Znsurface (i.e., (000 1)) showed a tendency to reconstruct with increasing temperature until terraces became evident at 900°C. Terrace heights were as small as 0.9 nm. In contrast, the O-surface (i.e., (000 ī)) was observe to change very little during the O2-atmoshere, thermal treatment and remained comparatively rougher than the Zn-surface. ZnO samples which were thermally processed under high vacuum (i.e., 5 × 10-7 Torr) conditions exhibited a more dramatic contrast. The vacuum annealed Zn-surface was observed to develop very smooth surface features (Roughness = 0.09 nm) at annealing temperatures within the 700 – 800°C range. In contrast, and as expected, the O-surface roughness increased due to surface reduction reactions. In addition to these findings, it is noted that AFM measurements may be utilized as a convenient method to distinguish between the two polar surfaces of ZnO.Aluminum nitride was deposited on the Zn- and O- surfaces from 700 to 850°C by pulsed laser evaporation. X-ray diffraction indicated that the AIN was c-axis oriented with no interface reaction products detected between the ZnO substrate and AIN film.