bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flashlamp-Pumped Dye and Excimer Laser Planarization of Thin Metal Films
Authors: Marella Paul F. , Tuckerman David B. , Pease R. Fabian 
Published: March 2011

ABSTRACTThe fundamental differences between excimer (≈ 30 ns pulse duration) and flashlamp-pumped dye (≈ 500 ns pulse duration) laser planarization are examined for 1.5-2 µm thick gold films over SiO2 layers. Test structures containing bar patterns (square waves) of 5000 Å peak-to-trough amplitude with spatial periods ranging from 10 µm to 100 µm were prepared and laser-irradiated. A linear model is presented which describes the time-evolution of the film's surface topography when melted with a dye laser pulse. Excimer laser planarization is found to be susceptible to evaporative recoil effects which may cause undesired pattern amplification.
Single & Multiple Pulse Ablation of Polymeric and High Density Materials with Excimer Laser Radiation at 193NM and 248NM
Authors: Elliott David J. , Piwczyk Ernhard P. , Elliott David J. , Piwczyk Bernhard P. 
Published: March 2011

ABSTRACTThe evolution of the excimer laser from a research tool in the 1970's to the industrial models of the 1980's has opened up numerous applications in semiconductor manufacturing, materials processing, and biological and medical research. Present production-capable, computercontrolled excimer systems with handling equipment enabling efficient automation can now operate for up to 50 million shots before undergoing scheduled maintenance, with fluences remaining within ±10% in most cases. Thus, although many uses for the excimer laser are still researchoriented, production applications are rapidly emerging.
Lif-Diagnostics of Cr During Laser-Induced Deposition from Cr(CO)6
Authors: Rieger D. , Rager B. , Bachmann F. 
Published: March 2011

ABSTRACTThe spatial and temporal distribution of Cr* in a laser-CVD arrangement has been studied by laser-induced fluorescence (LIF). Low excited Cr*(a5S2) atoms are produced by dissociation of Cr(CO)6 by a KrF laser ( λ = 248 nm) via two photon absorption. An observed disappearance of Cr* after photolysis is due to reaction with photofragments, quenching via collision relaxation and deposition. The diffusion constants for Cr* in He/Cr(CO)x mixtures could be determined. The Cr* density in the vicinity of a sample drops sharply by heating the sample. The decrease is due to thermal decomposition of Cr(CO)6 with an activation energy of 0.11 eV.
Micro-Indentation and Micro-Scratch Tests on Sub-Micron Carbon Films
Authors: Wu T. W. , Burn R. A. , Chen M. M. , Alexopoulos P. S. 
Published: March 2011

AbstractMicro-indentation and micro-scratch techniques were used to characterize the hardness and the adhesion strength of 0.11 μm thick sputtered carbon f-ilms on Silicon substrates. Hardness depth profiles and critical loads were measured using a microindenter under indentation and scratch testing modes, respectively. The carbon film with 6 mtorr argon sputtering pressure shows better practical adhesion (or higher critical load) and slightly higher hardness. The indentation fracture phenomenon observed on the 30 mtorr film is closely related to its poor adhesion. The failure mechanism will also be discussed.
Hardness and Elastic Modulus Measurements in CdTe and ZnTe Thin Film and Bulk Samples and ZnTe-CdTe Superlattices
Authors: Farthing L. J. , Weihs T. P. , Kisker D. W. , Krajewski J. J. , Tang M. F. , Stevenson D. A. 
Published: March 2011

AbstractHardness and modulus values of bulk and epilayer ZnTe and CdTe samples and of ZnTe-CdTe superlattices are reported. Both hardness and Young's modulus values increase with increasing ZnTe content in the ZnCdTe samples. Alloying effects and strains in the superlattice structure are proposed to explain the strengthening.
Mechanical Properties of Nanometre Volumes of Material: use of the Elastic Response of Small Area Indentations
Authors: Pethica J. B. , Oliver W. C. 
Published: March 2011

AbstractA new, differential method for determining the stiffness of a sub-micron indentation contact area is presented. This allows measurement of elastic modulus as well as plastic hardness, continuously during a single indentation, and without the need for discrete unloading cycles. Some of the new experiments that become possible with this technique, especially at the nanometre scale, are described. We show quantitatively that electropolished tungsten reproducibly exhibits the ideal theoretical lattice strength at small indentation loads.
Mechanics of Elastic Dislocations in Strained Layer Structures
Authors: Freund L. B. , Bower A. , Ramirez J. C. 
Published: March 2011

AbstractApplication of the elastic continuum theory of dislocations to modeling of phenomena associated with elastic strain relaxation in strained layer epitaxial heterostructures is discussed. The concept of critical thickness for onset of strain relaxation in a strained epitaxial layer is first reviewed, and some extensions to periodic arrays of dislocations and to multiple layers are described. Then, two issues are addressed that arise when the assumptions underlying the critical thickness concept are not met. One issue concerns the nucleation of dislocations at the growth surface of an epitaxial film, particularly the influence of surface irregularities on the activation energy for surface nucleation. A second issue concerns the kinetics of glide of a threading dislocation as it lays down an interface misfit dislocation when the layer thickness exceeds the critical thickness. A generalized driving force for the glide process is defined, and a relationship between this force and the glide speed is proposed.
Strain Relief Mechanisms and Nature of Misfit Dislocations in GaAs/Si Heterostructures
Authors: Sharan S. , Narayan J. , Salerno J. P. , Fan J. C. C. 
Published: March 2011

AbstractThe nucleation and glide of misfit dislocations in GaAs/Si system is investigated using transmission electron microscopy. GaAs epilayers of different thicknesses were examined by electron microscopy (plan and cross-section) and the elastic strain remaining in the film has been related to the average spacing of the misfit dislocations at the interface. A model is developed based on minimum energy considerations to determine the strain-thickness relationship. The theoretical predictions of strain relaxation are compared with experimental observations using high resolution electron microscopy.
Effect of Highly Strained Superlattices on the Threading Dislocation Behavior in GaAs Grown on Silicon
Authors: El-Masry N. A. , Tarn J. C. L. , Karam N. H. , Bedair S. M. 
Published: March 2011

AbstractGaAs films grown on silicon substrates suffer from a high density of threading dislocations. One technique to reduce these dislocations is the use of strained layered superlattices (SLS) InGaAs-GaAsP as buffer. We found that the effectiveness and interactions of the SLS with the threading dislocations strongly depend on the dislocation type and the strain field of the superlattices. Because of the high dislocation density in GaAs/Si, the SLS acts as a medium for dislocation interactions and annihilations. Highly strained SLS (∼ 2%) is required to bend the dislocations and keep them bent at the strained interfaces. We found that the combination between annealing and a highly strained superlattice coupled with selective epitaxy is an effective approach to reduce the threading dislocations in GaAs grown on Si. Transmission electron microscopy is used to study these effects.
Critical Thickness for Three-Dimensional Epitaxial Island Growth
Authors: Jagannadham K. , Narayan J. 
Published: March 2011

AbstractThe generation of misfit dislocation loops in three-dimensional epitaxial islands grown on thick substrates is analyzed. The coherent strain in the island is described by virtual interfacial dislocation loops situated in the interface. The traction free surface boundary conditions are satisfied by the surface dislocation loops situated on the surface of the island. A misfit dislocation loop is formed and the changes in the energy of the configuration used to determine if the total energy is lowered. The numerical analysis is carried out forhemispherical islands of GaAs grown on (100) silicon with a misfit dislocation of Burgers vector 3.84 Å. It has been found energetically favorable to nucleate a misfit dislocation loop at a distance of 3 å from the interface when the radius of the hemispherical island is equal to or greater than 40 å. In addition, a misfit dislocation loop could be nucleated at a larger distance from the interface when the size of the island is larger.
X-Ray Diffraction Studies of Annealed SiGe/Si SLS
Authors: Lowe Walter P. , Macharrie R. A. , Bean J. C. 
Published: March 2011

AbstractWe have done x-ray diffraction to study the affect of annealing on a SiGe/Si strained-layer superlattice (SLS). The post anneal spatial distribution of the Ge and Si atoms within the alloy layer is of particular interest. X-ray data taken from an annealed sample along the superlattice direction (100) show two sharp and well separated superlattice envelope functions. In contrast to the unannealed sample, and what would be a typical scattering spectra for a superlattice, the envelopes bisect the position of the unannealed sample's envelope function. The position of the envelope function is related to the tetragonal distortion εT in the SiGe alloy layers. The two separate envelopes (α and β) show that the SiGe alloy (100) planes have divided themselves into two groups with different interplanar spacings after the anneal. Each group with a tetragonal distortion such that and where εT is the tetragonal distortion in the unannealed sample. This is strong evidence for coherent phase separation perpendicular to the growth direction, along the SiGe alloy layer. In another investigation a search of reciprocal space for the 2 × 2 {… SiSiGeGe…} (111) chemically ordered state showed no evidence for the existence of such an ordered state.
The Cracking and Decohesion of Thin Brittle Films
Authors: Hu Mu-San 
Published: March 2011

AbstractFilm cracking and decohesion are two typical failure modes observed in thin coatings. In this investigation, failures were initiated in brittle Cr films deposited on both ductile and brittle substrates to study these phenomena. Fracture mechanics models were proposed to interpret the experimental observations. Excellent agreement between theory and experiment has been demonstrated.
Tailored Nicrostructures to Control Interfacial Toughness
Authors: Oh T. S. , Cannon R. N. , Ritichie R. O. 
Published: March 2011

AbstractFailure of ceramic-metal interfaces in response to residual or applied stress is frequently effectively brittle owing to the propensity for interfacial cracking caused by weaker than average chemical bonds and elastic or plastic discontinuities at the interface. Stronger atomic bonding derived from improved interfacial chemistry can enhance fracture resistance to a degree which may be limited by diversion of the crack into the brittle ceramic.Alternatively, methods under study promote interfacial fracture toughness in glass-Cu bonds via near-interfacial microstructures that encourage greater energy dissipation in a region near the interface fracture. Particular success has obtained from microvoid toughening wherein placement of controlled arrays of microcrack-like-voids in the ductile metal, suitably near the interface, can markedly enhance interfacial fracture energy, e.g. by as much as two orders of magnitude and to much greater toughnesses than for glass. The toughness develops with extension of the crack owing to formation of a bridging zone behind the crack wherein the crack flanks are spanned by ligaments of plastically deforming metal film.
Simple Models for Surface Cracking
Authors: Meakin Paul 
Published: March 2011

AbstractA simple model for crack growth in thin films deposited onto a substrate has been developed. This model results in the generation of cracking patterns which have a remarkably realistic appearance. In the simulations a slow crack initiation period is followed by a period of rapid crack growth in which quite linear cracks are formed. Later on the crack growth process becomes slower and less regular as the cracking process relieves much of the stress in the surface layer. In this model pre-existing defects have a large effect on the crack growth kinetics and morphology.
Adherence of Diamond Films Produced by Microwave Plasma Deposition on Sialon Tool Inserts
Authors: McCune Robert C. , Hoffman D. W. , Whalen T. J. , McHugh C. O. 
Published: March 2011

AbstractThe adherence of diamond films produced by microwave-enhanced chemical vapor deposition (CVD) on SiAlON tool inserts was assessed by scratch, indentation and machining tests on aluminum alloys. While the films are nominally adherent during handling and mild cutting operations, the measured adherence values are appreciably lower than values associated with conventional CVD coatings on cobalt-tungsten carbide cutting inserts. An indentation type adhesion test using polished substrates was found to yield reproducible behavior for interfacial crack extension at loads ranging from 15 to 150 kg. The “critical load” in scratch testing was found to be less than 10 N.
Long-Range Coherency Strain and Tilted Ipitaxy in Ag-Fe-Ag Sandwich Structures on Gaas(001) Substrates
Authors: Farrow R. F. C. , Speriosu V. S. , Parkin S. S. P. , Chien C. , Bravman J. C. , Marks R. F. , Kirchner P. D. , Prinz G. A. , Jonker B. T. 
Published: March 2011

AbstractWe find that epitaxial Fe films sandwiched between epitaxial Ag films grown on GaAs (001) substrates possess residual coherency strain at a thickness of 2000Å. The [001] directions of the Fe and Ag films are tilted with respect to the GaAs [001] axis. The tilts are coplanar with the tilt of the substrate surface normal to the [001] axis of GaAs and are qualitatively consistent with a recently proposed modol for tilted epitaxy.
Relationship Between Interfacial Strain and the Elastic Response of Multilayer Metal Film
Authors: Clemens Bruce M. , Eesley Gary L. 
Published: March 2011

AbstractWe have used x-ray diffraction and picosecond transient piezoreflectance to investigate the structural and elastic properties of three distinct multilayer systems: Mo/Ni, Pt/Ni and Ti/Ni. We demonstrate that the commonly observed lattice expansion perpendicular to the film plane is not a bulk effect, but is localized at the interface between the contacting metals. Incorporating the measured interfacial expansion into a universal binding relation, we show that the measured elastic softening versus compositional repeat distance can result from the interfacial strain.
Thin Film Stresses in TiW/AlCuSi/TiW Sandwich Structures
Authors: Wang Iton 
Published: March 2011

AbstractA highly reliable metallization for high current bipolar integrated circuits was developed with the aid of thin film stress analysis to optimize the process. The final structure was a sandwich layer of TiW and AlCuSi alloy. Film stresses were measured for individual TiW layers as well as for the sandwich layers of TiW/AlCuSi/TiW. In this paper, it will be shown how sputter deposition pressure can drastically affect film stress. For individual TiW layers, the film stress can be varied between compressive and highly tensile by adjusting the Argon pressure. Meanwhile, the AlCuSi layers were always tensile under the normal range of sputtering pressures. By controlling the individual film stresses, a sandwich layer can be designed so that the overall structure has a very low average stress. This work will also show how a TiW capping layer has a major effect on the final average stress of the sandwich structure.
Control and Variation of Stress in Pecvd SiNx Films on InP
Authors: Lopata J. , Dautremont-Smith W. C. , Lee J. W. 
Published: March 2011

AbstractStress in plasma enhanced chemical vapor deposited (PECVD) SiNx films on InP has been evaluated as a function of source gases (NH3 /SiH4 or N2/SiH4) and plasma operating frequency (high, » 1 MHz or low, « 1 MHz). All films were deposited at 300°C in the same parallel-plate, radial flow plasma reactor. Levels of stress in PECVD SiNx on InP within a continuous range from moderately high tensile (∼ 5 × 109 dyne cm−2) to very high compressive (2 × 1010 dyne cm−2 ) were obtained from appropriate choices of deposition parameters. Deposition from NH3/SiH4 at high frequency produces tensile stress, of magnitude increasing with NH3/SiH4 flow ratio. Deposition from N2/SiH4 at high frequency produces zero to low compressive stress. At low frequency compressive stress is always produced; for N2/SiH4 increasing the gas flow ratio from 25:1 to 500:1 reduces the compressive stress from 1.8 X 1010 to 7 × 108 dyne cm−2. The ability to vary the stress in a dielectric film of approximately constant chemical composition over such a broad range is beneficial for assessing the effects of stress on device performance.
Interfacial Fracture Mechanics
Authors: Hutchinson John W. 
Published: March 2011

AbstractThe mechanics of interface cracks has recently been clarified (e.g., [1]) and a number of efforts are underway to develop a mechanics of interface fracture with applications to composite materials, thin film/substrate systems, and coatings. An intrinsic feature of interfacial fracture is its mixed mode character wherein both shear and normal stresses act on the interface directly ahead of the crack. Depending on geometry and loading, the mixture of modes can range from purely normal stresses (mode I) to purely shear stresses (mode II). Toughness of an interface is characterized by critical combinations of mode I and mode II stress intensity factors (i.e., a locus of critical combinations) rather than just the single critical mode I stress intensity factor in the fracture of homogeneous materials. Equivalently, the critical energy release rate depends on the mode combination for interfacial fracture. Solutions are now available to the following problems: an interface crack in a layered structure where a very thin layer is sandwiched between two thick layers of different material [2], an interface crack between two layers of arbitrary thickness subject to arbitrary combinations of bending and stretching loads [3], and a crack in a substrate paralleling an interface between a thin film and the substrate driven by a variety of loadings including residual tension in the film [4]. These solutions can be used to analyze specimens for determining interfacial toughness and for predicting cracking in thin film or layered structures.
Silicon Nitride Fibers Using Micro Fabrication Methods
Authors: Koskinen J. , Johnson H. H. 
Published: March 2011

AbstractAmorphous LPCVD and PECVD Si3N4films have been patterned into fibers of various shapes using integrated circuit methods. A tensile test apparatus was developed which allows a simultaneous testing of up to 20 fibers. The average tensile strength of LPCVD Si3N4fibers with a 30 μm gauge section was 7.0 ± 0.4 GPa. The corresponding value for PECVD Si3N4was 2.4 ± 0.2 GPa. The following properties of the materials were measured: atomic composition (RBS, FRES), density, refractive index, internal stress, elastic modulus and micro hardness. A Weibull analysis of the tensile strength values was performed.
Mechanical Testing of Thin Films
Authors: Rosenmayer C. T. , Brotzen F. R. , Gale R. J. 
Published: March 2011

AbstractMetal films used as conductors in integrated circuits must be able to withstand stresses created during their deposition, caused by mismatches in thermal expansion coefficients and by bending which occurs during manufacture and installation. These stresses may be biaxial or uniaxial in nature. This paper discusses testing techniques and gives examples of results of mechanical testing of thin metallic films of aluminum, aluminum-copper(2%), copper, and tungsten in uniaxial and biaxial tension. The film specimens were deposited on and removed from production silicon wafers in order to simulate as much as possible actual device conditions. Basic considerations for the comparison of the two testing methods are also presented.
An Evaluation of Simplified Models for Surface Kinetics in Movpe Processes
Authors: Tirtowidjojo Max , Pollard Richard 
Published: March 2011

ABSTRACTA general MOVPE model has been used to assess the applicability of simplified representations for surface kinetics. With the general model, predictions for GaAs deposition on (111 )Ga using trimethylgallium and arsine show excellent agreement with observed growth rates. However, if Langmuir-Hinshelwood kinetics is assumed, the model only matches the deposition rates over a narrow range of operating conditions, even when several rate-limiting steps are included. This limitation arises because combinations of equilibrium constants and local partial pressures often do not give reasonable approximations for the surface concentrations of reactive intermediates. The form of the Langmuir-Hinshelwood relation(s) and the parameter values can be fitted empirically to experimental data, but this could lead to erroneous conclusions concerning process behavior and the model would have limited predictive capabilities. An alternative approach is to use surface reaction probabilities, but they can only be applied in an empirical fashion and their magnitudes depend on gas flow rate, inlet composition, and reactor pressure as well as surface temperature.
Eqilibrium Analysis of the TMGa-TMA1-AsH3-H2 Mocvd Epitaxial Growth System
Authors: Moon Hyuk J. , Stoebe Thomas G. , Chadwick Brian K. 
Published: March 2011

ABSTRACTThe thermodynamic equilibrium state of the Ga-Al-As-C-H system was determined theoretically by means of an iterative equilibrium constant method. This method of calculation is presented and discussed. With very little operator input, the program is capable of computing the partial pressures of the gas-phase species present in the equilibrated system.In these calculations the system was considered to be saturated with solid-phase A1GaAs and included 58 plausible gas-phase intermediates which evolved from the initially present gas species; trimethylgallium, trimethylaluminum, arsine, and hydrogen. Temperature and total system pressure ranges investigated were 750–1100 K and 0.1 atm-1.0 atm, respectively. The effects of temperature and pressure variations, in addition to effects caused by changes in the appropriate atom ratios, have been delineated. The properties of this equilibrated system are compared with those from recent thermodynamic research efforts on AlGaAs systems consisting of only gaseous constituents.
Investigation of Ga Diffusion in (001) and (111) CdTe Layers Grown on (001) GaAs
Authors: Dubowski J. J. , Wrobel J. M. , Jackman J. A. , Becla P. 
Published: March 2011

ABSTRACTA secondary ion mass spectroscopy study of Ga diffusion in CdTe grown on (001) GaAs was carried out. The layers were grown by pulsed laser evaporation and epitaxy. Two characteristic regions with increased Ga concentration were found. The first was the CdTe/GaAs interface where the concentration of Ga decreases rapidly to the detection limit of −8 × 1014 cm−3. This region was usually less than 300 nm wide. The second was a surface region with a Ga accumulation of up to −1017 cm−3. Ion imaging revealed that in the (001) CdTe layers, Ga accumulates near the surface at localized spots, up to about 8 μm in diameter. This feature is less apparent in the (111) CdTe layers. Annealing at 500 °C for 1 h increased the Ga concentration in the whole layer to above 1016 cm−3. We also observe thermal annealing induced precipitation of Ga at the surface of bulk CdTe samples which were originally uniformly doped with Ga.