bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Electron Microscopy Study of the effects of Deposition Conditions on the Growth of Glow Discharge Prepared a-Ge:H Films.
Authors: Jones Scott J. , Turner Warren A. , Pang Dawen , Paul William 
Published: March 2011

ABSTRACTElectron microscopy techniques have been used to study the effect of deposition conditions on island growth and coalescence in r.f. glow discharge prepared a-Ge:H. Planar views of 500 Å thick films were obtained using transmission electron microscopy (TEM) while scanning electron microscopy (SEM) was used to investigate the cross-sectional microstructure of thicker films. Films were prepared on both electrodes of a capacitively-coupled, diode deposition system. The substrate temperature, level of applied power, externally applied d.c. substrate bias, and the germane to diluent gas ratio were systematically varied. For films prepared on the unpowered electrode, island coalescence was dramatically enhanced with increasing substrate temperature while columnar structure, found for samples prepared at lower substrate temperatures, vanished. Both effects are attributed to the elimination of a coalescence barrier with increased temperature. Increasing negative substrate bias slightly increased island coalescence while increasing the level of applied power had no visible effect on film microstructure. The island size decreased with increasing dilution of the gas plasma by H2. The addition of GeF4 to the gas plasma leads to a low density, porous film. This observation is attributed to either a difference in the plasma chemistry or increased film etching due to the presence of F in the gas plasma. High quality films prepared on the powered electrode were found to be more structurally homogeneous and environmentally stable than films prepared on the unpowered electrode at the same substrate temperature. Enhanced bombardment and/or a different plasma chemistry near the powered electrode are two factors which may contribute to the observed difference in microstructure.
Approach Towards Heteroepitaxial Growth of Functional Molecular Crystals by Vapour Deposition
Authors: Inoue A. , Ishino M. , Akagi Y. , Koba M. 
Published: March 2011

ABSTRACTIn order to realize a thin film of organic single crystals, we have been investigating fabrication process using vapour deposition technique. Up to now, highly oriented thin films of 2-methyl-4-nitroaniline(MNA) and 4-(N,N-dimethylamino)-3-acetamidonitrobenzene(DAN), both of which are promising organic materials for nonlinear optical devices, could be fabricated on a buffed polyimide and on a thermally oxidized silicon wafer, respectively. In the case of MNA films, a series of results by X-ray diffraction and by SEM observation showed weak two-dimensional characteristics suggesting the existence of topographic effects and/or of interaction between MNA molecules and molecular moieties of polyimide substrate. Small optical transmittance of both MNA and DAN thin films are explained in terms of light scattering by grain boundaries and surface roughness.
Characterization of Si/Si3N4 Layered Structures Grown By Physical Vapor Deposition/Ion Beam Assisted Deposition
Authors: Cotell C. M. , Donovan E.P. 
Published: March 2011

ABSTRACTLayered silicon/silicon nitride structures were fabricated on (100) Si with 0.1 mTorr of N2 background pressure. Evaporated Si (PVD) layers were alternated with layers grown by simultaneous nitrogen ion bombardment and Si evaporation (IBAD). The ion to vapor flux ratios were chosen to yield stoichiometric Si3N4 (XN=0.57) at 150, 500, 1000 and 1500 eV and varied at a constant energy of 500 eV to yield sub- and superstoichiometric Si1-xNx. The microstructures were examined by cross-sectional and plan-view TEM; composition of the layers was deteiTnined by RBS. Films grown at low substrate temperatures were amorphous. Stoichiometric and superstoichiometric compositions showed a cellular (5 nm) structure in the amorphous IBAD layers. In addition, the IBAD Si1-xNx layers showed variations in contrast parallel to the substrate interface, indicative of compositional fluctuations on a scale of <20 nm. The IBAD layers were dense, but the PVD-Si layers contained voids that were aligned with the direction of the impingement of the evaporant on the substrate surface. A high substrate temperature (750°C) yielded polycrystalline Si layers and phase-ordering in the Si1-xNx layers.
Interplay of Strain, Growth Kinetics and Surface Bonding in Growth Modes and Dislocation Generation in Strained Heteroepitaxy
Authors: Snyder C. , Pamulapati J. , Orr B. , Bhattacharya P. K. , Singh J. 
Published: March 2011

ABSTRACTIn this paper we examine the role of strain and growth kinetics on the growth modes in pseudomorphic growth. Regimes below critical thickness and above critical thickness are examined. Based on atomistic modelling and in-situ RHEED and STM studies we show that a competition between surface chemical energy and strain energy is shown to lead to 3-dimensional blend mode for high strain pseudomorphy. Consequences for dislocation generation are discussed.
Initial Growth of Ag/Si(100) Studied with High Spatial Resolution Aes and Sem
Authors: Luo Frank C. H. , Hembree Gary G. , Venables John A. 
Published: March 2011

ABSTRACTThe initial growth of Ag on reconstructed Si(100) has been studied with biassed secondary electron imaging (b-SEI) and Auger electron spectroscopy (AES) in an ultra-high vacuum (UHV) scanning transmission microscope (STEM) with nanometer resolution. Small Ag islands have been observed with strong contrast in b-SE images. Anisotropic growth, correlated with the (2×1) and (1×2) dimer reconstruction, is seen at room temperature and sub-monolayer (ML) coverage. Large Ag islands (∼1 μm) formed at 475 °C substrate temperature have even more dramatic forms with large aspect ratios. The Stranski-Krastanov (SK) mode is confirmed at both temperatures by AES and b-SEI between the islands, with the intermediate layer coverage equal to 0.5 ML or less.
Misfit Dislocations at the Critical Thickness for Ingaas/Gaas Strained Layers
Authors: Green G. S. , Tanner B. K. , Turnbull A. G. , Barnett S. J. , Emeny M. , Whitehouse C. R. 
Published: March 2011

ABSTRACTThe contrast of misfit dislocations in an InGaAs layer, close to the critical thickness and capped with GaAs grown by MBE on a (001) oriented GaAs substrate has been investigated by double axis synchrotron X-radiation topography. The layer thickness variation as a function of position has been measured to a precision of 1A by matching interference fringes observed in the 004 symmetric reflection double crystal rocking curves with simulations. The misfit dislocation density is highly anisotropic, varying from zero to a high value with increasing thickness. The contrast of the dislocations in the 004, 224 and 044 reflections has been examined in detail. All of the long dislocation segments characterized were 60° in character with ½<110> Burgers vectors inclined to the specimen surface. No dislocations were found which did not appear to be of this type. A surprising difference in contrast of the background in the 224 and 224 reflections is discussed.
Epitaxial Layer Misorientation in CdTe on GaAs‡
Authors: Inglefield H. E. , Matyi R. J. , Korenstein R. 
Published: March 2011

ABSTRACTX-ray diffraction has been used to characterize the relative misorientation of [001] and [111] CdTe layers grown by hot-wall epitaxy on GaAs substrates. The magnitude of the misorientation of the CdTe epitaxial layer relative to the GaAs substrate depends on the magnitude of the miscut of the substrate; in addition, the [111] oriented CdTe exhibited significantly larger misorientations than did the [001] CdTe films. The azimuthal direction of the tilt of the epitaxial layer depends strongly on the nominal crystallographic orientation of the film. The [111] CdTe exhibited an azimuthal dependence of the tilt that is approximately coincident with the miscut of the substrate, while the azimuthal direction of tilt in the [001] CdTe layers differed from the substrate miscut direction by as much as 116°. These observations of epitaxial layer misorientation are discussed in terms of a dislocation model for layer tilt and azimuthal rotation in lattice-mismatched epitaxial systems.
Development of Pseudomorphic Structure in Ge Films Deposited on Si(100) at Low Temperatures
Authors: Lyman P. F. , Thevuthasan S. , Grant M. W. , Hoogenraad J. H. , Seiberling L. E. 
Published: March 2011

ABSTRACTWe have studied the structure of 1 to 10 monolayer (ML) Ge films grown at room temperature on Si(100)–(2 × 1). Using transmission ion channeling spectroscopy, we have uncovered the first evidence for pseudomorphic structure in these films, contradicting the widely–held belief of amorphous growth at temperatures below 500 K. A model is proposed in which pseudomorphic domains constitute roughly half of the Ge films up to a critical thickness (∼4 ML), after which strain is relieved through defect introduction. Several of the films grown at room temperature were subsequently annealed for 20 min. at fixed temperatures ranging from 450 K to 790 K. A marked improvement in the epitaxial quality of the films is observed upon annealing that is consistent with growth proceeding from existing pseudomorphic domains.
Scanning Tunneling Microscope Study on Amorphous and Crystallized CoSi2 Films
Authors: Kuwabara M. , Smith D. A. , Welland M. E. 
Published: March 2011

ABSTRACTCoSi2 films were investigated using a scanning tunneling microscope (STM) to understand the film surface topology. The STM images showed that the as-deposited amorphous film had a nano-meter scale roughness which agrees with cross-sectional transmission electron microscope (TEM) observations and also had a uniform granular structure. Images of the crystallized film clearly show the crystal grain structure at the surface and the surface topography change associated with crystallization. In-situ crystallization was accomplished by operating the STM with a high bias; dome shape crystallites were produced at the surface of the amorphous films.
Interfacial Atomic Structures During Cobalt Silicidation
Authors: Catana A. , Schmid P.E. 
Published: March 2011

ABSTRACTHigh Resolution Electron Microscopy (HREM) and image calculations are combined to study microstructural changes related to the CoSi/Si-CoSi/CoSi2/Si-CoSi2/Si transformations. The samples are prepared by UHV e-beam evaporation of Co layers (2 nm) followed by annealing at 300°C or 400°C. Cross-sectional observations at an atomic scale show that the silicidation of Co at the lower temperature yields epitaxial CoSi/Si domains such that [111]Si // [111]CoSi and <110>Si // <112>CoSi. At about 400°C CoSi2 nucleates at the CoSi/Si interface. During the early stages of this chemical reaction, an epitaxial CoSi/CoSi2/Si system is observed. The predominant orientation is such that (021) CoSi planes are parallel to (220) CoSi2 planes, the CoSi2/Si interface being of type B. The growth of CoSi2 is shown to proceed at the expense of both CoSi and Si.
On The Nature of Multiple Orientation Relationships in Epitaxial Silicides
Authors: Felton L.E. , Dakshinamurthy S. , Rajan K. 
Published: March 2011

ABSTRACTThe Invariant Line Criteria (ILC) has been used to explain experimentally observed precipitation and epitaxial orientation relationships in a number of metallurgical systems. We propose that ILC may explain the crystallography of misoriented silicide grains in epitaxially grown silicide films. We test our hypothesis on the case of misoriented grains in CoSi2 on Si (001). Our analysis shows that the experimentally observed orientation relationship is predicted by the ILC.
Evolution of Residual Stresses in Thin Films Deposited on Mechanically Strained Substrates
Authors: Sheikh G. , Berger A. , Noyan I. C. 
Published: March 2011

ABSTRACTA simple model for the formation of residual stresses in thin films deposited on elastically strained substrates was derived and experimentally tested. In the experiments, Cu thin films were deposited on elastically stretched nickel substrates. These Cu films were2 to 4.m thick and were deposited through vapor phase evaporation or electroplating. The loads applied during the deposition were then relaxed, and the total stress in both the film and the substrate were monitored (by x-ray diffraction) during this relaxation. It was seen that the final (residual) film stresses were significantly different for bothdeposition methods. The causes of such differences are discussed.
Studies on the Surface Modification of Benzocyclobutene(BCB) Film By Plasma Ions
Authors: Paik Kyung W. , Saia Richard J. , Chera John J. 
Published: March 2011

ABSTRACTThe etch rates of BCB film in a reactive ion etcher(RIE) were measured using Ar, O2, O2+CF4, and O2+SF6 gas mixtures. Faster etch rates were obtained when CF4 and SF6 were added to oxygen, since the presence of atomic fluorine enhances the etch rate of organics, while also etching Si and SiO2 formed by exposure to oxygen gas. Surface compositional changes on the BCB film were observed by XPS after plasma modification. Pure O2 and O2+CF4 plasma oxidized the carbo-siloxane linkage (C-Si-O) of the BCB, resulting in the formation of SiO2 on the surface. The O2 +SF6 plasma, however, did not produce the surface SiO2, because of its faster Si and SiO2 etch rates. Ar ion sputtering following the plasma modification, restored the surface chemical composition to a state similar to the initial BCB surface.
Cavity Evolution in High Strength Electroless Copper
Authors: Pedraza A. J. , Godbole M. J. , Toth J. R. 
Published: March 2011

ABSTRACTSeveral industrial facilities produce electroless copper for use in printed circuit boards. One major class is the high- strength copper, so called because of its extremely high strength. During the deposition process, hydrogen is commonly incorporated into the film and it is thought to be the cause of poor ductility.In this work, the hydrogen content was measured by the fusion technique in three sets of high strength electroless copper specimens, respectively annealed at 423, 520 and 573 K. The hydrogen content decreased very rapidly at the two higher temperatures, and tended to a saturation value of approximately 20 ppm by weight with increasing annealing time. The cavity evolution with annealing time at 520 and 573 K was studied by transmission electron microscopy (TEM). It was found that the number of cavities increased with annealing time and with increasing temperature.The data indicate that hydrogen degassing is not controlled by bulk diffusion and, hence, that hydrogen must be trapped. A comparison with recrystallization results demonstrates that more than half of the hydrogen retained in the electroless copper is in saturable traps. The TEM observations indicate that cavity coarsening takes place during annealing at 520 and 573 K.
Mechanical Properties of CVD Tungsten Fibers
Authors: Lilienfeld David , Steinwall James , Borgesen Peter 
Published: March 2011

ABSTRACTTungsten fibers were fabricated with dimensions relevant to microelectronics and microfabrication. The strength and modulus were 1.57±0.7GPa and 276±lO%GPa, respectively. The failure mode was most consistent with intergranular fracture.
Multi-Chip-Module Interconnections by Laser Direct Writing
Authors: Müller Heinrich G. , Paredes Alvaro , Buschick Klaus , Reichl Herbert 
Published: March 2011

ABSTRACTA very flexible maskless technique for thin film hybrid formation has been developed. Lay outs are transferred directly from work stations to laser controls. Openings in ceramic substrates are achieved through laser cutting, and chips are embedded to give a common chip-to-substrate surface, flat to within 2 μm. Dielectric layers of polyimide are formed by spin on techniques and are then laser structured for via hole formation.Interconnections of the embedded chips are generated by laser direct writing of thin copper lines from copper formate, followed by chemical copper deposition. Chemical pretreatments of the aluminum contact pads allow for reasonable chip contacting with these methods. Electrical measurements on the dc line conductivity and the high frequency behaviour of these interconnections have also been performed.
The Formation and Morphology of Stress Induced Voids in Thin Narrow Aluminum Lines
Authors: Paszkiet C. A. , Korhonen M. A. , Li Che-Yu 
Published: March 2011

ABSTRACTThin, narrow, lines were reactive ion etched from a highly textured aluminum film deposited on (100) silicon substrates; some arrays of lines were covered with a passivation layer of silicon nitride. Passivated and unpassivated lines were heat treated at 400°C.Voids were present in nitride covered lines which were aged for over three months at room temperature as well as in nitride covered lines examined immediately after heat treatment. Voids were not visible in bare, heat treated lines. Void nucleation occurred at the points of intersection of grain boundaries with line edges and growth appeared to follow grain boundaries.
A Fracture Mechanics Approach to Thermal Fatigue Life Prediction of Solder Joints
Authors: Pao Yi-Hsin 
Published: March 2011

ABSTRACTThe approach developed is based on the assumption that thermal fatigue crack propagation in solder joints is primarily controlled by C* and J integrals. The effect of microstructural coarsening on crack propagation is discussed. A fracture criterion, J≥Jc, is used to define the failure of the joints. A crack growth governing equation has been formulated and can be numerically integrated to obtain the crack growth history given stress history as an input. The approach was applied to model the experiment by Wong and Helling [15]. In their experiment, surface-mounted electronic devices using eutectic Pb/Sn solder were tested in thermal cycles of −20 to 100°C and −55 to 125°C. A unified constitutive equation was assumed for the eutectic Pb/Sn solder. An equation for solving the shear stress in the joint was formulated and is coupled with the crack growth equation. Both equations were solved simultaneously by the Runge-Kutta method for the stress-time and crack growth history. The results of the prediction are in a good agreement with the experimental data, which indicates that fracture mechanics may be applied to describe the failure process of solder joints under cyclic thermal loadings.
Integrated Matrix Creep: Application to Lifetime Prediction of Eutectic Tin-Lead Solder Joints
Authors: Knecht Sheera 
Published: March 2011

ABSTRACTThe matrix creep failure indicator developed by Shine and Fox is extended to cases when strain is multiaxial and varies with position in the structure. Analysis of a thermal fatigue test of leaded surface mount devices found in the literature illustrates application of the method. A butt joint surface mount configuration is then tested in simple mechanical loading and also analyzed using the finite element method. It is found that the matrix creep “damage integral” method gives good correlation with observed solder fatigue failures for both cases.
Structural Investigation of the Silver—Polyimide Interface by Cross—Sectional Ten and Ion—Beam Sputtering
Authors: Foitzik A. , Faupel F. 
Published: March 2011

ABSTRACTWhen metals are deposited on polymers at low rates and elevated temperatures extended and non—uniform interfaces may form, the structural investigation of which requiresspecial techniques. In this paper the morphology of the silver—PMDA—ODA boundary formed during vapor deposition of the metal at 360 ºC has been investigated by means of cross—section TEM and a radiotracer technique in combination with ion—beam sputtering (IBS) for depth profiling. Ag was found to form clusters at the interface, but nearly spherical Ag particles up to diameters as large as 28 nm were also observed within the bulk of the polymer. The formation of Ag clusters is also reflected in the depth profiles, which, in addition, provide direct evidence for the diffusion o; singel Ag atoms deep into the polyimide. Diffusivities in the range of 10–21 – 10–18 m/s were determined for 300 ºC< T < 400 ºC. The Arrhenius plot is curved in accordance with a free—volume mechanism of diffusion. Cross—sectional TEM and low—energyIBS—depth profiling turned out to be an ideal combination for the investigation of extended metal—polymer interfaces.
Measurement of the Triaxial Stress State of Confined Line Structures During Thermal Cycling
Authors: Moske M.A. , Ho P.S. , Mikalsen D.J. , Cuomo J.J. , Rosenberg R. 
Published: March 2011

ABSTRACTA method based on the bending beam technique has been developed to measure the mechanical stresses of fine lines confined by a dielectric layer. This method has been employed to determine the thermal stress of AI(2at%Cu) lines passivated by a quartz overlayer between room temperature and 400ºC. The effect of quartz confinement was analyzed by matching the thermal strains at the metal/quartz interfaces and imposing a mechanical equilibrium condition on the structure. The analysis enables us to deduce the triaxial stress components of metal and quartz from measurements of the substrate bending parallel and perpendicular to the length direction of the lines. Results of the measurementshow a substantial stress enhancement as a result of the confinement, with the stress level significantly higher than that of a passivatecd blanket film. The magnitude of the stress depends on the line geometry, the layer deposition conditions and the extent of plastic deformation during thermal cycling. Results of this measurement are consistent with those determined using X-ray techniques.
Low Temperature Ceramic Coatings for Environmental Protection of Integrated Circuits
Authors: Chandra Grish 
Published: March 2011

ABSTRACTA novel concept for improved environmental protection of integrated circuits uses thin, in-situ formed ceramic layers on the circuit surface. Metastable ceramic precursors, hydrogen silsesquioxane and silacyclobutane, convert to pure silica and amorphous silicon carbide dielectric films respectively upon processing at temperatures from 175 to 250ºC. These twolayer ceramic films were shown to protect silicon CMOS circuits from industry-recognized autoclave and HAST exposure environments for more than 400 hours whereas unprotected circuits always failed within 200 hours.
Kinetics of Thermal Decomposition of Group-Hi Metal Alkyls on GaAs(100)
Authors: Donnelly V. M. , Mccaulley J. A. , Shul R. J. 
Published: March 2011

ABSTRACTWe report studies of the kinetics of thermal decomposition of triethylgallium (TEGa), trimethylgallium (TMGa), and trimethylindium (TMIn) adsorbed on GaAs(100) in ultrahigh vacuum. The adsorbed layers were prepared by dosing GaAs(100) at room temperature, to either saturated coverage or coverages below saturation. Subsequent heating leads to loss of adsorbed hydrocarbons. The relative coverage of carbon was monitored by X-ray photoelectron spectroscopy (XPS), and products were detected with a differentially pumped quadrupole mass spectrometer. The kinetic analysis also includes measurements of laser-induced, rapid thermal decomposition (heating rates of ∼1011°C/s).TEGa dissociatively chemisorbs on GaAs(100). Heating the substrate results in desorption of diethylgallium radicals at low temperature and C2H4 (and some C2H5) at higher temperatures, after most of the diethylgallium has desorbed. TMGa decomposes to yield a Ga-alkyl desorption product (either dimethylgallium, or a mixture of dimethylgallium and TMGa) at low temperature and CH3 at higher temperature. TMIn undergoes a methyl exchange reaction on GaAs(100) where a Ga-alkyl desorbs with the same cracking pattern as in TMGa decomposition. Decomposition mechanisms for these group-III metal alkyls are proposed, Arrhenius parameters are presented, and some implications are discussed for growth of Ga-containing III-V compound semiconductor films from these precursors by chemical vapor deposition and molecular beam techniques.