bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of TiN Anneal Ambient on The Microstructure and Electromigration Performance Of Al-Based Alloys
Authors: Olowolafe J. Olufemi , Lee Charles , Kawasaki Hisao , Gelatos Carol , Blumenthal Roc , Theodore N. David , Gregory R. B. 
Published: March 2011

AbstractA strong correlation has been established between TiN substrate anneal ambient and electromigration performance of Al-based alloys. Excellent electromigration lifetimes were measured for AlSiCu (and AlCu) films on sputtered TiN substrates annealed in N2 and slowly cooled down in furnace. The films annealed in N2-O2 and N2-H2 showed poorer electromigration performance, in that order. Stronger Al (111) texture, larger median grain size and uniform grain size distribution have been responsible for the improved electromigration performance of the N2-annealed (furnace-cooled) films. On the contrary, Al alloy films on TiN substrates annealed in N2 (but air-cooled), N2-O2, or N2-H2 ambient showed weaker Al (111) textures and smaller median grain sizes.
An In Situ STM Investigation of Stranski - Krastanov Growth of Ag on Au (111) Electrodes
Authors: Corcoran S. G. , Chakarova G. S. , Sieradzki K. 
Published: March 2011

ABSTRACTWe present in situ scanning tunneling Microscopy (STM) results which show the morphological aspects of Ag electrodeposition on Au (111). The experimental conditions enabled us to follow, in real time, with monolayer resolution, the morphological details of Stranski-Krastanov (SK) growth under a fixed electrochemical potential (constant supersaturation). Two epitaxial layers of Ag were sequentially formed prior to the heterogeneous nucleation of three-dimensional Ag crystallites. STM images are presented showing that the second silver monolayer has a coarsened (surface) diffusion-limited-aggregation growth front. IMMediately after the completion of the second silver monolayer which took approximately five Minutes, we observed the formation of 3D clusters preferentially at step edges. Our analysis of the SK growth process indicates that it is not well described by heterogeneous-nucleation thermodynamics owing to the almost identical lattice parameters of Ag and Au. Instead, we argue that the wetting-nonwetting transition we observed was kinetically stabilized by the relatively high activation energy involved with the motion of Ag adatoms over a descending Ag step.
Scanning Tunneling Microscopy Study of the Dynamic Scaling Properties of Rough Vapor-Deposited Silver Films
Authors: Palasantzas G. , Krim J. 
Published: March 2011

ABSTRACTWe investigated the scaling behaviour of vapor-deposited silver films at room temperature by means of scanning tunneling Microscopy. The film-thickness range was ≈ 10 – 1000 nm. The roughness exponent H is observed to be H = 0.82 ± 0.05. The growth and dynamic scaling exponents are respectively observed to be β = 0.29 ± 0.06, and z = 2.53 ±0.50.
Temperature Dependence of morphology of InP Films Grown by metalorganic molecular Beam Epitaxy
Authors: Cotta M.A. , Hamm R.A. , Chu S.N.G. , Harriott L.R. , Temkin H. 
Published: March 2011

ABSTRACTTwo regimes of growth are observed for epitaxial films of InP prepared by metalorganic molecular beam epitaxy. Below a minimum growth temperature, kinetic roughening is observed. At temperatures higher than smooth morphologies are obtained. From the dependence of on the substrate Misorientation, we estimate a value of ∼0.4–0.5eV for the Schwoebel barrier. At growth temperatures higher than we observe two types of defects: large oval defects related only to the initial conditions of the substrate surface and small defects with the density strongly dependent on the growth condition. Increasing temperature above or decreasing V/III ratio, results in increased density of these defects. In addition, their density increases with an activation energy that depends on the substrate Misorientation. The origin of the oval defects is attributed to non-stoichiometric, P-defficient, clusters on the growing surface, formed either by enhanced cracking of metalorganic s on the substrate due to the presence of contaminants or by a low V/III ratio used for growth.
Adhesion of Nanoscale Metal Clusters to Semiconductor Surfaces: A Scanning Tunneling Microscopy Examination
Authors: LIN SHIHCHER T. , ANDRES R. P. 
Published: March 2011

ABSTRACTScanning tunneling Microscopy (STM) is used to investigate the initial stage of metal overlayer formation on semiconductor surfaces. STM scans are presented of preformed nanometer diameter Au clusters deposited at room temperature on molybdenum disulfide and hydrogen terminated silicon substrates. These scans show that the Au clusters are substantially deformed by interfacial forces between the cluster and substrate. The extent of deformation depends on the substrate.
the Microstructure and Electrical Resistivity of Cluster-Based thin Films
Authors: Bielefeld Jeffery D. , Andres Ronald P. 
Published: March 2011

ABSTRACTCluster-assembled thin metal films exhibit properties which are different from those of films obtained by conventional atomic-deposition. We present TEM data on the evolution of 2-D Microstructure and SFM data on the evolution of 3-D Microstructure in thin films grown by vacuum deposition of preformed silver clusters and of preformed acetylene-silver clusters on flat SiO2, and Mica. Electrical resistivity measurements of cluster-based Ag and Ag/C2H2 films deposited on glass substrates with nominal film thicknesses of 5 nm - 50 nm are also presented and discussed.
the Critical Thickness of Dislocation-free Stranski-Krastanov Growth Atop a Deformabile Substrate
Authors: Grinfeld Michael 
Published: March 2011

AbstractWe investigate the influence of mass forces (in particular, of gravitation and van der Waals forces) on the critical film thickness of thin films attached to solid substrates and establish corresponding corrections of the earlier published formula Hcril = ΣΜ/τ2 (where Σ is the surface energy, Μ - the shear Modulus, and τ - the mismatch stress). It is assumed that the films’ particles are able to rearrange their relative positions in the lattices, and the equilibrium rearrangement is determined by minimizing the total static energy. Recently, it was demonstrated that morphological stability of interfaces in crystalline solids with the rearrangement is extremely sensitive to the presence of shear stresses. Equilibrium theory of elasticity of pre-stressed solids with the rearrangement of their material particles has already allowed the prediction of the appearance of corrugations in He4 films and to explain the dislocation-free Stranski-Krastanov pattern of epitaxial growth of thin solid films. The explicit asymptotic formulae announced here are especially useful in the case of small mass force, the effects of which can be detectable and even significant for some of the above mentioned phenomena.
Dynamic Scaling of the Island-Size Distribution and Percolation in a model of Sub-Monolayer Molecular Beam Epitaxy
Authors: Amar Jacques G. , Family Fereydoon , Lam Pui-Man 
Published: March 2011

ABSTRACTThe results of a detailed study of the scaling and percolation behavior of the sub-Monolayer in a model of molecular beam epitaxy are presented. In our model adatoms are randomly deposited on a square lattice and then allowed to diffuse. Whenever an adatom encounters another adatom or an island, it is attached to them and becomes immobile. We have found and studied four distinct scaling regimes, corresponding to a low-coverage (nucleation) regime, intermediate-coverage regime, an aggregation regime, and coalescence and percolation regime. At low coverage the islands have a dendritic structure such as seen in Au/Ru (0001) while at higher coverages they become compact. The scaling of the cluster fractal dimension, island density, Monomer density, island size distribution, and structure factor and pair-correlation function are studied as a function of the coverage θ and the ratio R = D /F of the diffusion rate to the deposition rate.
Surface Evolution During Mbe Growth of Eute Studied by Uhv-Stm and Rheed Investigations
Authors: Frank N. , Springholz G. , Bauer G. 
Published: March 2011

ABSTRACTMBE growth of 2% lattice-Mismatched EuTe on PbTe (111) is studied combining in-situ reflection high-energy electron diffraction (RHEED) with UHV scanning tunneling Microscopy (STM) to investigate the evolution of the EuTe surface Morphology. Using RHEED we have found that 2D nucleation and layer-by-layer growth occurs only in a very narrow range of growth conditions as a result of a strain induced coherent islanding of the surface[l], which leads to a roughening transition at the critical layer thickness hc of 45 Monolayers (ML). Starting with a very smooth initial (111) PbTe surface with terrace widths of 50 to 200 nm, islands of monolayer height are formed due to 2D nucleation of EuTe. For EuTe layer thicknesses below hc, the root mean square roughness (RMS) is essentially constant and equal to about one ML. Beyond hc, the surface roughness increases strongly and islands of about 20 ML height are observed for an EuTe layer thickness of 66 ML.
Raman Spectroscopy of Tin Films Deposited on Silicon (001) Substrate by Laser Physical Vapor Deposition
Authors: Jagannadham K. , Chowdhury R. , Biunno N. , Narayan J. 
Published: March 2011

ABSTRACTWe have carried out the Raman spectroscopy of titanium nitride films grown on Si(001) substrate by laser physical vapor deposition. The first order Raman defect induced acoustic and optical phonon peaks have been recorded for films grown at different substrate temperatures ranging from room temperature 25°C to 600°C.The ratio of the acoustic and the optical peak intensities and the width of the peaks are correlated with the nitrogen deficiency, crystalline size and stresses in the films. The results of Auger analysis, resistivity measurements and microstructural observations substantiate the finding that the stoichiometry of the films in terms of nitrogen concentration is improved at higher substrate temperatures.
Microstructure and Electromigration Properties of Submicron Al (.5%Cu) Lines
Authors: Prybyla J. A. , Kola R. R. , Hull R. , Eaglesham D. J. , HUGGINS H. A. 
Published: March 2011

ABSTRACTThe evolution of the microstructure of submicron Al (.5wt%Cu) lines has been examined as a function of annealing and electromigration stressing time. We have studied lines of two different thicknesses (4000 and 2000 Å) and a range of widths from 0.2 to 1.0 Μm. Pre- and post- stressing studies of the microstructure have been performed, as well as real-time studies during stressing inside the transmission electron Microscope (TEM). We report the results of temperature cyclings over the range 400–525 C for both passivateci and unpassivated lines. IMprovements in the microstructure were observed in all cases. The Most dramatic improvement occurred for the unpassivated lines when annealed to 450 C and for the passivated lines upon annealing to 525 C. In both cases a true bamboo structure was very nearly achieved for lines of width ≤0.5 Μm. Grain growth was by far the greatest in the pads. In the 2000 Å thick passivated lines, voiding upon temperature cycling is more pronounced than for the thicker lines. Also, the bamboo microstructure is more difficult to obtain compared to the 4000 Å lines. Finally, we report our preliminary results on the microstructural changes which occur as a result of electromigration. Voiding and hillock formation are examined. Microstructure is correlated with electromigration reliability.
Thermal Stability of the TiSi2 Film Under the Dielectric Capping Layer
Authors: Kim Y.W. , Lee N.I. , Ahn S.T. 
Published: March 2011

ABSTRACTThe thermal stability of titanium disilicide (TiSi2) film under dielectric capping layers was studied. Dielectric capping layers prevent changes in sheet resistance and the film stress of the TiSi2 film during annealing at 900°C. The enhancement of thermal stability of the TiSi2 film was dependent on the nature of dielectric; thermal stability of the TiSi2 film was enhanced more effectively by the plasma-enhanced silicon nitride (PE-SiN) capping layer rather than the undoped silicate glass (USG; S1O2) capping layer. The dependence of thermal stability of the TiSi2 film with the nature of dielectrics was due to the difference in stress of dielectrics at anneal temperature. At 900°C, stress of the USG film was nearly twice of that of the PE-SiN film. Agglomeration of the TiSi2 film under the dielectric capping layer at high temperature annealing can be explained by a diffusional flow of atoms called Nabarro-Herring Microcreep. As the size of Ti-polycide lines becomes smaller, the nature of the dielectric film on the TiSi2 film will be more important for achieving thermal stability.
An in Situ Transmission Electron Microscopy Study During NH3 Ambient Annealing of Cu-Cr Thin Films
Authors: Atzmon Z. , Sharma R. , Mayer J.W. , Hong S.Q. 
Published: March 2011

ABSTRACTNitridation of Cu-Cr alloy films under an NH3 ambient was studied using in situ transmission electron Microscopy. Cu-Cr thin films (40–100 nm) were deposited on a single crystal NaCl substrate by electron beam coevaporation, and were heat treated up to 750°C at 2.5–3.0 Torr NH3. The films were also vacuum (10-6 Torr) annealed under the same conditions for comparison. Initial observation of Cu and Cr crystallization occurred at 470°C for both environmental conditions. The nitridation process of Cr to form CrN was observed initially at 580°C and was followed by evolution of faceted Cu grain growth in the CrN Matrix.
The Study of Seam Line Defects in Silicon-On-Oxide by Merged Epitaxial Lateral Overgrowth
Authors: Shih Yangchin , Lou J. C. , Oldham W. G. 
Published: March 2011

ABSTRACTSelective Epitaxial Growth of silicon through windows in SiO2 using low-temperature SiH2Cl2/H2 chemistry in a hot wall LPCVD system was used to form Epitaxial Lateral Overgrowth (ELO) regions of Silicon-on-insulator. In cases where pattern ‘width was less than two times epi film thickness, the ELO regions merged to form a continuous epitaxial film. In this study, 2.5 μm thick single crystal silicon layers were grown perfectly over oxide regions with very low dislocation density (< 104/cm2). The epitaxial Si/oxide interfaces were smooth and defect-free. However, a “seam”-like defect was occasionally observed in the epitaxial film on top of the oxide, at the locations where two growth fronts merged together. This crystallographic defect in some case extends through the whole Silicon-on-Oxide film and would be expected to be detrimental to electronic devices built on or close to it. The sturctures of these seam line defects were investigated in detail by transmission electron Microscopy (TEM). The formation mechanisms of these seam line defects and possible origins are discussed.
Effects of Nitrogen Doping in the Insulational Character of Anodically Oxidized Films of Tantalum
Authors: Nakamura Y. , Yamamoto T. , Okamoto Y. , Morimoto H. , Akagi Y. 
Published: March 2011

ABSTRACTThe effects of nitrogen doping as a terminator in an anodically oxidized film of tantalum have been investigated.In the oxide film of nitrogen-free tantalum, the electric leakage current abruptly increased with the applied voltage. It is well-known as the Poole-Frenkel effect [1] [2]. After annealing at 623K in a hydrogen atmosphere, the leakage current increased.On the other hand, in the oxidized films of nitrogen-doped tantalum the leakage current increased in proportion to the applied voltage, but it was very small as compared with the nitrogen-free oxide. Moreover the leakage current decreased after annealing. The decrement strongly depended on the amount of doped nitrogen.
Modeling of mechanisms of Formation of Quasi-Epitaxial Organic Interfaces
Authors: Zhang Yajiong , Forrest S. R. 
Published: March 2011

ABSTRACTWe introduce a model to calculate the static equilibrium configuration between two monolayers of large, planar organic molecules bonded by van der Waals (vdW) forces. The Model significantly simplifies analysis by replacing the conventional atom-atom potential summation with a single ellipsoidal potential centered in the molecular plane. Our results indicate that recent observations of crystalline “quasi-epitaxial” growth of these planar molecular films in ultrahigh vacuum results from the relatively large intralayer elasticity as compared to the small interlayer stress. Good agreement between calculated and observed structures is achieved using no adjustable parameters. The Model is used to predict molecular structures which are likely to form quasi-epitaxial layers. Quasi-epitaxy is a general feature of large planar molecules of similar shape and size in adlayers and substrates where there is comparatively weak vdW bonding between layers.
Surface Stress, Morphological Development, and Dislocation Nucleation During Strained-Layer Epitaxy
Authors: Jesson D. E. , Pennycook S. J. , Baribeau J.-M. , Houghton D. C. 
Published: March 2011

ABSTRACTUtilizing Marker layer experiments and Z-contrast imaging, we have observed the formation of surface cusps during SixGe1−x alloy growth. The formation of cusps can be understood in terms of stress-driven surface diffusion, and we consider the large stress build-up at the cusp tip as a potential source for the nucleation of misfit dislocations.
Epitaxy of Germanium on SI(001) Grating Templates
Authors: Umbach C.C. , Blakely J.M. 
Published: March 2011

ABSTRACTEpitaxial Ge films (< 3 ML) have been grown at elevated temperatures on Si (001) grating substrates (repeat spacing of 2.0 μm) and imaged using room temperature scanning tunneling Microscopy (STM). The Ge films exhibit the 2×n reconstruction associated with missing dimer rows. The value of n and the growth morphology are influenced by the deposition rate and by annealing. At substrate temperatures of 600° C and deposition rates >0.5 ML/Min., islands elongated along the the dimer row direction nucleate at steps and on terraces. With sufficient annealing at 800° C, the islands coarsen and are eventually eliminated. The roughness of the A-type step becomes greater than that of the B-type step, which is the reverse of the situation with pure Si (001). The separation between missing dimer rows and hence the value of n are increased by annealing. Differences in substrate terrace widths due to the periodically varying step density of thegratings affect the growth Modes: two-dimensional islands occur near the extrema of the gratings whereas step flow occurs when steps are separated by ∼150 Å or less.
Dislocation Nucleation from a Surface CUSP
Authors: Li Jiangwei , Chiu Cheng-hsin , Gao Huajian 
Published: March 2011

ABSTRACTTheoretical and experimental studies have suggested that surface roughness may significantly enhance the nucleation of misfit dislocations in a strained heteroepitaxial film, especially in view of a stress-induced roughening instability which tends to form cusp-like stress singularities along the film surface. In this paper, the process of dislocation nucleation is perceived as a single dislocation emerging from a gradually sharpening surface groove. An analysis similar to the Rice-Thomson model for dislocation nucleation from a crack tip is carried out to determine the nucleation condition in terms of the depth and curvature of the surface groove. Specific applications are made to Si1−xGex alloy films on Si (100) substrates.
Evolution of Surface Roughness of a Strained Epitaxial Film Due to Interface Misfit Dislocations
Authors: Jonsdottir F. , Freund L. B. 
Published: March 2011

ABSTRACTThe appearance of misfit dislocations at the interface between a strained layer and its substrate induces a nonuniform chemical potential along the surface of the layer. Under the assumption that the resulting chemical potential gradient will drive coherent mass rearrangement by surface diffusion, a model of evolution of surface shape is considered which leads to estimates of the surface roughness induced by this mechanism.
Surface Alloying and Surfactant Action of Sb ON Ag (111)
Authors: Oppo Sabrina , Fiorentini Vincenzo , Scheffler Matthias 
Published: March 2011

ABSTRACTWe report ab initio calculations for Sb and Ag adsorption on Ag (111): evidence is found for substitutional adsorption and surface segregation of Sb, and for the formation of a disordered surface Sb-Ag alloy. The average diffusion barrier for Ag is enhanced on Sb-covered Ag (111), which favors the formation of a high density of small-sized islands: this is suggested to be the cause of the surfactant action of Sb on Ag reported recently.
An Investigation of PT/PT (111) Homoepitaxy with Molecular Dynamics Simulation and Static-Energy Calculation.
Authors: wang Ruoping , Kalp Bryan S. , Fichthorn Kristen A. 
Published: March 2011

ABSTRACTWe present the results of a study of Pt/Pt (111) epitaxial thin-film growth with Molecular-dynamics simulation and static-energy calculation. Interatomic forces are modeled with Corrected-Effective-Medium theory. Atomic details of deposition, such as dissipation of the kinetic energy of an impinging gas atom, adatom motion on and approaching descending step edges, effects of the geometry of a step edge on the interlayer transport of adatoms, etc., have been intensively investigated. We have observed a novel mechanism for adatom incorporation into descending-step edges which involves a concerted motion of the adatom and edge atoms. Our study supports the “island size and shape” model which has been proposed to explain the reentrant layer-by-layer growth mode seen experimentally in Pt/Pt (111) homoepitaxy.
Facet Formation on One-Dimensionally, Periodic Si Substrates
Authors: Adams D.P. , Yalisove S.M. 
Published: March 2011

ABSTRACTThe development of surface morphology during homoepitaxial growth on one-dimensionally periodic, patterned Si substrates and subsequent annealing has been investigated using transmission electron Microscopy. Si layers grown by MBE are characterized in terms of facets which develop at a trench edge. 1000 Å thick films deposited at ∼ 600°C on Si substrates develop large (311) facets at the bottom and top of the sidewall. After annealing at high temperatures for short times (∼ 1 hour), the amplitude of corrugation decreases but the surface profile is facetted along its length. The “annealed shape” at the trench edge is shown to consist of several surfaces including: (211), (311), (511), and (711). This evidence suggests that (311) facets develop as a result of the growth kinetics.
Numerical Simulation of Diffusion Controlled Surface Evolution
Authors: Chiu Cheng-Hsin , Gao Huajian 
Published: March 2011

ABSTRACTAs a model for Stranski-Krastanow island formation in strained heteroepitaxial layers, this paper investigates the surface-diffusion controlled morphological evolution of a two dimensional semi-infinite solid loaded in the lateral direction. Numerical Methods are developed to simulate the surface diffusion process, and examples are presented to demonstrate three distinct evolution patterns which are characterized by two critical wavelengths. The results show that, according to the wavelength, a slightly wavy surface can evolve into a cusped, a smoothly undulating, or a flat configuration. The diffusion wavelength and cusp-formation time compare favorably with recent experimental observations.