bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Ion-Implanted Aluminum and Iron by Spectroscopic Ellipsometry
Authors: Brodkin J. S. , Franzen W. , Culbertson R. J. , Williams J. M.
Published: March 2011

The change in the optical constants of aluminum alloy and iron samples caused by implantation with nitrogen and chromium ions has been investigated by spectroscopic ellipsometry. The objective is to develop a method for simple, non-destructive characterization of ion-implanted metals.
Suppression of Crystal Nucleation in Amorphous Si Thin Films by High Energy Ion Irradiation at Intermediate Temperatures
Authors: Im James S. , Shin Jung H. , Atwater Harry A.
Published: March 2011

In situ electron microscopy has been used to observe crystal nucleation and growth in amorphous Si films. Results demonstrate that a repeated intermediate temperature ion irradiation/thermal annealing cycle can lead to suppression of nucleation in amorphous regions without inhibition of crystal growth of existing large crystals. Fundamentally, the experimental results indicate that the population of small crystal clusters near the critical cluster size is affected by intermediate temperature ion irradiation. Potential applications of the intermediate temperature irradiation/thermal anneal cycle to lateral solid epitaxy of Si and thin film device technology are discussed.
Lattice Disordering, Phase Transition, and Substrate Temperature Effects in MeV-ION-Implanted III-V Compound Semiconductors
Authors: Xiong Fulin , Tsai C. J. , Vreeland T. , Tombrello T. A.
Published: March 2011

An experimental study of lattice disordering, the crystalline-to-amorphous (c-a) phase transition, and substrate temperature effects in MeV-ion-implanted III-V compound semiconductor crystals is presented. A comparison has been made between the GaAs and InP systems, which have been implanted with 2 MeV oxygen ions at either room temperature (RT) or near liquid nitrogen temperature (LT). A strong in situ dynamic annealing has been found in the RT implanted GaAs, and the LT implanted GaAs exhibits heterogeneous (at the end-of-range of the ions) and homogeneous (at the subsurface region) c-a phase transitions. In InP crystals, in situ annealing is much less pronounced in RT implantation, and dose-dependent damage nucleation and layer-by-layer amorphization take place. LT implantation results in lattice disordering and phase transition with a critical dose at least one order lower than that for GaAs. The mechanisms and kinetics of lattice disordering by ion irradiation are also discussed.
Atomistic Simulation of Radiation-Induced Amorphization of the B2 Ordered Intermetallic Compound NiTi
Authors: Sabochick Michael J. , Lam Nghi Q.
Published: March 2011

Amorphization of the B2 intermetallic compound NiTi under electron irradiation has been investigated using molecular dynamics. The effect of irradiation was simulated using two processes: 1) Ni and Ti atoms were exchanged, resulting in chemical disorder, and 2) Frenkel pairs were introduced, leading to the formation of stable point defects and also chemical disorder upon mutual recombination of interstitials and vacancies. After ∼0.1 exchanges per atom, the first process resulted in an energy increase of approximately 0.11 eV/atom and a volume increase of 1.91%. On the other hand, after introducing ∼0.5 Frenkel pairs per atom, the second process led to smaller increases of 0.092 eV/atom in energy and 1.43% in volume. The calculated radial distribution functions (RDFs) were essentially identical to each other and to the calculated RDF of a quenched liquid. The structure factor, however, showed that long-range order was still present after atom exchanges, while the introduction of Frenkel pairs resulted in the loss of long-range order. It was concluded that point defects are necessary for amorphization to occur in NiTi, although chemical disorder alone is capable of storing enough energy to make the transition possible.
Copper Laser Induced Chemical Vapor Deposition of al Films
Authors: Yankova M. I. , Shanov W. , Ivanov B.
Published: March 2011

The focused output from a copper laser (λ = 510nm) has been used for direct writing of Al on silicon substrates by pyrolitical decomposition of trimethilaluminum (TMA). These results demonstrate that direct writing can be accomplished at room temperature by a single-step deposition process induced by a single light source. For a laser power density between 5 and 50 kW cm−2, the widths of the stripes varied between 60 and 200 μm with corresponding thickness between 0.5 and 0.8 μm. The width of the stripes proved to be independent of the scanning velocity, Vs, within the range 50 μm s−1 < Vs < 300 μm s−1. The analysis included scanning electron microscopy (SEM) to study the film morphology, a step profiler to evaluate the thicknesses and the profiles of the stripes, and energy dispersive spectroscopy (EDS) to provide their chemical compositions.
Optical Effects Induced by the Multilayer Nature of SOI Films During Transient Thermal Processing with a Radiant Line Heat Source.
Authors: Wong Peter Y. , Miaoulis Ioannis N. , Zavracky P.
Published: March 2011

Radiation heat transfer has been found to have the greatest Impact on the quality of the thin recrystalllzed silicon film during zone-melting recrystallizatlon (ZMR) processing. This study focused on the radiation effects during ZMR with an Infrared radiant line heat source such as a graphite strip heater. The multilayer nature of the capped sllicon-on-tnsulator (SOI) structure Induces complex optical effects which affect the temperature distribution during processing. A two dimensional numerical model of the ZMR process has been developed using a finite difference scheme. The effect of the radiant line heat source’s emission into the wafer has been modeled with a matrix method using Fresnel coefficients. A numerical parametric study was conducted to observe the effects of varying the thickness of the different layers In a capped SOI wafer on the maximum temperature and melt width attained. Results indicate that the variation of either the capping or insulating silicon oxide layer causes significant fluctuations of the reflectivity and temperature profile of the film. Increasing the thickness of the Si layer results in a nearly linear increase in temperature and melt width after complete melting. Layering schemes that are sensitive to small variations In thickness that may result in large changes in reflectivity were Identified.
The Effect of Photoexcitation on Formation of Radiation Defects in Si
Authors: Mordkovich V. N. , Danilin A. B. , Erokhin Yu. N. , Boldyrev S. N.
Published: March 2011

Photoexcitation of the Si electronic subsystem during ion implantation was found to be able to control radiation damage accumulation. Conditions when additional light illumination during ion bombardment suppresses radiation defect formation are determined. The model of effect observed taking into account recombination of nonequilibrium electron and holes is proposed. Coefficient between the change in amount of damage accumulated and the rate of nonequilibrium charge carriers generation is estimated.
UV Laser Ablation of Ferroelectrics
Authors: Haglund R. F. , Arps J. H. , Tang K. , Niehof A. , Heiland W.
Published: March 2011

We have investigated laser ablation of excited atoms from the ferroelectrics LiNbO3 and KNbO3 at 308 nm. Comparisons of the yields for O*, K* and Nb* from pure and undoped KNbO3 show the effects of changing intensity, surface condition and irradiation time on the yield of excited atoms. Below about 20 GW cm−2, the mechanisms for production of excited atoms differ among the various species; above that intensity, the production of a dense electron-hole plasma appears to impart a collective character to the ablation mechanism.
Optical Monitoring of Y-Ba-Cu-O Ion Beam Sputtering
Authors: Klein J.D. , Yen A.
Published: March 2011

Emission spectra resulting from ion beam sputtering an Y-Ba-Cu-O target were observed as a function of beam voltage and time using an optical multichannel analyser. The observed spectra were clean with several peaks attributed to each of Y, Ba, and Ar. A well defined O peak and a weak CuO peak were available for comparison. The intensities of the cation peaks were linear with respect to beam voltage above 450 V. Presputtering of a previously stored target was characterized by the diminishment of an initially large H peak as the cation peaks emerged.
KrF Excimer Laser Direct Writing of Titanium Lines: Modeling and Application to the Fabrication of Ti:Linbo3 Waveguides
Authors: Meunier M. , Lavoie C. , Boivin S. , Izquierdo R. , Desjardins P. , Najafi S. I.
Published: March 2011

The deposition of titanium lines by KrF excimer laser direct writing on lithium niobate (LiNbO3) has been investigated. A detailled study of the line profile has been performed since this is critical in the fabrication of Ti:LiNbO3 optical waveguides. We show that at a low power density E, the maximum thickness t is proportional to E, while increasing E leads to the diffusion of Ti into LiNbO3 resulting in a saturation and even a decrease in thickness. Preliminary results on Ti:LiNbO3 optical waveguides show that their characteristics are similar to those made by conventional methods.
Similarities and Differences in the Mechanisms of High and Low Energy Ion Mixing
Authors: Cheng Yang-Tse , Simko Steven J. , Militello Maria C. , Dow Audrey A. , Auner Gregory W. , Alkaisi M. H. , Padmanabhan K. R.
Published: March 2011

High energy ion mixing occurs when an ion beam of a few hundred keV bombards an interface under the surface. Low energy ion mixing arises when an ion beam of a few keV bombards an interface near the surface during, for example, sputter depth profiling and low energy ion assisted deposition. At low temperatures, the rate of both high and low energy ion mixing can be influenced by thermodynamic parameters, such as the heat of mixing and the cohesive energy of solids. These effects are demonstrated by ion mixing experiments using metallic bilayers consisting of high atomic number elements. A model of diffusion in thermal spikes is used to explain this similarity. Low energy ion mixing can also be strongly affected by surface diffusion and the morphological stability of thin films. These effects are illustrated using results obtained from sputter depth profiling of Ag/Ni bilayers at elevated temperatures. High energy ion mixing at low temperatures can be influenced by the anisotropic momentum distribution in a collision cascade as seen from a set of marker experiments to determine the dominant moving species in high energy ion mixing. These similarities and differences between high and low energy ion mixing illustrate the diversity of ion-solid interactions.
Schottky Properties of Tungsten Compounds Refractory Contacts on n-GaAs Fabricated by Ion Beam Assisted Deposition
Authors: Park C. S. , Lee J. S. , Lee J. W. , Kang J. Y. , Lee J. Y.
Published: March 2011

A low energy ion beam assisted deposition (IBAD) technique has been developed to fabricate refractory W-Si-N films for the application to gate electrode of GaAs metal-semiconductor field effect transistors( MESFETs ). Thermal stability of the IBAD refractory metal/n-GaAs interface was investigated by examining the microstructure and Schottky diode characteristics. The Schottky barrier heights of 0.71, 0.84, and 0.76 eV were obtained after thermal annealing at 850°C for the W/, WN0.27/, and WSi0.3N0.4/GaAs diodes, respectively, and these values are comparable to those of the best results published with conventional reactive sputtering. While some crystalization of the deposit and reaction between film and substrate at the interface were observed with TEM for the W/ and WN/GaAs contacts annealed at 800°, the WSiN film remained amorphous and showed clear interface with the GaAs substrate without significant morphological change. The WS0.3N0.4/GaAs diode showed good thermal stability of Schottky barrier heights with only 20 meV variation in the temperature range between 700 and 850°C, and that is proposed to be due to the stable microstructure.
Quantitative Studies on the Evolution of the Polysilicon/Silicon Interfacial Oxide Upon Annealing
Authors: Ajuria Sergio A. , Reif Rafael
Published: March 2011

Polysilicon/silicon interfacial oxides are shown by cross-sectional Transmission Electron Microscopy studies to agglomerate upon annealing. In addition to presenting highlights of microscopy results, we report on electrical characterization data obtained from Cross-Bridge Kelvin Resistors. Resistor data not only support a model for agglomeration proven on microscopy data, but also allow for a quantitative macroscopic understanding of the agglomeration of polysilicon/silicon interfacial oxides over a wide range of times and temperatures.
Lpcvd Polycrystalline Silicon Thin Films: The Evolution of Structure, Texture and Stress
Authors: Krulevitch P. , Nguyen Tai D. , Johnson G. C. , Howe R. T. , Wenk H. R. , Gronsky R.
Published: March 2011

An investigation of undoped LPCVD polycrystalline silicon films deposited at temperatures ranging from 605 to 700 C and silane pressures from 300 to 550 mTorr revealed large variations in stress with processing conditions and a correlation between stress and texture. TEM and HRTEM analysis show that morphology differences also exist. At lower temperatures (≈605 C) and higher pressures (≈400 mTorr), the films appear to deposit in an amorphous state and crystallize during the deposition to form microstructures characterized by equi-axed grains, tensile residual stress, and a texture with {110} and {11/} (/=2 or 3) components. Higher temperatures (between 620 and 650 C) produce films that nucleate at the Si02 interface, creating a {110} oriented columnar microstructure. At 700 C, the grains are still columnar, but the dominant texture is {100}. Films deposited at temperatures greater than 620 C exhibit compressive stress, and some contain regions of hexagonal silicon. This paper proposes possible causes of the varying stresses, textures, and microstructures in the films.
The Nucleation and Epitaxial Growth of Au and Ag on Thin Silicon Studied With a Scanning Transmission Electron Microscope
Authors: Xu Peirong , Miller Peter , Silcox John
Published: March 2011

An UHV Scanning Transmission Electron Microscope (STEM) has been used to study the nucleation and epitaxial growth of Au and Ag deposited at room temperature on H-passivated thin silicon (111) and (100) substrates. Direct observations of the initial stages of overlayer growth were made using bright field (BF) and annular dark field (ADF) imaging modes. Gold was found to grow on silicon in a quasi-continuous layer mode, while 3D island growth with density as high as 4×1012/cm2 was observed in Ag/Si systems. Electron diffraction studies reveal a good epitaxial relationship for Ag films grown both on silicon (111) and (100) substrates. Diffraction also indicates that Au (111) grows on the silicon (111) surface but the grains may be azimuthally rotated.
Thin Film Growth and Magnetic Properties for Fe/GaAs(100).
Authors: Andrien Bruce A. , Miller David R.
Published: March 2011

Thin Fe films, 1 nm to 90 nm, have been grown on GaAs (100) substrates in ultra high vacuum, base pressure = 2×l0−8 Pa. The growth of the films has been followed with Auger electron spectroscopy and a recently developed in-situ UHV M/H hysteresis loop tracer. The Auger signal provides an indication as to when the Fe covers the GaAs substrate or when it clusters into three dimensional islands. The magnetic hysteresis loop tracer provides the coercivity and the saturation magnetic moment, from which the saturation magnetization or average film thickness can be obtained. The coercivity of thin films is sensitive to structure, strain, and to the grain size, in analogy to its sensitivity to particle size for small particles. The data show that the coercivity, Hc, as a function of film thickness, is very sensitive to the annealing procedures and to the resulting morphology, continuous versus local clustering of the iron film. Under proper conditions a clear maximum in Hc versus film thickness is observed for these films near 5 nm thickness, in analogy to three dimensional small particle curves.
Investigation of Diamond Particles Grown by Microwave Plasma CVD on Tungsten Wire Tips.
Authors: Stuart Sue-Anne , Prawer Steven , Hoffman Alon , Moodie Alec , Weiser Paul
Published: March 2011

Large diamond particles up to 30μm in diameter have been deposited on W wire tips using Microwave Plasma Chemical Vapour Deposition. Raman, SEM and TEM investigations were all carried out on a single particle. Large growth steps were observed on (100) facets but were absent on the (111) facets. Raman measurements indicated greater crystalline quality for (100) than (111) facets. TEM revealed the (111) facets to be covered with small islands of diamond about 10Å high. The dominant defect was found to be stacking faulting on the {111} planes which gives rise to some hexagonal spacings in the electron diffraction pattern. The results suggest that growth in the <111> and <100> directions are driven by different mechanisms.
Influence of Silicon Substrate Ion Implantation on the Subsequent Microstructure Evolution in Cobalt Silicide Films
Authors: Xiao Z. G. , Honeycutt J. W. , Rozgonyi G. A.
Published: March 2011

The influence of amorphization of the Si substrate by Ge+ implantation on the microstructural evolution of CoSi2 thin films has been investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD) and four-point-probe measurement. While the silicide films formed on unimplanted or recrystallized Si were similar in formation kinetics, microstructure and resistivity, unique features were found for silicide films formed on amorphized Si. The phase transformation to CoSi2 on amorphized Si was considerably accelerated, the silicide grain size was smaller, and the CoSi2/Si interface was much smoother on the amorphized Si. Direct evidence of grain boundary diffusion induced silicide/Si interface roughness was obtained. The origin of the difference in both the microstructure and kinetics on different Si substrates is explained by the latent energy stored in amorphous Si, increasing the silicide nucleation rate. Weak XRD peaks and different texture were found for the CoSi2 formed on amorphized Si. The facts that the dominant diffusing species during CoSi2 formation is Co, and the new phase was developed in an amorphous medium are thought to be responsible for these phenomena.
X-Ray Diffraction From Surfaces and Interfaces: Atomic Structure and Morphology
Authors: Vlieg E. , Robinson I.K. , van der Veen J.F.
Published: March 2011

The emergence of synchrotron radiation sources has greatly stimulated the use of X-ray scattering in surface science. The absence of multiple-scattering effects allows a straightforward data analysis. In addition to determining geometric structures, it is also possible with X-ray scattering to obtain information on various types of surface disorder. The large penetration depth enables the investigation of interfaces.
Microstructure of Epitaxial Al(111)/Si(111) Films Studied by Synchrotron Grazing Incidence X-Ray Diffraction
Authors: Hung H. H. , Liang K. S. , Lee C. H. , Lu T.-M.
Published: March 2011

We report the results of our x-ray diffraction studies on epitaxial Al(111)/Si(111) films prepared by the partially ionized beam deposition technique. Significant changes were observed in intensity profiles for samples before and after annealing. In the in-plane radial scan of Al(220) peak, the shift of Bragg peak is shown due to misfit strain. A weak satellite is also observed which indicates a semicoherent interfacial structure of the annealed film with misfit dislocations. A possible picture of misfit-induced incommensurate structure of Al films is discussed.
Morphology of Ultra-Thin Metal Films Using Infrared Reflection Adsorption Spectroscopy
Authors: He J.-W. , Kuhn W. K. , Goodman D. W.
Published: March 2011

The adsorption of carbon monoxide on ultra-thin films of Cu, Ni and Co on Rh(100) and Mo(110) substrates has been studied using infrared reflection absorption spectroscopy (IRAS). The CO vibrational frequency on Cu/Rh(100) and Cu/Mo(110) at low Cu coverage (∼0.1 ML) shows a blue-shift relative to its gas phase stretching frequency (2143 cm−1). This blue-shift is explained as arising from CO adsorbed on well-dispersed Cu adatoms which are either slightly positively charged due to charge transfer from Cu to the substrate or self-polarized because of a strong Cu-substrate interaction. It is further shown that three-dimensional Cu clusters, well-ordered pseudomorphic two dimensional Cu islands and single Cu atoms are distinctively characterized by the CO IR peaks at 2074 cm−1, 2095 cm−1, and 2162 cm−1, respectively. In addition, it is found that IR spectra of CO adsorbed on Ni/Mo(110) show a remarkable sensitivity to surface structural phase transitions at the Ni-Mo interface.
Step Structures Created on Vicinal Si(111) During Resistive Electrical Heating
Authors: McClelland R. J. , Homma Y.
Published: March 2011

Scanning reflection electron microscopy was used to examine step structures which form on vicinal Si(111) specimens during resistive electrical heating under ultrahigh vacuum. Heating-current-induced step bunching occurred, forming substantially linear step-bands in specific temperature regions. Small pinning points disrupted the linearity of steps. The interaction between step-bands and large pinning points resulted in the formation of macrosteps, which showed some stability against dispersal during current reversal. Ion-etched grooves influenced step orientation during current-induced step migration.
Reverse Dependence of Ge Surface Segregation on Growth Temperature in Si-Mbe
Authors: Miyao Kiyokazu , Miyao Masanobu
Published: March 2011

Ge surface segregation on Si(100) and Si(111) substrates during silicon molecular beam epitaxy is studied as a function of growth temperature. During growth, the Ge atoms are partly incorporated into the growing layer and the residuals segregate on the grown surface. The incorporation coefficient cannot be expressed in terms of a simple thermal activation process. That is, the Ge segregation phenomena increase to maxima at around 450°C for the Si(100) substrates and at around 650°C for the Si(111) substrates. Segregation decreases above these temperatures. These reverse temperature dependences enable not only good crystallinity of the heteroepitaxial layer, but also abrupt heterointerfaces. The incorporation coefficients for Si(111) are much larger than those for Si(100), which is explained by a model based on surface migration.
Molecular-Dynamics Study of the Growth of Si1-xGex on Si(100)2×1
Authors: Ethier Stéphane , Lewis Laurent J.
Published: March 2011

We use molecular-dynamics simulations to study the growth of pure Si, Si0.5Ge0.5 and pure Ge on the reconstructed (100) surface of Si. The atoms interact with one another via effective potentials of the Stillinger-Weber form with parameters adjusted such as to describe all types of triplet interactions. Motivated by recent experimental studies of molecular-beam epitaxial films,1 we examine in particular the structure of the deposits for various substrate temperatures. We also examine the relaxation of the structure resulting from high-temperature annealing. Finally, we investigate the interdiffusion of the species at the substrate-deposit interface.
Sputter Deposition of Indium Nitride on The (111) Face of Elemental and Compound Semiconductors
Authors: Morgan J. S. , Kistenmacher T. J. , Bryden W. A. , Ecelberger S. A.
Published: March 2011

The structure, morphology, and transport properties of thin films of InN grown on several cubic semiconductors has been studied as a function of substrate temperature. Films were deposited using rf-magnetron sputtering onto the (111) face of GaAs, Ge, Si and ZrO2. In general, the film structure is such that (00.1)InN parallels the (111) plane of the cubic substrate above some deposition temperature. The in-plane structural coherence duplicates the magnitude of the calculated lattice mismatch between InN and the substrate. Electrical transport properties for growth onto (111) ZrO2 were characterized by n-type carrier concentration and mobilities ranging up to 44 cm2 /Vsec. A morphology-induced decrease in electrical mobility is observed for deposition temperatures above 350°C, as shown by SEM.
Si(100) Surface Preparation by In-Situ or in-Vacuo Exposure to Remotely Plasma-Generated Atomic Hydrogen: Applications to Deposited SiO2 and Epitaxial Growth of Si
Authors: Yasuda T. , Ma Y. , Habermehl S. , Kim S. S. , Lucovsky G. , Schneider T. P. , Cho J. , Nemanich R. J.
Published: March 2011

This paper addresses the in-situ/in-vacuo preparation of Si (100) substrates by hydrogen plasma cleaning prior to low temperature deposition of SiO2, or epitaxial growth of Si or Ge. The paper emphasizes the effectiveness of this type of substrate surface preparation following ex-situ wet-cleaning procedures that include: i) conventional RCA cleans; ii) modified RCA cleans, which incorporate exposure of the Si substrate to ozone, O3; and iii) ozone exposure, with all of these terminated by the removal of sacrificial oxides by dilute HF. We conclude: i) all ex-situ surface cleaning of Si (100) substrates leaves behind sub-monolayer oxygen and carbon surface contamination; ii) that virtually all of the carbon can be removed by exposure of the Si surface to atomic hydrogen at a temperature of <300°C; and iii) that a necessary condition for: (a) the formation of Si/SiO2 interfaces with low defect densities, Dit<l−3×1010cm−2-eV−1, and (b) the growth of epitaxial films of Si; is that the processed Si surface exhibit a 2×1 reconstruction, as detected by LEED or RHEED, following the exposure to atomic hydrogen.
Structural Defects of Silicon Epitaxy and Epi/Substrate Interface Related to Improper In-Situ Surface Cleaning at Low Temperatures
Authors: Yew Tri-Rung , Reif Rafael
Published: March 2011

This paper investigates the defect formation at the epi/substrate interface and epitaxial layers due to an improper in–situ Ar or Ar/H2 plasma cleaning at 500–800 °C Deposition process was carried out immediately after the in–situ cleaning process by ultralow pressure chemical vapor deposition process (ULPCVD) from SiH4/H2. Characteristics of the defects and their relationship with damage or impurity contaminations at the interface are presented. Finally, an optimum cleaning condition which ensures high quality epitaxial growth is addressed.
Two-Dimensional Phase Transitions Associated with a Surface Miscibility Gap in Cu-Ag Alloys
Authors: Liu Y. , Wynblatt P.
Published: March 2011

A surface phase transition associated with a surface miscibility gap has been observed on the (111) surface of Cu-Ag alloys both in computer simulations and in experimental measurements of surface composition. This transition is characterized by an abrupt change in surface composition associated with changes in either bulk composition or temperature.The simulations have revealed that the transition from a Cu-rich to a Ag-rich surface phase is accompanied by interesting changes in surface structure. The experiments show that the surface critical temperature lies somewhere between 505 and 560°C.
Ion Beam Damage of Clean Gold Surfaces
Authors: Dunn D. N. , Zhang J. P. , Marks L. D.
Published: March 2011

We investigate the ion beam damage of clean Au (001) single crystals prepared under standard surface science techniques using sputter - anneal cycles. Under initial ion milling conditions using 4 keV Xe ions a significant amount of Xe was implanted into the bulk of the crystal. After a short period of time a Xe super structure developed which yielded 12 Å moire fringes under bright field imaging conditions. With a short anneal the implanted Xe concentration was reduced to the detection limit of Parallel Electron Energy Loss Spectroscopy (PEELS). With extended annealing, the bulk point defect concentration slowly decayed, independent of the surface reconstruction.
Rapid Thermal Annealing of GaAs Films on (001) Si Substrate Grown by Solid Phase Epitaxy Technique
Authors: Choo W.K. , Cho K.I. , Lee J.Y. , Park S.C. , Kwon O.J.
Published: March 2011

GaAs layers grown by solid phase epitaxy on (001) Si substrate were subjected to post-growth rapid thermal anneal (RTA) at 700, 800, and 900°C for 10s in a N2 atmosphere. Rutherford backscattering/channeling showed a substantial improvement in crystalline quality of GaAs epilayer after RTA at 800°C. After RTA at 900°C for 10s, stacking faults (and/or microtwins) were eliminated entirely, and the dislocation densities in both the interface region and the film interior were reduced. High-resolution transmission electron micrographs showed a significant change in misfit dislocation structure at the interface after RTA; namely, the 90° pure edge and 60° misfit dislocations were transformed to an evenly distributed array of 90° dislocations at the interface.
Formation of Stacking Faults and Misfit Dislocations During Zn Diffusion-Enhanced Intermixing of a GaInAsP/InP Heterostructure
Authors: Park Hyo-Hoon , Soo Nam Eun , Tak Lee Yong , Lee El-Hang , Yong Lee Jeong , Kwon O'Dae
Published: March 2011

The microstructural degradation of a lattice-matched Ga0.28 In0.72As0.61P0.39/InP heterointerface during atomic intermixing induced by Zn diffusion has been investigated using high-resolution transmission electron microscopy and Auger electron spectroscopy. The localized interfacial stress caused by intermixing appears to create stacking faults in the Ga-mixed InP substrate, and dislocation tangles in the In-mixed GalnAsP layer. The results are attributed to the contrasted effect of tensile and compressive stresses upon the nucleation of partial dislocations from both sides of the intermixed interface. A qualitative model is proposed for the homogeneous nucleation of misfit dislocations from the locally stressed interface.
Stress Orientation Dependence of Dislocation Glide in Epitaxial Films
Authors: Dakshinamurthy S. , Rajan K.
Published: March 2011

The effect of different stresses on the glide of the commonly observed dislocations in epitaxial films is systematically investigated. The possibility of planar dissociation of perfect dislocations and the conditions for their subsequent glide are explored.

Slip transfer from one plane to another is affected by the crystal orientation relative to the stress axis. This process is quantitatively analyzed by calculating iso-Schmid factors on a stereographic projection. The results of this model are correlated with those found in the literature.
Effect of the Substrate on Electrical and Microstructural Changes of Coevaporated NiSi2±x(x-0.2) Thin Films
Authors: Grimberg I. , Weiss B.Z.
Published: March 2011

Electrical and microstructural changes of NiSi2±0.2 alloy thin films coevaporated on two different substrates were studied as a function of temperature. In-situ resistivity measurements, transmission electron microscopy, and X-ray diffraction were applied. The substrates used were: a) silicon single crystal grown in the [100] direction, and b) similarly grown single crystal but thermally oxidized to a depth of 500 nm. Substantial differences were observed in the morphology and the kinetics of crystallization on both substrates. It was found that the crystallization temperature depends on the composition of the deposited film as well as on the type of substrate. An increase in the Si content of the alloy film deposited on the inert substrate lowers the crystallization temperature, while with the active substrate a rise in the crystallization temperature was observed. The final crystallized phase was identified as NiSia for the alloy films codeposited on Si. For the alloy film deposited on the thermally oxidized substrate NiSi and NiSia were observed when Ni content was higher than 33.3 at.% The crystallization process occurs by homogeneous growth in the film on either substrate. Heating to higher temperature probably results in regrowth of epitaxial MiSis accompanied by the appearance of stacking faults in the alloys deposited on Si (100).
Glancing Angle X-Ray Study of Crystallization of Amorphous Ge at the Ge-A1 Interface
Authors: Heald S. M. , Jayanetti J. K. D. , Budhani R. C.
Published: March 2011

The amorphous to crystalline transformation of Ge in Al/Ge thin film couples has been studied using glancing angle EXAFS, x-ray reflectivity and diffraction. It was found that crystallization occurs at a much lower temperature (118-150 °C) than for bulk Ge, and initiates at the Al/Ge interface. X-ray diffraction studies were made at 152 °C to study the kinetics of the reaction. After an initial period we find good agreement with a square root dependence of the time, characteristic of a diffusion limited reaction.
Evolution of Buried Cobalt Silicide Layers Formed by Co Implantation in Si(111)
Authors: Hsieh Yong-Fen , Hull Robert , White Alice E. , Short Ken T.
Published: March 2011

Coalescence and microstructure of buried CoSi2 layers formed by 100 keV Co+ implantation at 350°C into Si(111) are studied. Doses ranged from 1×1016 to 1.6×l017 cm−2. The critical dose (dc) required to form a continuous layer is found to be the same, 1.1±0.1×l017 cm−2, in both (111) and (001) substrates, despite pronounced differences in precipitate morphology. Three types of precipitates are observed in Si(111) during the mesotaxial process: A–type (fully aligned), B0–type (twinned on the (111) plane parallel to the surface), and B1,2,3–type (twinned on one of the three (111) planes inclined to the surface). The fraction of each varies with both the implantation and annealing conditions. Formation of a continuous, twinned (B0–type), buried layer after 1000°C annealing is shown to be possible for the first time by this synthesis technique in samples implanted at dc.
Interfacial Reactions Between Thin Films of Co and InP (100)
Authors: Ben-Tzur M. , Yu K. M. , Haller E. E.
Published: March 2011

The interfacial reactions between thin films of Co and single crystal InP have been studied. The reaction between the Co and the InP substrate already start in the as-deposited state to form In and P rich compounds. During annealing at 250°C for 30 min., phase separation takes place. In addition to unreacted Co, we find Co rich compounds, a Co-P compound in contact with the substrate, and Co-In compound in contact with the metal layer. The general morphology appears to be stable up to 500°C. At higher temperatures (500–600°C) P is released from the substrate. CoP4, Co2P, CoIn2 and In were detected by X-ray diffraction. At this stage the reaction is no longer uniform.
Nanometer Resolution Studies of Microstructural Evolution During the Heteroepitaxy of Ge on Vicinal Si(100)
Authors: Krishnamurthy Mohan , Drucker Jeff S. , Venables J. A.
Published: March 2011

We have studied the initial stages of island formation and coarsening for epitaxial Ge on vicinal Si (100) using in-situ deposition and nanometer resolution biassed secondary electron imaging (b-SEI) in a UHV-STEM. Ge is deposited using MBE techniques on nominally flat Si(100) substrates as well as those misoriented 1° and 5° toward <110>. The temporal evolution of the islanded microstructure can be studied by analysis of computer generated island size distributions. Good statistics can be obtained for islands with radii between 2nm and lOOnm using high resolution b-SE imaging and a large magnification range. Both MBE and Solid phase MBE (SP-MBE) processes have been studied.

We explain the evolution of the islanded microstructure in terms of competition for Ge adatoms among the various available sinks. For the MBE case, control of diffusion distances by varying the substrate temperature has allowed us to identify effects related to coherently strained and highly dislocated Ge islands as well as contaminant particles. In all cases, coherently strained Ge islands appear to be the weakest sinks and contaminant particles the strongest. Metastable growth of the intermediate layer during interrupted depositions at 375°C may be a direct consequence of an energy cost for incorporating adatoms into coherently strained islands. For depositions at higher temperatures, strong adatom sinks influence nucleation densities and size distributions of Ge islands by reducing the effective supersaturation. Island size distributions analyzed for the case of room temperature deposition in the early stages of coarsening also show evidence of effects due to coherently strained islands. These size distributions evolve from an initial distribution to one with increasing number of large islands while the distribution of the smaller islands (< 10nm radius) remains constant.
Development of Polyphenylene—Oxide Film for Selective Encapsulation in Microelectronics
Authors: Ton-That Y-Tri , Troyk Philip R.
Published: March 2011

Corrosion control of microelectronic devices which operate in high humidity is essentialfor reliability. A selective encapsulation method based on the electrochemical synthesisof polyphenylene—oxide (PPO) film has been investigated. The monomer is electrochemically polymerized and simultaneously deposited on the device surface to form an adherent coating. Electrical properties of PPO coatings on gold substrates subjected to water immersion and voltage bias were measured. The influence of coating thickness, adhesion promoter, and substrate cleanliness were investigated and optimized. In the early stage of biased immersion, coating failure was mainly caused by defects at the metal—polymer interface, whereas failure after extended testing was due to the slow degradation of polyphenylene—oxide in an aqueous media.
Hardness of Thin Polymer Coatings on Glass
Authors: Ritter J. E. , Sioui D.R. , Gu W. , Lardner T.J.
Published: March 2011

For a soft coating on a hard substrate the overall hardness of the coating/substrate system increases substantially when the indenter penetrates into the substrate sincethe substrate can now directly support some of the indenter load. A model for the overall hardness is developed by accounting for the indentation load shared by the coating andsubstrate. This model accounts for the additional load supported by the coating due to the pile-up of coating material underneath the indenter. The model predicts the overall hardness as a function of coating and substrate bulk hardness and coating thickness. Comparison of the model to experimental data for two polymer coatings (epoxy and epoxy acrylate) on soda-lime glass substrates shows good agreement.
Ceramics and Glass-Ceramics in Electronic Packaging
Authors: Tummala Rao R.
Published: March 2011

An overview of ceramic packaging as it evolved over the last two decades from dual-in-line packages to state-of-the-art multilayer multichip packages ispresented. IBM's 69 layer glass-ceramic/copper multilayer multichip substrate with dielectric constant of 5.0, thermal expansion exactly matching silicon and exceptional dimensional control is summarized.
Overview of High Performance Packaging Materials
Authors: Johnson Barry C.
Published: March 2011

High Performance Integrated Circuits form the basic building blocks of modern electronic systems that are designed to process ever larger numbers of electrical signals at greater signal velocity and fidelity. In such applications, each circuit must be packaged in order to provide it with necessary mechanical support, environmental protection, electrical interconnection and thermal cooling. The package, however, can also impose certain constraints on the chip. It can degrade electrical performance, add size and weight, introduce reliability problems and increase cost. Thus, packaging can be viewed as a complex balance between the provision of desired functions and the reduction of associated constraints.

The ability to strike a proper balance has become increasingly difficult in recent years due to the relentless march of integrated circuits toward higher levels of complexity, size, speed, heat flux and customization. It is anticipated that the continuing evolution of high performance circuits and systems will soon be limited by the package designs and materials-of-construction, rather than by the devices on the semiconductor chip.

The intent of this talk is to provide a brief overview of high performance packaging and the related materials issues. The approach is to (a) present the forecasted trends in relevant circuit performance characteristics, (b) discuss the impact of these characteristics on current chip and board level packaging methods, and (c) present new package and materials concepts that might furnish potential solutions to the developing circuit-package performance gap.
Interfacial Studies on Cr and Ti Deposited on Benzocyclobutene (BCB) Film
Authors: Paik Kyung W. , Cole Herbert S.
Published: March 2011

Interfacial characteristics such as chemical reaction, metal diffusion, and morphology were investigated for Cr/BCB and Ti/BCB structures. Using Auger and XPS depth profiling, the formation of Ti carbide and Cr oxide was confirmed at the metal/BCB interface. Annealing at 250 °C for extended time periods resulted in diffusion of Cr and Ti into the BCB and subsequent formation of CrSi2and Ti-Si compound precipitates. The reaction is a thermal diffusion controlled process which was dependent on time and temperature. It was also found that Ar backsputtering treatment on BCB film before metallization was found to roughen the surface resulting in metal spikes which penetrate into the BCB film.
Effect of Geometry on the Fracture of Metal-Polymer Interfaces
Authors: Chiu Shih-Liang , Ho Paul S.
Published: March 2011

The fracture behavior of the Au(Cr)/PMDA-ODA interface was investigated using a stretch deformation method. The study has been focused on thc effects of metal dimension on the delamination behavior, the fracture morphology, and energy dissipation rate of the interface. The delamination behavior shows complex geometrical dependence, with changes observed in the magnitude of strain at failure as well as the progression of the fracture process. The fracture morphology and energy dissipation rate also show apparent dependence on the metal dimensions. The crack growth, as examined by the rate of energy dissipation, seems to consist of thrce stages: crack initiation, crack growth and post growth. Only the growth region exhibits a constant dissipation rate and the fracture energy determined in this stage is in good agreement with that obtained from energy balance. These results can be attributed to the change in the mechanical coupling between the metal and the polymer layers, which was evaluated using a finite element analysis with plastic deformation taken into aiccount.
Electroless Copper Deposition for Multilevel Metallization
Authors: Wong S.Simon , Cho James S. , Kang Ho K. , Ting C.H.
Published: March 2011

Increases in cross-talk disturbance, signal delay and current density have a significant impact on the performance of integrated systems as the metal pitch continues to be scaled down. A metal, such as copper, which has high conductivity and high resistance to migration, will greatly alleviate these problems. A selective technique for the deposition of copper, such as electroless plating, is highly desirable because it circumvents the potential problem of dry etching copper and inherently planarizes the surface topography.
A Damage Integral Approach to Solder Joint Fatigue
Authors: Li C.-Y. , Subrahmanyan R. , McGroarty J.
Published: March 2011

The application of a damage integral approach which provides numerical accounting of the accumulated fatigue damage in solder joint is reviewed. The instantaneous fatigue damage rate is determined by the solder stress state, temperature and environment using a phenomenological crack growth law. The stress is calculated using state variable constitutive relations for inelastic deformation. The material parameters for the crack growth law are determined from isothermal fatigue data. Representative damage integral calculations are used to illustrate the application of the approach. Finally, the significance of failure criteria on the apparent fatigue life is discussed in terms of the damage integral approach.
Infrared Characterization of RF Sputter Etching of Polyimide Thin Films
Authors: Molis S.E. , Kim D.G. , Kowalczyk S.P. , Kim J.
Published: March 2011

We present infrared spectroscopy as a means of characterizing polyimide structural changes occurring by RF argon ion sputtering. Samples of PMDA-ODA polyimide on chromium coated substrates have been sputter etched from initial thicknesses of 400 Å down to 10 Å. Relative intensity changes in imide vibrational absorption bands have been interpreted in terms of orientational reordering which occurs during the ion sputtering process. The appearance of a new vibration at 1580 cm–1 in the spectra of samples etched below 50 Å is assigned as the Elu mode of graphite corresponding to a surface damage layer which is of a graphitic form.
Properties of a Photoimageable Thin Polyimide Film
Authors: Maw Taishih , Hopla Richard E.
Published: March 2011

Mechanical properties (tensile modulus, tensile strength, elongation at break), thermal properties (T8' CTE, thermo-decomposition temperature, and rate of weight loss) and electrical properties of Problmlde 414 cured films have been determined. The mechanical properties of Probimide 414 thin films are highly dependent on the hard-bake temperature, hard-bake time, and purge gas, but not dependent on the level of the exposure energy or the presence of 1% Irganox 1010 (w/w) as a stabilizer. At a hard-bake temperature of 350ºC and a nitrogen purge rate of 15 SCFH, Probimide 414 films showed excellent retention of the mechanical properties during extended heat treatment.
Corrosion Engineering in Device Packaging
Authors: Latanision R.M. , Nagarkar P.V. , Kloppers M. , Bellucci F.
Published: March 2011

Corrosion processes affecting electronic devices are chemical and electrochemical in nature. Ionic contaminants, applied voltages, and relative humidity accelerate failure of integrated circuits. Although packaging materials often reduce the corrosion rate of the underlying circuitry, a complete understanding of the mechanism for the basic processes taking place at the coating/metallic circuitry interface is missing.

In this paper the role played by water and ionic contaminants on coated metallic substrates is considered. Transport properties of free standing polyimide membranes have been examined. The corrosion behavior of polyimide/Fe and polyimide/Al systems has been investigated using electrochemical polarization, and a.c. impedance measurements. For the AI/PI system underfilm degradation has been examined using x-ray photoelectron spectroscopy (XPS). Results indicate that the flux of ions is very small compared to that of oxygen and water and yet metallic failure can be ascribed mainly to the transport of ions across the packaging material. XPS showed that considerable degradation takes place at the metal/polyimide interface prior to visible corrosion or delamination.
Investigations of (1,3-Dimethyl-3-methylsilamethylene - disilacyclobutane) as a Single Source CVD Precursor to Silicon Carbide
Authors: Larkin David J. , Interrante Leonard V. , Hudson John B. , Han Bin
Published: March 2011

The low pressure chemical vapor deposition (LPCVD) of silicon carbide from (CH3)HSiCH2SiCH2 (CH3)CH2 SiH2 (CH 3) on Si(100) has been investigated between 700 and 1100°C at ca. 1.0 torr total pressure using a flow of argon as a carrier gas in a cold-wall LPCVD system. The gaseous byproducts were determined using quadrupole mass spectrometry (QMS) and gas chromatography - Fourier transform IR (FTIR) spectroscopy. The coating surface morphology varied from smooth to a columnar structure with increasing substrate temperature. Film composition and crystallinity were monitored as a function of deposition temperature using Auger electron spectroscopy (AES) and powder XRD.