bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Biaxial Stress on Solid Phase Epitaxy of Silicon
Authors: Lu Guo-Quan , Gupta Tapan K. 
Published: March 2011

ABSTRACTThe effect of biaxial stress on solid phase epitaxial growth (SPEG) rate of crystalline Si(100) into self-implanted amorphous surface layer has been measured. Biaxial stresses in the crystalline and amorphous phases were generated by bending the silicon wafer using the residual stresses in Ge films deposited on the back side of the wafer. Stresses were determined at SPEG temperatures by optical measurements of wafer bending curvatures. Tensile stresses up to 13 MPa in the crystalline phase and 34 MPa in the amorphous phasewere achieved during SPEG at 530ºC. An optical system based on the time-resolved reflectivity (TRR) technique was devised to measure the growth rates of two adjacent samples during a single SPEG run. This enables a direct comparison of the growth rates under different stress conditions without concern for run-to-run temperature variations. We found that the growth kinetics in all the samples were retarded as the c/a interface approached the free surface. However, the extent of this rateretardation was reducedin the stressed samples, leading to stress-enhanced growth kinetics. We speculate that the application of the biaxial tensile stresses might slow down the incorporation of hydrogen into the amorphous phase, a mechanism for the rate-retardation.
Epitaxial Lateral Overgrowth of Silicon on SiO2 Investigated by X-Ray Topography
Authors: Jenichen B. , Köhler R. , Nagel N. , Bergmann R. , Bauser E. 
Published: March 2011

ABSTRACTSilicon lamellae grown laterally over silicon dioxide by liquid phase epitaxy are investigated using X-ray double crystal topography. The lamellae are grown from Indium solution. All of the lamellae show growth striations with indium concentration differences of about 1016...4x1017 cm−3 Overgrowth widths up to 320μm are obtained on sides of the seeding window by growth under conditions of low supersaturation. Facetting of the lamella edges then becomes less pronounced and, therefore,striations are detected farther away from the windows.About 60% of the lamellae are free of crystallographic defects. In the defective lamellae single dislocations parallel to the sample surface are detected. They extend between seeding window edges and re—entrant corners at the lamella edges. Dislocations probably form during the cooling process due to strains near the edges of the seeding windows, and as a result of indium incorporation in high concentration.
In Situ Monitoring of the Smear-Out of the Ge Profile in GAS Source SiGe MBE Using Rheed Intensity Oscillations
Authors: Werner K. , Butzke S. , Maes J.W. , Schannen O.F.Z. , Trommel J. , Radelaar S. , Balk P. 
Published: March 2011

ABSTRACTWe have studied the deposition of GexSi1−x layers on (100) Si substrates by gas source molecular beam epitaxy (GSMBE) using disilane and germane.The investigation of RHEED intensity oscillations during growth reveals the well known rate enhancement obtained when adding a small amount of germane to the disilane flux. However, when exposing a previously deposited Ge layer to a pure disilane flux the growth rate during the first few monolayers remains at an enhanced value but returns to its homoepitaxial value after about 10 to 15 monolayers. This behaviour was observed under a variety of growth conditions. It is in marked contrast to the experience obtained in conventional Si/Ge MBE and suggests a catalytic effect of the particular surface present during GSMBE growth. We propose that this effect is caused by the surface segregation of Ge species and leads to a smear-out of the Ge profile in the layer.
Heteroepitaxial Growth of Transition-Metal Nitride Films
Authors: Shinn M. , Mirkarimi P.B. , Barnett S.A. 
Published: March 2011

ABSTRACTThe nucleation of epitaxial transition-metal nitride films with different lattice mismatch and growth of the corresponding supcrlattices were studied. In-situ Auger electron spectroscopy (AES) was used to characterize the nucleation mechanisms of V0.3Nb0.7N films on TiN (1.7% mismatch), TiN films on VN (2.4% mismatch), TiN films on NbN (3.6% mismatch), NbN films on VN (5.7% mismatch), and VN films on NbN grown by ultra-high vacuum reactive magnetron sputtering. The initial growth mechanism was layer-by-layer for mismatch values up to 3.6%, but three-dimensional island nucleation occurred for 5.7% mismatch. Scanning tunneling microscopy (STM) observations of NbN films showed threedimensional islands, confirming the AES results. X-ray diffraction spectra from the corresponding superlattices showed strong superlattice reflections except for the large-mismatch NbN/VN combination. Cross-sctional transmission electron microscopy studies showed that the superlattice layers were.velldefined and planar for low mismatch, but were irregular and non-planar for VN/NbN, in agreement with the X-ray, AES, and STM results. The maximum lattice mismatch for epitaxial nitride superlattice growth was thus limited by island nucleation and in the range from 3.6 - 5.7%.
Characterisation of Extended Defects in Si and Si1−x Gex Alloys: The Influence of Transition Metal Contamination
Authors: Higgs V. , Lightowlers E.C. 
Published: March 2011

ABSTRACTPhotoluminescence (PL) spectroscopy, cathodoluminescence (CL) spectroscopy and imaging, transmission electron microscopy (TEM), and preferential defect etching and optical microscopy have been used to characterise dislocations in plastically deformed Si and in Si1−x Gex alloys. The PL spectra from plastically deformed Si produced under clean conditions, contained no dislocation related luminescence features. However, after deliberated Cu contamination and annealing, the PL spectra were dominated by the four main D-bands (D1-D4). CL spectroscopy and imaging revealed that the D3 and D4 bands originate on the slip lines, whereas D1 and D2 are dominant between the slip lines. Pseudomorphic Si1−x Gex layers grown by molecular beam epitaxy (MBE) and forced to relax by Cu contamination and annealing have also been examined. Both the PL and CL spectra were dominated by the D1-D4 bands, and monochromatic CL imaging showed that the D3 and D4 bands originate at the misfit dislocations with the location of the Dl and D2 bands being much less well defined. PL spectra from Si1−x Gex capping layers, grown by MBE on linearly compositionally graded buffer layers, were dominated by bound exciton luminescence features, identical with those observed in bulk grown alloys, and showed relatively weak D-band features. PL spectra obtained after chemical step etching, and CL spectra obtained with different beam energies, showed that the D-bands originated in the buffer layers which contained high densities of misfit dislocations. Well defined monochromatic CL images of the misfit dislocations could only be obtained using a narrow band pass filter centred on the D4 band. No D-band luminescence was observed from Si1−x Gex layers grown by high temperature chemical vapour deposition (CVD). However, after deliberate contamination with Ni, the D-bands became the dominant features and CL imaging clearly showed that the D4 band originates at the misfit dislocations and the D2 band predominantly between the misfit dislocations.
Tem Structure Investigations of Low-Temperature MBE Grown Inalas Layers on INP<001> Substrate
Authors: Werner P. , Liliental-Weber Z. , Yu K.M. , Weber E.R. , Rek Z. , Metzger R. 
Published: March 2011

ABSTRACTThe real crystal structure of In0.52A10.48As layers grown on InP<001> substrate as a function of the growth temperature (between 150°C and 450°C) was investigated. The following structural / electrical analyses were applied to the samples: transmission electron microscopy (TEM), x-ray diffraction and particle induced x-ray emission (PIXE). In the temperature range between 200°C and 450°C good epitaxial growth of InAlAs layers can be achieved with a low density of dislocations and stacking faults. Ordering of group-III elements on {111} planes was observed for these layers. Structure models of such ordered domains are discussed. At growth temperatures below 300 °C additional As (≈2%) is incorporated in the lattice. Growth at temperatures below 200°C leads to the formation of pyramidal defects with As grains in their cores. As-grown as well as annealed InAlAs layers show a nearly constant, high electrical resistance (106-107Ωcm) in the whole temperature range.
The Dependence of Defect Density in GexSi1−x/Si Heterostructures Grown by Remote Plasma-Enhanced Chemical Vapor Deposition on Deposition Parameters
Authors: Kinosky D. , Qian R. , Hsu T. , Irby J. , Mahajan A. , Thomas S. , Banerjee S. , Tasch A. , Magee C. , Grove C.L. 
Published: March 2011

ABSTRACTThe density of misfit dislocations in GexSi1−x films has been measured as a function of deposition temperature and r-f plasma power in Remote Plasma-enhanced Chemical Vapor Deposition (RPCVD). The misfit dislocation density decreases as the deposition temperature is lowered from 450°C to 410°C. As the plasma power is increased from 6.6 to 16W, the dislocation density peaks at lOW and then decreases with increasing power.
Sticking and Desorption Coefficients of As4 and As2 During Group V and Group III Controlled MBE Growth
Authors: Fernandez Rouel 
Published: March 2011

ABSTRACTReflection High Energy Electron Diffraction (RHEED) oscillations under arsenic and gallium-controlled Molecular Beam Epitaxy (MBE) growth conditions have been used to measure the sticking and desorption coefficients of As2 and As4. The coefficients are obtained from measurements of the arsenic incorporation rates. Comparisons are made with measurements obtained from desorption rates using modulated beam mass spectroscopy. The transition from gallium to arsenic-controlled growth is observed to occur after excess gallium atoms accumulate on the surface. The maximum intrinsic arsenic sticking coefficients occur when the maximum number of gallium atoms can be incorporated for a given arsenic flux. The intrinsic maximum arsenic sticking coefficients are found to be 0.75 and 0.50 for As2 and As4, respectively. During galliumcontrolled growth, the arsenic sticking coefficients are independent of substrate temperature as long as the sticking coefficient of gallium is equal to one. However, a temperature dependent maximum gallium-controlled arsenic sticking coefficient exists. It can be measured by the maximum Ga to As4 flux ratio that produces specular film surfaces. During gallium-controlled growth, the Ga to As flux ratios are shown to be equal to the gallium-controlled arsenic sticking coefficients. The activation energy for arsenic desorption during arsenic-controlled growth conditions was measured as -0.50 eV for independent As4 and As2 incident fluxes. During gallium-controlled growth with incident As4 fluxes, an activation energy for arsenic desorption of -0.70 eV was measured for the maximum gallium-controlled arsenic sticking coefficients.
Initial Studies on The Heteroepitaxial Growth of Thin Films of (AI/In)N on Ain-Seeded (00.1) Sapphire by Single-Target Reactive Magnetron Sputtering
Authors: Kistenmacher T. J. , Ecelberger S. A. , Bryden W. A. 
Published: March 2011

ABSTRACTThin films of (AI/In)N alloys have been deposited on AIN-nucleated (00.1) sapphire by reactive (pure N2 gas) magnetron sputtering and characterized by X-ray scattering, stylus profilometry, optical spectroscopy, and electrical transport measurements. Initial efforts have concentrated on producing films with compositions near Al0.31In0.69N (bandgap tailored to GaN). The alloy sputtering targets were disks fabricated by cold pressing appropriate molar mixtures of beads of 99.99% purity Al and In. The resulting thin films are composed of heteroepitaxial grains {(00.1)InNll(00.1)sapphire; (10.0)InNll(11.0)Sapphire} and their chemical composition has been deduced from the variation in the a cell constant (as measured by the X-ray precession method) to yield equilibrium film compositions near Al0.04In0.96N and Al0.25In0.75N, respectively. Preliminary results are presented on the dependence of the quality of heteroepitaxial growth and electrical and optical properties of. these AlxIn1−xN alloy films on various growth parameters: such as chemical composition; film thickness; morphology; and substrate temperature.
Cure Studies of Fluorinated Polyamic Acids by Thermal-IR
Authors: Roginski Robert T. , Fjare Douglas E. 
Published: March 2011

AbstractThe thermal curing chemistry of a fluorinated polyamic acid based on 6FDA (hexafluoroisopropylidene bis(phthalic anhydride)) and APBP (4,4′-bis(4-aminophenoxy)biphenyl) was studied by thermal-IR spectroscopy. Anhydride formation was observed at intermediate cure temperatures and maximized at approximately 220°C. The degree of anhydride formation was affected by the solvent, being least in 2-methoxyethyl ether and increasing in the solvent order: 2-methoxyethyl ether < NMP < 2-(2-ethoxy)ethoxyethanol. In addition to the back reaction of amic acid to anhydride and amine, at least one additional mechanism of anhydride formation is observed. The onset of the second mechanism of anhydride formation is coincident with the onset of imidization, which leads us to propose that water generated by imidization can react with anhydride during the curing process, before escaping from the film, to form diacid. Cyclization of diacid to anhydride is proposed as the second mechanism of anhydride formation.
Cure Technology for Controlled Stress in Thin Benzocyclobutene Coatings
Authors: Townsend P. H. , Burdeaux D. C. , Stokich T. M. , Dibbs M. G. 
Published: March 2011

AbstractThe stress at room temperature in many typical polymer coatings used for microelectronic dielectrics is near 40 MPa. Polymer coatings derived from divinylsiloxane bisbenzocyclobutene (BCB), (CAS 117732-87-3), have a stress level of ca. 38 MPa after a conventional thermal oven cure. In this work, a novel approach based on curing the BCB polymeric network in the vitrified state has been used to achieve far field stresses of 24 MPa in the final coatings. This represents a 36% reduction in the far field stress of BCB coatings cured at 250 °C. The cure methodology and compatibility with device process design are discussed.
Stresses in Polyimide Films during Cure and Thermal Cycling
Authors: Monk David J. , He Yongxiang , Soane David S. 
Published: March 2011

AbstractSeveral electronics packaging schemes involve polymer/inorganic interfaces, including: dual-in-line packages, tape automated bonding and multilayer interconnects. Typically, the thermal expansion coefficients are disparate, so these interfaces often cause high stress. Therefore, a phenomenological model describing transient stresses in spin-coated polyimide films was developed. The model is based on linear viscoelastic theory, and it accounts for shrinkage caused by solvent evaporation and imidization, viscoelastic relaxation, and thermal expansion mismatch. Strains have been defined from three mechanisms: thermal expansion mismatch, chemical curing, and solvent evaporation. Stress is, then, calculated by using the Classical Maxwell Model with one element. The concept of free volume is used throughout the model to estimate viscosity, modulus, and other quantities related to calculating strains. Model predictions for stress as a function of temperature during film cure and thermal cycling are fit with experimental data obtained from a bending beam apparatus.Stress has been estimated by using the thin film approximation of the Timoshenko bilayer stress equation. Experimental data agree well with wafer bowing stress measurements. Although the technique does not yet take into account changing polyimide thickness during curing, the results still show qualitative curing dynamics. This preliminary study revealed good agreement between predicted and observed effects of material properties on stresses developed during cure and thermal cycling. Specificially, an unexpected high in-cure stress was observed for a standard low CTE polyimide. High stresses during curing can be as detrimental to an electronics device as high stress during device operation, so this technique may be useful when screening polyimides and/or prescribing curing schedules. Future work will improve the predictive capability of the model.
Thermal and Mechanical Analysis of a Multichip Module
Authors: Hu M. S. 
Published: March 2011

AbstractHigh speed, high density packaging requirements have made multichip modules (MCM) one of the most active areas of research in the electronic industry.High density printed wiring board (PWB) have low production cost and good electrical performance. However, the most questioned issue in application is the reliability. As a result, a thermal and mechanical analysis on a MCM has been conducted to understand its feasibility. The results indicate that with proper design, the components can operate under satisfactory conditions on PWB laminates.
Stresses in Thin Film Multilayer Interconnect Structures
Authors: Bruck S. M. , Knorr D. B. 
Published: March 2011

AbstractThe difference in coefficient of thermal expansion (CTE) between substrate, polymer, and metal leads to complicated stress fields in multilevel interconnect structures that can potentially compromise reliability. This study uses a materials set representative of the General Electric High Density Interconnect (HDI) multichip module technology to monitor the stress level in the thin film layers of metal and polymer. A Kapton HN® film is bonded to a substrate with heat and pressure using a thin layer of Ultem 1000® thermoplastic as an adhesive. Mechanical test structures consist of single or multilayer thin films fabricated on oxidized silicon or alumina substrates. Layers consist of Ultem, Ultem/Kapton, metal (Ti/Cu/Ti), and Ultem/Kapton/metal. The composite stress due to fabrication and thermal cycling between ambient and 275°C is determined by substrate deflection. The initial stress in the polymer materials is due to the thermal excursion during fabrication. Initial metal stress is intrinsic but becomes extrinsic upon thermal cycling. The composite stress in multilayer structures shows a contribution from each individual layer. The relatively low processing temperature minimizes the magnitude of the stress.
Characterization of Fluorinated Polyimide Films
Authors: Nagarkar Pradnya V. , Lu Jiong Ping , Volfson David , Jensen Klavs F. , Senturia Stephen D. 
Published: March 2011

Abstract:X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) have been used to characterize the polyimide film based on 4,4′ hexafluoro-isopropylidene -bis pthalic anhydride (HFDA) and 4,4′ -bis (4-aminophenoxy) biphenyl (APBP). Films of varying thicknesses made from diluted precursors were studied by IR and XPS. An elemental analysis and a tentative peak assignment for C 1s in XPS is presented. The HFDA-APBP thick films are stoichiometric in composition and binding energies are in good agreement with data on hexafluorodianhydride-oxydianiline (HFDA-ODA). For thinner films, certain chemical modifications were observed at high cure temperatures.
Formation Kinetics and Thin Film Stress of Tin Containing Intermetallic Compounds
Authors: Chan Chin-Jong , Chang Jei-Wei , Chin Leo A. 
Published: March 2011

AbstractThin film reactions and its influence on mechanical stress have been investigated in Cr/Cu/Sn and Cr/Ni/Sn multilayer structures. Thin film stresses of different intermetallic compounds in each material system were evaluated using substrate bending technique. Stress state in the thin film structures was round directly related to formation kinetics and thermal properties of intermetallics. In Cu-Sn system, a large internal stress increase in tension was generally observed after being heat treated at high temperatures. In Ni-Sn systems, formation of intermetallics is a relatively slow reaction at elevated temperatures as compared to that of Cu-Sn samples. Contrary to that of Cu-Sn system, formation of Ni-Sn intermetallics causes a decrease in stress in the thin film structure. The correlation of thin film stress state and the structure evolution at the interface is studied and discussed in details.
Development of New Polymeric Materials for Linear Waveguides
Authors: Kim H. K. , Kahn S. , Mates T. , Barclay G. , Ober C. K. 
Published: March 2011

AbstractWe have evaluated the use of either poly(phenylene) prepared via spin-coatable polymeric precursors or fluorinated polysilynes for optical waveguides. Poly(phenylene) precursors were converted into poly(phenylene) by either curing at 300 °C or by deep-UV exposure in the presence of a photoacid generator. The poly(phenylene)s have a number of desirable properties for optical waveguide applications including good near IR transmission, low dielectric constant, thermal and environmental stability and ease of pattern fabrication using microlithographic techniques. Copolysilynes were spin-coated onto various types of substrates and then exposed by deep-UV radiation. Upon exposure of deep UV irradiation in the presence of air, they undergo photooxidative crosslinking to give insoluble glass-like materials. This photo-oxidation process is accompanied by a large decrease in refractive index from n=1.61 to n= 1.485. The photooxidation results suggest that their potential applications are as photoresists and optical waveguides.
Stress Measurement Using a Bilayer Metal-Ceramic Strip
Authors: Kapur Shukla , Flaltz Philip L. 
Published: March 2011

AbstractResidual stresses that develop in metal/ceramic bonded systems due to thermal expansion mismatch have been calculated using finite element modelling and measured experimentally using a simple bilayer strip. Bending in the strip occurs during cooling due to the stress asymmetry. Residual stresses are calculated by measuring the deflection of the strip and the temperature at which the strip is flat. Various compositions of both copper and nickel pastes, with and without glass and other second phase additions were evaluated on glass-ceramic. The effects of further processes, e.g. thermal cycling, brazing and plating, are also reported in this work.
The use of Microindentations to Measure the Mechanical Protection Provided by Polymeric I.C. Buffer Coatings
Authors: Gealer C.A. , Jeng Y.H. , Sundahl R.C. , Kinsman K.R. , Gaudette J.M. 
Published: March 2011

AbstractA technique combining the use of microhardness indentations and an aluminum etch decoration process has been developed to measure the relative ability of polymer coatings to protect an integrated circuit (I.C.) device surface from mechanical damage. A threshold for inducing a crack in a passivated silicon surface was measured by applying a grid of indentation loads and measuring the load at which the aluminum etchant revealed damage in the passivation. A polyimidesiloxane and two polyimide materials, with widely different elastic moduli, were tested.The ability of a coating to protect the chip surface was found to increase with increasing compliance of the film. The materials with the higher threshold loads had lower elastic moduli and allowed greater indenter penetration depth for a given load. Our finite element mechanical model supports the hypothesis that the stress generated by the indenter tip is absorbed and distributed by the lower modulus materials. The stress is transferred to the passivated silicon in the case of the higher modulus film, leading to damage at lower loads.
Area Array Solder Joints for Passive Alignment
Authors: McGroarty John , Yost Boris , Børgesen Peter , Li Che-Yu 
Published: March 2011

AbstractPassive alignment techniques using area array solder joints are currently under investigation as a cost effective method of achieving electro-optical interconnects in electronic packages. Several investigators have developed models that describe the shapes of and forces produced by the liquid solder drops during reflow. These models are reviewed to provide a scientific basis for the application of such techniques.