bluuebunny/crossref_metadata_2025_split huggingface dataset:
Correlation Between Defect Density and Process Variables In Step-Graded, Relaxed Si0.7Ge0.3 Grown on Si by Rtcvd
Authors: Watson G. Patrick , Fitzgerald Eugene A. , Jalali Bahram , Xie Ya-Hong , Weir Bonnie , Feldman Leonard C. 
Published: March 2011

ABSTRACTThe effect of the average grading rate and of the number of incremental Ge alloy steps on the threading dislocation density has been studied in 30% Ge relaxed films formed by rapid thermal chemical vapor deposition (RTCVD) on Si substrates. Electron beam induced current (EBIC) images and transmission electron microscopy (TEM) show that threading defects fall in two categories: individual threading dislocations (dark spot defects), and organized clusters of these threads (pile-ups, or dark line defects). The overall surface defect density must include both categories to properly characterize the material. The lowest defect density, 4 × 105cm−2, was found in specimens grown at an average grading rate of 10% Ge per pm thickness.
Evaluation of a vertical tube concept for RTP
Authors: Cho Byung-Jin , Vandenabeele Peter , Maex Karen 
Published: March 2011

ABSTRACTA new RTP system concept is proposed and demonstrated. The system uses a vertical cylindrical quartz tube, while the wafer is placed horizontally. Linear halogen lamps are arranged in an hexagonal shape. Optimal power control results in a temperature difference within ±1.5 °C over a 6 inch wafer in steady state. Oxidation under optimal conditions results in a 1.37% standard deviation for an average oxide thickness of 110.4 Å. The temperature nonuniformity during the transient has been greatly improved by using dynamic control. The main advantages of this new system concept are its excellent temperature uniformity and the good accessibility of the wafer for technological treatments and in situ measurements.
Investigation of Dynamical Temperature Behaviour in Rtp
Authors: Leitz Gunnar , Pezoldt JÖrg , Patzschke Ingo , ZÖllner Jens-Peter , Eichhorn G. 
Published: March 2011

ABSTRACTFor Rapid Thermal Processing one of the essential problems is the dynamical temperature controlling to reduce temperature nonhomogeneities during heating up and cooling down, which are responsible for layer nonhomogeneities and slip generation. A pyrometer row consisting of five sensors is used for temperature distribution measurement in radial direction, which allows to investigate the dynamical behaviour during the heating cycles. Together with a developed software tool, which is suitable for calculation of the dynamical temperature distribution across the wafer under process conditions where the convective heat losses can be neglected, the influence of heating-up velocities is investigated. The obtained results show that in a scalar controlled system process conditions optimized for steady state lead to maximum temperature nonhomogeneity during the heating-up period, due to the changing heat balance in the system.
Rapid Thermal Processor Modeling, Control, and Design for Temperature Uniformity
Authors: Riley Terrence J. , Gyurcsik Ronald S. 
Published: March 2011

ABSTRACTWith the ability to perform heat cycles on a wafer quickly and within low thermal budgets, Rapid Thermal Processor (RTP) systems offer potential advantages over conventional furnaces. However, RTP' have an inherent problem with wafer temperature uniformity which can cause process nonuniformity and wafer stress.In this work, a thermodynamic model of a wafer is used to form an understanding of the wafer heating problem. This model shows that an idealized heating flux density profile can maintain thermal uniformity at steady-state temperatures. This profile uniformly heats the wafer while counteracting the additional cooling at the wafer edge. However, this profile induces temperature nonuniformities during wafer temperature transients, such as overheating of the edge during temperature rises. Therefore, a dynamic flux-density profile is needed during temperature transients to ensure continuous temperature uniformity. The model is used to predict the steady-state and dynamic profiles required to process a wafer with complete temperature uniformity. The predicted profiles can be used to adapt an RTP chamber and control system to approach production of uniform wafers and also for the design of new systems. This paper will explain the theory of wafer heating, describe the dynamic profiles required for continuous uniformity, review the wafer model, show the result of an idealized profile for steady state and transients processing, and present a new control methodology to achieve uniform temperatures.
Gate Oxide Integrity as Affected by Hf Last Wafer Treatments and Passivating Techniques
Authors: Hawthorne R.C. , Thakur R.P.S. , Morinville K. , Kauffman R. 
Published: March 2011

ABSTRACTAs device performance requirements increase, device features become smaller and films become thinner. The resultant sensitivity to defect density is such that controlling the condition of wafer surfaces prior to primary process steps becomes more and more critical. Wafer cleaning technologies of the past may not be optimum in providing needed device characteristics and reliability of tomorrow's semiconductors. In this paper, we compare the currently used RCA wafer clean chemistries to newer HF last, vapor dry technologies which use direct displacement of liquids to minimize contaminants. Subsequent passivation of these hydrophobic wafer surfaces is accomplished by various methods of oxidation including chemical treatments and RTP processing. Data collected from I-V, SIMS and DEFECT DENSITY testing will be included in the presentation.
Titanium Disilicide Formation on Cmos Structures with Phosphorous Doped Gates
Authors: Chtttipeddi S. , Nanda A. K. , Kannan V. C. , Cochran W. T. 
Published: March 2011

ABSTRACTSelf aligned refractory metal silicides such as titanium disilicide have been used extensively in VLSI and ULSI structures. Unlike earlier work which has relied on undoped substrates and a single implant species, in the present study TiSi2 formation on phosphorous doped poly-Si in the presence of multiple dopants has been investigated. TEM micrographs are discussed which show the difference in silicide formation for the case of the BF2 and arsenic implanted samples. We have found that the presence of fluorine in the BF2 implant retards the silicide formation for phosphorous doped poly-Si substrates. Additionally, the effect of substrate grain size on TiSi2 formation has been investigated using undoped α-Si and poly-Si substrates.
Influence of Rapid Thermal Processing Conditions on the Characteristics of Sputter Deposited Titanium Nitride Thin Films
Authors: Ramaswami Sesh , Iacoponi John , Cheung Robin 
Published: March 2011

ABSTRACTSputter deposited TiN films are commonly used as diffusion barriers for an aluminum based metallization and as glue layers for tungsten films in ULSI device processing. TiN is also used in conjunction with Ti and/or a-Si for local interconnect and salicide processing. For the above applications, TiN films are also subjected to rapid thermal processing.This paper discusses these applications focusing on sub-half micron technologies where high aspect ratio contacts causes poor step coverage at the base of the contacts and compact design rule requirements pose an additional burden to Ti-silicide processes. Preferred grain orientation, microroughness, film stress, sheet resistance, diffusion barrier qualities and analytical spectroscopy techniques have been used to characterize the material modifications by RTP of Ti and Ti/TiN thin films.
Diffusion of Cations Along the Polymer/Metal Interface Under an Applied Electrical Potential
Authors: Nguyen T. , Pommersheim J. M. 
Published: March 2011

AbstractDiffusion of cations along the polymer/metal interface controls the rate of blistering of polymer coatings on metals exposed to electrolytes. Cations are driven by both concentration and electrical potential gradients. A theoretical and experimental study was carried out on the diffusion of sodium ion along the polymer coating/steel interface under an applied potential. Mathematical models, consisting of initial and propagation stages, are derived based on a moving boundary diffusion problem. Model variables include ion diffusivity, potential gradient and distance between defects and delamination sites. Models are solved to predict ion fluxes and concentration in the blistering areas. Experimental data are analyzed to extract model parameters. Model predictions agreed well with experimental data and practical observations
Grafting of Polymers to Solid Surfaces by using Immobilized Azoinitiators
Authors: Prucker O. , Rühe J. 
Published: March 2011

AbstractThe covalent attachment of polymers such as polystyrene, polymethylmethacrylate and polyacrylonitrile to microparticulate silica and to silicon wafers through immobilized radical chain initiators (especially azocompounds) is described. The initiator is bonded to the surface using α,ω-substituted silanes, which have only one functional group at the silane head group.Up to 10 g of polymer per g of silica could be covalently bonded to the surface. The attached monolayers were characterized using diffuse reflectance FTIR spectroscopy, XPS and elemental analysis. After the cleaving off of the attached layers molecular weights up to 300.000 g/mol were measured. Transmission electron micrographs generated with an element specific imaging technique (ESI) clearly show a continuous, about 10 nm thick, polymer layer around the silica particles.
Oxygen Bombardment Induced Activation of Glassy Carbon
Authors: Jenkins G. M. , Ila D. , Williams E. K. 
Published: March 2011

AbstractWe have studied the effect of oxygen ion bombardment of glassy carbon at room temperature, using a composite bi-energy beam of 3.2 and 3.1 MeV ions. Carbon specimens were prepared in-house by pyrolysis of phenolic resin at 1000° C. Raman microprobe spectra of the surface and implanted volume before and after irradiation showed that the implanted oxygen ions had disrupted translational symmetry at the surface and caused maximum damage in the carbon 3.5 μm below the surface. By analogy to the “activation” of charcoals1 we conclude that pores are opened up by preferential attack of strained carbon sites.
Role of Coating/Oxide/Steel Interfaces on Cathodic Disbonding of Pipeline Coatings
Authors: Payer J. H. , Trautman B. , Gervasio D. , Song I. 
Published: March 2011

AbstractFusion bonded epoxies (FBE) in combination with cathodic protection (CP) are widely used to protect the soil side of buried pipelines from corrosion. Cathodic disbonding of the epoxy coating is a degradation process involving accelerated loss of adhesion of FBE because of chemical and electrochemical processes due to CP. Results are presented from our study to determine the mechanism of cathodic disbonding.
Cleavable Thermosetting Epoxies: a Tool for Monitoring Cure Chemistry Perturbation at an Interface
Authors: Gilbert Michael D. 
Published: March 2011

AbstractA diepoxide containing a disulfide linkage, capable of being reductively cleaved was synthesized. This compound was cured with standard amine curing agents to form intractable network polymers, which were then decomposed into soluble fragments, allowing the effects of network formation on cure chemistry to be evaluated. This system was then used to investigate the effects of an alumina interface on epoxy network formation.
Ceramic-Polyimide Systems for Electronic Packaging
Authors: Marsh Wayne E. , Kanakarajan K. , Osborn Garry D. 
Published: March 2011

AbstractA family of new high performance thermoplastic polyimide adhesives have been developed that can be directly laminated to ceramic substrates, polyimide films, metals, and/or sputter metallized for eventual circuit fabrication. We have also developed new heat-sealable composite polyimide films that have improved CTE, that have good dimensional stability and that can also be directly bonded to ceramic and glass-ceramic substrates. With these new material sets various constructions of ceramic-polyimide rigid-flex systems can be conceived to meet the more demanding needs of the electronics industry. We have laminated these films to metals and various ceramic substrates such as alumina, aluminum nitride, glass, etc. and investigated the bond stabilities under thermal and humidity aging conditions.
In-Situ Synchrotron X-Ray Scattering Studies of Polybenzoxazole Fiber Spinning
Authors: Nolan S. J. , Broomall C. F. , Bubeck R. A. , Landes B. G. , Rudolf P. R. , Mills M. J. , Radler M. J. 
Published: March 2011

AbstractInitial results are presented of in-situ wide angle x-ray scattering (WAXS) studies of structure and orientation development in the draw zone during fiber spinning of poly(p-phenylene benzobisoxazole) (PBO) in polyphosphoric acid (PPA). The diffraction patterns show strong [100] and [002] reflections. The coherence lengths found from the [100] and [002] reflections are consistent with those found by electron diffraction and suggest important elements of the microfibrillar morphology may already be present in the texture of the extrudate before coagulation. Increasing extrusion rate is found to produce little improvement in molecular orientation. Molecular orientation initially increases with increasing draw ratio from 1 to 10 but, remains constant for higher draw ratios. These results are compared to an affine deformation model during elongational flow.
“Recoil” Compressive Strength Test and the Evolution of Compressive Behavior in PAN-Based Carbon Fibers
Authors: Jiang Hao , Damodaran S. , Abhiraman A. S. , Desai P. , Kumar S. 
Published: March 2011

AbstractThe compressive properties of PAN-based carbon fibers were measured with the tensile recoil method. The recoil fracture morphology was also examined. In addition to the axial compression, flexure during recoil affects the test results. Compressive failure may be caused by shear failure and/or bending buckling of the microfibrils/fibrils. Study of the evolution of compressive and other mechanical properties discloses that, in general, the compressive strength bears a similar tendency to the tensile strength and torsion modulus up to the carbonization temperature of 1500 °C. However, the relative rate of evolution is different. To some extent, the bending buckling mechanism may relate to the structural units which govern the tensile strength.
The Influence of Sputter Deposited Coatings on Strain Transfer in Embedded Fiber Optic Sensors
Authors: Madsen J. S. , Jardine A. P. , Meilunas R. J. , Pak Y. E. , Tobin A. 
Published: March 2011

AbstractUnderstanding elastic interactions that occur between an embedded optical fiber and its host matrix is important for implementation of optical strain sensors into aerospace structures. A previously developed analytical model predicted the effects of fiber coating thickness and elastic modulus on the strain transfer from an isotropic matrix to an embedded coated fiber optic.To verify this, a series of tungsten coatings were magnetron sputtered onto bare intrinsic Fabry-Perot sensors that were embedded into a neat epoxy resin block. The block was then compression loaded and the optical strain response measured. Comparisons between the responses of both coated and uncoated sensors indicated that the experimental measurements of strain transfer in embedded fiber-optic devices yielded good agreement with the analytical model.
Thermoplastic in-situ Molecular Composites
Authors: Wiff D. R. , Lenke G. M. 
Published: March 2011

AbstractThe basic concepts of in-situ molecular composite formation are presented with a polyazomethine/nylon 6 system as an example. All the encouraging attributes of molecular reinforcement - increased Tg, solvent resistance and mechanical properties were observed. This provides a commodity resin, such as nylon 6, with properties normally associated with higher priced engineering/specialty resins.
The Phase Behavior of a Hydrogen Bonding Molecular Composite
Authors: Dadmun M. D. , Han C. C. 
Published: March 2011

AbstractThe phase behavior of a blend containing poly(hydroxypropyl L-glutamine) (PHOPG), a rod-like polypeptide, and a coil-like random copolymer with 1.5% hydrogen bonding monomer is studied using light scattering, DSC, and optical microscopy. The results show that this system has an LCST. The phase behavior of this binary system is complicated by a glass transition and an ordering transition. Evidence is also observed of a possible change in phase demixing process, from nucleation and growth to spinodal decomposition, for a 50/50 blend with a change in temperature.
The Effects of Physical Ageing and of Prior Immersion on the Esc Behaviour of Polycarbonate in Ethanol
Authors: Arnold J. C. , Eccott A. R. 
Published: March 2011

AbstractThe effects of physical ageing and prior immersion time on the ESC behaviour of polycarbonate in ethanol were studied. Constant strain rate tensile tests were performed at a range of strain rates for samples with ageing times varying from 100 hours to 3000 hours and for prior immersion times of between 1 hour and 500 hours. Comparison of tests performed in ethanol and in air gave a good indication of the point of craze initiation. The results showed that there was a reduction in strain to crazing as the strain rate decreased, apart from with the lowest strain rate used. A longer prior immersion time also promoted craze formation. Both of these results are attributable to diffusion effects. Physical ageing had little effect on the ESC behaviour, due to the large amounts of deformation encountered in this system.
An Investigation of Stable Free Radicals in Polyimides Using EPR Spectroscopy
Authors: Ahn Myong K. , Stringfellow Thomas C. , Lei Jianming , Bowles Kenneth J. , Meador Michael 
Published: March 2011

AbstractPolyimide resins are used as matrix materials in fiber reinforced composites. Such composites are lightweight, have relatively high strength, and can be used at temperatures above 300°C. Postcured PMR-15 produces room temperature electron paramagnetic resonance (epr) spectra from stable free radical species formed during the postcuring stages. The variable temperature EPR spectral intensities indicate the presence of at least two free radical species. The thermo-oxidative degradation involves free radicals generated during the postcuring process in the presence of oxygen gas. These and other recent results including ENDOR and HYSCORE work are discussed.
Synthesis and Characterization of Soluble, High Temperature 3-Phenylethynyl Aniline Functionalized Polyimides via the Ester-Acid Route
Authors: Meyer G. W. , Jayaraman S. , Lee Y. J. , Lyle G. D. , Glass T. E. , McGrath J. E. 
Published: March 2011

AbstractThe synthesis of soluble imide oligomers of controlled molecular weight endcapped with the 3-phenylethynyl aniline endcapping agent is described. The 3-phenylethynyl aniline was employed to afford a higher curing temperature (380 - 420°C) which widens the processing window compared to commercially available acetylene endcapped polyimides. The polyimides were synthesized via solution imidization techniques, using the ester-acid of various dianhydrides and various aromatic diamines. The “one pot” procedure utilizes NMP as the solvent and o-dichlorobenzene as the azeotroping agent, and reproducibly exhibit fully imidized soluble polyimides with Mw/Mn values of ∼2.0 determined by gel permeation chromatography. Thermally cured samples display good solvent resistance and exhibit glass transition temperatures comparable to their high molecular weight linear analogs. These polyimides show excellent thermal stability at 700°F aged in air up to 100 hours. Mechanical testing has been performed on a pyromellitic dianhydride (PMDA) and a phosphine oxide-based system. The flow properties have been studied by parallel plate rheology and the cure cycle has been monitored using 13CNMR.
Water Soluble Benzobisazole Rigid-Rod Copolymers
Authors: Dang Thuy D. , Arnold Fred E. 
Published: March 2011

AbstractAlthough benzobisazole rigid-rod polymers are well recognized for their outstanding tensile and modulus properties as well as their excellent thermal and thermal-oxidative stabilities, they can only be fabricated from acidic solvents. Benzobisirnidazole polymers containing pendent benthiazole or sulfonic acid groups exhibit partial solubility in DMSO. Reaction of these systems with sodium methylsulfinylmethide in DMSO abstracts the acidic proton from the benzobisimidazo unit and forms the polyanion. Subsequent reaction of the polyanion with 1,3-propanesultone provides water soluble systems. Random copolymers containing benzobisimidazo and benzobisthiazole repeat units were prepared in polyphosphoric acid and subjected to the derivatization reaction. Benzobisimidazo content in the copolymers varied from 10–0 mole percent. Minimum ionic charge along the rigid-rod backbone to obtain water solubility was determined to be approximately 10 mole percent as reflected in the benzobisimidazole repeat units.
Polyphosphazene Composites: a Report on Initial Properties
Authors: Stone Mark L. 
Published: March 2011

AbstractPolymers based upon inorganic elements are becoming more important in the field of high performance materials because of their outstanding mechanical, thermal, and chemical stabilities. Polyphosphazenes, which are based upon a nitrogen-phosphorus backbone, show promise as new engineering materials. The large number of different chemical structures possible allows the synthesis of phosphazene polymers for specific applications. Initial tests on one phosphazene-based set of materials show that they are very hard, stiff, and have excellent resistance to organic chemicals.
The Interphase in Fibre Reinforced Polymers; New Ideas on How This Controls the Composite Strength
Authors: Piggott Michael R. 
Published: March 2011

AbstractMuch work has recently been done on the interphases between fibres and polymers and it is now clear that they are usually brittle. This requires a re-examination of our basic ideas on how composites achieve their strength. The Kelly-Tyson approach, which is based on ductile metal behaviour, has never received unequivocal support. In addition, work during the last ten years in the author's laboratories indicates that it is incorrect in one of its major predictions: that the stress-strain plots of short aligned fibre composites should be curves. In this paper we present the evidence and introduce a new failure model which eliminates these difficulties.
Photoemission Measurements Of Photocathode Materials In The 115–400 Å Range
Authors: Grantham S. , Richardson M.C. , Watts R. , Lucatorto T. , Tarrio C. , Pollack F. 
Published: March 2011

AbstractWith the intent of finding a sensitive photocathode material in the 130 Å (100eV) X-ray range for use in a high resolution soft X-ray Conversion Microscope, photoelectron yields of several materials (mostly alkali halides), were measured at the National Institute of Standards and Technology's (NIST) Synchrotron Ultraviolet Radiation Facility II (SURF II). These measurements were made as a function of wavelength in the spectral range 115 Å-400 Å. The measured values are comparable to previous measurements of the photoelectron yields of these and similar materials, and to an existing model of photoemission [1–3]. We also determined the effects of prolonged exposure to X-ray light on performance. Moreover, because of the hygroscopic nature of Alkali Iodides, measurements of the photoelectron yield versus wavelength were repeated for samples of CsI that were kept in storage for periods of time to determine the effects of storage time and water absorption on the photoelectron yield.