bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stability of Ultra-Thin Gate Oxides with Boron Doped Polysilicon Gate Structures After Rapid Thermal Annealing
Authors: Zhang Bojun , Maher Dennis M. , Denker Mark S. , Ray Mark A. 
Published: March 2011

ABSTRACTWe report a systematic study of dopant diffusion behavior for thin gate oxides and polysilicon implanted gate structures. Boron behavior is emphasized and its behavior is compared to that of As+ and BF2+. Dopant activation is achieved by rapid thermal annealing. Test structures with 100 Å, 60 Å and 30 Å gate oxides and ion implanted polysilicon gate electrodes were fabricated and characterized after annealing by SIMS, SEM, TEM, and C-V rpeasurements. For arsenic implanted structures, no dopant diffusion through a gate oxide of 30 Å thickness and an annealing condition as high as 1 100*C/1Os was observed. For boron implanted structures, as indicated by SIMS depth profiling, structures annealed at 1000*C/10s exhibit a so-called critical condition for boron diffusion through a 30 Å gate oxide. Boron dopant penetration is clearly observed for 60 Å gate oxides at an annealing condition of 1050 0C/10s. The flatband voltage shift can be as high as 0.56 volts as indicated by C-V measurements for boron penetrated gate oxides. However, 100 Å gate oxides are good diffusion barriers for boron at an annealing condition of 1100°C/10s. For BF2 implanted structures, the diffusion behavior is consistent with behavior reported in the literature.
Enhanced Boron Diffusion in Silicon with BF2-Implanted CoSi2 AS Diffusion Source and Under Rapid Thermal Annealing
Authors: Lin J. , Chen W. , Sultan A. , Banerjee S. , Lee J. 
Published: March 2011

ABSTRACTIn this paper, B diffusion in Si with BF2-implanted CoSi2 as a diffusion source has been studied using SIMS analysis. The concentration-dependent diffusivity of B in single crystal Si is obtained by Boltzmann-Matano analysis. The data show that the B diffusivity in single crystal Si is more than one order of magnitude higher than the published data where a conventional B diffusion source (BN or B2H2) is used. Anomalous concentration dependence of the B diffusivity in Si for ultra-shallow B SIMS profiles was also observed. Possible physical mechanisms which involve implant damage in the Si substrate, the generation of point defects such as Si vacancies and interstitials during silicide formation, and B-defect interactions are discussed.
Using CoSi2 /Polysilicon Polycide Structure as a Gate Diffusion Source in Rapid Thermal Processing
Authors: Chen W. , Lin J. , Banerjee S. , Lee J. 
Published: March 2011

ABSTRACTIon implanted CoSi2 as a gate doping source has been studied as a compatible process to the Silicide-As Diffusion-Source (SADS) process which has been widely considered for shallow source/drain junction formation. The effects of the polysilicon gate microstructure on diffusion behavior and the thermal stability of CoSi2 has been investigated. It has been found that CoSi2 formed on reoxidized polysilicon gates has poor thermal stability but requires short time to achieve degenerate doping near the polysilicon/gate oxide interface. On the other hand, CoSi2 formed on as-deposited amorphous silicon has excellent thermal stability but requires longer time to achieve degenerate doping near the polysilicon/gate oxide interface. The trade-off between the required thermal budget to achieve degenerate doping and thermal stability of the CoSi2/polysilicon gate structure will be discussed. In optimizing the process, our results indicated that reoxidized amorphous Si gates have both good thermal stability as well requiring short time to achieve degenerate doping. The thermal degradation of CoSi2 was found to have little effect on the gate oxide breakdown voltage.
Semi-Empirical Model for Boron Diffusion During Rapid Thermal Annealing of BF2 Implanted Silicon
Authors: Huang Tzu-Hsin , Kinoshita H. , Kwong D. L. 
Published: March 2011

ABSTRACTThe mechanism of the enhanced diffusion of boron during rapid thermal annealing (RTA) of BF2-implanted Si has been investigated, and a diffusion model is accordingly developed for a wide range of implant and annealing conditions. Simulation results are in excellent agreement with experiments for BF2 implant doses from 2×1013 to 5×1015cm−2, implant energies from 6 to 45 keV, and annealing temperatures from 950 to 1100°C. This model not only accounts for the transient enhanced diffusion due to the annealing of point-defect clusters and dislocation loops, but also for the retarded diffusion due to dopant precipitation. All the parameters used in this model are analytically determined.
Nitrogen-Atom Bonding at Sio2/SI Interfaces in Metalinsulator-Semiconductor (MIS) Stacked Gates Made by Integration of Plasma Assisted Oxidation-Deposition and Rapid Thermal Processing
Authors: Ma Y. , YAsuda T. , Lucovsky G. 
Published: March 2011

ABSTRACTSiO2 thin films were deposited by remote PECVD on Si surfaces exposed to species generated in O2/N2 and O2/NH3 plasmas. The surface chemistry was studied by Auger Electron Spectroscopy, AES, and the electrical properties of the SiO2/Si interface by high frequency and quasi-static Capacitance-Voltage, C-V, measurements. The AES results showed that Ccontamination was removed by exposure to both plasma-excited gas mixtures, but that N-atoms were incorporated into the SiO2 film, and Si-N bonds were formed at the SiO2/Si interface. C-V measurements indicated that the Si-N bonding structure, rather than the N-atom concentration, is critical in determining the interface electrical properties. The effects of Rapid Thermal Annealing, RTA, on the electrical properties of these SiO2/Si interfaces were also studied.
Substrate Doping and Orientation Effects on Dielectric Growth on Siucon in a Nitrous Oxide Environment
Authors: Harrison H.B. , Dimitrijev S. , Sweatman D. , Misiura A. , Reeves G.K. 
Published: March 2011

ABSTRACTIn this paper both the substrate doping concentration and single crystal silicon orientation are considered when dielectrics are grown on silicon in a nitrous oxide environment. Our initial preliminary findings show that for heavily doped subtrates thicker layers of dielectric result compared to their lower doped counterparts. Furthermore we find a crossover point of temperature for growth rate for <111> compared to <100>. We believe that the different growth rates are attributable to nitrogen build up at the dielectric interface.
Formation of TiSi2 During Rapid Thermal Annealing: In Situ Resistance Measurements at Heating Rates From 1°C/S to 100°C/S.
Authors: Ganapathiraman Ramanath , Koh S. , Ma Z. , Allen L. H. , Lee S. 
Published: March 2011

ABSTRACTIn VLSI technology, there is interest in monitoring the sequence of phase formation of TiSi2 (c-Ti ⇒ a-TiSi ⇒ C49 TiSi2 ⇒ C54 TiSi2), with the prospect of reducing the temperature of formation of the stable C54 TiSi2 phase. In this study, phase formation characteristics of TiSi2 during rapid thermal annealing(RTA) of Ti-Si bilayers are investigated by means of in situ four point probe resistance measurements. Ex situ X-ray diffraction(XRD) was used for phase identification and characterization. Results indicate that the same multi-step sequence of transformations precede the formation of the C54 TiSi2 phase for heating rates from 1°C/s to 100°C/s. Also, all intermediate and metastable phases which occur at l°C/s also occur at 100°C/s. Temperature dependence and kinetics of the C49 TiSi2 and the C54 TiSi2 phase formation were studied over a wide range of heating rates. Activation energies estimated for the two processes were ∼2eV and ∼5eV respectively. Finally, a new Electrical Thermal Annealing(ETA) technique for heating at rates up to 30000°C/s is introduced. Preliminary in situ resistivity measurement results of TiSi2 formation at these high heating rates are also presented.
Rapid Titanium Silicidation: A Comparative Study of two Rta Reactors
Authors: Bariatro M. , Fontes A. , Quacchia J. Q. , Furlan R. , Santiago-Aviles J. J. 
Published: March 2011

ABSTRACTIn this work we studied titanium silicide formation by cosputtering onto silicon dioxide. Samples deposited with various (Si/Ti) atomic ratios were analyzed by Rutherford Backscattering Spectrometry (RBS). Isocronal annealings were conducted by means of Rapid Thermal Processing (RTP) in two types of furnaces: a vacuum and an atmospheric pressure (argon). Phase formation was monitored by resistivity measurements, X-Ray diffraction (XRD), and Scanning Electron Microscopy (SEM). It is observed that the final phase formation follows the thennodynamic equilibrium diagram, determined by stoichiometry, occurring at 800°C for the vacuum furnace, and at 900°C for the atmospheric RTP furnace. Sequential thermal treatments indicated the formation of TiSi2-C49 and/or TiSi after 400°C.
X-Ray Absorption Studies of Ti/Polymer and Cr/Polymer Interfaces
Authors: Opila R. L. , Konstadinidis K. , Ibidunni A. O. , Davenport A. J. , Isaacs H. S. 
Published: March 2011

AbstractThe interface formed between metals, Ti and Cr, and polymers, epoxy and triazine, have been studied, nondestructively, using x-ray absorption spectroscopy. The metals were sputtered onto the polymer surfaces. Titanium reacts extensively, up to Ti thicknesses of 100 Å while Cr remains primarily metallic. In situ heating at 200°C increases the extent of reaction for both metals. Heating has a greater effect on metal/epoxy interfaces than metal/triazine. Titanium and Cr were ion implanted into the polymer in order to determine the interactions of isolated metal atoms with the polymer. Titanium and Cr appear to form oxides as the final reaction product, and the Ti is tetrahedrally coordinated.
In Situ Kinetics and Thermodynamics of Polymer Adsorption on Chemically Modified Silica
Authors: Zazzera Lawrence A. , Tirrell Matt , Evans John F. 
Published: March 2011

AbstractIn situ Fourier transform infrared (FT-IR) spectroscopy in an attenuated total reflection mode has been employed to examine the chemical modification of ozone-cleaned, native oxide on single crystal Si(100). This planar model for silica is subjected to solution modification using silane reagents which impart variable polarity to the modified surface through different termini of the modifier. These chemical modifications are followed in real time using FT-IR as a diagnostic of surface preparation; either by examining the appearance of a band for an IR chromophore of the modifier which is attached, or by monitoring the loss of the surface silanol groups consumed in the reaction. Following modification, polymer solutions (acrylates, siloxanes) are introduced into the cell and the dynamics of the adsorption followed by a chromophore of the polymer. Not only can the total amount of bound polymer be determined, but also in cases of strong interactions between the polymer and surface modified (e.g. OH... O=C) the bound fraction can be determined. Correlations between surface polarity and these experimentally determined quantities give insight in to the configuration(s) of the adsorbed polymers.
Solvent Induced Morphological Changes to Polycarbonate
Authors: Briscoe B. J. , Stuart B. H. , Thomas P. S. 
Published: March 2011

AbstractThe interface shear properties of thin bisphenol-A-poly(carbonate) films are measured and interpreted in terms of the effects of the morphology induced by solvent plasticisation. The variations in the interface rheology are discussed in terms of the Eyring stress modified thermally activated flow model. The changes in the molecular architecture, induced by plasticisation, are also examined using vibrational spectroscopy. A correlation is made between the proposed mechanism for microshear and the conveyed morphological properties of the polymer film at the molecular level.
Thickness Measurements and Optical Characterization of Thin Polymer Films
Authors: Wall J. F. , Brumfield J. C. , Murray R. W. , Irene E. A. 
Published: March 2011

AbstractPolyphenylene oxide (PPO) films have been investigated as protective coatings and as selective inhibitors to permeants.1,2,3 These films have been shown to be passivating materials and therefore are potentially interesting for a variety of applications. It is important for further applications to be able to measure the thickness of thin films by nondestructive techniques, which is the subject of this report. In this study PPO films of various thicknesses were electrodeposited on highly oriented pyrolytic graphite (HOPG) electrodes and examined by spectroscopic ellipsometry (SE) and atomic force microscopy (AFM). These techniques are combined to yield the thickness of the polymer film and the optical properties of the HOPG substrate and the PPO overlayer in the visible and near ultraviolet spectral region.
Characterization of the Interphase in Model Associative Polymer/Titanium Dioxide and Polystyrene Latex Systems
Authors: Heck Connie S. , Roberts J. E. 
Published: March 2011

AbstractThe adsorption behavior of model associative polymers in aqueous titanium dioxide (TiO2) and polystyrene latex (PS) particle dispersions has been studied using liquid-state Nuclear Magnetic Resonance (NMR) and a modified serum replacement technique (SRT). The structure of the associative polymer is a linear, water soluble, A-B-A block copolymer with a polyethylene oxide backbone and hydroxyl (H) or hexadecyl (C16H33) endgroups.Absolute intensity NMR measurements allow the determination of the adsorbed polymer configuration at the solid-solution interface and adsorption isotherms for comparison to the SRT results. Both the SRT and NMR results demonstrate that the adsorption/desorption of the C16 and H polymers is strongly affected by the substrate. For the polymer/PS particle systems, there is good agreement in complete surface saturation values for the SRT and NMR methods. In the polymer/TiO2 systems, the H polymer plateau as determined by NMR differs slightly from that determined by SRT. For the C16/TiO2 system the interpretation is less straightforward. Either the NMR saturation value is at least double that of the SRT value or the C16 and H polymers have very similar isotherms by NMR. This would suggest that on TiO2 the effect of the hydrophobe is minimal. For all the polymers the polymer/particle interaction on PS is strong and desorption is difficult while on TiO2 it is weak and completely reversible. A pancake-to-brush conformation change on the PS surface is evident for the C16 polymers and probably for the H polymer as well. The H polymer seems to form a multi-layered structure on PS from the NMR and laser light scattering results. The contribution of the hydrophobe and the effect of increasing the backbone molecular weight are clearly illustrated.
Interfacial Water Transport and Embrittlement in Polymer-Matrix Composites
Authors: Lekatou A. , Qian Y. , Faidi S. E. , Lyon S. B. , Islam N. , Newman R. C. 
Published: March 2011

AbstractDisordered glass microsphere-epoxy composites have been used in a study of diffusional, electrical and mechanical effects of interfaces in polymer-matrix composites exposed to pure water. Mass gain measurements on composites manufactured from 10 μm silane-treated microspheres indicate initial near-Fickian diffusion with water saturation times on the order of 500 h. However, electrical measurements indicate water transport at rates at least 100 times more rapid. This behaviour is interpreted in terms of a cellular microstructure with areas of low cross-link density separating highly cross-linked areas. Rapid water transport can thus occur in areas of low cross-linking, even without the contribution of connected clusters of particles where rapid interfacial water transport occurs substantially ahead of the main diffusion front. Reductions in ultimate tensile strength and fracture energy in dry and water-saturated tensile test specimens are observed with increasing volume fraction of glass spheres but with a distinct plateau between about 6% and 12% Vf. This can be explained in terms of secondary cracking below the percolation threshold which causes toughening of the composite. However, a few % above pc (≍ 16%), most particles belong to the percolating cluster and the primary crack can grow without hindrance.
Plasma Polymerization of Allylamine onto Pan-Based Carbon Fibers
Authors: Smiley R. J. , Delgass W. N. 
Published: March 2011

AbstractThe plasma polymerization of allylamine onto PAN-based carbon fibers has been investigated by XPS and SEM. Fiber surfaces were cleaned and oxidized by treating in an O2 plasma for 5 minutes. XPS characterization of pretreated samples showed surfaces functionalized with COH, C=O, and COOH species. Fibers were coated with poly(allylamine) by introducing a monomer-saturated stream of Ar gas into the plasma chamber and reacting for 2–30 minutes. Some samples were further treated in an O2 plasma to determine the stability of the polymer coating. N(1s) spectra from the fiber surfaces showed two nitrogen peaks at 399.9 eV and 400.7 eV, which may be assigned to amine and amide groups, respectively. C(1s) spectra showed a decrease with treatment in the amine carbon peak at 287.2 eV and a corresponding increase in the peak at 288.7 eV, assigned to carboxyl and/or amide carbon. The increase in higher binding energy carbon corresponded with an increase in the 400.7 eV N(1s) peak and gave evidence for the conversion of amines to amides. Total O(1s) intensity initially decreased following 2 minutes of allylamine treatment but increased with further treatment. In addition to the carbon fiber samples, a silica wafer was coated and analyzed by XPS. Quantitative XPS results revealed that all the nitrogen present on the surface was in the form of amine and not amide species. Oxygen in the form of carboxyl species was also present on coated silica surfaces. Most likely, oxygen dissolved in the allylamine monomer was carried into the plasma chamber by the Ar gas. Comparing the silica wafer with the fiber samples revealed treatments were strongly sample dependent. Even after only 2 minutes of treatment, fiber samples showed the presence of amide and substituted amide species. SEM revealed coatings filled in the fiber grooves and left clumps of material on the surface. Micrographs of fibers treated for longer times revealed surfaces covered with particles < 0.25 μm in diameter. Finally, the XPS N(1s)/C(1s) and O(1s)/C(1s) intensity ratios indicated that some polymer remained on the fiber surface even after 15 minute post O2 plasma treatment. These experiments illustrate that plasma polymerization can be effective for functionalizing carbon fiber surfaces, but that optimization of conditions is necessary to improve wetting and control amine/amide functionality.
Electro-Active Polymer-Ceramic Composites for Piezoelectric and Pyroelectric Applications
Authors: Dias C. , Das-Gupta D. K. 
Published: March 2011

AbstractPresent work reports the results of a study of characterization of dielectric, piezoelectric and pyroelectric properties of calcium modified lead titanate ceramic/poly (vinylidene-trifluorethylene) composites with zero-three connectivity. The paper also presents a theoretical model to optimize such properties with respect to particle size, dielectric constant and composition.
Ultimate Properties of Polymer Chains
Authors: Adams W. Wade , Pachter Ruth , Haaland Peter D. , Horn Thomas R. , Wierschke Scott G. , Crane Robert L. 
Published: March 2011

AbstractNew polymers with exceptional properties are needed for applications in high-performance structures, novel electrical, optical and electro-optical devices, and for multi-functional smart materials. Concurrently, new computational capabilities and methods for properties prediction and analysis have enabled the study of a variety of polymer chain architectures to examine the principles that govern their high-performance properties. By semi-empirical and ab initio computational methods, flexible, stiff-chain, rigid-rod, and biological structures could be analyzed. Single chain molecular stress-strain curves for axial tension and compression were calculated, and the strain dependence of the molecular modulus and vibrational frequencies were compared to measurements of molecular deformation, such as IR and Raman spectroscopy. However, of special interest is the distinctly different response of alpha-helical biopolymer chains to strain. Indeed, in this study we compare on a theoretical basis the ‘spring-like’ microscopic mechanical response of alpha-helical biopolymers having a reinforcing intra-molecular hydrogen bonding network to analogous synthetic extended chain polymers, especially poly(para-phenylene terephthalamide) (PPTA) [KEVLARTM]. The theoretical verification of the absence of compressive buckling in alpha-helical biopolymer chains rationalizes the molecular elasticity and resistance to ‘kinking’ of those strands, manifested by the prevalence in Nature for coiled coils. The understanding of the structure-tofunction relationship in biopolymers explaining the role of the alpha-helix in these systems as a requirement for superior compressive mechanical properties, may enable new guidance for the synthesis of motifs consistent with molecular frameworks optimized by Nature.
Characterization Of Capillary-Optic Materials For Use In X-Ray Lithography
Authors: Dozier C. M. , Bell M. I. , Newman D. A. , Freitag R. K. , Brown D. B. , Rosenstock H. B. 
Published: March 2011

AbstractCapillary optics appear to permit the fabrication of practical collimator systems for laserdriven x-ray point sources. With such collimators, the illumination of wafers can meet the tight requirements for lithographic patterning of sub-micron device structures. However, the use of x-radiation with photon energies between 800–1200 eV makes capillaries of conventional silica-based glass capillaries marginal due to their low reflectivity. The reflectivity of various materials were examined with the goal of finding alternate glasses, elements for doping glasses or surface coatings that may enhance these collimators for lithographic applications. Coating capillary surfaces with more reflective materials may be the most viable method for improving the radiation transport properties for capillary optics to be used in x-ray lithography.
Mask Technology For X-Ray Nanolithography
Authors: Schattenburg M. L. , Carter J. , Chu W. , Fleming R. C. , Ghanbari R. A. , Mondol M. , Polce N. , Smith Henry I. 
Published: March 2011

AbstractIn this report we describe a system of technologies we have developed for fabricating, patterning, and replicating x-ray masks with linewidths as fine as 50 nm (0.05 μm). This effort has evolved into a fairly routine service supporting a growing community of researchers at MIT interested in fabricating sub-micron and nanometer scale structures and devices. Strong, transparent, silicon-rich nitride (SiN) membranes bonded to optically-flat Pyrex rings and patterned with gold absorbers form the basic x-ray mask structure. We have recently completed the installation of a vertical thermal reactor (VTR) for the deposition of SiN coatings. Results indicate superb film uniformity, decreased defect counts, and increased strength over previously available nitrides. Patterning of the masks is performed at an off-site location by electron-beam lithography followed by development and gold electroplating at MIT. We describe a new fountain plating bath and mask chuck which allows us to obtain clean, uniform gold films of low stress. Once completed, the so-called “master” masks are replicated onto new x-ray mask substrates which are then processed into “daughter” masks. The resulting polarity-reversed patterns are required in order to achieve the desired pattern in positive resist when printed onto substrates. We will describe our in-house built x-ray aligner which features a high-power electron bombardment source and SiN vacuum isolation window to achieve exposures in a helium environment.