bluuebunny/crossref_metadata_2025_split huggingface dataset:
An in Situ Electron Microscopy Technique for the Study of Thermally Activated Reactions in Multilayered Materials
Authors: Wall M.A. , Barbee T.W. , Weihs T.P. 
Published: April 2011

ABSTRACTA novel in situ transmission electron microscopy technique for the observation of reaction processes in multilayered materials is reported. The technique involves constantheating rate experiments of multilayered materials in image and diffraction modes. Because the fine scale microstructure of multilayered materials is typically a small fraction of the TEM specimen thickness, realistic comparison of the microstructural evolution with that of similarly processed thick foil samples is possible. Such experiments, when well designed, can provide rapid characterization of phase transformations and stability of nano-structured materials. The results of these experiments can be recorded in both video and micrograph format. The results and limitations of this technique will be shown for the Al/Zr and A1/Monel multilayered systems.
Structural Studies of Sputtered Ni80Co20/Cu Multilayers
Authors: Bian X. , Altounian Z. , Ström-Olsen J. O. , Sutton M. , Cochrane R. W. 
Published: April 2011

ABSTRACTThe structure of magnetron-sputtered Ni80Co20/Cu multilayershas been investigated by low and high-angle X-ray diffractometry. Low-angle x-ray reflectivity data reveal well-defined compositional modulation along the film growth direction for a wide Cii thickness range of 5-40 Å. The data analysis, based on anl optical model, shows that interfacial mixing is limited to ∼3-4 Å As the number of bilayers increased from 8 to 100, the interface roughness increased by a factor of 3. Better layered structures were found for relatively thick Cu layers (tCu>10Å). The high-angle diffraction data were analyzed using a trapezoidal model. The results indicate that the films have a polycrystalline structure with a preferred (111)orientation with coherent interfaces of ∼ 100-240 Ådepending on the Cu layer thickness. The relatively large expansion of (111) spacings in NiCo alloy layers gives rise to the lower atomic ordering in NiCo/Cu multilayers.
Superconducting Multilayers: Microstructural Properties Studied by X-Ray Diffraction
Authors: Vailionis A. , Brazdeikis A. , FlodstrÖm A.S. 
Published: April 2011

ABSTRACTStructural properties of molecular beam epitaxy-grown Bi2Sr2Cu1Oy'Bi2Sr2Ca1Cu2Oy multilayers have been studied by x-ray diffraction. A one-dimensional kinematic x-ray diffraction model has been used to describe the structural quality of the multilayers. Interface roughness, stacking defects and unit cell disorder are obtained by an iterative fitting of the calculated diffraction profile to the experimental spectra. The type and amount of disorder in the films was qualitatively determined. Results demonstrate that structural imperfections are present in the multilayers and have to be considered when transport properties are studied.
Metal/Al2O3 Multilayers As High-Temperature X-Ray Mirrors
Authors: Morawe CH. , Zabel H. 
Published: April 2011

ABSTRACTBy if-sputtering we have prepared high-quality metal/Al2O3 (metal: Co, Pt, W) artificial multilayers on sapphire (1120) substrates. We obtain interface roughnesses of about 0.2 nm and x-ray reflectivities of nearly 100 % at the first satellite reflection using Cu Kα radiation. The multilayer structures remain stable up to 700°C – 900°C without appreciable loss in reflectivity. Annealing causes structural changes depending on the chosen metal. Pt/Al2O3 forms a coherent superlattice structure whereas Co and W exhibit a gradual internal oxidation at the metal/Al2O3 interface. Beyond 900°C all systems are destroyed.
Compositional Characterization of Very Thin SiO2/Si3N4/SiO2 Stacked Films by XPS Using The “Auger Parameter Method”
Authors: Santucci S. , Lozzi L. , Passacantando M. , Picozzi P. , Alfonsetti R. , Fama F. , Moccia G. 
Published: April 2011

ABSTRACTONO (SiO2/Si3N4/SiO2) structures with thickness less than 10 nm were deposited onto silicon wafers by successive steps using two different method. The effects of the forming time and temperature on the stoichiometry of the single layers and of the whole sandwich have been studied using X-ray Photoelectron Spectroscopy (XPS). This paper demonstrates that the “Auger parameter method” is highly suitable in quantifying the composition of very thin insulating structures.
Microstructural Characterization of Al-.5Cu AND Al-1Si ON 0.6nm TCA-SiO2/Si Following Heat Treatment at 400°C in N2 - Mechanisms Providing Stability and A High Break Down Voltage for The Al-.5Cu Mos Device
Authors: Mccarthy Jack M. 
Published: April 2011

ABSTRACTAl-.5Cu is used as an interconnect conductor in ultra large scale integration (ULSI) devices. The specific use investigated in this study is as a gate electrode deposited directly on extremely thin 6 nm TCA SiO2. Changes in microstructure and reactions between the AI-.5Cu and SiO2 following heat treatment were characterized using analytical electron microscopy. When Al-iSi or AI-.5Cu are used as gate electrodes in a metal oxide Si field effect transistor (MOSFET) a conducting diffusion barrier layer of TiN or heavily doped poly-Si is usually deposited between the AI alloy and the SiO2. The addition of this relatively high resistivity barrier layer increases the power consumption of a MOSFET constructed with this gate electrode, increases the operating voltage necessary and decreases the frequency at which the MOSFET can be switched.1 An Al-.5Cu metal oxide silicon (MOS) device maintained a high break down voltage without a diffusion barrier following heat treatment by forming an Al-Cu intermetallic at the silica/metal interface.
Solid State Reactions in the ZR-AL-CU-NI Bulk Metallic Glass Forming Alloy System
Authors: Busch Ralf , Bakke Eric , Johnson William L. 
Published: April 2011

ABSTRACTDiffusion couples combining a h.c.p. Zr90Al10 supersaturated solid solution with a fc.c. Cu64Ni36 solid solution were annealed at 410°C for different times. The reaction at the interface was investigated by transmission electron microscopy (TEM) and energy dispersive x-ray spectroscopy (EDAX). Cross sectional TEM images and electron diffraction patterns reveal the formation of a non-crystalline layer at the interface between the two solid solutions which grows to a maximum thickness of more than 0.3 μm. Using EDAX, the concentration profiles across the layerswere determined. The glassy layer consists of a Zr-Ni-Al alloy with a small amount of Cu.The concentration profiles reveal that two non-crystalline phases coexist in the diffusion couple. One phase is Ni-rich and the other is Zr-rich. A small gradient of the Ni concentration in the Ni-rich amorphous phase and a steeper gradient in the Zr-rich non crystalline phase indicate that the Ni diffusion constant in the Ni-rich phase is larger than the Ni diffusion constant in the Zr-rich phase. In the late stage of the reaction, the growth of a nanocrystalline layer with an average concentration of Cu 90Nij 0 is observed on the Cu-Ni side of the diffusion couple. Crystallization starts at the Zr-Al side of the diffusion couple.
Measuring the Adhesion of Diamond Thin Films to Substrates Using the Blister Test
Authors: Sizemore Jim , Hohlfelder R. J. , Vlassak J. J. , Nix W. D. 
Published: April 2011

ABSTRACTIt is shown that the blister testing technique can be used to measure the adhesion of thin films to their substrates. A brief discussion of blister test mechanics is presented here, leading to a simple equation relating adhesion to the height of the blister and the pressure causing it to grow. Blister test data for plasma-enhanced CVD diamond films on Si substrates have been analyzed using this relation. The tests show adhesion energies of 1.8– 2.6 J/m2.
The Pressure-temperature Phase and Reaction Diagram for Carbon
Authors: Bundy Francis P. 
Published: April 2011

ABSTRACTCarbon atoms form very strong bonds to each other, yielding materials like: (i) crystalline graphite, diamond and their many “amorphous” hybrids; (ii) crystalline forms of giant closed–surface molecules such as the fullerenes; and (iii) liquid and gas phases which have molecular contents which are complicated and not yet defined or understood. Because of the high bonding energy the melting and vaporization temperatures of the solid forms are very high, and the activation energies required to transform one solid form to another are large. One consequence is that at lower temperatures the different solid phases may continue to exist metastably far into aP, Tregion in which another solid phase is the thermodynamically stable one.In the thermodynamic sense the vapor pressure line of graphite, the graphite/liquid/vapor triple point, the graphite melting line, the graphite/diamond equilibrium line, and the graphite/diamond/liquid triple point are quite well established. Data for the melting temperature of diamond vs. pressure are sparse and rough, but they indicate that the melting temperature increases with pressure,-in agreement with some theories. Although carbon should transform to a solid metallic state at very high pressures, experimental evidence shows diamond to be stable to over 400GPa, and theoretical calculations indicate that it could be the stable form up to pressures of 1200 to 2300GPa. Attention is given to the solid state transformations which can take place when graphite is compressed and heated along differentP, Tpaths under different conditions.
Adhesion of Polymers to Synthetic Diamond Films
Authors: Stromberg Earl W. , Drory Michael D. 
Published: April 2011

ABSTRACTA preliminary study of the adhesion of polymers to diamond substrates was conducted by examining the wetting characteristics of coupling agents to diamond. The contact angle between several commercial liquid coupling agents and a CVD diamond surface was measured. A silane, Z-6026, was found to wet the diamond surface. Several other coupling agents, including a titanate and an organometallic blend, wet the diamond surface significantly better than most of the other materials in this survey. It was found that water did not wet the diamond.
Molecular Dynamics Simulation of Mechanical Deformation of Ultra-Thin Amorphous Carbon Films
Authors: Glosli J. N. , Philpott M. R. , Belak J. 
Published: April 2011

ABSTRACTAmorphous carbon films approximately 20nm thick are used throughout the computer industry as protective coatings on magnetic storage disks. The structure and function of this family of materials at the atomic level is poorly understood. Recently, we simulated the growth of a:C and a:CH films 1 to 5 nm thick using Brenner's bond-order potential model with added torsional energy terms. The microstructure shows a propensity towards graphitic structures at low deposition energy (<1eV) and towards higher density and diamond-like structures at higher deposition energy (>20eV). In this paper we present simulations of the evolution of this microstructure for the dense 20eV films during a simulated indentation by a hard diamond tip. We also simulate sliding the tip across the surface to study dynamical processes like friction, energy transport and microstructure evolution during sliding.
Nanoindentation and Nanoscratching of Hard Carbon Coatings for Magnetic Disks
Authors: Tsui T. Y. , Pharr G. M. , Oliver W. C. , Bhatia C. S. , White R. L. , Anders S. , Anders A. , Brown I. G. 
Published: April 2011

ABSTRACTNanoindentation and nanoscratching experiments have been performed to assess the mechanical properties of several carbon thin films with potential application as wear resistant coatings for magnetic disks. These include three hydrogenated-carbon films prepared by sputter deposition in a H2/Ar gas mixture (hydrogen contents of 20, 34, and 40 atomic %) and a pure carbon film prepared by cathodic-arc plasma techniques. Each film was deposited on a silicon substrate to thickness of about 300 nm. The hardness and elastic modulus were measured using nanoindentation methods, and ultra-low load scratch tests were used to assess the scratch resistance of the films and measure friction coefficients. The results show that the hardness, elastic modulus, and scratch resistance of the 20% and 34% hydrogenated films are significantly greater than the 40% film, thereby showing that there is a limit to the amount of hydrogen producing beneficial effects. The cathodic-arc film, with a hardness of greater than 59 GPa, is considerably harder than any of the hydrogenated films and has a superior scratch resistance.
Monte Carlo Simulation of Optical Temperature Sensors in RTP Systems
Authors: Cole J. Vernon , Knutson Karson L. , Fiory Anthony T. , Jensen Klavs F. 
Published: April 2011

AbstractWe present simulation and experimental results for determining the distribution of radiation throughout an RTP system and evaluating the design of optical temperature sensors. The simulations are performed with a general purpose, three dimensional Monte Carlo method. The simulation models internal reflection, absorption, and transmission within participating media explicitly, and includes wavelength, temperature, and material dependent properties. Simulation results are compared to measurements of the lamp intensity profile within the lamphouse and at possible sensor locations. Simulations are used to examine the effect of several optical probe designs. The predicted responses of potential sensor designs resulting from these studies are presented.
Characteristics of Dielectrics Formed or Annealed in a Nitric Oxide Ambient
Authors: Harrison H. B. , Yao Z. -Q , Dimitrijev S. , Sweatman D. , Yeow Y. -T. 
Published: April 2011

AbstractThe resultant physical and electrical characteristics of dielectric layers grown or annealed in nitric oxide are presented. The layers formed or modified in nitric oxide are thinner but generally superior in quality to those grown in nitrous or dry oxide. The indications are that dielectrics formed or annealed in nitric oxide are a viable alternative to other techniques of producing ultra thin (≤ 5nm) dielectrics.
Rapid Thermal Oxidation of Heavily Doped Silicon for Advanced Solar Cell Processing
Authors: Sivoththaman S. , Laureys W. , Nijs J. , Mertens R. 
Published: April 2011

AbstractCrucial steps in solar cell processing such as emitter diffusion and surface oxide passivation have been carried out by rapid thermal processing (RTP). Rapid thermal diffusion (RTD) of boron into silicon from APCVD borosilicates has been studied. Rapid thermal oxidation (RTO) of the heavily B-doped surfaces of these shallow junctions (0.2 μm) has been studied in view of applicability of this technique in solar cell processing. These shallow diffusions have excellent lateral uniformity over large areas and have high surface concentrations depending on the APCVD deposition conditions and on RTP conditions. The surface passivating oxides resulting from the RTO are exceptionally thick in case of heavy boron diffused surfaces. RTO does not cause considerable drive-in of the diffused junction profiles. In the contrary, the thick RTO oxides considerably reduce the surface concentration, thereby reducing the heavy doping effects in the junctions, making them more suitable emitters for devices such as solar cells. p+nn+ solar cells have been fabricated on n-type CZ silicon wafers by RTD of boron followed by RTO. The cells result in conversion efficiencies as high as 16.2% The passivation effect of RTO oxides have been investigated by analysing RTO MOS capacitors and are compared to conventional furnace oxides.
Characterizations of Ultra-thin Dielectrics Grown by Microwave Afterglow O2/N2O Plasma Oxidation at Low Temperature with Rapid Thermal Annealing
Authors: Chen Po-ching , Hsu Klaus Yung-jane , Loferski Joseph J. , Hwang Huey-liang 
Published: April 2011

AbstractMicrowave afterglow plasma oxidation at a low temperature (600 °C ) and rapid thermal annealing (RTA) were combined to grow high quality ultra-thin dielectrics. This new approach has a low thermal budget. The mid-gap interface state density of oxides pretreated in N2O plasma was decreased to about 5×1010 cm−2eV−1 after rapid thermal annealing at 950 °C.It was found that RTA is very effective for relieving the oxide stress and reducing the interface state density. Nitrogen incorporated in oxides by the N2O plasma pretreatment of the Si surface helped to reduce the interface state density. Microstructures of ultra-thin oxide grown by microwave afterglow oxidation with or without RTA were revealed by extended-X-ray-absorption-finestructure (EXAFS) and X-ray photoelectron spectroscopy (XPS) analysis.
The Necessity of RTCVD in Advanced Epitaxial Growth of Si and SiGe
Authors: Boer W. B. De , Theunissen M. J.J. , Linden R. H. J. Van Der 
Published: April 2011

AbstractDevice-quality epi material can be grown at temperatures ranging from 600 to 800°C in commercially available production reactors. The exceptionally steep transitions of Ge, B and, to a lesser extent, P, are characteristics of Si and strained SiGe epi growth from dichlorosilane and germane in hydrogen ambient at atmospheric or reduced pressure. Although the growth rates depend on the dopant gas flows at low temperatures, layer thickness and doping level control is excellent. Selective multilayer growth at reduced pressure seems a viable process and can be applied in e.g. HBT's.In spite of the fact that a lot of the progress in low-temperature epitaxy has been made in lampheated reactors, it is argued that RTP is not needed for low-temperature epitaxy. This is in contrast to conventional (high-temperature) epitaxy where RTP is becoming indispensable. Real RTP, heating and cooling the wafer in just a couple of seconds, would improve the throughput of the present generation single wafer epi reactors tremendously and seems feasible.
Rapid Thermal Processing-Based Heteroepitaxy: Material and Device Challenges
Authors: Hoyt J. L. , Kuo P. , Rim K. , Welser J. J. , Emerson R. M. , Gibbons J. F. 
Published: April 2011

AbstractMaterial and device challenges for Rapid Thermal Processing (RTP) of heterostructures are discussed, focusing on RTP-based epitaxy in the Si/Si1−xGex system. While RTP-based heteroepitaxy offers enhanced processing flexibility, it also poses significant challenges for temperature measurement and control. Several examples of Si/Si1−xGex device structures are discussed from the point of view of the sensitivity of device parameters to variations in layer thickness and composition. The measured growth kinetics for Si and Si1−xGex are then used to estimate growth temperature tolerances for these structures. Demanding applications are expected to require temperature control and uniformity to within 0.5°C.Future research challenges include the fabrication of structures with monolayer thickness control using self-limited growth techniques. Atomic layer epitaxy (ALE) is a well-known example of such a growth technique. In ALE, the wafer is cyclically exposed to different reactants, to achieve layer-by-layer growth. An RTP-based atomic layer epitaxy process, and its application to the growth of CdTe films, is briefly discussed. The extension to Column IV alloys follows readily. The RTP-based process enables self-limited growth for precursor combinations for which isothermal ALE is not feasible.
Structural and Electrical Characterization of FeSix – Layers (1≤ X ≤2) Prepared by RTP of Fe Layers Sputtered on Si (100)
Authors: Líbezný M. , Poortmans J. , Amesz P. H. , Donaton R. A. , Larsen K. Kyllesbech , Vandenabeele P. , Jonckx F. , Maex K. , Nijs J. 
Published: April 2011

Abstractβ-FeSi2 is a semiconductor with a potential for photovoltaic and optoelectronic applications. The preparation of β-FeSi2-layers by rapid thermal processing (RTP) of Fe layers on silicon is investigated in this paper. Fe layers with typical thicknesses of 30 nm were sputtered on Si (100) substrates. We correlated the surface morphology of samples subjected to different RTP treatments with their composition and phase content. Phase transformations during the anneal were also studied by in-situ emissivity measurements. Rectifying and contacting behaviour of silicide/silicon heterojunctions prepared at several RTP-temperatures is presented at the end of this paper. Since it is not possible to prepare β-FeSi2-layers without a presence of either FeSi or α-FeSi2 metallic phases, these structures have poor heterojunction characteristics.
Effects and Applications of Multiple-Gas Rta Treatment on Ti-Based Metallization for Future Dram Devices
Authors: Drynan John M. , Koyama Kuniaki 
Published: April 2011

AbstractThe effects of N2, O2, and Ar gas RTA treatments on Ti, TiN, and Ti-polycide film characteristics have been investigated in anticipation of the trend in DRAM development toward lower resistance materials to replace the standard WSi2, WSi2 on doped polycrystalline silicon (W-polycide), and doped polysilicon conductors used in interconnections, transistor gates, and contact-hole plugs, respectively. The reactivities of Ti and TiN in N2 and O2 gases are markedly different. Film characteristics such as sheet resistance, crystallinity, and elemental composition remain unchanged for TiN RTA-treated in N2 but vary significantly for Ti. In the case of Ti, XRD and XPS data indicate the formation of intermediate Ti-rich TiN or Ti2N compounds prior to the final TiN phase. Similarly, RTO-treated TiN shows a slower oxide growth rate compared with that of Ti. In the case of TiN, a surface layer of rutile phase TiO2 is directly formed, whereas for Ti the data suggest the formation of Ti-rich oxides such as Ti2O or TiO prior to the final TiO2 rutile phase. RTA treatment in different ambient gases can be used to create multilayer Ti-polycide and TiN/Ti metallization with self-aligned TiO2 passivation and etch-stop layers. TiN can also be applied with other materials and processes to form new DRAM memory cell capacitor structures.
RTA-Treated Ohmic Contacts To GaAs Containing WSiN Barriers
Authors: Nebauer E. , Merkel U. , Würfl J. , Österle W. 
Published: April 2011

AbstractFor III-V device operation at 300 °C or above ohmic contacts have to consist of multilayered systems comprising an amorphous diffusion barrier. The contact system Au/Pt/Ti/WSiN/ Au/Ge/Ni-n-GaAs (n ≈ 5.1017 cm−3) has been developed and optimized with respect to the parameters of the barrier as well as the internal Au/Ge/Ni layers. The WSiN layer was deposited via reactive dc magnetron sputtering, the other layers by electron beam evaporation without breaking the vacuum. Annealing has been performed in a halogen lamp furnace. The contact resistance Rc as determined by TLM structures was measured as function of the annealing temperature and time. It was found that short-time annealings lead to a broad Rc minimum at 0.1 ωmm. For such Rc's the Au/Ge/Ni layer thicknesses must be ≥ 20/10/6 nm. Extended microstructural analysis was accomplished by XTEM/EDS and by AES and SNMS depth profiling. The typical alloying depth of the contact in the GaAs has been found to be about 50 nm, i.e. smaller than for the conventional Au/Ni/AuGe contact. The secondary phases formed (Au(Ga), NiGe(As)) are similar. With annealing conditions producing the desired Rc value, both Au(Ga) and NiGe(As) were observed in a bamboo-like arrangement at the metal-semiconductor interface. Degradation of Rc could be attributed to burying of the nickel-rich phases beneath gold-rich phases. This contact system is stable up to ≈ 300°C.