bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transmission Electron Microscopy of Semiconductor Based Products
Authors: Mardinly John , Susnitzky David W. 
Published: April 2011

AbstractThe demand for increasingly higher performance semiconductor products has stimulated the semiconductor industry to respond by producing devices with increasingly complex circuitry, more transistors in less space, more layers of metal, dielectric and interconnects, more interfaces, and a manufacturing process with nearly 1,000 steps. As all device features are shrunk in the quest for higher performance, the role of Transmission Electron Microscopy as a characterization tool takes on a continually increasing importance over older, lower-resolution characterization tools, such as SEM. The Ångstrom scale imaging resolution and nanometer scale chemical analysis and diffraction resolution provided by modem TEM's are particularly well suited for solving materials problems encountered during research, development, production engineering, reliability testing, and failure analysis. A critical enabling technology for the application of TEM to semiconductor based products as the feature size shrinks below a quarter micron is advances in specimen preparation. The traditional 1,000Å thick specimen will be unsatisfactory in a growing number of applications. It can be shown using a simple geometrical model, that the thickness of TEM specimens must shrink as the square root of the feature size reduction. Moreover, the center-targeting of these specimens must improve so that the centertargeting error shrinks linearly with the feature size reduction. To meet these challenges, control of the specimen preparation process will require a new generation of polishing and ion milling tools that make use of high resolution imaging to control the ion milling process. In addition, as the TEM specimen thickness shrinks, the thickness of surface amorphization produced must also be reduced. Gallium focused ion beam systems can produce hundreds of Ångstroms of amorphised surface silicon, an amount which can consume an entire thin specimen. This limitation to FIB milling requires a method of removal of amorphised material that leaves no artifact in the remaining material.
Microstructural Changes in W-Polycide Gates Capped with A Thin Polysilicon Layer
Authors: Kima Y. O. , Bevk J. , Furtsch M. , Georgiou G. E. , Mansfield W. , Masaitis R. , Opila R. , Silverman P. J. 
Published: April 2011

AbstractWe find that sheet resistance of tungsten polycide can be reduced up to 40% by depositing thin polysilicon layers on the top of the films. Transmission electron microscopy shows no significant differences in the crystal structure, grain size, or dislocation density inside the films by adding a polysilicon cap, but it clearly shows roughening of the top interface. Auger depth profiling shows substantial reduction of the Si/W ratio in the capped films. Both results imply that the excess Si segregates to both polysilicon interfaces, effectively lowering the Si/W ratio and resulting in a low sheet resistance.
Electron Microscopy on GaAs Based Devices
Authors: Etienne P. , Magis M. , Cassette S. , Delage S. , Galtier P. 
Published: April 2011

AbstractWe present a methodology suitable for SEM and TEM analysis on Heterojunction Bipolar Transistors (HBT) developed for microwave applications. The Focused Ion Beam (FIB) technique has been investigated for SEM observations. It is found that best results are obtained when the active areas are micromachined from the back side and at a low incidence angle. The help of backscattered electron imaging for metallurgical assessment is emphasized on that kind of devices. A combination of both precision dimpling and FIB micromachining is found to be a good solution for the achievement of TEM slabs with an acceptable thickness. Finally we present the design of a dual beam system which uses Ar+ or Ga+ ions for highest TEM slab quality built into a SEM for an accurate localization and monitoring of the milling process. The respective advantages and limitations of this method are stressed in term of precision of localization of device features, surface roughness, contamination and slab thickness. The possibility to apply this technique on 0.1 µm silicon based technology will be discussed.
Microstructure Analysis of Barium Strontium Titanate Thin Film
Authors: Chen Wei , Hooker Joe , Monarch Kathy , Fejes Peter , Chu Peir 
Published: April 2011

AbstractMicrostructures of Barium Strontium Titanate (Ba, Sr)TiO3 [BST] thin film play an important role in determining the electrical properties of BST. In particular, it is found that the grain size distribution as a function of deposition conditions correlates with the dielectric constant of BST film. Traditionally, Transmission Electron Microscopy (TEM) provides an accurate method for determining microstructures such as interface structure between BST and electrodes and BST grain size distribution. However, TEM analysis relies heavily upon successful sample preparation, and film adhesion for BST proves to be a difficult problem to overcome for successful sample preparation. With the state of the art Scanning Electron Microscope (SEM) and Atomic Force Microscopy (AFM), useful information can be obtained for BST and electrode microstructures requiring little or no sample preparation. A good correlation among TEM, SEM and AFM techniques is achieved which allows useful information of BST grain size distribution to he obtained via SEM and AFM analyses. Power spectral density (PSD) analysis of contrast enhanced AFM images proves to be an efficient method for estimating BST grain size distribution.
Reduction of the Damage Induced in an Fib-Fabricated X-Tem Specimen
Authors: Kato N. I. , Tsujimoto K. , Miura N. 
Published: April 2011

AbstractIn focused ion beam (FIB) fabrication of cross-sectional transmission electron microscopy (X-TEM) specimens, highly accelerated ion beams sometimes cause serious damage. The damage can be induced in both the specimen surface and in the side walls. We used X-TEM observations to investigate the side-wall damage induced by FIB fabrication in crystalline silicon. The damaged layer was found to be about 20 nm thick in the case of 30-keV FIB etching. We tried to reduce the damage by several methods, such as gas-assisted etching (GAE) with iodine, broad argon ion milling and wet etching. The damaged layer was 19 nm for GAE and 12 nm for argon ion milling with a beam current of 70 mA and the tilt angle between the beam and the specimen of 15 degrees. Wet etching using a mixture of nitric and hydrofluoric acid removes most of the damaged layer.
Evaluation of Single Semiconductor Defects Using Multiple Microanalysis Techniques
Authors: Kinney P. D. , Uritsky Y. , Principae E. L. , Savoy R. , Mowat I. , McCaig L. 
Published: April 2011

AbstractNew analytical techniques are being employed to meet the stringent requirements for controlling defects in semiconductor manufacturing. While SEM/EDX continues to be an effective tool for root-cause analysis of particles and defects on the wafer surface, increasingly it is necessary to employ multiple techniques in analysis of a single defect to obtain sufficient information to resolve the problem. Until recently, this approach was impractical because the defects were too difficult to locate in standard analytical tools, especially on unpatterned wafers. But with the newly developed Mark-Assisted Defect Analysis (MADA) technique, the positioning problem has been eliminated, and it is a simple matter to employ multiple techniques on the same defect. In this paper we present results for defects analyzed by SEM/EDX, TOFSIMS, μ-ESCA, and AUGER, highlighting how these techniques compliment each other. Particular emphasis is given to the issue of the analytical technique changing the sample chemistry and influencing the results of subsequent analysis techniques.
Crystallographic Analysis of Cvd Films by Using X-Ray Polychromatic Radiation
Authors: Lavelle B. , Brissonneau L. , Baggot E. , Vahlas C. 
Published: April 2011

ABSTRACTThe Energy Dispersive X-ray Diffiractometry (EDXD) technique was tested for in-situ crystallographic characterization of nickel films processed by chemical vapor deposition (CVD). The diffracted beam at low Bragg angle was analyzed in energy by a solid state detector. A nickel reference sample was used to face the problems of EDXD background signal and uncertainty of sample location. The relative accuracy on lattice parameters measurements is 1.5.10−3, to be compared to 0.5.10−3 for classical (monochromatic) X-Ray diffraction. Texture measurements yields results in agreement with those obtained from recent texture goniometer. Finally, an estimation of the thickness was obtained from the intensity of nickel fluorescence peak. In view of the obtained results, EDXD appears to be a promising technique for in-situ studies. Although less powerful compared to the synchrotron facility, it is more flexible and can be applied at lower cost.
Interfacial Effects in Multilayers
Authors: Barbee Troy W. 
Published: April 2011

ABSTRACTInterfacial structure and the atomic interactions between atoms at interfaces in multilayers or nano-laminates have significant impact on the physical properties of these materials. A technique for the experimental evaluation of interfacial structure and interfacial structure effects is presented and compared to experiment. In this paper the impact of interfacial structure on the performance of x-ray, soft x-ray and extreme ultra-violet multilayer optic structures is emphasized. The paper is concluded with summary of these results and an assessment of their implications relative to multilayer development and the study of buried interfaces in solids in general.
X-Ray Fluorescence Microtomography on a SiC Nuclear Fuel Shell
Authors: Naghedolfeizi; M. , Chung J.-S. , Ice G. E. , Yun W. B. , Cai Z. , Lai B. 
Published: April 2011

ABSTRACTTRISO fuel particles contain a small kernel of nuclear fuel encapsulated by alternating layers of C and a barrier layer of SiC. The TRISO fuel particle is used in an advanced nuclear fuel where the SiC shell provides the primary barrier for radioactive elements in the kernel. The performance of this barrier is key to containment. We have used x-ray fluorescence microtomography to measure the trace element distribution in a SiC shell. Prior to our measurements the nuclear fuel and C layers were leached from the particle. The shell was then encapsulated by kapton tape to simplify handling. The shell was mounted on a glass fiber and measurements were made with an ∼1 x3 ωm2 x-ray probe on beamline 2-ID at the APS. The distribution of trace elements in the SIC shell was reconstructed after correcting the data for artifacts arising from absorption and scattering off the kapton tape. The observed trace elements are distributed in small <1ωm regions through the SiC shell. The trace elements can be attributed to radiation enhanced diffusion of elements in the kernel or to trace elements introduced during fabrication. X-ray fluorescence microtomography is an ideal tool for this work because it is a penetrating nondestructive probe sensitive to trace elements in a low Z matrix and because it provides a picture of the elemental distribution in the shell.
Characterization of Silver Binding in Cryptomelane by X-ray Absorption Spectroscopy
Authors: Ravikumar R. , Fuerstenau D. W. , Waychunas G. A. 
Published: April 2011

ABSTRACTUsing silver K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy, two different samples of silver-containing manganese oxide were analyzed in the fluorescence mode. For the first sample, silver ions from solution were sorbed onto one synthetic manganese oxide phase, namely cryptomelane (KxMn8O16, where l<x<2). The second sample was a silvermanganese oxide from Colorado. From the EXAFS analysis, silver was found to occupy two different sites in the synthetic sample. The natural samples from Colorado also exhibited a very similar coordination distances as the synthetic samples. In the low temperature spectrum of the synthetic sample at 10 K, the Ag-O peak was found to be missing and the amplitude of the Ag- Ag peak was approximately three times larger than the corresponding room temperature sample.
Contrast Mechanism in Superscrew Dislocation Images on Synchrotron Back-Reflection Topographs
Authors: Huang X. R. , Dudley M. , Vetter W. M. , Huang W. , Wang S. , Carter C. H. 
Published: April 2011

ABSTRACTThe topographic contrast of superscrew dislocations in 6H-SiC crystals has been studied by synchrotron white-beam x-ray topography in the Bragg reflection geometry. The diffraction images of these dislocations are simulated using a ray-tracing method. Systematical simulations, which coincide with the dislocation images taken by back-and grazing-reflection topography, clearly reveal the kinematic diffraction mechanisms of the superscrew dislocation, and illustrate that synchrotron reflection topography is capable of providing accurate descriptions of the strain fields, the Burgers vector magnitudes, and the senses of these dislocations. In addition, our experiments and simulations demonstrate straightforwardly the relation between the topographic contrast and the lattice distortions, and therefore the general mechanisms underlying contrast formation of defect images in synchrotron reflection topographs are provided.
Strain and Shape in Self-Assembled Quantum Dots Studied by X-Ray Grazing Incidence Diffraction
Authors: Kegel I. , Metzger T. H. , Peisl J. , Fratzl P. , Lorke A. , Kotthaus J. P. , Garcia J. M. , Petroff P. M. 
Published: April 2011

ABSTRACTWe have developed a method to determine the relationship between strain and lateral size of coherent self-organized quantum dots. In our approach, X-ray grazing incidence diffraction is used to collect information on strain and shape effects in the vicinity of a prominent surface reflection. We demonstrate that for highly strained nano-scale islands it is possible to separate strain-induced and form factor-induced scattering without comparing different reflections. Experimental data from InAs on GaAs(100) quantum dots is discussed with respect to this model. Reciprocal space mapping around the (220) surface reflection shows a linear relationship between relaxation from the substrate lattice parameter and the outer perimeter of the dot. In addition, the functional form of the gradient of relaxation is found to be nonmonotonous and rapidly increasing towards the tip of the dot.
Structure and Magnetotransport Properties of La2/3Ca1/3MnO3 Thin Films Prepared by Pulsed Laser Deposition
Authors: Lebedev O.I. , van Tendeloo G. , Amelinckx S. , Leibold B. , Habermeier H.-U. , Phillipp F. 
Published: April 2011

AbstractLa1-xCaxMnO3-δ (LCMO) thin films are grown by pulsed laser deposition on a (100) SrTiO3 substrate at temperatures between 530°C and 890°C. The magnetotransport properties show a high negative magnetoresistance and a shift of the maximum of the R(T) curve as function of temperature. The Curie temperature changes with deposition temperature and film quality in the range of 100-220K. The film quality is characterised by X-ray diffraction and transmission electron microscopy (TEM); film and target compositions were verified by atomic emission spectroscopy. The local structure of the film depends on the growth conditions and substrate temperature. TEM reveals a slight distortion of the film leading to a breakdown of the symmetry from orthorhombic to monoclinic. At the highest growth temperatures, a well defined interface is observed within the LCMO film, parallel to the substrate surface; this interface divides the film into two lamellae with a different microstructure. The lamella close to the substrate is perfectly coherent with the substrate, suggesting that it is strained as a result of the lattice parameter mismatch; the upper lamella shows a typical domain structure with unusual translation interfaces characterised by a displacement vector of the type 1/2 [010]m and 1/2[001]m when referred to the monoclinic lattice.
Pulsed Laser Deposition of High Coercivity Barium Ferrite Films
Authors: Song W. D. , Lu Y.F. , Wang J.P. , Zeng X.T. , Lu L. , Low T.S. 
Published: April 2011

AbstractBarium ferrite films with high coercivity (>2000 Oe) have been prepared on single crystal sapphire substrates by laser in-situ deposition. The structures of these films were characterized by x-ray diffractometry. X-ray diffraction pattern shows a preferential c-axis orientation normal to the film plane at a high deposition temperature and a random orientation at a lower deposition temperature. The magnetic properties of the films were analysed by a Vibrating Sample Magnetometer (VSM) and surface morphology was analysed by an Atomic Force Microscope (AFM).
Deposition and Characterization of Carbon Nitride Films by Laser Processed Methods
Authors: Kumar Ashok , Alexandrescu R. , George Michael A. 
Published: April 2011

AbstractLaser assisted methods such as laser physical vapor deposition (LPVD) and laser induced chemical vapor deposition (LCVD) have been utilized to grow carbon nitride (CNx) films on various substrates. It has been shown that the both techniques produce good quality thin films of CNx. In LPVD, a laser beam (λ= 248 nm) has been used to ablate the pyrolytic graphite target in nitrogen atmosphere, where as CO2 laser was to irradiate carbon-nitrogen containing mixtures such as C2H2/N2O/NH3 in LCVD method. A comparative analysis will be presented in terms of structural properties of CNx films prepared by both techniques.
Microscopic Diffusion Mechanism of Iron in FeAl Revisited by New Methods
Authors: Vogl G. , Sepiol B. , Czihak C. , Rüffer R. , Weinkamer R. , Fratzl P. , Fähnle M. , Meyer B. 
Published: April 2011

ABSTRACTThe elementary diffusion jump of Fe atoms in the ordered intermetallic alloy FeAl is studied in a coordinated effort of atomistic experimental techniques, Monte Carlo simulation and abinitio electron theory. The experiment demands that the elementary diffusion jump is a jump into an antistructure site on the Al sublattice which is occupied for a much shorter time than the sites on the Fe sublattice. The diffusion path can be followed by Monte Carlo simulations which can perfectly explain the experiments. Since ab-initio theory yields a very low concentration of Al vacancies it is suggested that correlated jumps of two atoms prevent the creation of a fully developed Al vacancy.
Kinetics and Mechanisms of Intermetallic Growth by Surface Interdiffusion
Authors: Kaganovskii Yu.S. , Paritskaya L.N. , Bogdanov V.V. 
Published: April 2011

ABSTRACTKinetics of growth and lateral spreading of an intermetallic layer along a free surface during surface interdiffusion in binary systems have been studied both theoretically and experimentally. By comparison of experimental data on intermetallic growth kinetics with the proposed theory, the surface diffusion constants have been calculated for intermetallics Cd21Ni5 and Cu5Zn8, and mechanisms of surface diffusion have been discussed.
Determination of Ionic Diffusion Mechanisms in Solids
Authors: Corish John 
Published: April 2011

ABSTRACTThe experimental and atomistic simulation methodologies by which microscopic diffusion mechanisms can be determined in solids are described. Measurement of the Haven Ratio requires evaluation of the diffusion coefficient and of the ionic conductivity for the species in pure and doped specimens and is, in practice, limited to simpler materials. Atomistic simulations using lattice statics, molecular dynamics and Monte Carlo techniques can yield very detailed information on the pathways followed by migrating ions and are being utilised more extensively for this purpose. Examples of such experimental and simulation studies are discussed.
Oxygen Ion and Proton Transport in Mixed Metal Oxides
Authors: Islam M. Saiful 
Published: April 2011

ABSTRACTComputational techniques are now well established tools in the study of structural properties and transport mechanisms in solid state ionic materials. This paper will highlight recent developments of such methods, with a strong emphasis on their use in the elucidation of ion diffusion mechanisms or pathways at the atomic level. In particular, contemporary work will be illustrated by accounts of calculations on oxygen ion and proton conduction in LaMO3 perovskite-type oxides, which find use in various electrochemical applications. We have used atomistic simulation, molecular dynamics (MD) and ab initio techniques to provide fresh insight as to their defect and ion diffusion properties.
Mobility of Self-Interstitials in FCC and BCC Metals
Authors: Osetsky Yu.N. , Serra A. , Priego V. , Gao F. , Bacon D.J. 
Published: April 2011

ABSTRACTDiffusion of self-interstitial atoms (SIAs) has been studied in bcc-Fe and fcc-Cu using molecular dynamics and interatomic potentials of different types. The Fe potentials describe SIA configurations of different stability. The temperature dependence of the SIA diffusion mechanisms is qualitatively similar for both potentials. At high temperature the diffusion is three-dimensional via the <110> dumbbell mechanism. The contribution of one-dimensional mechanism via the <111> crowdion increases when temperature decreases. At low temperature (<300K) the diffusion mechanism depends on the stable configuration of the SIA.In fcc-Cu all the potentials reproduce the same stable configuration, namely the <100> dumbbell. The migration mechanism is mainly a three-dimensional random walk via this dumbbell with small contributions from the <110> crowdion at high temperature and a two-dimensional caging mechanism at low temperature.
Surface Interaction of Inflammatory Species with Titanium and Titanium Oxide
Authors: Suzuki R. , Hirata G. , McKittrick J. , Frangos J.A. 
Published: April 2011

AbstractTitanium has been successfully used for decades in dental and orthopedic implants, but the mechanism for this metal's biocompatible properties have not been determined. Our hypothesis is that this biocompatibility involves interaction between the surface layer of titanium dioxide on the metal implant and reactive oxygen mediators of the inflammatory response. The affect of different titanium surface oxide layers on the reactive oxygen mediators produced during the inflammatory response has never been examined. Peroxynitrite is a highly reactive and unstable compound produced in vivo by the reaction of nitric oxide with superoxide. We investigated if titanium oxides affect the stability of peroxynitrite by promoting its breakdown. Peroxynitrite levels can be measured by its absorbance at 302 nm. At pH= 13.2, we found a 100% increase in the rate of degradation of peroxynitrite in the presence of titanium particles. Peroxynitrite is capable of nitrating 4-hydroxyphenolacetic acid (4-HPA). The nitrated form of 4-HPA can be measured by its absorbance at 432nm. 3-morpholinosydnonimine (SIN-1), a nitric oxide donor, has been shown to produce superoxide during its breakdown resulting in the formation of peroxynitrite. At physiological pH (7.4), a solution of 0.5mM 4-HPA was exposed to 5mM SIN- 1 on passivated titanium surfaces. There was a decrease of 58% nitrated 4-HPA in the solution exposed to passivated titanium compared to controls. Unpassivated titanium surfaces resulted in only a 10% decrease of nitrated 4-HPA while titanium treated with hydrogen peroxide resulted in a 70% decrease in nitrated 4-HPA concentrations compared to controls. Zirconium and palladium were also tested. These experiments suggest that titanium is capable of enhancing the breakdown of the inflammatory compound peroxynitrite which may account for the metal's biocompatible properties.