bluuebunny/crossref_metadata_2025 huggingface dataset:
Approach to Unidirectional Coupled CFD–FEM Analysis of Axial Turbocharger Turbine Blades
Authors: Filsinger D. , Szwedowicz J. , Scha¨fer O.
Published: July 2002

This paper describes an approach to unidirectional coupled CFD–FEM analysis developed at ABB Turbo Systems Ltd. Results of numerical investigations concerning the vibration behavior of an axial turbocharger turbine are presented. To predict the excitation forces acting on the rotating blades, the time-resolved two-dimensional coupled stator–rotor flow field of the turbine stage was calculated. The unsteady pressure, imposed on the airfoil contour, leads to circumferentially nonuniform and pulsating excitation forces acting on the rotating bladed disk. A harmonic transformation of the excitation forces into the rotating coordinate system of a single blade was elaborated and the complex Fourier amplitudes were determined. The bladed rotor was modeled by a single symmetric segment with complex circumferential boundary conditions. With respect to different nodal diameter numbers, free vibration analyses of the disk assembly were then effectively performed. For calculated resonance conditions, the steady-state responses of the turbocharger bladed disk were computed. By using this coupled CFD–FEM analysis, the dynamic loading of the turbine blades can be determined in the design process.
Fitting Freeform Shape Patterns to Scanned 3D Objects
Authors: Vergeest Joris S. M. , Spanjaard Sander , Horva´th Imre , Jelier Jos J. O.
Published: July 2002

This paper describes a new approach to locate freeform shape patterns in measured point data and to fit their parameter values. The method is based on the direct matching of parameterized shape templates to digitized points. For a given class of feature, the optimal pose and the optimal intrinsic shape parameters are determined. Although this principle was previously used in digital image processing and also for fitting of regular shaped features, it has rarely been applied in 3D to freeform features. Yet, several engineering applications may profit from improved feature fitting. The motivation of our investigation is to enable the reuse of precedent shapes, available in the form of physical parts. We aim at an extension to what is generally known as reverse engineering of shape. However, the proposed technique can also be used to extract feature parameters from imported CAD models. This paper addresses computational aspects of the method and presents the algorithms, implementation tests and numerical results.
Plane-Stress Deformation in Strain Gradient Plasticity
Authors: Chen J. Y. , Huang Y. , Hwang K. C. , Xia Z. C.
Published: July 2002

A systematic approach is proposed to derive the governing equations and boundary conditions for strain gradient plasticity in plane-stress deformation. The displacements, strains, stresses, strain gradients and higher-order stresses in three-dimensional strain gradient plasticity are expanded into a power series of the thickness h in the out-of-plane direction. The governing equations and boundary conditions for plane stress are obtained by taking the limit h→0. It is shown that, unlike in classical plasticity theories, the in-plane boundary conditions and even the order of governing equations for plane stress are quite different from those for plane strain. The kinematic relations, constitutive laws, equilibrium equation, and boundary conditions for plane-stress strain gradient plasticity are summarized in the paper. [S0021-8936(00)02301-1]
Passive Control of Rotating Stall in a Parallel-Wall Vaneless Diffuser by Radial Grooves
Authors: Kurokawa Junichi , Saha Sankar L. , Matsui Jun , Kitahora Takaya
Published: July 2002

In order to control and suppress rotating stall in the diffuser of a centrifugal turbomachine, a passive method of utilizing radial shallow grooves is proposed and its effect is studied theoretically and experimentally. The results show that radial grooves of 3 mm depth on one wall or of only 1 mm depth on both walls can suppress rotating stall in a vaneless diffuser for the entire flow range. Theoretical considerations have revealed that this remarkable effect of radial grooves is caused by two mechanisms; one is a significant decrease in tangential velocity at the diffuser inlet due to mixing between the main flow and the groove flow, and the other is a remarkable increase in radial velocity due to the groove reverse flow. Both effects have the same contribution to increase the flow angle. [S0098-2202(00)02901-1]
Effect of Surface Roughness in a Narrow Porous Journal Bearing
Authors: Gururajan K. , Prakash J.
Published: July 2002

This paper examines the effect of surface roughness in hydrodynamic narrow porous journal bearings operating under steady conditions. The problem is formulated mathematically and solved analytically with appropriate boundary conditions. It is shown that the results are significantly different than those for the case of an infinitely long journal bearing. [S0742-4787(00)00602-0]
Historical Development—The Pressure Vessels and Piping Division
Authors: Zamrik Sam Y. , Farr James R.
Published: July 2002

Historical information concerning the Pressure Vessels and Piping Division was presented by James Farr at the 25th Anniversary Celebration, describing events from 1966 through 1991. Further developments since 1991 are briefly summarized in this presentation for the Millennium Issue. The PVP Senate has been the historian of the Division’s growth and activities. [S0094-9930(00)02803-1]
Life Management of High-Temperature Piping and Tubing in Fossil Power Plants
Authors: Viswanathan R.
Published: July 2002

Aging of power plants and competitive pressures to operate and maintain (O&M) these plants at reduced costs have heightened industry interest in life assessment and management technologies. Piping and tubing systems carrying high-pressure steam at temperatures exceeding 1000°F (530°C) have notably been the center of focus of many of these activities. Enormous progress has been made in understanding mechanisms of damage and their rate of evolution. Progressive application of improved calculational, nondestructive and destructive techniques have enabled optimum utilization of components at reduced costs. In addition, the efficacy of weld repair techniques to extend the lives of aged components has been investigated in detail. This paper will review the damage mechanisms encountered in fossil power plant boiler pressure parts and then describe in more detail life management tools that have been developed. [S0094-9930(00)01503-1]
Editorial
Authors: Reid Robert L.
Published: July 2002

[S0199-6231(00)00501-3]
Orthorhombic YBa2Cu3O7 Cleaved Single Crystal by XPS
Authors: Fowler D. E. , Miller D. C.
Published: July 2002

X-ray photoemission spectra from the cleaved surface of a single crystal of the high temperature superconductor, YBa2Cu3O7, are presented. All spectra were taken with the sample at room temperature. The spectra of this material are dependent on which cleavage planes are exposed following crystal fracture. Extremes in the spectra are given from the continuum of observed surfaces. These extremes are obtained from cleaves leaving large macroscopic terrace planes (larger than probe size), and from cleaves leaving highly stepped surfaces with microscopic terraces (smaller than the probe size). A distinct Fermi edge is observed in the valence band. The freshly cleaved surface is free from contamination, but the spectral line shape of O 1s changes with time. This may be related to the formation of contamination compounds and/or a chemical bonding instability at the cleaved surface of the superconductor.
E-75 Pitch-based Carbon Fiber by Core Level and Valence Band XPS
Authors: Xie Yaoming , Sherwood Peter M. A.
Published: July 2002

Both XPS core level and valence band spectra were obtained from Du Pont E-75 pitch-based carbon fiber surface. The XPS data showed that the E-75 fiber had more oxygen content on the surface than the Du Pont higher modulus pitch-based carbon fiber (E-120), but less than the lower modulus pitch-based carbon fibers (Amoco P55X fiber and Du Pont E-35 fiber) and the PAN-based carbon fibers (Hercules AU4 and AS4). [See Y. Xie and P. M. A. Sherwood, Appl. Spectrosc. 43, 1153 (1989); Chem. Mater. 1, 427 (1989); 2, 293 (1990); Appl. Spectrosc. 44, 797 (1990); Chem. Mater. 3, 164 (1991); Appl. Spectrosc. 44, 1621 (1990); 45, 1158 (1991); Y. Xie, T. Wang, O. Franklin, and P. M. A. Sherwood, ibid. 46, 645 (1992).] The E-75 fiber also had a graphitic structure in both the surface and the bulk as evidenced by both XPS and XRD. No nitrogen was found on this E-75 fiber and other pitch-based carbon fiber surfaces, but it was found on PAN-based fibers. Our previously reported work [Y. Xie and P. M. A. Sherwood, Chem. Mater. 1, 427 (1989); 2, 293 (1990); Appl. Spectrosc. 44, 797 (1990); Chem. Mater. 3, 164 (1991); Appl. Spectrosc. 44, 1621 (1990); 45, 1158 (1991); Y. Xie, T. Wang, O. Franklin, and P. M. A. Sherwood, ibid. 46, 645 (1992)], showed that XPS valence band spectra were more sensitive to chemical environment on the carbon fiber surface than core level spectra and could be well interpreted by X–α calculations with model compounds.
E-120 Pitch-based Carbon Fiber by Core Level and Valence Band XPS
Authors: Xie Yaoming , Wang Tiejun , Rooke Michael A. , Sherwood Peter M. A.
Published: July 2002

Both XPS core level and valence band spectra were obtained from an E-120 high modulus pitch-based carbon fiber surface. The XPS data show that the E-120 fiber had the least oxygen content on the surface compared to various other pitch-based (e.g., E-35, E-75,P-55X, etc.) and PAN based carbon fibers (e.g., AU4, TypeII, etc.). [See Y. Xie and P. M. A. Sherwood, Appl. Spectrosc. 43, 1153 (1989); Chem. Mater. 1, 427 (1989); 2, 293 (1990); Appl. Spectrosc. 44, 797 (1990); Chem. Mater. 3, 164 (1991); Appl. Spectrosc. 44, 1621 (1990); 45, 1158 (1991); Y. Xie, T. Wang, O. Franklin, and P. M. A. Sherwood, ibid. 46, 645 (1992).] E-120 also had the most graphitic structure in both the surface and the bulk among these fiber samples as evidenced by both XPS and XRD. No nitrogen was found on E-120 and other pitch-based carbon fiber surfaces but it was found on PAN-based fibers. Our previously reported work [Y. Xie and P. M. A. Sherwood, Chem. Mater. 1, 427 (1989); 2, 293 (1990); Appl. Spectrosc. 44, 797 (1990); Chem. Mater. 3, 164 (1991); Appl. Spectrosc. 44, 1621 (1990); 45, 1158 (1991); Y. Xie, T. Wang, O. Franklin, and P. M. A. Sherwood, ibid. 46, 645 (1992)], showed that XPS valence band spectra were more sensitive to chemical environment on the fiber surface than core level spectra and could well be interpreted by X–α calculations with model components.
Solution Cast Silicone on Glass Substrate by XPS
Authors: Ackeret Michael
Published: July 2002

X-ray photoelectron spectroscopy was used to examine a film of silicone evaporated onto a 13 mm diameter glass substrate. The material was dissolved into toluene, deposited onto the glass substrate, then the toluene was allowed to evaporate. Data were collected, stored and processed with a Hewlett-Packard model 5950B ESCA. Measured atomic percentages very closely matched the expected stoichiometry at three different electron take off angles, indicating homogeneity.
Core Level and Valence Band XPS Spectra of E-120 Pitch-based Carbon Fiber Potentiostatically Oxidized in HNO3 Solution
Authors: Xie Yaoming , Sherwood Peter M. A.
Published: July 2002

Du Pont E-120 high modulus pitch based carbon fiber was potentiostatically oxidized in HNO3 solution and analyzed with both core level and valence band XPS. Compared to the untreated E-120 fiber, the potentiostatically oxidized fiber had a much higher oxygen content on its surface. Both surface and bulk graphitic structures were severely disordered by the electrochemical treatment as evidenced by both XPS and XRD studies. [See Y. Xie and P. M. A. Sherwood, Appl. Spectrosc. 43, 1153 (1989); Chem. Mater. 1, 427 (1989); 2, 293 (1990); Appl. Spectrosc. 44, 797 (1990); Chem. Mater. 3, 164 (1991); Appl. Spectrosc. 44, 1621 (1990); 45, 1158 (1991); Y. Xie, T. Wang, O. Franklin, and P. M. A. Sherwood, ibid. 46, 645 (1992).] However, no nitrogen was found on this pitch-based carbon fiber either before or after the treatment in HNO3 solution. Our previously reported work [Y. Xie and P. M. A. Sherwood, Chem. Mater. 1, 427 (1989); 2, 293 (1990); Appl. Spectrosc. 44, 797 (1990); Chem. Mater. 3, 164 (1991); Appl. Spectrosc. 44, 1621 (1990); 45, 1158 (1991); Y. Xie, T. Wang, O. Franklin, and P. M. A. Sherwood, ibid. 46, 645 (1992)] showed that XPS valence band spectra were more sensitive to chemical environment on the carbon fiber surface than core level spectra, and could be well interpreted by X–α calculations with model compounds. In this work, the valence band spectrum, together with the O 1s core level spectrum, showed that there was only one single-type oxygen-containing functional group formed on the fiber surface when the fiber was electrochemically oxidized in HNO3 solution. We also reported [see Y. Xie and P. M. A. Sherwood, Appl. Spectrosc. 44, 1621 (1990)] that the highly oxidized carbon fiber surface functionality would gradually decompose after exposure to the x rays inside the XPS spectrometer, and that [see Y. Xie and P. M. A. Sherwood, Appl. Spectrosc. 45, 1158 (1991)] the reproducibility of the potentiostatic treatment was not as good as that of the galvanostatic treatment, although the results from potentiostatic oxidation and galvanostatic oxidation were about the same.
AS4 PAN-based Carbon Fiber by Core Level and Valence Band XPS
Authors: Xie Yaoming , Sherwood Peter M. A.
Published: July 2002

Hercules AS4-6k PAN-based carbon fiber surface was analyzed with both core level and valence band XPS. Compared to Du Pont and Amoco's pitch-based carbon fibers with different modulus and Hercules’ AU4-12k PAN-based fiber, the AS4 fiber had much more oxidized components on the surface [Y. Xie and P. M. Sherwood, Appl. Spectrosc. 43, 1153 (1989); Chem. Mater. 1, 427 (1989); 2, 293 (1990); Appl. Spectrosc. 44, 797 (1990); Chem. Mater. 3, 164 (1991); Appl. Spectrosc. 44, 1621 (1990); 45, 1158 (1991); Y. Xie, T. Wang, O. Franklin, and P. M. Sherwood, ibid. 46, 645 (1992)]. The AS4 PAN-based fiber had a much less graphitic structure in both the surface and the bulk than the pitch-based fibers as evidenced by both XPS and XRD. It also had a higher nitrogen content on its surface than the AU4-12k PAN-based fiber, but no nitrogen was found on any of the pitch-based carbon fibers measured in our laboratory. Our previously reported work [Y. Xie and P. M. Sherwood, Chem. Mater. 1, 427 (1989); 2, 293 (1990); Appl. Spectrosc. 44, 797 (1990); Chem. Mater. 3, 164 (1991); Appl. Spectrosc. 44, 1621 (1990); 45, 1158 (1991); Y. Xie, T. Wang, O. Franklin, and P. M. A. Sherwood, ibid. 46, 645 (1992)] showed that XPS valence band spectra were more sensitive to chemical environment on the carbon fiber surface than core level spectra, and could be well interpreted by X–α calculations with model compounds. In this work, the valence band spectrum showed that there were nitrogen and at least two different types of oxygen species on the AS4 fiber surface.
Elemental Lead by AES
Authors: Bozack Michael J. , Bryant Kenneth W.
Published: July 2002

An AES spectrum of elemental lead (Pb) is presented. The Pb foil was supplied commercially (Goodfellow Corp.) as a 0.1 mm thick specimen of quoted purity 99.95%. The KE range 50–2350 eV is documented.
Poly (ethyl methacrylate) by XPS
Authors: Moulder J. F. , Stickle W. F. , Sobol P. E.
Published: July 2002

XPS measurements for poly (ethyl methacrylate). The data include the valence band region and the principal core levels.
SrBr2 by XPS
Authors: Vasquez Richard P.
Published: July 2002

X-ray photoemission measurements for high purity, ultradry SrBr2 which has not been exposed to the atmosphere are presented. The data include measurements of the valence band region and energy losses from the principal core levels.
A Tl2Ba2CaCu2O8+δ Epitaxial Thin Film by XPS
Authors: Vasquez Richard P. , Olsen William L.
Published: July 2002

X-ray photoemission spectra from a chemically etched epitaxial thin film of the high temperature superconductor Tl2Ba2CaCu2O8+δ are presented. A clear Fermi edge is observed in the valence band region, indicating a high quality surface.
SrI2 by XPS
Authors: Vasquez Richard P.
Published: July 2002

X-ray photoemission measurements for high purity, ultradry SrI2 which has not been exposed to the atmosphere are presented. The data include measurements of the energy losses from the principal core levels.
Study of the First Row Transition Metals by AES
Authors: Lambers Eric S.
Published: July 2002

AES spectra have been obtained from metals in the first row of transition elements using a Perkin Elmer PHI Model 660 scanning Auger electron microprobe. The goal was to obtain spectra which represented what would normally be obtained under typical operating conditions. Auger spectra were taken from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Ge samples under identical conditions. Each elemental spectrum was obtained using electron beam energies of 3, 5, 10, and 20 keV and 50 nA beam currents. Data from the LMM peak from a Cu sample was used to calculate the signal-to-noise ratio and to check instrumental calibration. The signal-to-noise ratio before and after analysis was the same and equal to 25, 48, 45, and 45 for 3, 5, 10, and 20 keV beams, respectively. The instrumental resolution used for all spectra was 0.6%.
Characterization of 1,1,2,2-Tetrahydroperfluorooctyl Acrylate (PTAN) by XPS
Authors: Kassis Camille M. , Steehler Jack K. , Linton Richard W.
Published: July 2002

A sample of 1,1,2,2-tetrahydroperfluorooctyl acrylate (PTAN), a low surface energy polymeric material prepared by homogeneous free radical solution polymerization in supercritical CO2, has been investigated by x-ray photoelectron spectroscopy (XPS) using a Perkin-Elmer Physical Electronics Model 5400 spectrometer with monochromatic Al Kα x rays. Knowledge of the surface composition of PTAN is significant since potential applications of this homopolymer include use in polymer blends where this material would be expected to be the surface active species. Controlled surface studies were conducted on a thick polymer film (∼0.5 μm) spun cast from solution onto silicon. Although the F 1s and O 1s regions were structurally straightforward to interpret, the C 1s window showed the expected pattern of functional group components.
Study of the First Row Transition Metals by X-ray Photoelectron Spectroscopy
Authors: Lawson Catherine S. , Tielsch Brian J. , Fulghum Julia E.
Published: July 2002

XPS spectra have been obtained from six metals in the first row of transition elements using a Kratos AXIS HS x-ray photoelectron spectrometer. The six metals analyzed include Cu, Ni, Zn, V, Ge, and Fe. Each sample was Ar+ ion etched before XPS analysis to remove the majority of C and O contamination. The spectra include standard survey scans and high-resolution scans of the photoelectron peaks, as well as x-ray induced Auger peaks. Each spectrum was collected using a monochromatic Al Kα x-ray source operated at 300 W (20 mA, 15 kV). Survey scans were collected using an 80 eV pass energy, while high resolution scans were recorded using a 20 eV pass energy unless indicated otherwise.
Poly(bisphenol A carbonate) During XPS Measurements
Authors: Girardeaux Ch. , Pireaux J.-J.
Published: July 2002

We present XPS measurements of poly(bisphenol A carbonate) [C16O3H14]n (Polysciences Europe GmbH). This polymer is a constituent of polymer blends (PC + PMMA) studied for their superficial composition versus blend composition.
Surface Phonon Spectra of V6O13(001) in the Metallic and Semiconducting Phase
Authors: Poelman H. , Fiermans L.
Published: July 2002

V6O13 is known as the most important lower oxide of V2O5 and as such is assumed to play a primordial role in the catalytic activity of the latter. Like many other transition metal oxides, it exhibits a phase transition, situated at about 150 K, from metallic behavior at room temperature to semiconducting at low temperature. In view of its catalytic applications, the vibrational properties of single crystal V6O13(001) above and below 150 K were examined using HREELS, with an instrumental resolution of 2.8 meV. A clean (001) surface was obtained by annealing the sample in O2 and subsequently in UHV. At room temperature, the energy loss spectrum was found to exhibit surface phonon losses superposed upon a free electron background, due to inefficient electron screening. Upon LN2 cooling below 150 K, the spectrum displayed considerable changes in both loss structure and electronic background.
Analysis of a Thermoplastic Elastomer (TEO) by XPS
Authors: Lannon John M. , Meng Qingru
Published: July 2002

We report x-ray photoemission spectra for a thermoplastic elastomer (TEO), ethylene rubber modified poly(propylene). XPS spectra were acquired with a SSI model SSX-100 instrument using monochromated Al Kα x-rays. We present the survey spectrum (binding energy 0–1000 eV) and a narrow spectrum of the C 1s and O 1s photoelectron peaks.
Tl Cuprate Superconductors Studied by XPS
Authors: Vasquez R. P. , Siegal M. P. , Overmyer D. L. , Ren Z. F. , Lao J. Y. , Wang J. H.
Published: July 2002

XPS measurements on epitaxial thin films of the Tl cuprate superconductors Tl2Ba2CaCu2O8, Tl2Ba2Ca2Cu3O10, and Tl0.78Bi0.22Ba0.4Sr1.6Ca2Cu3O9−δ are presented. These data, together with previous measurements in this lab on Tl2Ba2CuO6−δ and TlBa2CaCu2O7−δ, comprise a comprehensive data set for comparison of Tl cuprates in which the number of Tl–O and Cu–O layers, and hence the chemical and electronic properties, vary.
Electronic Structures of the Heusler Compounds XMnSb (X = Ni, Pd, Pt) Using Photoemission Spectroscopy
Authors: Kang J.-S. , Olson C. G.
Published: July 2002

Mn-based Heusler alloys of NiMnSb and PtMnSb have been predicted to be half-metallic ferromagnetic metals, with 100% spin-polarized conduction electrons at the Fermi level. In this study, the valence-band and Sb 4d core levels of the XMnSb-type Heusler alloys (X = Mi, Pd, Pt) have been investigated using synchrotron-radiation photoemission spectroscopy. Samples were made by melting the appropriate amount of constituent elements in vacuum-sealed quartz tubes at 1100 °C, and subsequent annealing at 600 °C for one week. Photoemission measurements were performed on the Mark V beamline at the Synchrotron Radiation Center at the University of Wisconsin-Madison. Polycrystalline samples were fractured in situ and measured at about 60 K in a vaccum better than 4 × 10−11 Torr. The instrumental resolution of the system is about 0.2 eV at hν=40 eV and about 0.4 eV at hν = 150 eV, respectively. The incident photon flux was monitored by the yield from a gold mesh and all the spectra were normalized to the incident photon flux. Due to the photon energy dependence of the photoionization cross sections, the valence-band spectra around 120 and 150 eV in PdMnSb and PtMnSb, respectively, can be considered to represent the Mn 3d partial spectral weight (PSW) distribution. The extracted Mn 3d PSWs of PdMnSb and PtMnSb are found to be very similar to each other. The measured Sb 4d core level spectra are very similar for NiMnSb and PtMnSb. In contrast, the Sb 4d spectrum for PdMnSb is less structured, as compared to NiMnSb and PtMnSb, indicating a larger lifetime broadening and a smaller surface core level shift in PdMnSb.
A Comparison of Auger Electron Spectra from Stoichiometric Epitaxial TiN(001) After (1) UHV Cleaving and (2) Ar+ Sputter Etching
Authors: Finnegan N. , Haasch R. T. , Gall D. , Kodambaka S. , Greene J. E. , Petrov I.
Published: July 2002

We present Auger electron spectroscopy (AES) spectra from epitaxial B1-NaCl-structure TiN(001) layers grown on MgO(001)1×1 by ultrahigh vacuum magnetron sputter deposition. The layers are stoichiometric with a N/Ti ratio of 1.01 ± 0.02 as shown by Rutherford backscattering spectroscopy (RBS). AES spectra were obtained from clean TiN(100) surfaces by cleaving 5-μm-thick layers in situ in the Auger spectrometer at a vacuum of 2 × 10−10 Torr. For comparison, we also show spectra obtained following sputter etching for 5 min with a 3 keV Ar+ beam at an incident current density of 0.11 mA cm−2 in order to simulate typical “sputter cleaning” conditions following sample air exposure. The Ar+ beam was incident at an angle of 58° with respect to the cleaved surface normal [100]. We show that sputter etching reduces the N/Ti ratio to 0.89 due to preferential sputtering. In the experiments, the AES spectra were collected using primary electron beam energies of 3, 5, 10, and 20 keV.
Optical and microstructural properties of MgF2 UV coatings grown by ion beam sputtering process
Authors: Quesnel E. , Dumas L. , Jacob D. , Peiró F.
Published: July 2002

The optical, mechanical, and microstructural properties of MgF2 single layers grown by ion beam sputtering have been investigated by spectrophotometric measurements, film stress characterization, x-ray photoelectron spectroscopy (XPS), x-ray diffraction, and transmission electron microscopy. The deposition conditions, using fluorine reactive gas or not, have been found to greatly influence the optical absorption and the stress of the films as well as their microstructure. The layers grown with fluorine compensation exhibit a regular columnar microstructure and an UV-optical absorption which can be very low, either as deposited or after thermal annealings at very low temperatures. On the contrary, layers grown without fluorine compensation exhibit a less regular microstructure and a high ultraviolet absorption which is particularly hard to cure. On the basis of calculations, it is shown that F centers are responsible for this absorption, whereas all the films were found to be stoichiometric, in the limit of the XPS sensitivity. On the basis of external data taken from literature, our experimental curves are analyzed, so we propose possible diffusion mechanisms which could explain the behaviors of the coatings.
Anisotropic etching of RuO2 and Ru with high aspect ratio for gigabit dynamic random access memory
Authors: Yunogami Takashi , Nojiri Kazuo
Published: July 2002

Anisotropic RuO2 and Ru etching technology for gigabit dynamic random access memory has been developed using high density O2+10% Cl2 plasma in an inductively coupled plasma etching system. Under the conditions of low pressure, high gas flow rate, and large overetching times, we have demonstrated 0.2 μm wide patterns in 0.3-μm-thick RuO2/Ru films and 0.1 μm wide patterns in 0.45-μm-thick Ru films, both with an almost perpendicular taper angle of 89°.
Stability and chemical composition of thermally grown iridium-oxide thin films
Authors: Chalamala Babu R. , Wei Yi , Reuss Robert H. , Aggarwal Sanjeev , Perusse Scott R. , Gnade Bruce E. , Ramesh R.
Published: July 2002

The effect of growth conditions on the thermal stability and chemical composition of iridium-oxide thin films fabricated by annealing Ir films in O2 is presented. The oxide growth as a function of anneal temperature was studied by x-ray photoelectron spectroscopy depth profile analysis and the thermal stability was determined using temperature programmed desorption spectroscopy. We observed that with increasing anneal temperature, the surface oxidized to IrO2 (110) and the thermal stability of the resulting oxide increased. X-ray photoelectron spectroscopy depth profiles showed that IrO2 starts to form at 600 °C simultaneous with an increase in the surface roughness of the film.
Vacuum–Carbon Deoxidation of Iron Melts in a 70% Alumina Brick Crucible
Authors: Olen K. R.
Published: July 2002

A series of 0.20 and 1.00% C-Fe melts was processed under various reduced pressures of carbon monoxide at 1600°C in a 70% alumina crucible made from commercial quality refractory brick. The bath aluminum and oxygen contents were found to be a nonlinear function of treatment pressure, whereas the bath silicon content was found to be pressure independent. The results support a previously proposed model in which melt-refractory interactions limit oxygen removal during vacuum processing.
Recent Developments in Hard and Soft Vacuum Electron-Beam Welding
Authors: James H. A.
Published: July 2002

Electron-beam welding at hard vacuum (10−6–10−3 Torr) has been a valued and increasingly widely used method of metal joining ever since its origination in the middle 1950's by Dr. J. A. Stohr. Extensive application of the process has been made by the aircraft and aerospace industry, in particular, for primary structural members. Means have been developed to permit the welding of such parts along straight or irregular paths over lengths of more than thirty feet. The increasing interest to apply electron-beam welding to an even broader range of industrial welding situations has led to development of high production, short pumpdown time machines that weld in the soft vacuum range of 0.001–1.0 Torr at rates of more than 1000 parts/h. Some of the recently developed means to accomplish this in a particular case are described in detail. This paper also discusses the new developments which greatly simplify initial alignment of the electron beam and the workpiece, and make possible the guidance of the beam along the straight or irregular welding path. Some discussion of the special equipment facilities required for production of these weldments is included.
Use of Fringing Fields in the Monopole
Authors: Dawson P. H.
Published: July 2002

Previous computations of ion trajectories in the monopole mass spectrometer [P. H. Dawson and N. P. Whetten, Rev. Sci. Instr. 39, 1417 (1968)], for ion injection parallel to the instrument axis, have predicted asymmetric peaks with a tail on the low mass side and only 40% ion transmission. This is because an off-axis object cannot be completely focused at the exit from the analyzer. It is shown here that superior focusing at the analyzer exit, leading to symmetrical peaks, 100% ion transmission and, in some conditions, a reduction in the necessary rod-Vee Block spacing, and therefore in rf power, can be obtained by proper use of a fringing field at the monopole entrance. A simple linear entrance ramp, where ion trajectories are mathematically unstable, and which is apparently harmful to the quadrupole mass filter [W. M. Brubaker, Advan. Mass Spectry. 4, 293 (1967)], can be beneficial in the monopole. Examples of computed ion trajectories and peak shapes are given and various entrance ramps are compared. The chance use of an entrance ramp probably explains some of the high performance monopoles that have been constructed.
Analysis of Residual Gases from Television Cathode-Ray Tubes
Authors: Kloba A. A. , Olmstead R. D.
Published: July 2002

Analysis of residual gases has been performed on large numbers of production television tubes. This paper describes the system, CRT break-in equipment, and quadrupole RGA sampling procedure. With the system background pressure in the 10−11 Torr range, CRT gases were released, analyzed, and recorded. Included is data on residual gases during the oxide cathode processing, after final tube production and after-life test. The difficulty encountered in relating data on residual gases from final production tubes against the data from life-tested tubes which are at a lower pressure (4–8×10−9 Torr) is outlined along with the effects of phonic desorption of gases during the CRT break-in. The value of residual gas analysis in evaluating the effects of changes in manufacturing processes is discussed.
Solution of Vacuum Problems Using Magnetic Mass Spectrometers
Authors: Cleaver J. S.
Published: July 2002

The evaluation of vacuum processes often requires the use of residual gas analyzers and when ease of operation, robust construction, and reliability are of importance, the magnetic deflection type of instrument can often be satisfactorily used. The use of a 180 ° mass spectrometer of 1.5-cm radius. is exampled in the monitoring of the oxygen partial pressure in an rf sputtering process. Information on the release of other gases during the sputtering process is also given. The influence of the pre-evacuation cycle on the gas atmosphere in a Penning pump system has been investigated using a 7.5 cm radius 60 ° sector field instrument with fast scanning capabilities. The same instrument has also enabled information to be obtained on the outgassing products from certain plastic materials when heated in vacuum. The decomposition of diffusion pump oils at elevated temperatures has been studied using a larger 60 ° spectrometer of 15 cm radius.
Analysis of Gases Entrapped in Glass Using a Mass Spectrometer–Ultrahigh Vacuum System
Authors: Fenstermacher James E.
Published: July 2002

The system consists of a 60 ° magnetic sector mass spectrometer and a bakeable stainless-steel vacuum system which is oil-diffusion pumped and liquid-nitrogen trapped. The technique developed to analyze gas samples ranging from 10−3 to less than 10−7 Torr liter quantities is described. Gases of interest include N2, CO, H2, CH4, CO2, O2, SO2, H2S, H2O, and Ar. Minimum detectabilities extend from 10−7 Torr liter for N2 and CO to less than 10−8 Torr liter for argon. Sample-system interactions and the limitations they place on the analysis are also discussed.
Experimental Techniques for the Study of Solid Surfaces
Authors: Propst F. M.
Published: July 2002

The techniques currently used for the study of solid surfaces will be reviewed and discussed. Emphasis will be placed on the comparison of the capabilities and limitations of the various techniques. In addition, the relationships between the various kinds of measurements will be discussed. Some areas of potential development will also be presented.
The Effect of Substrate Temperature on the Structure of Titanium Carbide Deposited by Activated Reactive Evaporation
Authors: Raghuram A. C. , Bunshah R. F.
Published: July 2002

A change in substrate temperature produces a marked change in the microstructure, preferred orientation, and microhardness of TiC deposits. At low temperatures (∼500 °C) the structure consists of tapered crystallites and changes to a structure consisting of columnar grains at the higher temperatures (∼1000 °C). The high temperature deposits exhibit very high microhardness values (∼4500–5000 kg/mm2 KHN).
UHV Outgassing Measurements on Various Carbons
Authors: Beitel George A. , Benson David K.
Published: July 2002

Mass spectral analyses were made of gases desorbed from carbon samples at increasing temperatures up to 2200 °K. Samples were initially outgassed above 2000 K, exposed to air for several hours at room temperature, and then tested in ultrahigh vacuum following a 24-hr bake at 300 °C. Four forms of carbon were tested (a) pyrolytic carbon, (b) Grafoil™ (Union Carbide), (c) vitreous carbon, and (d) pyrolyzed-phenolic fibers. The equivalent of several monolayers of gas (mostly H2 and CO) are evolved from all of the carbons except vitreous carbon. Less than a monolayer of gas is evolved from vitreous carbon during outgassing to 2000 K.
Atomistic simulation of fluorocarbon deposition on Si by continuous bombardment with energetic CF+ and CF2+
Authors: Abrams Cameron F. , Graves David B.
Published: July 2002

We have conducted molecular dynamics simulations of continuous CF+ and CF2+ ion bombardment of Si with incident energies Ei of 50, 100, and 200 eV at normal incidence. Continuous deposition of a fluorocarbon layer with a fluorine-to-carbon ratio (F/C) of about 0.5 occurs at all incident energies for CF+ ions. This layer grows on top of a mixed amorphous SixCyFz interfacial layer whose thickness increases with Ei. In the case of CF2+ bombardment, the steady-state transitions from relatively slow net fluorocarbon deposition at Ei=50 eV to relatively slow apparent net Si etching at Ei=200 eV. For CF2+, at all Ei’s, a relatively thin carbon-rich fluorocarbon overlayer with a F/C ratio of 0.5 also forms on top of a more fluorine-rich mixed interfacial layer whose thickness again increases with Ei, though not as sensitively as in the case of CF+. These findings support the important conclusion that the transition from net deposition to net etching due to fluorocarbon ion bombardment of Si is intimately related to the amount of energetic fluorine available due to ion fragmentation, which increases with both F content in the ion and ion energy.
Development of vacuum ultraviolet absorption spectroscopy technique employing nitrogen molecule microdischarge hollow cathode lamp for absolute density measurements of nitrogen atoms in process plasmas
Authors: Takashima Seigou , Arai Shigeo , Hori Masaru , Goto Toshio , Kono Akihiro , Ito Masafumi , Yoneda Katsumi
Published: July 2002

We have developed a vacuum ultraviolet absorption spectroscopy (VUVAS) technique employing a high-pressure nitrogen molecule (N2) microdischarge hollow cathode lamp (N2 MHCL) as a light source of the atomic nitrogen (N) resonance lines for measuring absolute N densities in process plasmas. The estimations of self-absorption and the emission line profiles of the N2 MHCL, which are necessary for absolute N density determination, were carried out. The measurement of absolute N densities have been demonstrated for an inductively coupled N2 plasma using the VUVAS system employing the N2 MHCL.
Band offset and structure of SrTiO3 /Si(001) heterojunctions
Authors: Chambers S. A. , Liang Y. , Yu Z. , Droopad R. , Ramdani J.
Published: July 2002

We have measured the band offsets and materials properties of epitaxial SrTiO3/Si(001) heterojunctions for both n and p substrates, with and without an interfacial SiO2 layer. The through-air transfer from the growth chamber to the photoemission system results in significant surface hydroxylation and roughening, although the SrTiO3–Si interface is undisturbed. Surface hydroxylation notwithstanding, the structural quality of 20 Å thick epitaxial SrTiO3 on Si(001) is comparable to that of bulk SrTiO3(001). We find valence and conduction band offsets of ∼2.1 and ∼0.0 eV, respectively, independent of doping type and the presence of SiO2. These results are consistent with theoretical band offset predictions based on the electron affinity rule, modified by the presence of an interface dipole.
Dynamic mixing deposition of niobium nitride films by cathodic arc plasma in ambient nitrogen
Authors: Zhang T. , Song J. H. , Tian X. B. , Chu P. K. , Brown I. G.
Published: July 2002

Two cathodic arc plasma deposition processes have been used to deposit niobium nitride films in ambient nitrogen: (a) cathodic arc plasma deposition without dynamic mixing and (b) cathodic arc plasma deposition with energetic ion dynamic mixing. Smooth and continuous niobium nitride films were fabricated at low temperature in process (b) but at higher temperature (500 °C) in process (a). The effects of the substrate temperature on the film composition and preferred orientation were investigated. In process (a), films deposited at room temperature and 300 °C exhibited a preferred orientation of (220) whereas those deposited at 500 °C showed a preferred orientation of (200). The nitrogen content in the film synthesized in process (b) is higher than that in the films deposited in process (a). Our results show that with energetic ion dynamic mixing, niobium nitride films with excellent properties can be fabricated at low substrate temperature using a niobium metal arc plasma source in a nitrogen plasma immersion configuration.
Ion energy distributions and optical emission spectra in NF3-based process chamber cleaning plasmas
Authors: Hsueh Hsin-Pai , McGrath Robert T. , Ji Bing , Felker Brian S. , Langan John G. , Karwacki Eugene J.
Published: July 2002

To minimize ion bombardment induced damage in NF3-based chamber cleaning plasmas, we have studied the effects of diluent gases and reactor pressure on ion energy distribution functions in NF3 plasmas. We have utilized plasma ion mass spectrometry, ion energy analysis, and optical emission spectroscopy in 25 mol % NF3 plasmas with argon, helium, and oxygen diluents. We have also compared the NF3-based plasma measurements to those of 50 mol % C2F6/O2 plasmas. We have demonstrated that diluting with helium and operating at higher pressures will reduce ion energies in NF3 plasmas while maintaining superior chamber cleaning performance. In addition, we have correlated the intensity ratio of specific argon emission lines to average ion energies at the grounded electrode. This correlation provides a practical diagnostics tool for further optimization work.
Quantitative analysis of nanoscale electronic properties in an AlxGa1−xN/GaN heterostructure field-effect transistor structure
Authors: Schaadt D. M. , Miller E. J. , Yu E. T. , Redwing J. M.
Published: July 2002

Local dC/dV spectroscopy performed in a scanning capacitance microscope is used to map, quantitatively and with high spatial resolution, lateral variations in the threshold voltage of an AlxGa1−xN/GaN heterostructure field-effect transistor epitaxial layer structure. Theoretical analysis and numerical simulations are used to quantify charge concentrations, the corresponding threshold voltage shifts, and the influence of the measurement apparatus on these results. High-resolution scanning capacitance and the associated threshold voltage images reveal round features <150 nm in diameter within which a shift in threshold voltage of about 1.5–2 V is measured. Theoretical analysis and numerical simulations indicate that these features are consistent with the presence of charged threading dislocations with a linear charge density of ∼107 e/cm−1 that cause localized partial or full depletion of carriers from the two-dimensional electron gas. Large-scale scanning capacitance images reveal variations in contrast over areas several microns in size with corresponding threshold voltage shifts of approximately 1 V. These large features are postulated to arise from a combination of thickness and composition variations in the AlxGa1−xN layer.
Characterization of iodoheptafluoropropane as a dielectric etchant. III. Effluent analysis
Authors: Karecki Simon , Chatterjee Ritwik , Pruette Laura , Reif Rafael , Vartanian Victor , Sparks Terry , Beu Laurie
Published: July 2002

The work presented in this article represents the third and final part of a series of articles which present a systematic evaluation of iodoheptafluoropropane (C3F7I) as a potential replacement for perfluorocompound chemistries in dielectric etch applications. In the experiments discussed in this series, 1- and 2-iodoheptafluoropropane based etch processes had been employed in a via etch application in an inductively coupled high density plasma etch tool. Part I of this article discusses etch process behavior of 1- and 2-iodoheptafluoropropane, while Part II examines films deposited by the 1-iodo isomer. This article will focus on the composition of the process effluent stream, as characterized by Fourier transform infrared (FTIR) spectroscopy. Data generated by both isomers of the compound will be presented and compared to those generated by conventional (C3F8- and C2F6-based) etch processes. Significant reductions in global warming emission (on the order of 80%–85%) were obtained relative to the conventional processes. Additionally, FTIR data were correlated with process and film analysis data presented in Parts I and II to generate better understanding of key plasma mechanisms in iodofluorocarbon etch environments.
Characterization of iodoheptafluoropropane as a dielectric etchant. I. Process performance evaluation
Authors: Karecki Simon , Chatterjee Ritwik , Pruette Laura , Reif Rafael , Vartanian Victor , Sparks Terry , Beu Laurie , Novoselov Konstantin
Published: July 2002

1- and 2-iodoheptafluoropropane were characterized extensively as potential replacement etchants for perfluorocompounds used in an oxide etch application. In the present study, via holes of critical dimension down to 0.35 μm were etched in an inductively coupled high density plasma tool. Oxide etch rate, mask and stop layer selectivities, and feature profile were among the principal metrics used to evaluate the performance of these compounds. A conventional (C3F8-based) etch process was used as a reference. Process behavior as a function of a number of variables—namely source power, bias power, etch gas flow, additive gas CH3F) flow, roof, wall, and chiller temperatures, and pressure was studied. While good etch rates and feature profiles were obtained, mask and stop layer selectivity was found to be limited. As a supplement to the experimental work, a set of ab initio quantum chemical calculations was undertaken to obtain enthalpies of dissociation for each of the bonds in the iodoheptafluoropropane molecules in order to better understand their dissociation pathways in plasma environments. Part I focuses on trends in process behavior as a function of the variables explored and discusses key mechanisms responsible for the observed effects. Parts II and III will focus on deposited film characterization and global warming emissions, respectively.
Development of an advanced low-energy electron diffraction technique using field-emitted electrons from scanning tunneling microscope tips
Authors: Mizuno Seigi
Published: July 2002

A prototype instrument has been demonstrated which employs a new technique for determining surface structures. The instrument consists of a scanning tunneling microscope (STM) tip as a field emission gun and a detector for projecting electron scattering patterns. The operation of the tips under a field emission condition with bias voltages of 14–50 V made it possible to observe the electron scattering patterns. These experimentally obtained patterns have been compared with calculated results showing close correlation, signifying that the obtained patterns are caused by the electrons scattered on a sample surface after emission from a STM tip. Suitable bias voltages between the tip and the sample for this system are discussed. Although further improvements in the method of extracting electrons are necessary in order to obtain certain diffraction patterns on this instrument, the results demonstrate that the new technique is capable of probing nanometer scale surface structures.
Gratings of regular arrays and trim exposures for ultralarge scale integrated circuit phase-shift lithography
Authors: Fritze M. , Tyrrell B. , Astolfi D. , Yost D. , Davis P. , Wheeler B. , Mallen R. , Jarmolowicz J. , Cann S. , Chan D. , Rhyins P. , Carney C. , Ferri J. , Blachowicz B. A.
Published: July 2002

Current semiconductor technology requires optical lithography to image feature sizes smaller than the exposure tool wavelength. In order to achieve this subwavelength imaging, some form of optical resolution-enhancement technology is required, with phase-shift methods offering the greatest potential enhancement. Major impediments to the wide-scale adoption of this technology have included mask cost, inspectability/repair, and turnaround time. The correction of optical proximity effects, which are typically large in phase-shift techniques, have also been an important issue. In this work, we propose a new type of phase-shift approach utilizing gratings of regular arrays and trim exposures. This method makes use of multiple-exposure phase-shift imaging of dense-only features. Proximity effects can be nearly eliminated along with the complex optical proximity corrections typically required on the mask. The simple phase-shift masters can also be reused for multiple designs, thereby addressing cost and turnaround time issues.