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Dieter P. Griffis - One of the best experts on this subject based on the ideXlab platform.
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SIMS analysis of high‐performance accelerator niobium
Surface and Interface Analysis, 2014Co-Authors: P. Maheshwari, Fred A. Stevie, Ganapati Rao Myneni, Gianluigi Ciovati, J. M. Rigsbee, Pashupati Dhakal, Dieter P. GriffisAbstract:Niobium is used to fabricate superconducting radio frequency accelerator modules because of its high critical temperature, high critical magnetic field, and easy formability. Recent experiments have shown a very significant improvement in performance (over 100%) after a high-temperature bake at 1400 °C for 3 h. SIMS analysis of this material showed the oxygen profile was significantly deeper than the native oxide with a shape that is indicative of diffusIon. Positive Secondary Ion mass spectra showed the presence of Ti with a depth profile similar to that of O. It is suspected that Ti is associated with the performance improvement. The source of Ti contaminatIon in the anneal furnace has been identified, and a new furnace was constructed without Ti. Initial results from the new furnace do not show the yield improvement. Further analyses should determine the relatIonship of Ti to cavity performance. Copyright © 2014 John Wiley & Sons, Ltd.
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Model study of electron beam charge compensatIon for Positive Secondary Ion mass spectrometry using a Positive primary Ion beam
Applied Surface Science, 2008Co-Authors: Zhengmao Zhu, Fred A. Stevie, Dieter P. GriffisAbstract:A new modeling approach has been developed to assist in the SIMS analysis of insulating samples. This approach provides informatIon on the charging phenomena occurring when electron and Positive primary Ion beams impact a low conductivity material held at a high Positive potential. The concept of effective leakage resistance aids in the understanding of the dynamic electrical properties of an insulating sample under dynamic analysis conditIons. Modeling of steady state electron beam charge compensatIon involves investigatIon of electron injectIon and charge drift. Using a Monte Carlo program to simulate electron injectIon and dc conductIon calculatIons to predict charge drift, detailed informatIon regarding charging phenomena can be determined.
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Improved understanding of an electron beam charge compensatIon method for magnetic sector Secondary Ion mass spectrometer analysis of insulators
Journal of Vacuum Science & Technology A: Vacuum Surfaces and Films, 2007Co-Authors: Zhengmao Zhu, Fred A. Stevie, Dieter P. GriffisAbstract:Good charge compensatIon has historically been difficult to achieve for Secondary Ion mass spectrometry Positive Secondary Ion depth profile analysis of highly insulating samples using a magnetic sector Secondary Ion mass spectrometer. A new charge compensatIon method has been developed utilizing an adjacent electron beam approach. A combinatIon of computatIonal simulatIon and quantitative characterizatIon of the charge compensatIon phenomenon was used to elucidate the underlying mechanisms of this charge compensatIon technique with the goal of further improving this method. Results of this approach show that a low intensity electron shower consisting of Secondary and backscattered electrons resulting from the impact of the primary electron beam with elements in the electron beam flight path may be responsible for charge compensatIon. It is also determined that the charge compensatIon provided by the adjacent impact technique can be further improved to provide better profile stability, higher mass resolut...
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Improved charge neutralizatIon method for depth profiling of bulk insulators using O2+ primary beam on a magnetic sector SIMS instrument
Applied Surface Science, 2004Co-Authors: A. L. Pivovarov, Fred A. Stevie, Dieter P. GriffisAbstract:Use of electrons for charge neutralizatIon during Positive Secondary Ion SIMS analysis of insulators has typically been achieved using coincident primary Ion and electron beams. The normal incidence electron gun on CAMECA magnetic sector SIMS instruments can effectively eliminate sample charging during analysis of thin insulating films if the electron energy is sufficient to penetrate the film. However, Positive Secondary Ion SIMS bulk insulator analysis using this instrument can be difficult, especially if high sputtering rates are required. A neutralizatIon method has been developed utilizing electron beam impact of a regIon adjacent to the sputtered area. Prior to analysis, the surface of the sample is coated with gold which provides a conductive surface layer and which has a high Secondary and backscattered electron yield. Results have been obtained showing excellent neutralizatIon for a variety of bulk insulators including glass, silica, alumina, and lithium niobate. Sputtering rates exceeding 2 nm/s have been achieved in bulk silica. The technique should be applicable to minerals and possibly for other materials in cases where the analyzed area cannot be directly irradiated with an electron beam.
R. G. Wilson - One of the best experts on this subject based on the ideXlab platform.
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Secondary Ion mass spectrometry quantificatIon of elements in TiSi2, TiN, and TiW matrices
Journal of Vacuum Science & Technology A: Vacuum Surfaces and Films, 1993Co-Authors: G. E. Lux, Fred A. Stevie, R. G. Wilson, P. M. Kahora, G. W. CochranAbstract:The titanium based matrices TiSi2, TiN, and TiW are used extensively in current semiconductor fabricatIon. QuantificatIon of elements in these matrices using Secondary Ion mass spectrometry (SIMS) is hampered by a lack of available informatIon on the relative Secondary Ion yields for the elements of interest and by a large number of mass interferences. This study provides the Ion yields in the form of relative sensitivity factors (RSFs) for a large number of elements Ion implanted into these three matrices and describes methods of analysis to circumvent mass interferences of important elements. The RSFs can be organized into patterns of Positive Secondary Ion RSFs versus IonizatIon potential and negative Secondary Ion RSFs versus electron affinity, similar to those measured for other matrices. The use of molecular Ions can improve detectIon limits for some elements with mass interferences that are beyond the mass resolutIon capabilities of many SIMS instruments. Depth resolutIon in TiW is adversely affect...
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Depth profiling and Secondary Ion mass spectrometry relative sensitivity factors and systematics for polymers/organics
Journal of Applied Physics, 1993Co-Authors: R. G. Wilson, G. E. Lux, C. L. KirschbaumAbstract:Depth profiles and Secondary Ion mass spectrometry (SIMS) relative sensitivity factors (RSF) for quantificatIon (inverse relative Ion yields) are reported for oxygen Ion bombardment and Positive Secondary Ion mass spectrometry and for cesium bombardment and negative Secondary Ion mass spectrometry measured for implants of more than 40 elements in PMMA/polymethyl methacrylate/Lucite/AZ111, polypyromellitimide/polyimide/Kapton, and epoxy, using magnetic sector SIMS instruments (CAMECA IMS 3f or 4f). The RSFs are plotted versus IonizatIon potential (Positive Secondary Ions) and versus electron affinity (negative Secondary Ions), and the resulting patterns are compared among themselves and with those for semiconductors reported previously. Charge compensatIon using electron flooding was employed in most cases for both oxygen (oblique incidence flooding) and cesium (normal incidence flooding) primary beams. Profiles in these low atomic number materials are relatively deep. Crater depths are sometimes difficult...
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Systematics of Positive Secondary Ion mass spectrometry relative sensitivity factors for Si and SiO2 measured using oxygen and argon Ion bombardment
Journal of Applied Physics, 1991Co-Authors: S. W. Novak, R. G. WilsonAbstract:We have measured normalized Positive Ion yields of more than 20 elements implanted into SiO2 and compare them with Positive Ion yields of the same elements sputtered from Si by oxygen and argon Ion bombardment. All measurements were made using similar instruments and similar primary Ion beam conditIons; thus, we compare Secondary Ion emissIon from an unoxygenated matrix (Si using argon Ion bombardment), from a partially oxygenated matrix (Si using oxygen Ion bombardment), and from a fully oxygenated matrix (SiO2). Plots of the logarithm of Secondary Ion yield or Secondary Ion mass spectrometry relative sensitivity factor (RSF) versus IonizatIon potential of the sputtered impurity elements exhibit primary linear trends for these three conditIons, the slopes of which decrease with increasing oxygenatIon. A trend line of opposite slope for impurity elements that have IonizatIon potential greater than about 10.5 eV is observed in each case. This latter trend moves to lower values of yield (higher RSF) with increasing oxygenatIon, perhaps as the result of competitIon from electronegative elements with oxygen in forming element–Si bonds. These observed changes are primarily the result of increasing the oxygen content in the surface of the Si.
Fred A. Stevie - One of the best experts on this subject based on the ideXlab platform.
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SIMS analysis of high‐performance accelerator niobium
Surface and Interface Analysis, 2014Co-Authors: P. Maheshwari, Fred A. Stevie, Ganapati Rao Myneni, Gianluigi Ciovati, J. M. Rigsbee, Pashupati Dhakal, Dieter P. GriffisAbstract:Niobium is used to fabricate superconducting radio frequency accelerator modules because of its high critical temperature, high critical magnetic field, and easy formability. Recent experiments have shown a very significant improvement in performance (over 100%) after a high-temperature bake at 1400 °C for 3 h. SIMS analysis of this material showed the oxygen profile was significantly deeper than the native oxide with a shape that is indicative of diffusIon. Positive Secondary Ion mass spectra showed the presence of Ti with a depth profile similar to that of O. It is suspected that Ti is associated with the performance improvement. The source of Ti contaminatIon in the anneal furnace has been identified, and a new furnace was constructed without Ti. Initial results from the new furnace do not show the yield improvement. Further analyses should determine the relatIonship of Ti to cavity performance. Copyright © 2014 John Wiley & Sons, Ltd.
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Model study of electron beam charge compensatIon for Positive Secondary Ion mass spectrometry using a Positive primary Ion beam
Applied Surface Science, 2008Co-Authors: Zhengmao Zhu, Fred A. Stevie, Dieter P. GriffisAbstract:A new modeling approach has been developed to assist in the SIMS analysis of insulating samples. This approach provides informatIon on the charging phenomena occurring when electron and Positive primary Ion beams impact a low conductivity material held at a high Positive potential. The concept of effective leakage resistance aids in the understanding of the dynamic electrical properties of an insulating sample under dynamic analysis conditIons. Modeling of steady state electron beam charge compensatIon involves investigatIon of electron injectIon and charge drift. Using a Monte Carlo program to simulate electron injectIon and dc conductIon calculatIons to predict charge drift, detailed informatIon regarding charging phenomena can be determined.
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Improved understanding of an electron beam charge compensatIon method for magnetic sector Secondary Ion mass spectrometer analysis of insulators
Journal of Vacuum Science & Technology A: Vacuum Surfaces and Films, 2007Co-Authors: Zhengmao Zhu, Fred A. Stevie, Dieter P. GriffisAbstract:Good charge compensatIon has historically been difficult to achieve for Secondary Ion mass spectrometry Positive Secondary Ion depth profile analysis of highly insulating samples using a magnetic sector Secondary Ion mass spectrometer. A new charge compensatIon method has been developed utilizing an adjacent electron beam approach. A combinatIon of computatIonal simulatIon and quantitative characterizatIon of the charge compensatIon phenomenon was used to elucidate the underlying mechanisms of this charge compensatIon technique with the goal of further improving this method. Results of this approach show that a low intensity electron shower consisting of Secondary and backscattered electrons resulting from the impact of the primary electron beam with elements in the electron beam flight path may be responsible for charge compensatIon. It is also determined that the charge compensatIon provided by the adjacent impact technique can be further improved to provide better profile stability, higher mass resolut...
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Improved charge neutralizatIon method for depth profiling of bulk insulators using O2+ primary beam on a magnetic sector SIMS instrument
Applied Surface Science, 2004Co-Authors: A. L. Pivovarov, Fred A. Stevie, Dieter P. GriffisAbstract:Use of electrons for charge neutralizatIon during Positive Secondary Ion SIMS analysis of insulators has typically been achieved using coincident primary Ion and electron beams. The normal incidence electron gun on CAMECA magnetic sector SIMS instruments can effectively eliminate sample charging during analysis of thin insulating films if the electron energy is sufficient to penetrate the film. However, Positive Secondary Ion SIMS bulk insulator analysis using this instrument can be difficult, especially if high sputtering rates are required. A neutralizatIon method has been developed utilizing electron beam impact of a regIon adjacent to the sputtered area. Prior to analysis, the surface of the sample is coated with gold which provides a conductive surface layer and which has a high Secondary and backscattered electron yield. Results have been obtained showing excellent neutralizatIon for a variety of bulk insulators including glass, silica, alumina, and lithium niobate. Sputtering rates exceeding 2 nm/s have been achieved in bulk silica. The technique should be applicable to minerals and possibly for other materials in cases where the analyzed area cannot be directly irradiated with an electron beam.
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Secondary Ion mass spectrometry quantificatIon of elements in TiSi2, TiN, and TiW matrices
Journal of Vacuum Science & Technology A: Vacuum Surfaces and Films, 1993Co-Authors: G. E. Lux, Fred A. Stevie, R. G. Wilson, P. M. Kahora, G. W. CochranAbstract:The titanium based matrices TiSi2, TiN, and TiW are used extensively in current semiconductor fabricatIon. QuantificatIon of elements in these matrices using Secondary Ion mass spectrometry (SIMS) is hampered by a lack of available informatIon on the relative Secondary Ion yields for the elements of interest and by a large number of mass interferences. This study provides the Ion yields in the form of relative sensitivity factors (RSFs) for a large number of elements Ion implanted into these three matrices and describes methods of analysis to circumvent mass interferences of important elements. The RSFs can be organized into patterns of Positive Secondary Ion RSFs versus IonizatIon potential and negative Secondary Ion RSFs versus electron affinity, similar to those measured for other matrices. The use of molecular Ions can improve detectIon limits for some elements with mass interferences that are beyond the mass resolutIon capabilities of many SIMS instruments. Depth resolutIon in TiW is adversely affect...
Bernhard Spengler - One of the best experts on this subject based on the ideXlab platform.
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Secondary‐Ion generatIon from large keV molecular primary Ions incident on a stainless‐steel dynode
Rapid Communications in Mass Spectrometry, 1992Co-Authors: Raimund Kaufmann, Dieter Kirsch, Hans‐achim Rood, Bernhard SpenglerAbstract:Positive and negative Secondary Ions from large (up to 40 KDa) peptide and protein primary Ions incident at 5–40 keV collisIonal energies on a stainless-steel (mesh) conversIon dynode have been investigated in a tandem (reflectron) time-of-flight arrangement. Negative Secondary-Ion spectra consisted mainly of H− and C2H−, C2H Ions; Positive Secondary-Ion spectra were more complex and contained prominent signals due to H+, Na+ and K+, and further signals at m/z. 28, 41, 43, 45, 73 up to m/z 326. The Secondary mass spectra were qualitatively very similar amongst the various peptide primaries and not different from those of other organic projectiles such as, for example, coronene or cyclodextrin. With increasing mass of the primary Ion, ratios of the Secondary-Ion abundances changed drastically in the negative Secondary-Ion spectra (increase of higher m/z signals, decrease of H−). Since most of the Positive Secondary Ions could be attributed to a silicon-organic surface contaminatIon of the dynode (vacuum grease), it is concluded that the formatIon of such Secondary Ions is due to sputtering rather than surface-induced dissociatIon.
Peter Hoppe - One of the best experts on this subject based on the ideXlab platform.
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SpeciatIon of Nitrogen-Bearing Species Using Negative and Positive Secondary Ion Spectra with Nano Secondary Ion Mass Spectrometry.
Analytical chemistry, 2016Co-Authors: Baerbel Sinha, Peter HoppeAbstract:In this study, we demonstrate that Nano Secondary Ion Mass Spectrometry (NanoSIMS) can be used to differentiate different nitrogen-containing species commonly observed in atmospheric aerosol particles with micrometer or submicrometer spatial resolutIon, on the basis of the relative intensity of Secondary Ion signals, both in negative and Positive Secondary Ion mode, without the need to chemically or physically separate the samples. Compounds tested include nitrate, nitrite, ammonium salts, urea, amino acids, sugars, organic acids, amides, triazine, imidazole, protein, and biological tissue. We show that NO2– Secondary Ions are unique to the decompositIon of nitrate and nitrite salts, whereas NH4+ Secondary Ions are unique to samples containing ammonium Ions, with low signal intensities observed from amino groups but none from biological tissue. CN– signals are obtained from all nitrogen-bearing compounds, but relative signal intensities are the highest for organic nitrogen-containing compounds. We demonst...