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A study of the initial oxidation of evaporated thin films of aluminum by AES, ELS and ESD
Classified abstracts 5562-5571 identify the phases present. The depth pro&s have characteristic features consistent with the phases identified by x-ray diffraction: Cubic TiN, tetragonal T&N and hexagonal a-Ti, cubic ZrN and hexagonal a-Zr and a-Hf N solid solutions. The Hf nitride surface phase was too thin to be detected by x-rays. A semiquantitative analysis of Auger intensities is described utilizing the composition of the phases identified by x-ray diffraction. (Canada) P T Dawaoa ad S A J Staayk, J Vat Sci Technol, 21 (l), 1982.36-41. 37 5562. A new metbod for tbe investigationof stress in MIS devieea ting SEM electron clmnneliogpttaar. (USA) A proposed new method to measure the elastic stress in silicon induced by the presence of a thin amorphous layer is presented. The method is based on measuring the di&rence in the selected area channeling patterns generated by a stress-free region of the substrate and a stressed region located under an insulating layer. The maximum thickness of the amorphous insulating layer which can be used before the backscattered signal is totally absorbed was found to be approximately 600 A for silicon dioxide and 400 A for silicon nitride. The strain in SiO, and Si,N, was found to he thickness dependent. For silicon dioxide, the stress varied between lo9 to 10” dynes cmv2. For silicon nitride, the stress was on the order of 10” dynes cm-‘. G E Davis and M E Taylor, J Vat Sci technol, 19 (4), 1981, 1024-1029. 31 5563. Dealgn 8nd mormanee of qaadropol&aaed SIMS iustrmnents: a critical review. (GB) Currently employed quadrupole-based SIMS instrumentation is reviewed critically. The various problems of relevance are discussed in great detail The importance of phase space dynamics is outlined with particular reference to the acceptance characteristics of quadrupole mass filters. The performance of most instruments used to measure secondary ion energy spectra is found to be much less under control than anticipated. By contrast, quadrupole-based in-depth analysers and ion micro-probes appear to operate quite well. It is shown that in order to optimize the layout of SIMS instruments employed for trace analysis and depth profiling, a detailed knowledge of bombardment-induced dkts is mandatory. (West Germany) Klaus Wittmuk, Vacuum, 32 (2), 1982,65-89. 37 5564. A simple eflklent SIMS apparatm for ase on accelerator berm liws (GB) A simple SIMS system is described which can be used on an isotope separator beam line to provide immediate analysis of an implanted sample without breaking vacuum. A further feature of the devia is a retarding grid which will allow elimination of low energy components in the secondary ion spectra and can also be used to determine the energy distribution of the secondary species. Preliminary results for aluminium samples are given. H Boburi and J S Colllgon, Vacuwn, 32 (5), 1982,293-295. 37 spectroscopy study on interfacial reaetlons in multilayer thin film systans (USA) Interfacial reactions at room temperature in multilayer thin film systems have been investigated by the Auger Electron Spectroscopy method. The multilayer thin film structure consists of metal, native oxide and/or deposited interfacial layers on metal and semiconductor substrates, Various combinations of metals and interfacial layers on different substrates have been investigated. For the multilayer systems Au, Ag, Cu and Cr were used as metals, GeO,, B&O,, SnO,, Sb,O,, Ga,O, and As,O, were used as interfacial layers and GaAs, Si and Fe were used as substrates. Only ‘metal’ atoms from the interfacial oxide layers (Ge from GeOl, Sb from Sb203, Bi from B&OS, Sn from SnO, and Ga and As from the native oxide mixture of Ga,Oa and As,O,) were detected on the metal surface of Metal-Interfacial layer-Semiconductor and Metal-Interfacial layer-Metal-Semiconductor structures. This indicates that the interfacial reaction takes place only at the metal-interfacial layer interface. ‘Driveout’diffusion is present at all interfacial reactions. The interfacial reactions and the drive-out diffusion processes are thought to play an important role in the degradation of thin film multilayer structures. Klril A Pan&&v and Edward Y Wang, J Appf Phys, 53 (6). 1982, 4422-4421. 5566. Auger &etron
31 5566. Secondary loll mass spectmlnetry stndy of iigbt1ydoped f-type GlAs films grown by molecahr beam epitaxy. (USA) Lightly doped ptype GaAs films grown by molecular beam cpitaxy on Crdoped substrates have been chemically analysed using dynamic secondary ion mass spectrometry. Residual levels of Cr are, in general, below 4 x 10” cm-). A major source of impurities in such material is identified. The elTectof substrate temperature on the concentration of B, Mg, Al, Si, Ca, Cr, Mn, Fe and Cu are reported and their likely effect upon the minority carrier properties of the layers is discussed. (GB) J B Clegg et al, J Appl Phys, 53 (6), 1982,45184520. 37 5567. F, r&orp& on Sl oIm~ul with SIMS and QCM. (USA) The positive secondary ion mass spectra (SIMS) have heen observed following exposure of polycrystalline Si to molecular F, at room temperature. Si’ and SiF+ are the only positive ions containing Si or F which are seen with sign&ant intensity. The intensity of the SiF* peak has been measured as a function of the fluorine coverage as determined by quartz crystal microbalana (QCM) methods. The primary ion beam consisted of 1 keV Ar+ ions at a current density in the range of lo-’ A cm-*. The results of this SiF+ versus np (fluorine atom density) calibration were found to depend on the energy of the SiF+ ions selected by the energy tilter in front of the SIMS quadrupole. The SiF+ peak increases more strongly with nF when low energy SiF+ ions are monitored. This result is consistent with the notion that proportionately fewer low energy secondary ions are observed from surfaces which have a low secondary ion yield. J W Colnwn ct al, J Vat Sci Technol, 20 (3), 1982,480-483. ~ice&sz s%.Depthproti&agaIldlflterfaeealul*oalng metry. (USA) The use.of variable energy (1.5 to 5.5 eV) and variable angle of incidence (45” to 85’) ellipsometry makes possible a nondestructive analysis of thin lilms and interfaces, described in multilayer models. This is demonstrated for the following selected cases: depth profiling of B and Se implanted in GaAs with the thermal annealing, transition region betwcm a crystalline Si substrate and a CVD deposited Si,N. tilm. In this latter case+thermal nitridation of Si is examined in situ by attaching the ellipsometer to the CVD chamber and a rough transition between c-Si and SiaN, is confirmed. J B Theeten and M Ennan, J Vat Sci Technol, 20 (3), 1982,471-475. 37 5569. Quasi-liquid states observed on & heam microtextured surfaces. (USA)
Liquid-like properties have been observed on surface structures developed by means of ion beam microtexturing. The structures include cones, pyramids or wavelike formations. The observed liquid-like e!Tects are drips and ripples on the sides of cones, droplet formation, the apparent flow and coalescence of closely packed structures, wetting angle and other surfaa tension elfects and the bending ofcones by additional heating. The bulk temperatures are in the range of WC. These effects are seen to some extent on Cu, Al, Au, Pb and Ni substrates. S M Rosanagel and R S Rohlmon, J Vat Sci Techd, 20 (3). 1982,506-509. 37 5570. Hydrogen adsorptlen 011Si(lll)-(7 x 7). (USA) Deuterium adsorption on the clean Si( 111~(7 x 7) surface was quantitatively studied by determining the absolute coverage as a function of exposure using nuclear microanalysis. The coverage was correlated with structural changes seen by low energy electron diffraction and the high energy ion scattering surface peak. A saturation coverage of 1.25kO.13 monolayers was established for activated deuterium adsorption. R J Calhertaon et al, J Vat Sci 7’echnol. 20 (3), 1982, 868-871. 37 5571. A study of tbe initialoxidation of evaporated thin films of llumiaium by AES, EIS and ESD. (USA) The room temperature, low pressure, oxidation of evaporated aluminium thin films has been studied by AES, ELS and ESD. ESD was the most sensitive of the three methods to characterize a ‘clean’ aluminium surface. Two oxidation stages were distinguished in the &3CxlOL oxygen exposure range. Between 0 and 50 L, the chemisorption of oxygen atoms was characterized by a fast decrease of the 67 eV AES Al oeak and the 10 eV surface plasmon peak, and by a simultaneous increase-of the oxygen AES and ESD signals. The 52 eV AES peak of oxidized Al appeared only after 30 L. After 50 L, a change in slope in all AES and ESD signal variatiyns 357
Classified abstracts 5572-5579 was attributed to the slow growth of a thin layer of aluminium oxide, which after 3ooO L was still only a few angstroms thick. M Bujor et al, J Vat Sci Technol, 20 (3), 1982, 392-394. 17
5572. CorreIatio~~ between deposition condition,
Auger analysh eIectrical cbaracteristica of MBE-ttrown SiO films on GaAs. (GB)
alld
The possibility of insulating film d&position in a molecular beam kpitaxy (MBE) system is interesting for the in situ fabrication of electronic devices. The conditions of deposition of SiO which can be evaporated under vacuum at above 1ooo”C has been studied. A chart of SiO colours and associated thicknesses giving a refractive index of 2.15 has been obtained. When the deposition rates were about 5 A s-l, the maximum dielectric strength was small. But, with deposition rates of about 30 A se1 and a 300°C substrate temperature, some results were typically (i) breakdown electric field E=2x lo6 Vcn-‘, (ii) resistivity p=4 x 10’2 R cm at E=0.46 x 10’ V cm-‘, (iii) dielectric constant =4. Moreover, since these good values and the Auger electron spectroscopy (AES) were not modified by a 600°C substrate heating (30 min) after the deposition, the SiO can be considered stable enough. The Auger analysis has also shown the connection between stoichiometry and stability. Finally, the C/Vcurves of metal-SiO-GaAs structures allowed the examination of the depletion conditions. (France) R C BIancbet et ai, Vacuum, 32 (l), 1982, 3-8. 37 5573. Auger signal inter&y dependence on surface area (roughness). (USA) The effects of surface roughness on Auger electron spectroscopy (AES) and electron spectroscopy for chemical analysis (ESCA) have been a problem in surface analysis. In this study, the quantitative relationship between surface area and Auger signal intensity was studied using a variety of electrodeposited Cu foils. The foil surfaces studied here can be classified into two categories: Type A is cone shaped (dia about 5 b height about 5 p) and Type B is cone shaped with small nodules (dia about 1 p) on the surface. The surface area of foil samples was measured by the Brunauer, Emmett and Teller (BET) gas adsorption technique. In addition, the foil samples were characterized by scanning electron microscopy and light scattering experiments. The Auger signal intensities of foils were studied after thin film (gold or zinc oxide) deposition. The results indicate that (1) there are strong correlations between surface area data, Auger signal intensities and light reflectance data for both Type A and Type B foils; and (2) this kind of Auger signal intensity dependencc on surface area (roughness) is independent of the energy for the range studied (up to 1000 eV) here. 0 K T Wu and E M Butler, J Vuc Sci Tech&, M (3), 1982.453457.
accurately portrayed by using a molecular oxygen leak to enhance the secondary ion yields when sputtering with argon. Additionally, the analysis of trace elements at oxide-metal or met&metal interfaces is greatly enhanced due to the reduction of surface recontamination by reaction with the residual gas atmosphere of the chamber when the SIMS analysis is performed in ultrahigh vacuum (< 5 x lo-* torr) conditions. The above points will be illustrated by the analysis of oxide-metal structures, low kV ion implantations, and base semiconductor materials analysis. B F PbiIIips, J Vat Sci Tech&,
20 (3), 1982, 793-796.
5576. SurfPce analyses of severely corroded coal liquefaction components nod model Iaboratory films (USA)
37 vessel
When a high chloride content coal was run in the Wilsonville, Alabama Solvent Refined Coal (SRC) pilot plant, an unusually high rate of corrosion was observed in parts of a distiIlation tower. Appreciable corrosion was not observed during prior operation with lower chloride content coals. Corroded components were examined with ESCA with a goal of understanding the source and mechanism of the rapid corrosion. Process conditions were modeled in the IMMR laboratory with the goal of isolating the critical factors responsible for the severe corrosion. The addition of NH,Cl to low corrosivity SRC liquids resulted in severe corrosion of test samples. Films forming on the teat samples and the surfaces of components taken from the corroded areas of the SRC vessel has similar spectra suggesting that the laboratory experiment had duplicated the conditions leading to severe corrosion in the SRC tower. The consequences of a low level of chlorine in the components and the film are discussed. Depth profiles revealed a surface depletion of Fe and Cr in the samples. Possible corrosion mechanisms are considered. R B Shalvoy et PI, J Vuc Sci Tech&, 20 (S), 1982, 1060-1063. 37 5577. Artifacts observed during Auger profiling of Ta, Ti and W metals, nitrides and oxynitrides
(USA)
M Nisbijima et al, Reo Sci Instrum, 53 (6), 1982, 790-796.
Studies of C xyy Auger spectra indicate carbide formation in certain metals and compounds resulting from ion beam bombardment of contaminated (air exposed) surfaces. Carbide buildup on W, Ta and Ti surfaces after ‘static’sputter cleaning in an AES system, oaxlrred in the presence ofsmall partial pressures of CH, generated from the specimen chamber walls and ion pump well. This carbide buildup was greatly accelerated by electron beam irradiation. (Canada) S Ingey et al, J Vat Sci Tech&, 20 (4), 1982, 968-970. . 37 5578. An Auger electron spectroscopy (AES) study of the initial stages of oxidation of the single crystal Be (0001) surface. (USA) The oxidation of Be(OOOl),in particular the early stages of the reaction, was tracked dynamically by AES using acomputer controlled single pass CMA. The reaction was followed by monitoring the three Auger transitions, Be.(KVV), BeO(KVV) and O(KVV) in dN/dE mode. Because the Lk(KVV) and the EkO(KVV) signals overlap, a multiple linear regression analysis based on a linear combination of the spectra of clean, cleaved Be and a Be0 crystal was done to separate them. Results have been obtained for oxygen partial pressures ranging from 4.7 x lo-’ Pa (3.6 x 10e9 torr) to 1.3 x 10e4 Pa. Considerable structure is seen in the uptake curves suggesting the occurrence of multiple stages of growth. The oxidation process appears to be linearly dependent on pressure for high pressures. Further conclusions are made difficult due to the strong enhancement of the oxidation by the AES incident electron beam. Finally, at all pressures studied, an excess of oxygen signal compared to that expected from stoichiometric Be0 exists in the very early stage of the oxidation. D E Fowler and J M BIakely, J Vat Sci Technol, Xl (4), 1982, 93&933.
37 5575. SIMS analysis of thin surface Iayers and low kV ion implnnts relnted to VLSI and VHSIC materials devdopment. (USA) The production of smaller geometries and faster switching speeds in integrated circuits as a requirement for VLSI and VHSIC development has produced a whole new series of problems to be studied using surface analysis techniques. Scanning Auger electron spectrometry can achieve the high spatial resolution required for surface analysis but is complemented in the depth analysis mode by the increased sensitivity of secondary ion mass spectrometry (SIMS) for many elements either intentionally or accidentally present. If areas approximately 1 mm2 are available for analysis, B and As in Si can be depth-profiled down to the 10’6-10’Batoms cme3 range. Also, the ability to perform the depth profile slowly allows the near surface structure of low kV implants to be
37 5579. AES and SEM studies of oxide nod suIBde scales formed on sputterdeposited 304 stainless steel at #JO aad 950°C. (USA) High temperature (800-950°C) corrosion studies of fine-grained sputterdeposited 304 stainless steel have been conducted at low pressures (< lo-’ Pa) in an Auger electron spectroscopy (AES) uhv chamber and compared with studies performed in an environment of mixed gases containing 0 and S. In situ surface analysis performed at low gas pressures has provided a detailed examination of the diffusion processes that occur during alloy corrosion. Oxide scales formed at 10e2 Pa 0, on sputterdeposited fine-grained 304 stainless steel have been found to closely resemble those formed in mixed-gas environments at atmospheric pressure. suggesting that the same mechanisms are active in both
37 5574. Apparatus for high-resolution vibrational electron energy-loss spectroscopy of solid surfaces. (USA)
A high-resolution vibrational electron energy-loss spectrometer of 127”cylindrical electrostatic deflection type has been constructed for surface studies. In the direct mode, an electron current at the collector entrance of 2.3 x lo-” A is obtained with the energy spread (full width at halfmaximum) of60 cm- 1for electrons whose energy at the sample position is 5 eV. A ghost reduction slit is used to suppress spurious peaks due to the electron reflection from electrodes of the analyser. Electron energy-loss spectroscopy can be combined in situ with low-energy electron diffraction, Auger electron spectroscopy, and thermaldesorption mass spectroscopy. Design and performance of the apparatus are reported. The vibrational spectrum of the Ni(ll0) (1 x 2)-H surface formed at room temperature is presented and the location of hydrogen atoms on the surface is discussed.
(Japan)
358
31 5566. Secondary loll mass spectmlnetry stndy of iigbt1ydoped f-type GlAs films grown by molecahr beam epitaxy. (USA) Lightly doped ptype GaAs films grown by molecular beam cpitaxy on Crdoped substrates have been chemically analysed using dynamic secondary ion mass spectrometry. Residual levels of Cr are, in general, below 4 x 10” cm-). A major source of impurities in such material is identified. The elTectof substrate temperature on the concentration of B, Mg, Al, Si, Ca, Cr, Mn, Fe and Cu are reported and their likely effect upon the minority carrier properties of the layers is discussed. (GB) J B Clegg et al, J Appl Phys, 53 (6), 1982,45184520. 37 5567. F, r&orp& on Sl oIm~ul with SIMS and QCM. (USA) The positive secondary ion mass spectra (SIMS) have heen observed following exposure of polycrystalline Si to molecular F, at room temperature. Si’ and SiF+ are the only positive ions containing Si or F which are seen with sign&ant intensity. The intensity of the SiF* peak has been measured as a function of the fluorine coverage as determined by quartz crystal microbalana (QCM) methods. The primary ion beam consisted of 1 keV Ar+ ions at a current density in the range of lo-’ A cm-*. The results of this SiF+ versus np (fluorine atom density) calibration were found to depend on the energy of the SiF+ ions selected by the energy tilter in front of the SIMS quadrupole. The SiF+ peak increases more strongly with nF when low energy SiF+ ions are monitored. This result is consistent with the notion that proportionately fewer low energy secondary ions are observed from surfaces which have a low secondary ion yield. J W Colnwn ct al, J Vat Sci Technol, 20 (3), 1982,480-483. ~ice&sz s%.Depthproti&agaIldlflterfaeealul*oalng metry. (USA) The use.of variable energy (1.5 to 5.5 eV) and variable angle of incidence (45” to 85’) ellipsometry makes possible a nondestructive analysis of thin lilms and interfaces, described in multilayer models. This is demonstrated for the following selected cases: depth profiling of B and Se implanted in GaAs with the thermal annealing, transition region betwcm a crystalline Si substrate and a CVD deposited Si,N. tilm. In this latter case+thermal nitridation of Si is examined in situ by attaching the ellipsometer to the CVD chamber and a rough transition between c-Si and SiaN, is confirmed. J B Theeten and M Ennan, J Vat Sci Technol, 20 (3), 1982,471-475. 37 5569. Quasi-liquid states observed on & heam microtextured surfaces. (USA)
Liquid-like properties have been observed on surface structures developed by means of ion beam microtexturing. The structures include cones, pyramids or wavelike formations. The observed liquid-like e!Tects are drips and ripples on the sides of cones, droplet formation, the apparent flow and coalescence of closely packed structures, wetting angle and other surfaa tension elfects and the bending ofcones by additional heating. The bulk temperatures are in the range of WC. These effects are seen to some extent on Cu, Al, Au, Pb and Ni substrates. S M Rosanagel and R S Rohlmon, J Vat Sci Techd, 20 (3). 1982,506-509. 37 5570. Hydrogen adsorptlen 011Si(lll)-(7 x 7). (USA) Deuterium adsorption on the clean Si( 111~(7 x 7) surface was quantitatively studied by determining the absolute coverage as a function of exposure using nuclear microanalysis. The coverage was correlated with structural changes seen by low energy electron diffraction and the high energy ion scattering surface peak. A saturation coverage of 1.25kO.13 monolayers was established for activated deuterium adsorption. R J Calhertaon et al, J Vat Sci 7’echnol. 20 (3), 1982, 868-871. 37 5571. A study of tbe initialoxidation of evaporated thin films of llumiaium by AES, EIS and ESD. (USA) The room temperature, low pressure, oxidation of evaporated aluminium thin films has been studied by AES, ELS and ESD. ESD was the most sensitive of the three methods to characterize a ‘clean’ aluminium surface. Two oxidation stages were distinguished in the &3CxlOL oxygen exposure range. Between 0 and 50 L, the chemisorption of oxygen atoms was characterized by a fast decrease of the 67 eV AES Al oeak and the 10 eV surface plasmon peak, and by a simultaneous increase-of the oxygen AES and ESD signals. The 52 eV AES peak of oxidized Al appeared only after 30 L. After 50 L, a change in slope in all AES and ESD signal variatiyns 357
Classified abstracts 5572-5579 was attributed to the slow growth of a thin layer of aluminium oxide, which after 3ooO L was still only a few angstroms thick. M Bujor et al, J Vat Sci Technol, 20 (3), 1982, 392-394. 17
5572. CorreIatio~~ between deposition condition,
Auger analysh eIectrical cbaracteristica of MBE-ttrown SiO films on GaAs. (GB)
alld
The possibility of insulating film d&position in a molecular beam kpitaxy (MBE) system is interesting for the in situ fabrication of electronic devices. The conditions of deposition of SiO which can be evaporated under vacuum at above 1ooo”C has been studied. A chart of SiO colours and associated thicknesses giving a refractive index of 2.15 has been obtained. When the deposition rates were about 5 A s-l, the maximum dielectric strength was small. But, with deposition rates of about 30 A se1 and a 300°C substrate temperature, some results were typically (i) breakdown electric field E=2x lo6 Vcn-‘, (ii) resistivity p=4 x 10’2 R cm at E=0.46 x 10’ V cm-‘, (iii) dielectric constant =4. Moreover, since these good values and the Auger electron spectroscopy (AES) were not modified by a 600°C substrate heating (30 min) after the deposition, the SiO can be considered stable enough. The Auger analysis has also shown the connection between stoichiometry and stability. Finally, the C/Vcurves of metal-SiO-GaAs structures allowed the examination of the depletion conditions. (France) R C BIancbet et ai, Vacuum, 32 (l), 1982, 3-8. 37 5573. Auger signal inter&y dependence on surface area (roughness). (USA) The effects of surface roughness on Auger electron spectroscopy (AES) and electron spectroscopy for chemical analysis (ESCA) have been a problem in surface analysis. In this study, the quantitative relationship between surface area and Auger signal intensity was studied using a variety of electrodeposited Cu foils. The foil surfaces studied here can be classified into two categories: Type A is cone shaped (dia about 5 b height about 5 p) and Type B is cone shaped with small nodules (dia about 1 p) on the surface. The surface area of foil samples was measured by the Brunauer, Emmett and Teller (BET) gas adsorption technique. In addition, the foil samples were characterized by scanning electron microscopy and light scattering experiments. The Auger signal intensities of foils were studied after thin film (gold or zinc oxide) deposition. The results indicate that (1) there are strong correlations between surface area data, Auger signal intensities and light reflectance data for both Type A and Type B foils; and (2) this kind of Auger signal intensity dependencc on surface area (roughness) is independent of the energy for the range studied (up to 1000 eV) here. 0 K T Wu and E M Butler, J Vuc Sci Tech&, M (3), 1982.453457.
accurately portrayed by using a molecular oxygen leak to enhance the secondary ion yields when sputtering with argon. Additionally, the analysis of trace elements at oxide-metal or met&metal interfaces is greatly enhanced due to the reduction of surface recontamination by reaction with the residual gas atmosphere of the chamber when the SIMS analysis is performed in ultrahigh vacuum (< 5 x lo-* torr) conditions. The above points will be illustrated by the analysis of oxide-metal structures, low kV ion implantations, and base semiconductor materials analysis. B F PbiIIips, J Vat Sci Tech&,
20 (3), 1982, 793-796.
5576. SurfPce analyses of severely corroded coal liquefaction components nod model Iaboratory films (USA)
37 vessel
When a high chloride content coal was run in the Wilsonville, Alabama Solvent Refined Coal (SRC) pilot plant, an unusually high rate of corrosion was observed in parts of a distiIlation tower. Appreciable corrosion was not observed during prior operation with lower chloride content coals. Corroded components were examined with ESCA with a goal of understanding the source and mechanism of the rapid corrosion. Process conditions were modeled in the IMMR laboratory with the goal of isolating the critical factors responsible for the severe corrosion. The addition of NH,Cl to low corrosivity SRC liquids resulted in severe corrosion of test samples. Films forming on the teat samples and the surfaces of components taken from the corroded areas of the SRC vessel has similar spectra suggesting that the laboratory experiment had duplicated the conditions leading to severe corrosion in the SRC tower. The consequences of a low level of chlorine in the components and the film are discussed. Depth profiles revealed a surface depletion of Fe and Cr in the samples. Possible corrosion mechanisms are considered. R B Shalvoy et PI, J Vuc Sci Tech&, 20 (S), 1982, 1060-1063. 37 5577. Artifacts observed during Auger profiling of Ta, Ti and W metals, nitrides and oxynitrides
(USA)
M Nisbijima et al, Reo Sci Instrum, 53 (6), 1982, 790-796.
Studies of C xyy Auger spectra indicate carbide formation in certain metals and compounds resulting from ion beam bombardment of contaminated (air exposed) surfaces. Carbide buildup on W, Ta and Ti surfaces after ‘static’sputter cleaning in an AES system, oaxlrred in the presence ofsmall partial pressures of CH, generated from the specimen chamber walls and ion pump well. This carbide buildup was greatly accelerated by electron beam irradiation. (Canada) S Ingey et al, J Vat Sci Tech&, 20 (4), 1982, 968-970. . 37 5578. An Auger electron spectroscopy (AES) study of the initial stages of oxidation of the single crystal Be (0001) surface. (USA) The oxidation of Be(OOOl),in particular the early stages of the reaction, was tracked dynamically by AES using acomputer controlled single pass CMA. The reaction was followed by monitoring the three Auger transitions, Be.(KVV), BeO(KVV) and O(KVV) in dN/dE mode. Because the Lk(KVV) and the EkO(KVV) signals overlap, a multiple linear regression analysis based on a linear combination of the spectra of clean, cleaved Be and a Be0 crystal was done to separate them. Results have been obtained for oxygen partial pressures ranging from 4.7 x lo-’ Pa (3.6 x 10e9 torr) to 1.3 x 10e4 Pa. Considerable structure is seen in the uptake curves suggesting the occurrence of multiple stages of growth. The oxidation process appears to be linearly dependent on pressure for high pressures. Further conclusions are made difficult due to the strong enhancement of the oxidation by the AES incident electron beam. Finally, at all pressures studied, an excess of oxygen signal compared to that expected from stoichiometric Be0 exists in the very early stage of the oxidation. D E Fowler and J M BIakely, J Vat Sci Technol, Xl (4), 1982, 93&933.
37 5575. SIMS analysis of thin surface Iayers and low kV ion implnnts relnted to VLSI and VHSIC materials devdopment. (USA) The production of smaller geometries and faster switching speeds in integrated circuits as a requirement for VLSI and VHSIC development has produced a whole new series of problems to be studied using surface analysis techniques. Scanning Auger electron spectrometry can achieve the high spatial resolution required for surface analysis but is complemented in the depth analysis mode by the increased sensitivity of secondary ion mass spectrometry (SIMS) for many elements either intentionally or accidentally present. If areas approximately 1 mm2 are available for analysis, B and As in Si can be depth-profiled down to the 10’6-10’Batoms cme3 range. Also, the ability to perform the depth profile slowly allows the near surface structure of low kV implants to be
37 5579. AES and SEM studies of oxide nod suIBde scales formed on sputterdeposited 304 stainless steel at #JO aad 950°C. (USA) High temperature (800-950°C) corrosion studies of fine-grained sputterdeposited 304 stainless steel have been conducted at low pressures (< lo-’ Pa) in an Auger electron spectroscopy (AES) uhv chamber and compared with studies performed in an environment of mixed gases containing 0 and S. In situ surface analysis performed at low gas pressures has provided a detailed examination of the diffusion processes that occur during alloy corrosion. Oxide scales formed at 10e2 Pa 0, on sputterdeposited fine-grained 304 stainless steel have been found to closely resemble those formed in mixed-gas environments at atmospheric pressure. suggesting that the same mechanisms are active in both
37 5574. Apparatus for high-resolution vibrational electron energy-loss spectroscopy of solid surfaces. (USA)
A high-resolution vibrational electron energy-loss spectrometer of 127”cylindrical electrostatic deflection type has been constructed for surface studies. In the direct mode, an electron current at the collector entrance of 2.3 x lo-” A is obtained with the energy spread (full width at halfmaximum) of60 cm- 1for electrons whose energy at the sample position is 5 eV. A ghost reduction slit is used to suppress spurious peaks due to the electron reflection from electrodes of the analyser. Electron energy-loss spectroscopy can be combined in situ with low-energy electron diffraction, Auger electron spectroscopy, and thermaldesorption mass spectroscopy. Design and performance of the apparatus are reported. The vibrational spectrum of the Ni(ll0) (1 x 2)-H surface formed at room temperature is presented and the location of hydrogen atoms on the surface is discussed.
(Japan)
358