Volume 19, Issue 4, July 2001
- papers from the 47th international symposium of the avs
- flat panel displays
- industrial ecology
- material characterization
- magnetic interfaces and nanostructures
- micro-electro-mechanical systems
- manufacturing science and technology
- organic films and devices
- plasma science and technology
- plasma science and technology i
- plasma science and technology ii
- surface engineering
- surface science
- surface science i
- surface science ii
- surface science iii
- thin films
- vacuum technology
- dielectrics/electronics/manufacturing science and technology
- electronics/nanometer-scale science and technology
- flat panel displays/vacuum technology
- industrial ecology/plasma science and technology/manufacturing science and technology/surface engineering
- material characterization/nanometer-scale science and technology
- magnetic interfaces and nanostructures/electronics
- magnetic interface and nanostructure/nanometer-scale science and technology/nano 6
- micro-electro-mechanical systems/vacuum technology
- nanotubes/nanometer-scale science and technology
- nanometer-scale science and technology/nano 6
- nanometer-scale science and technology/nano 6/material characterization
- nanometer-scale science and technology/nano 6/micro-electro-mechanical systems
- nanometer-scale science and technology/nano 6/surface science/material characterization
- plasma science and technology/manufacturing science and technology
- plasma science and technology i/manufacturing science and technology
- semiconductors/electronics/surface science
- semiconductors i/electronics/surface science
- surface engineering/thin films
- surface science/material characterization
- surface science i/material characterization
- surface science ii/electronics
- surface science ii/vacuum technology
- surface science iii/material characterization
- thin films/electronics
- thin films/nanometer-scale science and technology
Index of content:
- PAPERS FROM THE 47TH INTERNATIONAL SYMPOSIUM OF THE AVS
Photovoltaic characteristics of BR/p-silicon heterostructures using surface photovoltage spectroscopy19(2001); http://dx.doi.org/10.1116/1.1369785View Description Hide Description
Purple membrane (PM) monolayers were deposited on hydrophilic or hydrophobicsilicon substrates through the Langmuir–Blodgett (LB) technique. The photovoltaic features and interfacial charge separation of p-Si/PM/indium tin oxide (ITO) heterostructure were studied by surface photovoltage spectroscopy (SPS). The different photovoltaic response values were obtained due to the nonrandom orientation of PM in the LB films on the hydrophilic versus hydrophobicsilicon substrates. The photovoltaic response value versus external potential of the p-Si/cytoplasmic-extracellular/ITO heterostructure showed an obviously rectifying behavior. Compared with the p-Si/ITO heterostructure, the response value of SPS increased more rapidly in the case of the positive external bias.
Observation of the bone matrix structure of intact and regenerative zones of tibias by atomic force microscopy19(2001); http://dx.doi.org/10.1116/1.1351798View Description Hide Description
Atomic force microscopy(AFM) was used to comparatively study the structure of the bone matrix of rat tibia from an intact region with that from regions submitted to surgical injury. We used young male adult rats (Wistar), with corporal masses between 250 and 300 g. Each injury was provoked by drilling a 1.5-mm-diam hole in one cortical tibia surface. The healing course was monitored at 8 and 15 days after the injury. Atomic force microscopyimages, at different magnifications, allowed the identification of the time dependence of the osteoblast activity, measured by the increase in the area of neoformed primary bone and in the organization of the collagen fibers of the bone matrix. Characterization of the natural recovery of the damaged bone tissue by AFM is potentially of great importance because it allows the comparison of natural recovery processes with those induced by medicines and other therapeutic procedures.
19(2001); http://dx.doi.org/10.1116/1.1368665View Description Hide Description
Structural and electrical properties of chemical vapor deposited (CVD) and were studied by structural, chemical, and electrical characterizations. W and layers were deposited on and at the growth temperature by low-pressure chemical vapor deposition utilizing and source gases. Structural and chemical properties of and interfaces were analyzed by x-ray diffraction, transmission electron microscopy, scanning electron microscopy, Rutherford backscattering spectroscopy, and Auger electron spectroscopy.Interfaces of were much sharper than those of Interfaces of are very rough presumably due to encroachment of SiGe layers caused by etching reaction of SiGe layers by Electrical properties of the and Schottky diodes were characterized by the current–voltage measurements. The measured effective Schottky barrier heights of the Schottky contacts were as the deposition temperature, of W layers increases from 350 to 550 °C, and Schottky contacts with layers grown at showed the values similar to those of
Fabrication of smooth diamond films on by the addition of nitrogen to the gas feed in hot-filament chemical vapor deposition19(2001); http://dx.doi.org/10.1116/1.1340657View Description Hide Description
Diamondfilms of small roughness have been deposited onto thermally oxidized Si substrates by a process of anisotropic crystalline growth induced by nitrogen in a hot-filament chemical vapor deposition reactor. Ethanol diluted in hydrogen and nitrogen, was used as the source of carbon. At high concentrations, nitrogen tends to suppress the diamondgrowth in the 〈100〉 direction, which allows the growth of square mesoscopic-like crystals (“plates”) of large area in the directions parallel to the surface of the substrate. These plates stack upon each other, forming a thick diamond coating of uniform thickness. Analysis of the films made by micro-Raman spectroscopy and atomic force microscopy revealed that it is possible to obtain diamond coatings of high quality with a roughness comparable to that of the at the interface, and of nanometric roughness on the surface of the plates. A model to explain the morphology of the plates based on the microscopic mechanisms that involve the possible passivation of the (100) plane and an increase of vacancies by nitrogen is also discussed.
Micro-crystalline diamond and nano-carbon structures produced using a high argon concentration in hot-filament chemical vapor deposition19(2001); http://dx.doi.org/10.1116/1.1366701View Description Hide Description
Micro-crystalline diamondfilms and nano-carbon structures in the form of wires have been grown by the introduction of argon at very high concentrations (60%–87.5% vol Ar) into the feed mixture (ethanol and hydrogen) of a hot-filament chemical vapor deposition reactor. The argon, in addition to acting as an inert diluent, also modified the kinetics of the carbondeposition process; its presence apparently minimized the deposition of intergranular hydrogenated species, induced an increase in the number of flaws between the diamond grains, increased the porosity of the films, and formed new carbonstructures. Well-faceted diamondfilms, diamond-like carbon (DLC) balls, spongy-like wires, and multilayer structures were observed at different concentrations of Ar. Raman spectroscopy of the deposited material showed that structures of high quality diamond (60%–65% vol Ar) and carbonstructures related to DLC, fullerenes and carbon nanotubes, may be deposited by this process.
19(2001); http://dx.doi.org/10.1116/1.1380227View Description Hide Description
High dielectricthin films were etched in an inductively coupled plasma as a function of the gas mixing ratio. Under (20)/Ar (80), the maximum etch rate of the BST film was 400 Å/min and the selectivities of BST to Pt and PR obtained were 0.4 and 0.2, respectively. Etching by-products remained on the surface of BST and resulted in varying the stochiometry. Therefore, we investigated the surface of the etched BST using x-ray photoelectron spectroscopy(XPS),atomic force microscopy(AFM), and x-ray diffraction(XRD). From the results of XPS analysis, we found that metal (Ba or Sr) chloride compounds remained on the surface of the etched BST for high boiling points. The morphology of the etchedsurface was evaluated with AFM. The surface roughness decreased as the increased in the plasma. From the results of XRD analysis, the crystallinity of etched BST films under Ar only and under (20)/Ar (80) was similar to that of as-deposited BST. However, the (100) diffraction peak abruptly decreased at the only plasma. It was assumed that metal (Ba or Sr) chloride compounds remained on the etched BST surface and changed the stoichiometry, resulting in crystallinity of the BST film during the etch process.
Etch characteristics of thin films as a buffer layer for the application of ferroelectric random access memory19(2001); http://dx.doi.org/10.1116/1.1376703View Description Hide Description
Cerium oxide thin film has been proposed as a buffer layer between the ferroelectricfilm and the Si substrate in metal–ferroelectric–insulator–silicon structures for ferroelectric random access memory applications. In this study, thin films were etched with a gas combination in an inductively coupled plasma. The etch properties were measured for different gas mixing ratios of while the other process conditions were fixed at rf power (600 W), dc bias voltage (−200 V), and chamber pressure (15 mTorr). The highest etch rate of the thin film was 230 Å/min and the selectivity of to was 1.83 at a gas mixing ratio of 0.2. The surface reaction of the etchedthin films was investigated using x-ray photoelectron spectroscopy(XPS)analysis. There is a Ce–Cl bonding by chemical reaction between Ce and Cl. The results of secondary ion mass spectrometer analysis were compared with the results of XPSanalysis and the Ce–Cl bonding was discovered at 176.15 (amu). These results confirm that the Ce atoms of the thin films react with chlorine and a compound such as CeCl remains on the surface of the etchedthin films. These products can be removed by Ar-ion bombardment.
Chemical interaction and adhesion characteristics at the interface of metals (Cu, Ta) and low-k cyclohexane-based plasma polymer (CHexPP) films19(2001); http://dx.doi.org/10.1116/1.1340658View Description Hide Description
Chemical interaction and adhesioncharacteristics between metals (Cu,Ta) and low-k plasma-treated cyclohexane-based plasmapolymer (CHexPP) films were studied. In order to generate new functional groups that may contribute to the improvement of adhesion between metal and plasmapolymer, we performed and mixture plasma treatment on the surfaces of CHexPP films. Chemical interactions at the interface between metals (Cu,Ta) and plasma-treated CHexPP films were analyzed by x-ray photoelectron spectroscopy. The effect of plasma treatment and thermal annealing on the adhesioncharacteristics was measured by a tape test and scratch test. The formation of new binding states on the surface of plasma-treated CHexPP films improved adhesioncharacteristics between metals and CHexPP films. Thermal annealing improves the adhesionproperty of Cu/CHexPP films, but degrades the adhesionproperty of Ta/CHexPP films.
- FLAT PANEL DISPLAYS
19(2001); http://dx.doi.org/10.1116/1.1345905View Description Hide Description
Polycrystalline Si films were deposited on poly(ethyleneterephthalate) (PET-Mylar®) and glass (7059 Corning) substrates at 140 and 200 °C, respectively. X-ray diffraction and Raman spectroscopy were used to confirm the polycrystalline nature of the films. The largest grain size obtained was 95 nm. Raman spectroscopy also showed a simultaneous presence of an amorphous phase. The relative fraction of this amorphous phase was controllable by adjusting the composition of the sputtering gas. Filmsdeposited with only Ar or sputtering gas show a very small polycrystalline Si peak. With the addition of up to 10% Kr to the gas mixture, a very strong polycrystalline peak appears in the Raman spectra. X-ray diffraction also confirmed the polycrystalline nature of the films. The Kr effect was related to the energetic condensation. The presence of Kr increased the energy of the sputtered atoms. Even after collision with the sputtering gas, these atoms impinge on the substrate surface with enough residual energy that the ad-atoms experience enhanced diffusion, which leads to polycrystalline film formation. For our system, the final energy of the ad-atoms was calculated to be 1.92 eV, which is more than the activation energy for surface self-diffusion for Si.
Cross-sectional transmission electron microscopy investigation of the dead layer of ZnS:Ag,Al phosphors in field emission displays19(2001); http://dx.doi.org/10.1116/1.1381405View Description Hide Description
The dead surface layer of blue-emitting ZnS:Ag,Al phosphor with Al metallized thin film in high-voltage field emission displays(FEDs) has been investigated by means of cross-sectional transmission electron microscopy. From these observations, it was found that electron irradiation at 6 keV excitation causes the decomposition of ZnS and the subsequent evolution of sulfur in the topmost surface layer ∼30 nm, and also causes the formation of lattice defects within the electron penetration depth of ∼300 nm in a life-end stage. When this evidence was taken into account, it was estimated that the decomposition rate of ZnS and the formation rate of lattice defects depend mainly on the degree of crystallinity and the atomic-scale surface roughness of ZnSphosphor particles. Necessary characteristics of ZnS:Ag,Al phosphors for longer luminescence lifetime in FEDs were suggested in this work.
19(2001); http://dx.doi.org/10.1116/1.1381402View Description Hide Description
Optical filters for plasma display panels (PDPs) have been studied. We obtained the sputtered seven-layer coatings (comprising alternate layers of silver and indium–tin–oxide) on substrates of polyethylene terephthalate by a roll-to-roll process. The coatings were designed in order to minimize interfacial reflectance between the coatings and the adjacent layer to it. The coatings have a surface resistance of 2.2 Ω/sq, a transmittance of 1%∼12% in the near-infrared region of 800–1200 nm, and visible-light transmittance of approximately 70%. In combination with these multilayercoatings working as shields of electromagnetic wave and near-infrared light, organic dyes were also applied to control transmission properties of the optical filters and to improve PDPs picture quality.
Effects of ZnO buffer layer on the luminous properties of thin-film phosphors deposited on ZnO/ITO/glass substrates19(2001); http://dx.doi.org/10.1116/1.1342871View Description Hide Description
and thin-filmphosphors which emit green and red light, respectively, were deposited on ZnO/ITO/glass and ITO/glass substrates by a rf reactive magnetron-sputtering method. To improve photo- and cathodoluminescent properties of the thin-filmphosphors,ZnObuffer layers were deposited between the thin-filmphosphor and the ITO-coated glass substrate. A transparent c-axis preferentially oriented ZnOthin-filmbuffer layer could be obtained on the ITO film, while ITO had an amorphous-like structure. and thin-filmphosphors were used to evaluate the effects of the ZnObuffer layer. The crystal structures of thin-filmphosphors deposited on ZnO/ITO/glass substrates were developed better than those on ITO/glass, consequently, the former showed photo- and cathodoluminescent intensity at least twice as high as the latter.
19(2001); http://dx.doi.org/10.1116/1.1369788View Description Hide Description
Long gas evacuation time before the introduction of the discharge gases into the panel is one of the major problems in the production of a plasma display panel (PDP). In this study, the outgassing characteristics during the panel evacuation stage were investigated using a quadrupolemass spectrometer. The origin of the impurity gas was studied by measuring the outgassed species from each layer comprising the PDP. Dominant species observed during the evacuation of the panel were and and water vapor was the most abundant species. When the outgassing characteristics of the panel were compared with the outgassing characteristics from each layer comprising the panel, the material most responsible for the water vapor turned out to be a MgO layer. The outgassing experiments of single panels have also shown that the long outgassing time of PDP is mostly related to the MgO layer and possibly also to red, green, and blue layers and white dielectric material coated on the each single panel. Therefore to reduce the gas evacuation time, controlled atmosphere appears to be required during the deposition of these materials and the storage of those deposited panels.
- INDUSTRIAL ECOLOGY
In situ analysis of perfluoro compounds in semiconductor process exhaust: Use of ion-attachment mass spectrometry19(2001); http://dx.doi.org/10.1116/1.1376704View Description Hide Description
Ion-attachment mass spectrometry is capable of accurate and in situanalysis of multicomponent gases that may even include unknown components. We developed a compact apparatus that uses this method and examined its performance for perfluoro compounds, a class of greenhouse gases, using typical standard gases, and subsequently applied the method to the in situanalysis of exhaust gases from a dry-etching machine, where plasma is generated. Perfluoro compounds of low concentration can be detected as quasimolecules without any fragmentation. In the exhaust gases, many components that are not considered in the current measurement protocol [J. Meyers, D. Green, P. Maroulis, and W. Reagen, Equipment Environmental Characterization Guidelines, Rev. 3.0 (INTEL, 1999)] are measured, as well as components already reported.
- MATERIAL CHARACTERIZATION
Quantitative comparison between Auger electron spectroscopy and secondary ion mass spectroscopy depth profiles of a double layer structure of AlAs in GaAs using the mixing-roughness-information depth model19(2001); http://dx.doi.org/10.1116/1.1345899View Description Hide Description
Application of the so called mixing-roughness-information (MRI) depth model to quantitative reconstruction of the in-depth distribution of the composition is demonstrated by comparing secondary ion mass spectroscopy(SIMS) and Auger electron spectroscopy(AES) depth profiles. A GaAs/AlAs reference sample consisting of two layers of AlAs [1 and 36 monolayer (ML)] separated by 44 ML of a GaAs matrix was depth profiled using almost identical sputtering conditions: ions of 3 keV impact energy and 52° (SIMS: CAMECA and 58° (AES: VG Microlab incidence angle. Both the intensity of the SIMS profile and the Al (LVV) intensity of the AES profile were quantified by fitting the measured profiles with those calculated with the MRI model, resulting in the same mixing length of similar roughness parameter (1.4–2 nm), and negligible information depth (0.4 nm). Whereas practically no matrix effect was observed for AES as well as for in the SIMS profile, quantification using dimer and trimer ions shows a marked nonlinearity between concentration and intensity, with the main effect caused by the simple mass action law probability of cluster ion formation.
19(2001); http://dx.doi.org/10.1116/1.1361036View Description Hide Description
Surfaces of high-performance carbon fiber/bismeleimide (BMI) composites (IM7/5260) have been characterized by x-ray photoelectron spectroscopy. An experimental technique to separately examine the chemical natures of the carbon fibers and BMI resin in the composite form was developed. This technique uses a flood gun to establish differential charging conditions on the BMI resin. The binding energies from the BMI resin were shifted by an amount of voltage applied to the flood gun, whereas those from the carbon fibers were uniquely determined due to their electrically conducting nature. By adding external bias voltage to the sample, the binding energies for conducting fibers were further shifted from those of the BMI resin, thereby separating the IM7 phase completely from the BMI phase in the binding energy scale, allowing independent measurement of the chemical changes associated with those peaks. Using this technique, the effects of thermal aging and surfaceplasma treatment on the IM7/5260 composite were studied.
19(2001); http://dx.doi.org/10.1116/1.1380716View Description Hide Description
X-ray photoemission spectroscopy was used to study Pt–metal oxide aerogel catalysts that have been developed to respond to increased emissions of lean-burn engines. Lean-burn engines, critical components of low and zero emission vehicles, produce much higher levels of engine-out and current three-way catalytic converters are not sufficient to meet Clean Air Act standards. Platinum catalysts were formed by the reaction of modified Pt coordination compounds with selected transition–metal alkoxides through sol–gel techniques into aerogels. Photoemission measurements of the Pt Si Ti O and C core lines were used to evaluate the chemistry of the material after each processing step. Results indicate Pt–O bonding and reduced Pt disbursed in the aerogel. In addition, Si Ti and O binding energies indicate an oxo-bridged network structure.
19(2001); http://dx.doi.org/10.1116/1.1349191View Description Hide Description
Scanning Auger microscopy(SAM) has been used to study the surface and interface microchemistry of a sheet bronze belt from the Urartian kingdom in NE Syria of the early first millennium B.C. We find that the patina contains no copper species at all (decuprification), whereas carbonaceous species, Ca-silicates and N-bearing species are detected, the last being tentatively identified as organic (primarily amine-like) residues deriving from the soil. A textured grain, which we qualify as a second phase of bronze originated by an imperfect alloying of the two major metals (i.e., consisting of Cu-rich and Sn-rich domains) is observed on the metallic side lying beneath the patina. SAM imaging with a submicron spatial resolution highlights the presence of oxide inside what appears to be the hollow veins of the grain, whereas a -like oxide is confined exclusively to the flat regions of the grain. We explain these results by noting that the hollow veins, offering a higher exposure to external fluids, are likely to have promoted preferential formation of the more stable tin oxide over copper oxide. In another region of the metal side we studied the chemistry of grain boundaries and their surrounding areas. We find that S species lie exclusively inside the grain boundaries, whereas Sn and Zn species accumulate just outside the boundary channels, and this lateral chemical inhomogeneity is highlighted with a ∼200 nm spatial resolution. Lateral segregation of Cu and Sn domains is imaged in another region with a spatial resolution of ∼15 nm. This result marks the best spatial resolutionany analytical method has yet achieved in highlighting chemical heterogeneities of ancient bronzes. Although archaeomaterials lie outside the mainstream applications of Auger techniques, this study provides convincing evidence that SAM can greatly advance our understanding of these materials, as it provides clues relating to corrosion and patination phenomena, as well as manufacturing processes that are not easily reachable by other microscopies or microanalytical techniques.
19(2001); http://dx.doi.org/10.1116/1.1361037View Description Hide Description
Secondary ion mass spectrometry(SIMS) is reported from multiple-element multiple-matrix ion implants. The implants include a thirteen element metal set and a six element gas set implanted into films of interest for microelectronics(silicon, silicides, wiring layers, liner metals, inorganic dielectrics, and polymer dielectrics.) Using these standards, this study performs a broad comparison of ion yields using a metric defined as the normalized useful yield. We find that the yield of with primaries is constant for almost all matrices, in keeping with a concept of ion yield saturation. The yield of with primaries approaches a yield saturation limit for titanium but the ion yield falls for materials with higher sputter yields, becoming 3.5× lower from copper. The variations in negative ion yields from matrix to matrix are much larger, with anomalies more pronounced, for weaker-yielding ions, becoming 50× for from Ti to Cu. In this article we document sets of ion implants, show some of the SIMS profiles, and note trends in ion yields and implications for SIMS analysis.
Surface potential measurement with high spatial resolution using a scanning Auger electron microscope19(2001); http://dx.doi.org/10.1116/1.1359551View Description Hide Description
The microscopic surface potential distributions were measured from the onset energies of secondary electron spectra using a scanning Auger electron microscope. The spatial resolution is several tens of nanometers and a sensitivity of the surface potentialmeasurement is 0.05 eV. We demonstrated the calibration of the instrument for local surface potentialanalysis based on the onset energy measurement of the secondary electronspectrum. Several applications of this technique for Nipolycrystal grains of different orientations, and a potential profile along the junction of a light-emitting diode were demonstrated.