ICMCTF1998 Session F4/B3: Microstructural Characterization - Microanalytical and Imaging Characterization

Wednesday, April 29, 1998 8:30 AM in Room San Diego

Wednesday Morning

Start	Invited?	Item
8:30 AM		F4/B3-1 The Control of the Structure and Properties of Oxide Coatings Deposited by Pulsed Magnetron Sputtering P. Kelly, R.D. Arnell (University of Salford, United Kingdom) Pulsed magnetron sputtering (PMS) is an enabling technique for the high rate deposition of defect-free ceramic coatings. Pulsing the magnetron discharge in the medium frequency range (10-100kHz) prevents the formation of arcs at the target and allows stability of the reactive deposition process to be maintained. Oxide coatings of aluminium, zirconium and tungsten have been deposited by closed-field unbalanced magnetron sputtering. The magnetron and substrate discharges were pulsed throughout the deposition process at a frequency of 20kHz. Control of the deposition process allowed coatings with compositions ranging from the pure metals to stoichiometric Al₂O₃, ZrO₂ and WO₂ to be deposited. Coating structures ranged from dense columnar, to fully dense, defect-free structures with featureless 'glass-like' fracture sections. Selected coatings were also examined by TEM. The coating properties were determined by X-ray diffraction and nano-indentation techniques. The relationships between structures and properties are considered in terms of the composition of the coatings.
8:50 AM		F4/B3-2 Microstructural Characterisation of Carbonaceous Dust Generated During the Deposition of Diamond-like Carbon Coatings A.P. Burden, J.V. Anguita, S.R.P. Silva (University of Surrey, United Kingdom) During Plasma Enhanced Chemical Vapour Deposition (PECVD) of diamond-like carbon coatings, material is routinely deposited on the electrodes and chamber walls of the system. After prolonged deposition times, this material exfoliates, contributing to dusty plasmas and affecting the quality and microstructural properties of the films. We have generated such dust in a Plasma Technology DP800 radio-frequency PECVD system, using a methane precursor at a variety of powers, pressures and electrode temperatures. A JEOL 2010 analytical electron microscope equipped with X-Ray analysis (EDX) has confirmed that this dust is carbonaceous with negligible metal contamination from the chamber. JEOL 2000 FX and JEOL 4000 EX High Resolution Transmission Electron Microscopes have been used to investigate the morphology and microstructure of these dust particles for comparison with the amorphous diamond-like carbon films that are more typically produced using the apparatus. A significant number of the dust particles analysed revealed highly curved graphene layers and microcrystalline nano-particles more typically observed in the soot following the arc-discharge generation of fullerenes. This is in contrast to the amorphous nature of the carbon coatings deposited over shorter times on silicon and glass substrates, which show very few microcrystalline inclusions.
9:10 AM		F4/B3-3 Computer Aided Analysis of Digital Transmission Electron Selected Area Diffraction Patterns S.D. Walck, P. Ruzakowski-Athey (PPG Industries, Inc.) When there are sufficient crystallites within the diffraction volume of a polycrystalline sample contributing to a transmision electron Selected Area Diffraction (SAD) Pattern, the pattern appears as continuous rings and is relatively straightforward to analyze. However, when this condition is not met and there are several phases present, the pattern is complex and can be difficult to analyze. Because of the large number of individual diffraction spots comprising such a pattern, computer aided analysis is typically required. WinJade from MDI is an X-ray diffraction (XRD) analysis program that will also produce an integrated circular density plot of intensitites from a 512x512 digital SAD pattern plotted against equivalent XRD 2θ values or d-spacings. These patterns can then be compared with standard diffraction databases such as the JCPDS or the NIST Crystal databases. When there are mixed "spotty" rings and continuous rings in a pattern, the intensities derived in the ICDP patterns are dependent on the manner in which the integrated intensitites are calculated. To investigate the effects of four analysis algorithms available in WinJade, simulated binary diffraction patterns consisting of single pixel wide circles and small pixel sized spots superimposed on black constant gray level, and a gradient gray level backgrounds were analyzed. The results show that the resolution of the ICDP patterns as well as the intensitites in the patterns are affected by the intensity calculation algorithm. Application of these altorithms with actual SAD patterns of pulsed laser deposited ZnO-WS₂ films and pyrolytically deposited, mixed, transition-metlal oxide coatings of Cr, Co, and Fe on glass are presented. The results indicate that the algorithm method chosen must be chosen carefully with respect to each SAD pattern.
9:50 AM		F4/B3-5 Technique for Characterization of Thin Film Porosity D.J. Taylor, P.F. Fleig, S.L. Hietala (TPL, Inc.) The properties of thin films change with, and as a result of, porosity. It is important to know and understand these effects; however, it is difficult to measure them. In this work, several films with different amounts of porosity were deposited by sol-gel methods and d.c. magnetron sputtering onto quartz substrates and analyzed using a combined SAW/BET technique. Gas adsorption is measured by surface acoustic wave (SAW), and porosity is then calculated using BET equations. The porosity data was compared and correlated to measurements made by ellipsometry (bulk refractive index) and profilometry (surface roughness). These techniques do not yield pore size distribution, and therefore are complimentary to the SAW technique, which directly measures porosity information.
10:10 AM		F4/B3-6 Microstructural Evolution as a Function of the Atmosphere Reactivity During Plasma Nitriding of Ti U. Figueroa, O. Salas, J. Oseguera (ITESM-CEM-DIA, Mexico) The reactive atmosphere during plasma nitriding in postdischarge flows exhibits a gradient in the concentration of the reactive species along the reactor length. The microstructural evolution that results from such gradient was analyzed after nitriding a long Ti piece in a microwave postdischarge reactor. The microstructural characterization was then related to an Optical Emission Spectroscopy analysis of the reactive atmosphere carried out at selected positions within the reactor chamber. Good agreement was found between both sets of results.
10:30 AM		F4/B3-7 Phase Identification During Aging of Nitrided Ferrous Materials G. Hinojosa, J. Oseguera, P. Schabes (ITESM-CEM-DIA, Mexico) A characterization study of the phases formed during aging of ferrous materials nitrided in a microwave postdischarge was performed by microhardness, electron microscopy (SEM, TEM and HREM) and x-ray diffraction. Iron and steel samples were nitrided for 10 minutes at 570°C and then quenched. The quenched samples were then annealed for treatment times ranging from 1/2h to 8 h at 400°C. The results from the microstructural characterization show the presence of a surface compact layer of epsilon nitride (Fe2-3N) and Fe4N needles underneath after nitriding. During annealing, the amount, size and morphology of the needles change as the treatment time progresses. The presence of Fe16N2 was also detected after aging and the amount of this phase seems to increase at longer treatment times. The microhardness measurements correlate well with the microstructural changes.
10:50 AM		F4/B3-8 Correlation Between Hardness and Embedded Argon Content of Magnetron Sputtered Chromium Films C. Paturaud, G. Farges, M.C. Sainte Catherine (DGA, France); J. Machet (LMCTS URA 320, Faculté des Sciences Limoges, France) Chromium films were produced on steel substrates by d.c. magnetron sputtering in pure argon at a target power density of 2, 4, 10 or 16 W Cm^-2 applying a negative substrate bias voltage, Vs, ranging from 4 V to 1000 V. The substrate temperature varied from 230 °C to 600 °C. Some experiments were conducted at a constant temperature of 600 ^oC. The film hardness was measured by Vickers microindentation and the residual stresses were determined by a beam curvature technique. Gas content in the films was analyzed by electron probe microanalysis. The film microstructure was investigated by X-ray diffraction and transmission electron microscopy. At constant deposition rate, while increasing the substrate bias, first the film hardness remained constant and beyond a threshold bias value, increased from 4 GPa to 11.5 GPa. The threshold bias value increased with the target power density. The temperature series performed at Vs = -500 V and a target power density of 4 W cm^-2 revealed that the film hardness decreased from 12 GPa to 8 Gpa when incresing the substrtae temperature from 300^oC to 600^oC. The microstructure and the residual stresses of the films were found varying with the deposition parameters. However, over the data for all the experiments performed here, a clear relationship has been established between the microhardness and the argon content of the films. Furthermore, the amount of argon embedded in the films produced at Vs = -500 V and a temperature of 600°C varied linearly with the square root of the deposition rate.
11:10 AM		F4/B3-9 Advances in SIMS for Surface and Interfacial Measurements V.K.F. Chia, M.J. Edgell (Charles Evans & Associates); B. Schueler (Physical Electronics) Thin films and interfaces are an integral result of many processes. The physical and chemical properties of these structures may be characterized by a suite of analytical tools. SIMS (secondary ion mass spectrometry) is a versatile tool for such applications because of the technique's ability to detect all elements, produce high precision depth profiles, provide quantitative elemental surface and bulk information with excellent detection sensitivity, and image. However, as films become thinner and wafers become larger additional capabilities to characterize thin films (<10 nm) and film homogeneity becomes important. This paper presents advances made in dynamic SIMS for acquiring quantitative distribution information with good detection sensitivities and depth resolution, automated depth profiling and defect search, and interleave reactive analysis for depth profiling and imaging. For example, accurate quantification at oxide surfaces may be achieved with oxygen flooding and low energy SIMS. The development of low energy ion guns enable SIMS to provide depth profiles with a depth resolution similar to that observed by Auger with Zalar rotation. Advantages of SIMS, in this comparison, are its higher detection sensitivities and sputter rates. A novel approach to increasing sensitivity for small area profiling and imaging is to interleave the primary ion species (e.g. Ga) with high current density probes (e.g. Cs). Examples of this research will be discussed and presented.
11:30 AM	Invited	F4/B3-10 EELS Imaging and Analysis of Thin Films J. Hunt (Gatan R&D, Inc.) Electron energy-loss spectroscopy (EELS) in the transmission electron microscope (TEM) is a powerful technique that analyzes the inelastic scattering distribution of the fast TEM electrons after they have lost energy within the sample. The resultant energy-losses are characteristic of elemental, chemical, and dielectric properties and are typically measured in one of two ways. Parallel-detection EELS spectrometers (PEELS) acquire large energy ranges of the energy-loss spectrum simultaneously for rapidly acquisition of spectral data at a single area. In contrast, the energy filtering TEM (EFTEM) acquires only a single energy band at once, but does so for thousands or even millions of image pixels simultaneously. Spectrum-imaging involves acquisition of detailed spectroscopic data sufficient for rigorous analysis at each pixel in a digital image. An EELS spectrum image “data cube” can be acquired by stepping a focused electron probe to each pixel and filling the spectrum image one spectrum at a time. This method has the advantage of producing the highest quality spectra with lowest specimen irradiation. Alternatively, the EFTEM can also be used to fill the spectrum image one energy plane at a time. This method produces image data very quickly but the technique becomes time consuming when a large number of energy channels is collected. Data acquisition can be anywhere from a few minutes to a few hours depending on the information desired. EELS spectrum-imaging experiments have demonstrated mapping of single atom sensitivity, sub-nanometer spatial resolution, chemical sensitivity < 1mol%, measurement of dielectric response and band-gap energy, and sensitivity to H. The ability to quantitatively measure these properties at each point in an image allows the scientist to minimize user bias as well as compare large collections of pixel values to bulk measurements.