Papers

ICMCTF2006 Session F4: Advanced Characterization / General Topics

Tuesday, May 2, 2006 1:30 PM in Room Royal Palm 1-3

Tuesday Afternoon

Start	Invited?	Item
1:30 PM		F4-1 Recent Developments in TOF-SIMS for Surface and Thin Film Analysis S.R. Bryan (Physical Electronics, Inc.) Time-of-flight secondary ion mass spectrometry (TOF-SIMS) has developed into one of the most important techniques for thin film characterization in recent years. The TOF-SIMS technique has several advantages for thin film analysis, including; 1) parallel detection of all elements; 2) high mass resolution; 3) trace level sensitivity; 4) submicron spatial resolution; and 5) sub nm depth resolution. One important application is the quantification of trace level impurities in the outer few nm of a surface. Because the primary ion beam is pulsed with a very low duty cycle (10-5) and all secondary ions are detected in parallel, TOF-SIMS has the highest detection efficiency of any surface analytical technique. Detection limits on the order of 1 part per million (ppm) are routinely achieved in the outer 1 nm of a surface. Depth profiling can be achieved by adding a second ion gun for sputtering the surface. This dual-beam approach to depth profiling provides more flexibility than the standard single ion gun approach used in conventional dynamic SIMS. The sputter ion gun can be optimized for depth resolution by using very low energies (< 500eV) while the analytical ion gun can be optimized for imaging (high energy). Using this approach a depth resolution of < 1 nm can be achieved. By acquiring a set of images at each cycle of the depth profile, a full 3D elemental characterization of the surface can be acquired. Recent examples of trace analysis, imaging, depth profiling, and 3D analysis will be discussed. This presentation will conclude with a short discussion of the recent research activities that have attempted to extend TOF-SIMS to molecular depth profiling of organic thin films.
2:10 PM		F4-3 SIMS Studies of Low-K Materials X.-F. Lin, S.P. Smith, I.A. Mowat, T.F. Fister, J.C. Huneke, P.M. Lindley (Evans Analytical Group) The continually shrinking dimensions of integrated circuits (IC) bring new challenges for materials characterization. The use of Cu instead of the Al for metallization in silicon devices and also the use of low-K dielectric materials to replace SiO₂ have led to significant advances in IC speed and performance, but also to complications with materials processing and integration. Accurate and efficient characterization of these materials is essential, and provides a great challenge and opportunity for analytical service businesses. Due to its uniquely high detection sensitivity during depth profiling of materials, Secondary Ion Mass Spectrometry (SIMS) is an excellent analytical choice for acquiring information such as dopant concentration profiles, junction depths, impurity levels, etc. needed to characterize and control film growth and device processing. However, the analysis of the low-K materials using SIMS presents new problems. The unique insulating properties and often porous nature of H- or C-rich low-K materials make SIMS analysis very challenging. Specifically, the electron beam used for sample-charging compensation during the SIMS analysis can significantly damage the low-K materials, introducing unknown measurement errors. Recently, we have made significant progress in conducting quantitative SIMS analyses of low-K materials. In this paper, we present new SIMS results from low-K materials, focusing on depth profiling and concentration quantification in several different low-K materials of different structure and composition. Dynamic SIMS with both Cs and O ion sources were used to examine the detection sensitivity and sample-charging compensation effects. Using quantitative X-Ray Photoelectron Spectroscopy (XPS) and Rutherford Backscattering Spectroscopy (RBS) results, we discuss the concentration quantification of the low-K materials by SIMS.
2:30 PM		F4-4 Extension of Phase Modulated Spectroscopic Ellipsometry (PMSE) to Generalized Ellipsometry E. Teboul, J. Yong (Horiba Jobin Yvon Inc.) Spectroscopic Ellipsometry (SE) has been successfully applied to a wide range of materials. However, nowadays the characterization of anisotropic and depolarizing materials has become increasingly important. Indeed, a significant part of the current research has been driven towards thin film deposition onto anisotropic polymer substrate. Moreover, when surfaces with significant roughness are investigated, phenomena such as depolarization and cross polarization could affect the ellipsometric measurements and should be taken into consideration. In this paper, we will describe how Phase Modulated Spectroscopic Ellipsometry (PMSE) can be used to measure twelve elements of the Mueller matrix and how the four remaining elements can be either measured using a second optical configuration or calculated. We will discuss the validity of the measured Mueller matrix by showing some ellipsometric measurements on isotropic (c-Si) and anisotropic (SnSe, PET) samples between 1.5eV to 6.5eV. The measurements confirm that for anisotropic samples, the off-diagonals elements of the Mueller matrix differs from zero as measured for the isotropic sample. As pointed it out above, the simultaneous determination of the sixteen elements of the Mueller matrix requires either a change in the optical configuration of the ellipsometer or a calculation. In this paper, we will introduce the unique optical set up of a new kind of spectroscopic ellipsometer which uses liquid crystal as polarizer and allow the determination of the full Mueller matrix in one time. We will show how the optical set up of this ellipsometer that used only fixed elements with no moving parts during the signal acquisition in order to minimize the error in the raw data measurements, allow the determination of the full Mueller matrix.
2:50 PM		F4-6 Investigation of Crystalline Nanostructures by Calculated Electron Energy-Loss Functions H.J. Steffen (Mannheim University of Applied Sciences, Germany) The investigation of nanostructured materials by electron spectroscopy may reveal the structure due to plasmon excitations that give rise to spectroscopic electron-energy loss signals near the main Auger or photoelectron line at lower kinetic energy. However, a quantitative analysis requires a principle understanding of the various electron density oscillations that may be excited in the nanostructure. Thus, it is essential for the evaluation of the electron-energy losses to calculate all modes of free electron oscillations that may occur in dependence on the individual nanostructure according to phases, their distribution, geometry and dimensions. This work presents model calculations of the eigenfrequencies of collective electron oscillations for two different crystals of Al nanoparticles (spheres and rods) based on the hydrodynamic and density functional theory. The stationary wave equation for the electron density variation is solved with boundary conditions that allow current through the interfaces. Subsequently, energy loss functions are derived for each oscillation mode under the assumption of a Drude-type permittivity. The stopping power of the nanostructure is then calculated assuming a simple non-weighted linear combination of the energy loss functions. The energy-dependant stopping power for both nanostructures reveals energy losses between 0 and ca. 8 eV with distinct local maxima. These plasmon energies have a considerable lower energy compared to the well known Mie-value for surface plasmon excitations in spheres (8.7 eV for Al). Conclusively, the corresponding structure information in electron spectra of those materials will be found in the immediate vicinity of the main transition line.
3:10 PM		F4-7 The Outer Surface, Ultra-Thin Layers and Contacts Studied by LEIS H.H. Brongersma (Calipso B.V., Netherlands) In modern technology new (sub-) nanometer materials and preparation techniques are being developed. Advancement relies heavily on the availability of analytic techniques that can validate and support the preparation. One of the few analytic techniques that is being used is Low-Energy Ion Scattering (LEIS or ISS). Its unique surface sensitivity makes it possible to selectively determine the atomic composition of the outer atoms of the surface, while LEIS can nowadays also be used for non-destructive in-depth analysis down to 6 - 10 nm below the surface. In Eindhoven we have developed a new type of analyzer and detector for LEIS. The use of a 2-dimensional array of detectors has increased its sensitivity by a factor of 3000 compared to conventional LEIS set-ups. The technique is just as well suited for the quantitative ananalysis of amorphous, insulating and extremely rough surfaces as for flat conducting single crystals. This has opened many new possibilities in microelectronics, coatings, adhesion control, catalysis, etc.. After an introduction of the technique, the focus will be on applications where valuable information has been obtained that is impossible (or very difficult) to obtain with other analytic techniques. The new possibilities will be illustrated with: - Atomic layer deposition (ALD) of ultra-thin layers for diffusion barriers and high-k dielectrics - Pinholes in coatings - Metal-polymer interfaces - Self-assembled monolayers - Intra- and inter-molecular segregation. The results and possibilities of this new type of LEIS will be compared and contrasted to those by more conventional techniques such as XPS, ToF-SIMS, Auger as well as higher energy ion scattering techniques (RBS/MEIS).
3:50 PM		F4-9 Corrosion Resistance of the Layers Formed on the Surface of Plasma-Nitrided AISI 304L Steel L.C. Gontijo (CEFET, Brazil); R. Machado (National Insitute of Metrology, Standardization and Industrial Quality, INMETRO, Brazil); S.E. Kuri (Federal University of Sao Carlos, Brazil); L.C. Casteletti (University of Sao Paulo, Brazil); P.A.P. Nascente (Federal University of Sao Carlos, Brazil) Austenitic stainless steels are employed in applications that require good corrosion resistance. Such steels present low hardness and, consequently, low wear resistance, limiting their use whenever surface hardness is required. There are various processes used for the surface modification of metallic materials, including the nitriding treatments that improve the mechanical and tribological properties of the material surfaces. These treatments have been successfully applied to stainless steels; however, at temperatures above 450°C, gas or salt bath nitriding processes decrease the corrosion resistance due to the formation of CrN and other phases within the modified layer. This formation of chromium compounds draws chromium and nitrogen from the adjacent regions, degrading the corrosion resistance of the material. The plasma nitriding technique permits the use of treating temperature, which can be as low as 350°C, without provoking degradation in the corrosion resistance of stainless steel. In this work, the Pulsed Glow Discharge (PGD) technique was used for nitriding steel (AISI304L) in order to investigate the effect of the temperature of this treatment in the morphology and, as a consequence, in the anodic behavior of the formed layers, in solution with and without chlorides ions. Four different temperatures were employed (350, 400, 450, and 500°C). The samples were characterized by optical microscopy (OM), scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), microhardness measurements, and electrochemical tests with potentiodynamic anodic polarization curves. The nitriding temperature alters the anodic behavior due to a displacement of the polarization curve towards higher currents, in a solution free of chlorides ions. In a chloride solution, the nitriding temperature increases the pitting potential up to the oxygen evolution region.
4:10 PM		F4-12 Characterizatin of PACVD Duplex TiN/TiB₂ Coatings on Hot Work Tool Steels by Integrated Electron Spectroscopy Techniques M. Jenko, V. Leskovsek, M. Godec (Institute of Metals and Technology, Slovenia) We have studied duplex coatings of TiN/TiB₂ on hot work tool steel AISI H11, deposited by Plasma Assisted Chemical Vapor Deposition (PACVD). This deposition technique is well suited for hard coating deposition onto large forging dies for hot work application. Polished investigated hot-work tool steel was modified by plasma nitriding and by TiN/TiB₂ coating. The thickness of investigated coating, consists of 21 layers, is 1.8 µmm. The surface micro hardness, measured by Fischer scope H100C is approximately 50GPa, which correspond to 5000 HV _0.003; roughness of hard coatings S_a is of 0.132 µm analysis techniques such as Field Emission Auger Electron Spectroscopy (FE-AES), AES depth profiling, X-ray photoelectron spectroscopy (XPS); also Field Emission Scanning Electron microscopy (FE-SEM) where SEI and COMPO techniques were used to study duplex coatings and energy dispersive/wave dispersive spectroscopy (ED/WD) analytical techniques for chemical composition estimation. For characterization of crystallographic orientation of grains of steel substrate as well as of coating, Electron Backscattered Diffraction (EBSD) was applied. The effect of crystallographic orientation of substrate on the growth of the coating will be also presented. Integrated electron spectroscopy techniques are an excellent tool for characterization of duplex TiN/TiB₂ coatings.
4:30 PM		F4-11 Characterization of Thermally Evaporated Silver Phthalocyanine Films A. Mahajan (D. A. V. College, India); H. Gupta, R.K. Bedi (Guru Nanak Dev University, India) Silver phthalocyanine (AgPc) films has been grown by thermal evaporation technique onto the glass substrates kept at different temperatures in a vacuum of 1.3C 10-3 Pa. These films are characterized by NMR, optical absorption (IR, visible, near-UV), X-ray diffraction and scanning electron microscopy. Besides these, the electrical properties of the films are determined in the temperature range 290-400 K. SEM micrographs of AgPc films show that the films are composed of well defined and uniformly distributed crystallites with preferred orientation nearly perpendicular to the plane of the substrate. Crystallites as large as 4 µm are observed in the case of films deposited at 423K. The X-ray diffraction pattern of these films show crystalline behaviour of films. The films deposited at higher substrate temperature suggest the formation of more ordered and crystalline films. Analysis of optical absorption measurements indicate interband transition energies of films lie in the range 1-2 eV. The current-voltage characteristics of films show ohmic behaviour of conduction within the investigated field and temperature range (10-60 V, 290-360 K). The substrate temperature appears to influence the properties of the films. The electrical conductivity, carrier concentration, drift mobility and optical band gap of the films increase with increases in substrate temperature, whereas activation energy decreases.