Methodology, Instrumentation and Analysis

• Critical dimension of biperiodic gratings determined by spectral ellipsometry and Mueller matrix polarimetry
  Authors: Foldyna M, De Martino A, Garcia-Caurel E, Ossikovski R, Licitra C, Bertin F, Postava K, Drevillon B
  EUROPEAN PHYSICAL JOURNAL-APPLIED PHYSICS 42 (3) 351-359 (2008)
  DOI: 10.1051/epjap:2008089
  Abstract: We characterized two samples consisting of photoresist layers on silicon with square arrays of square holes by spectroscopic ellipsometry (SE) and Mueller matrix polarimetry (MMP). Hole lateral dimensions and depths were determined by fitting either SE data taken in conventional planar geometry or MMP data in general conical diffraction configurations. A method for objective determination of the optimal measurement conditions based on sensitivity and parameter correlations is presented. When applied to MMP, this approach showed that for one of the samples the optimal incidence angle was 45 degrees, much below the widely used 70 degrees value. The robustness of the dimensional characterisation based on MMP is demonstrated by the high stability of the results provided by separated fits of the data taken at different azimuthal angles
  Email: martino@leonardo.polytechnique.fr
  
  
• Comparison of spectroscopic Mueller polarimetry, standard scatterometry and real space imaging techniques (SEM and 3D-AFM) for dimensional characterization of periodic structures
  Authors: De Martino A, Foldyna M, Novikova T, Cattelan D, Barritault P, Licitra C, Hazart J, Foucher J, Bogeat F
  METROLOGY, INSPECTION, AND PROCESS CONTROL FOR MICROLITHOGRAPHY XXII, PTS 1 AND 2 Book Series: PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) 6922 (1-2) P9221-P9221 (2008)
  Abstract: Spectroscopic Mueller polarimetry may provide a useful alternative to standard spectroscopic ellipsometry (SE) for the dimensional characterization of periodic structures, as it provides 16 quantities instead of 2 for SE. We present a detailed experimental comparison of the results provided by conventional scatterometry (0.7 - 5 eV) spectral range), Mueller polarimetry in the visible (450 - 825 nm), electron microscopy (top CD-SEM and cross section) and state-of-the-art CD-AFM (Veeco X3D). This last instrument was considered as the best reference currently available. The samples were 1D gratings etched in bulk Si, with 150 and 250 mn nominal CDs and several pitches for each CD. SE spectra were taken at zero azimuthal angles (i.e. with the grooves perpendicular to the incidence plane), as it is usually done with standard scatterometers, while Mueller spectra were measured at all azimuths in steps of 5 degrees, allowing significant consistency tests by comparing the results of the corresponding fits. Both techniques provided CD values in agreement with AFM and CD-SEM data to within 5 mn, comparable to the AFM precision. Grating thickness and sidewall angle (SWA) were best determined by Mueller polarimetry at 90 degrees azimuth, while in the usual zero azimuth configuration, SWA was typically underestimated by several degrees
  Email: martino@leonardo.polytechnique.fr
  
  
• Monitoring critical dimensions of bidimensional gratings by spectroscopic ellipsometry and Mueller polarimetry
  Authors: Foldyna M, De Martino A, Garcia-Caurel E, Ossikovski R, Bertin F, Hazart J, Postava K, Drevillon B
  PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE 205 (4) 806-809 (2008)
  DOI: 10.1002/pssa.200777808
  Abstract: In this work we characterized two bidimensional gratings consisting each of a square array of square holes etched in a photoresist layer deposited on silicon. Data were taken on both samples with a spectroscopic UV-VIS ellipsometer (SE) operated at 70 degrees incidence and zero azimuth (with the incidence plane parallel to the lines of holes) and a VIS Mueller matrix polarimeter (MMP) at various incidence and azimuthal angles. The robustness of the parameters derived from the MMP data was evaluated from the stability of the values provided by regression the spectra taken at different angles. The optimal measurement geometries, featuring high sensitivity and low correlation of the fitting parameters, were determined theoretically, and validated experimentally with the sample featuring wider holes (500 x 500 nm), for which 45 degrees incidence provided better results than the usual 70 degrees value.
  Email: martino@leonardo.polytechnique.fr
  
  
• Spectroscopic Mueller matrix polarimeter using four-channeled spectra
  Authors: Otani Y, Wakayama T, Oka K, Umeda N
  OPTICS COMMUNICATIONS 2818 (23) 5725-5730 (2008)
  DOI: 10.1016/j.optcom.2008.08.017
  Abstract: A Mueller matrix polarimeter acquired for four-channeled spectra is proposed. Both the polarizing and analyzing optics of this system consist of a linear polarizer and a high-order retarder. The polarizing elements can modulate the polarization states in the wavenumber space. By applying a Fourier transform method to a single-channeled spectrum, nine elements of the Mueller matrix can be deconvoluted without modifying the configuration of either the polarizing or analyzing optics. It is thus possible to determine the wavelength dependence of all the Mueller matrix elements from four-channeled spectra obtained using four different configurations for the polarizing and analyzing optics. The performance of this method is evaluated by measuring polarization properties, such as retardance, azimuthal angle, and linear diattenuation, from the obtained Mueller matrix in wavenumber space
  Email: wakayama@saitama-med.ac.jp
  
  
• Measuring the Normalized Jones Matrix of Anisotropic Samples by Means of Static Ellipsometry
  Authors: V.A. Shvets, E.V. Spesivtsev, S.V. Rykhlitskii
  OPTICS AND SPECTROSCOPY 105( 4) 633-638 (2008)
  Abstract: Functional capabilities of the static photometric scheme of ellipsometric measurements proposed earlier are considered as applied to anisotropic reflecting objects. Combination of different positions of the optical elements, as well as addition of two new positions of the polarizer (P = 0 degrees and 90 degrees) to those used before (P = +/- 45 degrees) made it possible to obtain 24 equations for determination of the normalized Jones matrix of an anisotropic sample. For the ideal compensator (rho(C) = i), this system breaks down to 12 pairs of mutually identical equations. However, in this case, all three elements of the Jones matrix can be determined provided that rho(pp) not equal rho(ps)rho(sp). Computer simulation of the Jones matrix measurement indicates high accuracy of determination of the elements rho(pp) and rho(ps) and much lower accuracy for determination of rho(sp).
  Email: shvets@isp.nsc.ru
  
  
• The method of total internal reflection ellipsometry for thin film characterisation and sensing
  Authors: A. Nabok, A. Tsargorodskaya,
  THIN SOLID FILMS 516 (24) 8993-9001 (2008)
  Abstract: Recently developed method of Total Internal Reflection Ellipsometry (TIRE) represents a very successful combination of the spectroscopic ellipsometry instrumentation with the Kretchmann type Surface Plasmon Resonance (SPR) geometry of the experiment. The modelling shows much higher sensitivity of the TIRE method to small changes in optical parameters (thickness and refractive index) of thin films, as compared to both traditional external reflection ellipsometry and SPR. Considering another advantage of performing the measurements in media of different optical density (and even opaque media), TIRE becomes very convenient for different sensing applications in both gaseous and liquid media, as well as for thin film characterisation. This work presents examples of applications of the TIRE method for the study of DNA hybridization and the registration of low molecular weight toxins.
  Email: a.nabok@shu.ac.uk
  
  
• Simultaneous Reflectivity, Ellipsometry and Spectrometry Measurements in Submicron Structures for Liquid Sensing
  Authors: M. Holgado, R. Casquel, C. Molpeceres, M. Morales, J.L. Ocana,
  SENSOR LETTERS 6 (4) 564-569 (2008)
  Abstract: Technology for nano-scale integration is achieving promising results for the development of novel sensors systems to explore its application to important medical, biopharmaceutical and environmental applications such as drug development and immunoassays. They use well-known optical structures such as waveguide Surface Plasmon Resonance (SPR), Mach-Zehnder (M-Z) interferometers, two-mode waveguide interferometry, but need complex optical coupling such as inverted taper and grating couplers. The proposed system is based on the observation of external reflectivity profiles. A dielectric micro-nano structure consisting of a triangular lattice of sub-micro-holes fabricated on a SiO2/Si wafer produces spectra interference patterns as a function of the angle of incidence for both p and s polarization directions as well as a phase shift between s and p polarisation. The measurements have been performed simultaneously by using a linearly polarized laser operating at 675 nm with a tightly focussed beam, which provides a sub-micrometer spot and therefore allow these measurements to be accomplished in a single sub-micro-hole. Consecutively the reflectivity of the photonic structures is measured and analyzed over a wide range of wavelengths of light as well. The sub-micro-holes are filled with optical liquids with different refractive indices, involving a change in the effective refractive index which produces variations in the phase shift and the interference reflectivity patterns. The optical system is able to measure extremely small volumes of analyte (approximately 0.1 femtolitres per hole). The simultaneous use of three optical techniques, remove ambiguities and improve reliability. The detection limit achievable with this system is up to 10(-6) R.I.U. which is competitive with the current state of the art, and could be improved with not complex changes for all the optical techniques. Furthermore, the complexity of coupling in the current photonic label-free biosensors is avoided, as the light is collected normally.
  Email: m.holgado@upm.es
  
  
• Single-angle-of-incidence ellipsometry
  Authors: Zaghloul YA, Zaghloul ARM
  Source: APPLIED OPTICS 47 (25) 4579-4588 (2008)
  We introduce single angle-of-incidence (SAI) ellipsometry [U.S. patent application 20070024850 (14 July 2006)] as a technique to completely identify, i.e., totally characterize, film-substrate systems. We show that only one measurement of the ellipsometric function p at one angle of incidence and one wavelength is totally sufficient to determine the optical constant of the film N-1, its thickness d, and the substrate's optical constant N-2. Obviously, it is also sufficient for characterizing only the film, determining N-1 and d, and for characterizing only the substrate, determining N-2 and d, as well as for characterizing only bare substrates. An inverse genetic algorithm (IGA) for complete identification is presented that is based on a physical condition of the transparent-film-absorbing-substrate system. This IGA is used to identify the film-substrate system in four separate cases. We show that removing the film thickness from the fitness function of the genetic algorithm and using the defined optimum population size to characterize the film reduces the computational effort from 20,000 to 69 fitness-function calculations; the number of calculations to characterize an absorbing layer is reduced from 80,000 to 180. This is a very significant reduction and is very welcome in real-time applications. An error analysis is presented that shows that the IGA is resilient to, not affected by, random experimental errors and that it gives very good results in the presence of both random and systematic errors of the ellipsometer system. Experimental results are given that also prove the robustness, stability, and high accuracy of the method. We present data only for the SiO2-Si film-substrate system, but the IGA works for any film-substrate system, physical or not.
  
  
• Polarization mixing error in transmission ellipsometry with two acousto-optical modulators
  Authors: Deng YL, Chai JL, Li XJ, Wu YB, Xu G
  OPTICAL ENGINEERING 47 (7) 075601 (2008)
  DOI: 10.1117/1.2955770
  Abstract: A transmission ellipsometer with the configuration of modified Mach-Zehnder heterodyne interferometer is demonstrated. Two acousto-optical modulators are employed to generate a 20-kHz beat frequency. The scheme offers high resistance to environmental turbulence because of the interferometric components passing through the same path. A single layer of indium tin oxide on a glass substrate was measured, and an error up to several nanometers of the sample thickness is observed. The polarization mixing error is mainly due to the imperfection of polarizing beamsplitters (PBSs) and to the elliptical polarization and nonorthogonality of the light beams produced by the laser source and wave plates. The mechanism governing the error and its influence on measurement accuracy is analyzed with the Jones matrix method. In contrast with interferometric reflection ellipsometry using a Zeeman laser, the theoretical analysis indicates that only second-order error is introduced in this system. The elliptical polarization and nonorthogonality, occurring only before the light splitting, have little influence on measurement accuracy; the imperfection of PBSs is the major contributor to the polarization mixing error.
  
  
• Temperature-modulated ellipsometry: A new probe for glass transition in thin supported polymer films
  Author(s): Efremov MY, Kiyanova AV, Nealey PF
  MACROMOLECULES 41 (16) 5978-5980 (2008)
  DOI: 10.1021/ma8011416
  
  
• Structure and thermotropic phase behavior of fluorinated phospholipid bilayers: A combined attenuated total reflection FTIR spectroscopy and imaging ellipsometry study
  Authors: Schuy S, Faiss S, Yoder NC, Kalsani V, Kumar K, Janshoff A, Vogel R
  JOURNAL OF PHYSICAL CHEMISTRY B 112 (28) 8250-8256 (2008)
  DOI: 10.1021/jp800711j
  Abstract: Lipid bilayers consisting of lipids with terminally perfluoroalkylated chains have remarkable properties. They exhibit increased stability and phase-separated nanoscale patterns in mixtures with nonfluorinated lipids. In order to understand the bilayer properties that are responsible for this behavior, we have analyzed the structure of solid-supported bilayers composed of 1,2-dipalmitoyi-sn-gjycero-3-phosphocholine (DPPC) and of a DPPC analogue with 6 terminal perfluorinated methylene units (F6-DPPC). Polarized attenuated total reflection Fourier-transform infrared spectroscopy indicates that for F6-DPPC, the tilt of the lipid acyl chains to the bilayer normal is increased to 39 degrees as compared to 21 degrees for native DPPC, for both lipids in the gel phase. This substantial increase of the tilt angle is responsible for a decrease of the bilayer thickness from 5.4 nm for DPPC to 4.5 nm for F6-DPPC, as revealed by temperature-controlled imaging ellipsometry on microstructured lipid bilayers and solution atomic force microscopy. During the main phase transition from the gel to the fluid phase, both the relative bilayer thickness change and the relative area change are substantially smaller for F6-DPPC than for DPPC. In light of these structural and thermotropic data, we propose a model in which the higher acyl-chain tilt angle in F6-DPPC is the result of a conformational rearrangement to minimize.
  
  
• Exact polynomial inversion for top transparent layer parameters on an arbitrary substrate in ellipsometry
  Authors: Russev SC, Tsutsumanova GG, Drolet JP
  JOURNAL OF PHYSICS-CONDENSED MATTER 20, 285225 (2008)
  DOI: 10.1088/0953-8984/20/28/285225
  Abstract: We consider the inverse ellipsometric problem for a transparent layer on top of an isotropic substrate, which may consist of an arbitrary number of plane parallel homogeneous layers with complex refractive indexes, or have an arbitrary depth profile variation of the complex refractive index. It is shown that the task of finding the top layer parameters can be split into two. First, the top layer dielectric constant is determined by the roots of a fifth degree polynomial and then the layer thickness is found. Error propagation analysis is provided on a sample system and the stability of the method is estimated.
  
  
• Membrane characterization by optical methods: Ellipsometry of the scattered field
  Authors: Wyart Y, Georges G, Deumie C, Amra C, Moulin P
  JOURNAL OF MEMBRANE SCIENCE 318 (1-2) 145-153 (2008)
  DOI: 10.1016/j.memsci.2008.02.039
  Abstract: The fouling phenomenon is the major drawback of membrane processes. To be able to localize membrane fouling could be a real progress in the fouling understanding and the optimization of membrane regeneration step. For that, the membrane structure parameters must be taken into account. Classical techniques; such as displacement, tracer retention and microscopy; provides only information about the pore size of the skin layer and the thickness of the successive layers. The angle-resolved light scattering technique and the analysis of the scattered wave polarization state via ellipsometry of angle resolved scattering (EARS) are used to characterize more accurately membrane structure and to discriminate microfiltration and ultrafiltration ceramic membranes. The main objective of this study is to show the potential of these recent optical techniques that are very little known in the domain of membrane processes. First, the techniques of light scattering and ellipsometry will be reviewed, and then the results obtained for several unused ceramic membranes with different cut-offs will be detailed. The low resolution analysis clearly shows that the observed light scattering comes essentially from the bulk, but fails to differentiate between cut-offs. High resolution angle-resolved measurements make it possible to obtain a specific signature to each cut-off. The higher the porosity, the greater the angular variations of the polarimetric phase shift. Simulations performed by applying a rigorous method for the resolution of Maxwell's equations will validate these observations.
  
  
• Ellipsometric inspection of the inner surface of pellicle-covered masks
  Authors: Lee S, Song C, Rhim J, Lee H, Kyoung J, Chin S, Ahn T, An I
  METROLOGY, INSPECTION, AND PROCESS CONTROL FOR MICROLITHOGRAPHY XXII, PTS 1 AND 2 Book Series: PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) 6922 (1-2) 92227-92227 (2008)
  Abstract: Crystal growth and haze formation on photomasks become serious problems in UV lithography. As the wavelength becomes shorter, photons carry more energy, so the chances of having a photochemical reaction become much higher. Pellicle, adhesive, residue from cleaning or resist strip process, and any contaminant in air can react with IN to form unwanted crystals and a haze layer on reticles. These will reduce the light transmission during exposure process. Thus, frequent mask inspection and periodic mask cleaning are needed to overcome these problems. However, these will in turn increase manufacturing cost and reduce mask life. Thus, a proper mask inspection tool is required to provide early warning of haze formation. In this work, we devised a new ellipsometric technique to investigate the inner surface of mask without removing pellicle. Ellipsometry is known to have mono-layer sensitivity and it can be used to measure any film or partial film formed on non-patterned spot in early stage of growth. However, when a pellicle covers the surface of mask, the ellipsometric data reflected from surface are extremely distorted due to the non-normal transmission through the pellicle. Thus, data analysis becomes extremely difficult without knowing the optical properties of pellicles. In order to solve this problem we developed compensation technique in which two blank pellicles are situated in the optical path in a way to compensate the polarization changes caused by the pellicle on mask. With this method, the conventional ellipsometry spectra of {Delta, Psi} are deduced.
  
  
• Sensitivity and performance estimates for the multiple wavelength, multiple incidence angle ellipsometry for OCD applications
  Authors: Kotelyanskii M, Jiang G
  METROLOGY, INSPECTION, AND PROCESS CONTROL FOR MICROLITHOGRAPHY XXII, PTS 1 AND 2 Book Series: PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) 6922 (1-2) O9223-O9223 (2008)
  Abstract: Optical metrology techniques are essential for process control of the gate formation process steps from lithography to the dielectric, spacers, gate and straining layer deposition in the sub-65nm technology nodes. Traditionally, optical metrology is based on the measurements of periodic lines or hole arrays using a spectroscopic ellipsometer or reflectometer, collecting data across a wavelength range at a single angle of incidence. In this paper, we discuss measurements using Focused Beam Ellipsometry (FBE), illuminating at discrete laser wavelengths while data is collected over a wide angle of incidence range. We verify precision estimates of the different model parameters with actual values obtained from measured data. We show sensitivity ranges for different applications over the space of measured wavelength spectrum from DUV to IR, angle of incidence range, and sample azimuthal orientations. Major factors contributing to the projected recipe performance - wavelength, orientation of the incident beam are discussed.
  
  
• Systematic errors for a Mueller matrix dual rotating compensator ellipsometer
  Authors: Broch L, Naciri AE, Johann L
  Source: OPTICS EXPRESS 16 (12) 8814-8824 (2008)
  Abstract: The characterization of anisotropic materials and complex systems by ellipsometry has pushed the design of instruments to require the measurement of the full reflection Mueller matrix of the sample with a great precision. Therefore Mueller matrix ellipsometers have emerged over the past twenty years. The values of some coefficients of the matrix can be very small and errors due to noise or systematic errors can induce distored analysis. We present a detailed characterization of the systematic errors for a Mueller Matrix Ellipsometer in the dual-rotating compensator configuration. Starting from a general formalism, we derive explicit first-order expressions for the errors on all the coefficients of the Mueller matrix of the sample. The errors caused by inaccuracy of the azimuthal arrangement of the optical components and residual ellipticity introduced by imperfect optical elements are shown. A new method based on a four-zone averaging measurement is proposed to vanish the systematic errors.
  
  
• Ellipsometric models for vertically inhomogeneous composite structures
  Author: Petrik P
  PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE 205 (4) 732-738 (2008)
  DOI: 10.1002/pssa.200777847
  Abstract: The optical properties of thin films usually depend on the preparation conditions. For example, the microstructure of ion implantation-caused damage, the grain size of deposited polycrystalline materials, or the porosity of chemically etched silicon largely depend on the parameters of ion implantation, deposition, and etching, respectively. Generally, as a first approach, these materials can be considered as a mixture of components described by reference dielectric function data from the literature using the effective medium approximation (EMA). Interface roughness and vertical inhomogeneity can be described by the volume fraction of components changing as a function of depth. The EMA models are robust, and provide useful information like damage depth profiles of ion implanted materials, crystallinity and surface roughness of deposited materials, or porosity of chemically etched porous silicon. The requirement for EMA is that the size of the components must be smaller than the wavelength of the measuring light, but large enough to retain their bulk dielectric properties. If the component sizes are large, diffraction and scattering has to be taken into account. For example, surface roughness is routinely modeled by EMA, but in case of rough surfaces with large correlation length EMA may become invalid as approaching small wavelengths in the UV part of the spectrum. If component sizes decrease, it may not be possible to describe the components using bulk reference data, because of size effects or strain. For example, fine grained polycrystalline silicon or highly porous silicon can not be modeled by the usual mixture of single-crystalline silicon (c-Si) and amorphous silicon (a-Si) for polycrystalline silicon, or mixing c-Si and voids for porous silicon, but a component representing an intermediate structure between c-Si and a-Si has to be used to describe the vanishing long-range order. A less robust but more detailed analysis is provided by parametrization of the dielectric function of the layer or the components in an EMA composition using model dielectric functions, critical point (CP) models, oscillator models, or empirical dispersion equations. In these cases, cross-correlation, parameter-coupling, selection of sensitive parameters, local minima, and regression in a multi-parameter space are crucial issues to be handled properly. Consideration of the optical penetration depth (OPD) is also important, when measuring vertically inhomogeneous semiconductor materials. Obviously, CP analysis in semiconductors is most sensitive around the CP photon energies, but the OPD is the smallest just at this region of the spectrum. In silicon, the OPDs at the E-1 and E-2 CP energies are about 10 nm and 5 nm, respectively. Consequently, CP analysis of structures below this depth is not possible using ex situ measurement of silicon. This work shows approaches and examples to model multi-component materials created using different methods including ion implantation, deposition, and electrochemical etching
  Email: petrik@mfa.kfki.hu
  
  
• Generalized ellipsometry determination of non-reciprocity in chiral silicon sculptured thin films
  Authors: Schmidt D, Schubert E, Schubert M
  PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE 205 (4) 748-751 (2008)
  DOI: 10.1002/pssa.200777906
  Abstract: We report on angle-resolved reflection-type generalized ellipsometry investigations of form-birefringent chiral silicon sculptured thin films. The nanodimensional structures within the sculptured thin films are designed in geometries of left-handed hollow-core three-, four-, and five-fold, and solid-core continuous screws. We identify their structurally induced non-reciprocal optical properties by comparison between off-diagonal Mueller matrix elements upon reversal of the light direction. The observed non-reciprocity cannot be described by the piecewise homogeneous approximation scheme using chiral arrangements of dielectrically anisotropic layers. We show that a simple sequence of light interaction with an ideal isotropic chiral rotator and an arbitrarily anisotropic but non-chiral surface produces non-reciprocity. We provide estimates of the optical rotary power of the nanostructures.
  Email: schmidt@bigred.unl.edu
  
  
• Precise phase-modulation generalized ellipsometry of anisotropic samples
  Authors: Halagacka L, Postava K, Foldyna M, Pistora J
  DOI: 10.1002/pssa.200777823
  Abstract: A procedure for the measurement of the generalized ellipsometric angles using a phase-modulation spectroscopic ellipsometer is described. Generalized phase-modulation ellipsometry combined with zone averaging enables precise characterization of samples with generalized anisotropy including anisotropic thin films with general axis orientation, liquid crystals, gratings, and anisotropic nanostructures. We employed a UVISEL Jobin Yvon spectroscopic ellipsometer with a photoelastic modulator (PEM). The Jones matrix formalism is applied to nondepolarizing samples and ellipsometer components description. The zone averaging proposed enables elimination of azimuth-angle error and component imperfection
  Email: kamil.postava@vsb.cz
  
  
• Imaging ellipsometry: quantitative analysis
  Authors: Asinovski L, Beaglehole D, Clarkson MT
  PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE 205 (4) 764-771 (2008)
  DOI: 10.1002/pssa.200777855
  Abstract: Imaging ellipsometry (IE) combines spatial resolution of optical microscopy with thin-film measurement capabilities of ellipsometry. It has gained significant interest in recent years and is been used for a wide range of applications from biotechnology to semiconductor metrology. Traditionally, IE is used either as a qualitative technique - not unlike polarized microscopy or Surface Plasmon Resonance (SPR) - with "ellipsometry images" showing surface topology variation, or as a quasi-quantitative technique where the change in "ellipsometry images" is used to deduce the change in film thickness. In this paper we give a brief critical review of different measurement systems configurations from the point of view of their fitness to quantitative IE measurement. We discuss the methods of calibration and correction that enable to achieve a truly quantitative IE measurement. We show that a fast and reliable quantitative IE can be practically implemented. It is consistent and can be used in lieu of a classical single point ellipsometry in many applications
  Email: Leo.Asinovski@semiconsoft.com
  
  
• n and k testing of magnetic heads with imaging spectroscopic ellipsometry
  Authors: Vaupel M, Yunfeng S, Zhimin Y
  PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE 205 (4) 772-778 (2008)
  DOI: 10.1002/pssa.200777743
  Abstract: The method of imaging spectroscopic ellipsometry is applied on magnetic read/write heads of hard disks. By means of spectroscopic ellipsometry, an optical model of the TiC/Al2O3 substrate including surface roughness and concentration gradient of TiC in the alumina substrate is generated. Surface roughness is measured with both ellipsometry and atomic force microscopy (AFM). The granular structure of TiC/Al2O3 is investigated in micrographs of n and k. It is discussed how Delta mapping of the magnetic pole area of the head can be used to measure DLC coating thickness and the variation of chemical constitution of the metal substrate. Repeatability of measurements of Delta is optimized in a one mu m(2) region of interest (ROI) on a metal stripe of the magnetic pole
  Email: mv@nanofilm.de