Renewed interest in mercerization as a pre-treatment for textile finishing has led to research on the effects of temperature on this process. Mercerization, the swelling of cotton in caustic soda, causes changes in crystallinity from a Cellulose I structure to a Cellulose II structure, along with changes in fiber physical dimensions, increased dyeability, luster and tensile strength. These changes are differentiated by light microscopy, image analysis and FT-IR, and transmission electron microscopy. Cotton yarns were mercerized with an aqueous solution of 23% NaOH and 1% wetting agent. The yarns were treated for 1 hour at 0, 20, 60, 80, and 110° C, and washed in distilled water at the same temperature as the treatment bath. Rapid embeddment procedures have been developed for analyzing the effects of treatments on cotton fiber structure. Cotton fiber cross-sections were prepared for light microscopy/image analysis by encasing the fibers in a tube,1 embedding in mefhacrylate plastic (Fig. la), polymerizing for 30 minutes with UV, and sectioning.

The microstructural and chemical characterization of catalysts is not only integral to their initial development but also to understanding and controlling their behavior over time. To better elucidate the morphology of these materials and relate physical properties to catalytic properties (e.g., activity, selectivity, etc.), “ex-situ” methods for studying catalysts under reactive conditions have been developed.

Because conventional transmission electron microscopy (CTEM) is conducted under high vacuum conditions, it is difficult to replicate the exact chemical environment of a catalyst (e.g., high pressure, variable gas mixtures, etc) within the TEM. Consequently, most analyses focus on comparing “fresh” and “spent” materials. In general, this methodology provides useful structural information albeit with limitations associated with the comparison of dissimilar regions and the effects of sampling inhomogenieties.

The focused ion beam (FIB) lift out (LO) technique has been used to prepare transmission electron microscopy (TEM) specimens from individual Zn powder particles [1]. The Zn microstructure observed by TEM was compared to the Zn microstructure analyzed by traditional metallographic preparation techniques. It was concluded that the Ga focused ion milling produced no apparent microstructural damage to the Zn [1]. A low magnification TEM image of the FIB prepared Zn specimen obtained from a Philips EM430 operating at 300 KeV is shown in figure la.

The Zn FIB LO specimen was then processed in a plasma cleaner. After subjecting the Zn specimen to the plasma cleaning operation, the specimen was observed in a Philips EM400 operating at 120 KeV. The Zn specimen completely transformed during in situTEM observation at 120 KeV. The specimen was then subsequently observed in an EM430 to analyze the transformed Zn at 300 KeV.

The field ion microscope is a point projection microscope, with the magnification inversely proportional to the radius of curvature (R) of the needle-shaped tip which comprises the specimen. The electric field at the specimen apex, which determines the trajectories of field evaporated ions, is given by F=V/(kR), where V is the specimen voltage and k is a geometric field reduction factor which increases with the specimen taper angle, θ. In the reconstruction of atom probe tomography (APT) data, the magnification, and thus the lateral extent of the analyzed region, is determined primarily by the specimen radius and taper angle. Asymmetric specimens may often be fabricated, even from materials which lend themselves to straightforward preparation. In addition, in certain materials, specimens with high aspect ratios may result from crystallographic preferential electropolishing. For accurate data reconstruction, it is important to know not only the specimen radius, but also, ideally, the degree of anisotropy (aspect ratio taper angle in orthogonal directions) of the specimen.

The continued reduction in the size of critical features in integrated circuits has resulted in the need to develop rapid, site-specific, sectioning techniques to enable efficient physical characterization of the structures of interest. We have implemented a mechanical polishing approach to achieve this objective with the additional goals of maximizing the number of targeted sites in a sample that can be analyzed, and minimizing physically destructive procedures, such as ion beam exposure. Precision sample preparation approaches have been under investigation for both transmission electron microscopy and scanning electron microscopy.

The mechanical specimen preparation approach used in this work is a variant of the well-known wedge polishing technique. Here we use a polishing tool that does not contact the grinding surface, thus allowing precise control of the wedge angle. Prior to sample preparation, the polishing tool head was precision aligned parallel to the platen.

Transmission Electron Microscopy technique is a powerful tool to examine microstructures. However, the specimen preparation process usually requires tedious and careful cutting and lapping. In this paper, we present a TEM specimen preparation process which is simple, requires about one hour, and allows specific areas of patterned films deposited on silicon dioxide to be examined. The sample consisted of three thin film layers deposited on a Corning 1737 glass substrate. The top layer was 1000 A thick, low temperature oxide; the middle layer, 1000 A thick; amorphous silicon; the bottom layer, 1000 A thick, low temperature oxide. The top oxide layer was patterned to contain a square array of 10 × l0um openings, with a 100 um center to center spacing. A thin nickel layer was the evaporated, and the specimen was heated to form nickel silicide in the 10 × 10 um areas where Ni and Si were in contact.

Electron energy loss spectroscopy (EELS) is a powerful microanalytical tool that can be used to characterize the composition and other properties of a wide range of materials. The compositional information is retrievable from the pattern of edges displayed in the energy-loss spectrum [1]. Under favorable experimental conditions, concentrations below 1000 ppm of many different elements can be detected on a nanometer scale [2].

The minimum detectable mass (MDM) and the minimum detectable mass fraction (MDF) attainable in practice depend on many parameters (sample thickness, incident beam convergence / acceptance angles, primary energy, electron dose, probe size, detector efficiency, etc.), and there are no easy rules that can be used to predict them. For instance, a minority element that gives rise to an edge situated at an energy just lower than a major edge due to a principal constituent is much easier to detect than a minority element that gives rise to an edge just above the major edge.

Trace element quantitation with EELS is a powerful tool for providing information about elemental distribution in biological and materials sciences. Linear least squares fit (LSF) to standards of the signal and the background is a widely used method for retrieving small signals superimposed on a large, slowly varying background. Theoretically, for most accurate background fitting, the fitting window should be as large as possible. However, when using a large window, there may be a mismatch between the fine structure of the standard and the measured background, due to instability of the instrument and the experimental conditions and radiation damage. This mismatch, distributed over the entire window, can severely affect the accuracy of the small signal extracted with LSF. To overcome this problem, a small window, slightly larger than the signal is often used. Fig. 1 shows the results of extracting a small Ca signal by using respectively, a large and a small window for fitting an EELS spectrum collected from a specimen containing 26.3 mmol/kg dry weight Ca.

Due to the penetration ability and absorption contrast mechanism, cone-beam X-ray microtomography is a powerful tool in studying 3D microstructures in opaque specimens. In contrast to the conventional parallel and fan-beam geometry, the cone-beam tomography set up is highly desirable for faster data acquisition, build-in magnification, better radiation utilization and easier hardware implementation. However, the major draw back of the cone-beam reconstruction is its computational complexity. In an effort to maximize the reconstruction speed, we have developed a generalized Feldkamp cone-beam reconstruction algorithm to optimize the reconstruction process. We report here the use of curved voxels in a cylindrical coordinate system and mapping tables to further improve the reconstruction efficiency.

The generalized Feldkamp cone-beam image reconstruction algorithm is reformulated utilizing mapping table in the discrete domain as: , where .

Pathologists, microbiologists and cytologists are very interested to automatically identify and quantify the sperms, cells or nucleus in the cellular level images. Complexities like voluminous data sets, variability in data sets, millions of colors, and different kinds of artifacts make the detection and quantification process very difficult. This paper is an attempt to design a sophisticated cellular diagnostic system based on color image processing, mathematical morphology and connected components based on run length encoding. This system runs on Windows ‘98/NT PC platform, in Visual C++, 6.0 environment using three different architectures: Single document interface, multiple document interface and dialog based applications. The system takes around 1.5 seconds per image of 512 x 484 square pixels using high speed threading architecture written on the on 400 MHz Pentiumll processor. The system has an accuracy of 95%. The software has been validated tested on NASA and machine vision real world images.

The phase shift of an electron wave compared with a reference wave amounts to [1]

where e is the electron charge (e > 0), h is Planck's constant, A is the magnetic vector potential, B is the magnetic induction and Фm is the magnetic flux through an area F bordered by the trajectories of the two waves. The absolute value of the vector F perpendicular to this area is given by F. As a simple example we qualitatively sketch the phase shifts by a uniformly magnetized sphere. The cross section of this sphere and the magnetic field lines are shown in Fig. 1. The electron wave travels perpendicular to the paper plane. On one side of the sphere the object wave through point 1 is compared with the reference wave through point 2 and on the opposite side the wave through point 3 is compared with the one through point 4.

ZnO varistor materials are polycrystalline materials that exhibit strong non-linear current-voltage characteristics. Their non-ohmic behaviour makes them suitable for overvoltage protection devices. It is the interfaces between ZnO grains that are the key to the non-linear behaviour of the varistor materials. Previous work has shown that the local microstructure determines the breakdown voltage of the individual ZnO/ZnO interface [1]. The pre-breakdown conductivity and the non-linearity in the breakdown region, which are both crucial to the performance of the varistor, are also affected by the height and the width of the potential barriers. In the present work, electron holography has been used to investigate the potential barriers in ZnO varistor materials.

Electron holograms were recorded at 200kV using a Hitachi HF-2000 field emission gun transmission electron microscope [2]. The electrostatic bi-prism was located near the second image plane. The bi-prism voltage was about 9 V and the fringe spacing in the holograms was about 1 nm.

Today's information-oriented society requires high-density, high-quality magnetic recording media. For the development of such new recording materials, the quantitative observation of magnetic fine structures by electron holography is eagerly awaited. However, the magnetic fields around particles smaller than 50 nm have not been observed because they are too weak to be observed in the usual way. Here, we report a highly precise phase measurement technique, improved phase-shifting electron holography. Using this method, we observed weak electric and magnetic fields precisely. The precision of the reconstructed phase image was as good as 2π/300 rad.

In phase-shifting electron holography, the phase images are reconstructed from a series of electron holograms whose interference fringes are shifted relative to one after another. The shifting of interference fringes is achieved by tilting the incident electron beam, which corresponds to shifting the initial phase of the incident electron waves in a specimen plane.

While electron holography has been around for many years (1948, see [1]), the process of obtaining a view into the phase world stayed a tedious one for a long time. When CCD cameras became available and started to replace film, many attempts were made to obtain a “live” view into the phase world. By far the most successful setup for a live phase display is described in [2]. There, Chen et al. use a mixture of digital and analog techniques to obtain phase images at TV-rate. This setup allows to move the sample and/or watch time dependent specimen changes in a unique way, i.e., live in the phase world. The reason why Chen uses a mixture between analog and digital methods is the capability of an optical lens system for fast Fourier processing.

Computers have become significantly faster since Chen's introduction of the mixed setup in 1992 and allow to process holograms rapidly and obtain about one phase image per second on present standard computer systems and acquisition cameras.

Pure phase objects having low spatial frequency such as electromagnetic fields in a vacuum can be visualized by electron holography or three-wave interference.1,2) Wavefront-division interference using a biprism requires a field-emission electron gun having high spatial coherency. On the other hand, amplitude-division interference using a thin crystal does not need high spatial coherency of electron source, i.e. an ordinary electron microscope with a LaB6 filament is good enough to form lattice fringes of high contrast. This is an advantage of amplitude-division interference.3,4)

We previously reported three-wave interference achieved by using two electron biprisms. Recently, we have realized amplitude-division three-wave interference by using a Si crystal as a splitter of an electron wave. Figure 1 shows the experimental set-up used to form an amplitude-division threewave interference pattern. A thin crystal prepared by ion-milling is installed at the standard specimen position, and a thin carbon film on which latex particles are sticking is placed at the selected area aperture position.

The problem of observing reverse-biased p-n junctions by means of transmission electron microscopy techniques is very challenging both from the experimental and theoretical points of view. In particular, in addition to standard Lorentz microscopy techniques, whose image contrast is able to give some information on the region of high field, also holographic methods have been successfully applied and an interference map of the twodimensional phase on the specimen plane obtained.

In this work we consider, in particular, the theoretical and interpretative aspects, as we have improved a model for the electric field associated to a periodic array of alternating p and n stripes lying in a half plane (physically corresponding to an array of zero-width step junctions) by taking into account that the junctions are tilted with respect to the specimen edge.

Scanning Probe Microscopy (SPM), in particular Atomic Force Microscopy (AFM), has become well establish member of the IC metrology tool arsenal which few IC manufacturers are without. Although Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) remain the “workhorse” metrology techniques, SPM (standard AFM, as well as Scanning Capacitance Microscopy (SCM), Scanning Spreading Resistance Microscopy (SSRM), Scanning Kelvin probe, Nanoindentaion and others) are being increasingly called upon to help solve IC production problems and to aid in research and development for next generation devices.

Topographical metrology with standard AFM is by far the most common application of SPM in the semiconductor industry. It is typically used to gain surface roughness and grain size information about thin films that can be used as feedback to modify deposition conditions until the desired film properties are obtained.

Atomic force microscopes (AFMs), which generate three dimensional images with nanometer level resolution, are increasingly being used as tools for sub-micrometer dimensional metrology in a wide range of applications. Measurements commonly performed with AFMs are feature spacing (pitch), feature height (or depth), feature width (critical dimension), and surface roughness. To perform accurate measurements, the scales of an AFM must be calibrated regularly. Presently available standards for this purpose are calibrated using stylus instruments and optical techniques. The effectiveness of this approach, however, is limited by the differences in the working ranges of the various techniques and by questions of methods divergence. Such divergence may occur between measurements made by instruments using different techniques to measure the same feature. A reflected light microscope and an AFM, for example, may have differing sensitivity to the cross-sectional profile of measured lines. For sufficiently steep lines, an AFM tip will only contact the features near the tops.

With the continuing push for reduction in the device dimensions into the deep sub-u,m dimensions, the critical need for physical and electrical characterization on this sub-μ,m scale is evident. The National Technology Roadmap has identified need for two-dimensional (2D) dopant/carrier profiling with a spatial resolution of 10 nm. Though current techniques used for dopant profiling such as secondary ion mass spectroscopy (SIMS) and spreading resistance profiling (SRP) have a high sensitivity, these offer good resolution only in the depth direction. The spatial resolution in the lateral direction in these techniques is limited to several tens or hundreds of microns. To acheieve the required lateral spatial resolution different scanning probe based techniques have been explored. One of the most promising of these class of techniques is scanning capacitance microscopy (SCM). In SCM a conductive atomic force microscope (AFM) probe tip is scanned across the surface and simultaneously an a.c. bias is applied between the tip and the sample.

Recent advances have been made on two fronts regarding the capability of the atomic force microscope (AFM) to characterize the mechanical response of polymers. Phase imaging with the AFM has emerged as a powerful technique, providing contrast enhancement of topographic features in some cases and, in other cases, revealing heterogeneities in the polymer microstructure that are not apparent from the topographic image. The enhanced contrast provided by phase images often allows for identification of different material constituents. However, while the phase changes of the oscillating probe are associated with energy dissipation between the probe tip and the sample surface, the relationship between this energy dissipation and the sample properties is not well understood.

As the popularity of phase imaging has grown, the capability of the AFM to measure nanoscale indentation response of polymers has also been explored. Both techniques are ideal for the evaluation of multi-phase and multi-component polymer systems.