It is well known that the “channeling contrast” and EBSD pattern formation, which is the basis for “orientation imaging microscopy” (OIM), is highly sensitive to specimen surface quality in SEM studies. Typically, specimens for these studies are prepared by a combination of mechanical grinding then chemical etching or electropolishing. As an alternative to the chemical step(s) in this technique, we report a method based upon broad ion beam etching equipment [1]. This alternative method is more universal and reliable for enhanced channeling contrast and EBSD/OIM of metallic materials.

A variety of polycrystalline metallic specimens were etched in an instrument dedicated for etching and coating SEM specimens [1] and examined in the SEM for channeling contrast and OIM mapping. Fig. la is a SEM image of an annealed titanium sheet specimen in as-received condition showing a well-defined surface texture. It can be seen that channeling contrast is absent, presumably due to the existence of a surface layer formed during the manufacturing process.

Argon ion beam etching has established itself as an alternative technique to “wet chemical” etching for the preparation of cross sectional SEM specimens of semiconductors [1]. Complementing this technique, we are reporting the results of an iodine RIBE method for improved etching/cleaning capabilities with a measurable increase in etching rates as compared to argon ion beam etching. RIBE systems have been used for decades in the semiconductor research/industry for wafer processing, patterning and surface cleaning. This same technique has also been used for high quality TEM specimen preparation of certain semiconductor materials [2,3]. The beneficial aspects of the iodide RIBE technique for surface etching for a variety of semiconductor structures along with the related instrumentation will be discussed. The semiconductor specimens include traditional ICs and more advanced copper technology devices.

The design and construction of the original system used in this work has already been reported [4].

A method for site specific characterization of the materials using a dedicated focused ion beam(FIB) system and an analytical transmission electron microscope (TEM) was developed. Needless to say, in TEM specimen preparation using FIB system, stability of a specimen is quite important. The specimen stage employed in the developed FIB system is the one designed for high resolution TEM, and the specimen drift rate of the stage is less than lnm/min. In addition, FIB-TEM compatible specimen holder which allows milling of a specimen with the FIB system and observation of the specimen with the TEM without re-loading was developed. To obtain thin specimen from the area to be characterized correctly, confirmation of the area before final milling is needed. However, observation of cross sectional view in a FIB system is recommended because it causes damage by Ga ion irradiation. To solve this problem, we used a STEM unit as a viewer of FIB milled specimen.

I present details of novel sample preparation techniques used for delineating two-dimensional dopant profiles in silicon devices. These techniques are based on selective chemical etch of doped silicon in a mixture of hydrofluoric and nitric acid, or simply in buffered HF. The altered topography of the etched surface is imaged by transmission electron microscopy (TEM). Two different strategies will be presented by focusing on their sensitive, resolution, and field of application.

In the first case the silicon device is subjected to the conventional thinning procedure for TEM observations in cross-sectional configuration. The final thickness is obtained by Ar ion milling and it can vary between 50 to 500 nm. Sample is then immersed in a chemical solution containing HF (40%), HN03 (65%), and CH3COOH (95%) in the ratio 1:10:10. In presence of an intense illumination this mixture preferentially etches those device regions which are doped with boron, while in order to delineate n-type regions, the etching procedure must be performed in the dark.

Preparation of lead and lead alloy specimens for metallographic examination is more difficult than preparation of the majority of other metals and their alloys. The troublesome difference is that lead and lead alloys are soft (lead has a Vickers hardness of 4-5 [1,2]), and therefore readily develop a cold-worked surface layer and disturbances in the subsurface layers during mechanical polishing. The specimen softness also allows embedding of the abrasive particles. If not removed, these mechanically introduced artifacts obscure the true structure of the specimen, and in some cases could develop a pseudostructure, especially if excessive frictional heat is involved [1]. Usually etchpolishing, consisting of cycles of alternately etching, polishing, and microscopic examination, is required to remove the above artifacts. This treatment either might not completely remove these artifacts or it might overetch the sample. In addition, etching could introduce its own artifacts, such as tarnishing, etching pits, or both.

Sample substrates for x-ray microanalysis of particles should be chemically simple and composed of low atomic number elements. Substrates meeting these requirements will generate a minimum number of low energy x-ray peaks that should not interfere with spectra generated by the particles of interest. Elemental carbon fulfills these requirements and carbon planchets are used for the majority of work involving x-ray microanalysis of particles. When particles of interest are carbonaceous, alternate substrates must be sought. Beryllium planchets have traditionally been used for the analysis of carboncontaining particles. However, concerns about beryllium toxicity along with regulations from the Occupational Safety and Health Administration (OSHA) have resulted in diminished use of beryllium as a substrate material. These toxicity issues prompted us to explore the possibility of using elemental boron as a substrate for microanalysis of carbon-containing particles.

Elemental boron is available from chemical supply houses and the material we purchased was in the form of irregularly shaped pieces, approximately 3 cm in the longest dimension.

Remote ice core, snow, and air filter samples can potentially profile past and present atmospheric characteristics, acting as media to preserve populations of particulate matter. Major constituents of these aerosols derive from combustion processes (fossil and biomass) and airborne minerals. Extraction and characterization of these particles with scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS) provide morphological and elemental data used in determining the presence and sources of atmospheric aerosols. Due to the minute quantity of carbonaceous particles in the snow and ice samples, ca. 1-10 ng g-1, the microscopist faces several principal challenges to prepare and analyze these samples. First, methodology must be established for particle removal in a clean and quantitative fashion. Secondly, since carbon is contained in many of the particles under analysis, techniques must be established to achieve quantitative carbon X-ray data. The SEM requires optimization in order to analyze the greatest number of particles in the least time.

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.