Serious artefactual structures can be introduced into transmission electron microscope specimens of compound semiconductors when the latter are prepared by ion milling under non-optimum conditions. In the present investigations, the nature of these artefacts is characterised and results obtained using conventional argon ion milling are compared with those obtained using alternative ion species, including iodine ions. This work demonstrates the large improvement in specimen structural quality which can be achieved by combining a logical selection of ion species with a careful choice of milling conditions.

Obtaining useful microstructural information about catalysts requires appropriate procedures for preparing specimens for the transmission electron microscope. Unfortunately, most descriptions of catalyst specimen preparation are scattered throughout numerous journal articles or are unavailable. Traditional techniques for preparing heterogeneous catalyst powders include primarily dilute dispersion and ultramicrotomy. The advantages and disadvantages of these will be discussed in terms of information obtainable and possible artifacts. In addition, techniques for preparing layered materials, as well as some novel approaches and model systems, will be presented. With these, as with more traditional approaches, the best method for a specific material will be arrived at only through experimentation. Our aim is to describe a variety of possibilities for getting an already synthesized catalyst into the microscope suitably neat, thin, and artifactfree.

Line widths of less than a micron and junction depths within devices of the order of a thousand angstroms are common practice In today's electronic components. Transmission electron microscopy (TEM) is fast becoming a very valuable and often essential tool in many areas of semiconductor manufacture. The characterization of a given device structure is often required to fully understand its electrical behavior. This paper will review the methods that can be used to prepare cross-sectional samples from specific regions within an integrated circuit device for examination in the TEM.

The first, and often the most critical, step in any electron microscopy investigation is the preparation of an electron transparent specimen which is representative of the bulk material and in which the features of interest can be clearly observed and interpreted. However, for many materials of technological importance, specimen preparation procedures are far from routine. The application of standard, established techniques may be limited by material inhomogeneities, by physical constraints such as size or geometry, or by material constraints such as toxicity, radioactivity, or reactivity. Examples illustrating techniques for overcoming some of these difficulties will be reviewed.

The aim of thin foil preparation is to produce a specimen for microscopy which is representative of a larger volume of material, and in which the detail can be seen and interpreted. It is in general necessary to undertake some initial preparation before the final thinning process. Both stages are described. The final preparation methods described in this paper include electropolishing, ion beam thinning, ultramicrotomy and replication. A guide to the choice of technique is presented.

Techniques for the preparation of specimens for Transmission Electron Microscopy analysis are described. Cross-sectional specimens of insulator/semiconductor heterostructures have been successfully prepared. The problem of differential thinning rates and interface amorphization during argon ion-milling have been overcome using low argon ion accelerating voltages and shallow angles of incidence. Techniques for preparation of plan view specimens include the preparation of silicon substrates for in-situ crystal growth in an ultrahigh vacuum Transmission Electron Microscope.

Direct observation of structure in liquid phase materials is made possible by a cryo-vitrification technique in which a thin liquid sample is frozen at a high cooling rate to prevent crystallization. We have applied this technique to observe the evolution of structure in ceramic sols and gels using TEM. The sample preparation technique is described in detail and results obtained from colloidal and polymeric sols and gels are presented to show the usefulness of the technique. Artifacts arising from radiation damage and beam heating are also discussed.

Liquid and colloidal microstructures can be imaged at high resolution with cryo-TEM and cryo-SEM by fast-freezing with a Controlled Environment Vitrification System. Frozen bare-films can be directly imaged by TEM, while films sandwiched between metal plates can be frozen, fractured, and directly imaged with cryo-SEM or indirectly imaged by TEM after replication. We describe sample preparation techniques and report cryo-SEM studies of particle distributions and fracture patterns in such specimens.

A technique for observing both plan view and cross sections of a specimen directly in a transmission electron microscope (TEM) without relying on a tedious thinning operation was developed. This technique involves cleaving a specimen perpendicular to the plane, so that the thin (electron transparent) section of the cleaved edge can be directly imaged by TEM. The only limitations of this technique are that a specimen must be readily criacked or cleaved and that, since the transparent region is often bounded by a 90° corner, the extent of electron transparent region is somewhat localized. Nevertheless, the technique has the advantages of the ease of specimen preparation, and the absence of contamination or damage introduced in other conventional thinning methods. The geometry of the cleaved specimen is also suitable for reflection electron microscopy.

Standard preparation techniques such as ultramicrotomy and ion-milling are essential for obtaining accurate and detailed information about the structural and/or chemical properties of various categories of materials. The choice of a formulated matrix media has improved the preparation of thin sections of various powders ranging in degree of hardness from zinc oxide to tungsten carbide. This medium has shown superior performance when utilized in ion-milling powders and composites of high hardness such as boron carbide. This support vehicle has facilitated analysis of various geometric structures including hollow ceramic spheres. The homogeneity of chemically derived dielectric powders has been investigated by studying crystallite lattice parameter data derived from analysis of thin sections.

The preparation of cross-sectional TEM samples from multilayer materials commonly encountered in electronic industry is difficult in general due to the large variation in chemical and physical etching rate. We have developed a technique consisting of a median incidence angle ion sputtering to perforation followed by a short time (<2 hours) low incidence angle sputtering with the glue line direction shielded from the ion beams. This technique takes advantage of the fast sputtering rate associated with the median incidence angle sputtering initially. The near normal (relative to the glue line direction) low angle sputtering in the second step smooths out any non-uniformity in thickness due to the strong dependence of sputtering rate on the sputtering angle. High quality TEM samples prepared from many different types of multilayer structures using this technique are demonstrated.

The increasing availability of intermediate and high voltage transmission electron microscopes, together with recent improvements in video recording equipment, have led to renewed interest in in situ dynamic experiments. To alleviate the problems encountered in preparing TEM specimens with the awkward geometries required for straining stages, a jet polishing technique has been developed which allows the use of a conventional twin-jet electropolishing unit, with all its attendant advantages. A pair of Teflon sheet inserts, with rectangular openings cut to a specific shape and size, are used in the conventional specimen holder. Specimens with elliptical holes close to the center of the gauge section, and with large electron transparent areas at both ends of the long axis, are produced routinely and rapidly. Samples of many annealed metals, such as brass, molybdenum, and aluminum, prepared by this method are stronger, and can be handled more easily, than those prepared by conventional methods.

The application of microtomy to Transmission Electron Microscopy (TEM) specimen preparation of zeolite catalysts is explained. Using a new acrylic resin (LR White®) thin sections (≤60 nm) may be cut with relative ease. Although the details described are specific to catalysts, microtomy and the use of the acrylic resin are applicable to any hard ceramic powder sample.

A procedure for preparing cross-section samples of specific regions on an integrated circuit die is outlined. The procedure involves the use of glass slabs to prepare the sample stack used for cross-sectioning. The transparent glass slabs on the top surface of the die enable monitoring of the region of interest during the thinning process. This ensures that the region of interest will be located in the electron-transparent section used for TEM imaging. Samples prepared using this technique are sturdy enough to survive successive thinning and observation in a TEM. The glass slides do not give any charging problems and generally thin much slower than the silicon so as to provide added stability to the sample. An additional advantage is that the sample thickness can be accurately measured using the vernier attachment on an optical microscope during the sample thinning process. The imaging of specific NMOS transistors fabricated on buried oxide layers is illustrated.

An ultramicrotomy technique for preparing SiC whisker cross-sections is described. With this method a large number of axially oriented whiskers can be examined.

Self-supporting, thin single crystal membranes can be fabricated from silicon wafers using ion implantation, anodic etching and subsequent annealing. Typically, membranes approximately 1200Å thick and about 250μm in diameter are formed in wafers 4 mil thick. Discs surrounding the membranes can be cut out to provide suitable TEM samples. In this paper, the steps for preparing such samples are presented with as much attention paid to experimental details as possible.

We describe a technique for preparing transmission electron microscope (TEM) cross-sectional specimens for observation during in situ annealing to high temperatures. The process utilizes a ceramic adhesive that is stable to a temperature of 1650°C. The technique, which was successfully used to observe the recrystallization of amorphized silicon, is being applied to high-energy ion-implanted silicon in an attempt to better understand the amorphous-to-crystalline phase transformation and defect formation mechanisms resulting from thermal processing.

A cooling device for use with the Fishione twin-jet electropolisher Model 110 has been developed for electropolishing TEM specimens at controlled and low temperatures necessary for some materials. This consists of an explosion-proof pump circulating methanol through a specially designed stainless steel bath, and a copper coil immersed in a mixture of methanol and dry ice in a dewar. A thermocouple with a temperature control unit provides precise temperature control.

With this device, electropolishing can be conducted at temperatures as low as −55°C. This allows electropolishing of certain materials which cannot be polished with conventional equipment. The precisely controlled temperature also improves the performance of the electropolishing equipment at all temperatures because the success of electropolishing depends on maintaining constant conditions during the process. The unit further allows the use of aggressive electrolytes and preparation of solutions which could otherwise become hazardous due to heat buildup during electropolishing or preparation.

Upon staining with OsO4, crazes in rubber-toughened themplastics show inverted contrast in microscopy of ultra-thin sections and the details of the craze microstructure are masked. This report presents a method of specimen preparation for obtaining correct contrast of light crazes in a darker background.

The practical details are presented for preparing cross-sectional samples of semiconductor epitaxial layers by cleaving. Examples of results are shown and a number of possible applications for the samples are discussed. A variation of the method can be used to prepare a TEM sample of a high Tc superconductor.