Oblique incidence magnetic thin films are considered to be the most appropriate recording media for the next generation of video tape applications. In order to study the microstructure of such thin films, a specimen preparation technique employing ultramicrotomy has been developed. Because oblique incidence thin films have a porous structure and poor adhesion to the substrate, the problem of splitting of the thin films from the substrate is severe. This problem is reduced considerably by the following exercises: 1. using an acrylic embedding resin e.g. LR White (London Resin Co.), 2. thorough degreasing with solvents, 3. using a 55° diamond knife, and 4. trimming the block with a microtome before actual sectioning. The details of this preparation technique and some results obtained with this technique are presented.

This work was undertaken to guide the development of methods for preparing very thin polymer samples on an atomically flat, conducting surface so that the molecules could be examined with a scanning tunneling microscope. Polymer molecules with segments in an extended configuration were sought so that details of polymer structure such as branching, distances between branches, and other structural features of the molecules could be examined. Three different methods, (mechanical deformation, solution entrapment, and solution spreading) used for preparing the samples resulted in the “self-assembly” of the polymer molecules into a variety of structures which are described below.

Thin specimens for transmission electron microscopy examination may be prepared by several techniques, such as electropolishing and ion-beam thinning. Ion-beam thinning, which employs the use of an argon ion-beam at high voltage (e.g. 6kV) to bombard the specimen, is a commonly used technique for preparing and/or cleaning thin foil specimens. The experimental results show that even short-time thinning of Al-Li-Cu alloys with argon ion-beams introduce dramatic microstructural changes. Interesting observations concerning the effect of the ion-beam on quasi-crystals in Al-Li-Cu alloys during the thinning process are presented. The results and causes of the ion-beam thinning in Al-Li-Cu alloys are discussed.

TEM specimens of mechanically alloyed elemental Ni and Nb powders are prepared by a new procedure. The alloyed powders are mixed with smaller Al powders and fill an aluminum ring (3mm outer diameter). This composite is cold pressed together with the Al powders taking most of the deformation. The compacted specimen can be mechanically thinned. Electropolishing and ion milling can then proceed by standard methods with special precautions to minimize differential polishing or milling rates.

The microstructural aspects of the formation of an amorphous phase by high-energy ball milling these powders have been studied. After 6 h each particle transforms to a heterogeneous layered composite of particles of one element in the matrix of the other. Particle size ranges from 15 nm to 90 nm. Mechanical alloying for 36 h results in the formation of an apparently uniform phase interspersed with a few small (4 nm to 30 nm) elemental crystalline particles. The uniformity of composition and the presence of C, O, and Fe were studied by EDX and EELS.

Electromigration in aluminum films has been identified as an increasing concern for integrated circuit reliability. Electromigration is the mass transport of atoms in a conductor under a current stress. Electromigration occurs in conductors experiencing current densities greater than 105 A/cm2 and is accelerated by high temperature. The damage to aluminum films manifests itself in the formation of voids, hillocks and whiskers along the conductor. This paper presents a test vehicle preparation procedure which can be used to investigate electromigration.

A grinding/polishing tool has been developed for preparing TEM samples. The hand-held tool is 2.50″ in diameter and 3.0″ high. Rough-cut samples, 300 to 600 microns thick, are routinely polished to 5 microns thick in four to six hours using this tool. As these 5 micron samples are so thin and uniform, a separate dimpling operation can be eliminated. Likewise, the time required to ion-mill the sample can be reduced to 0.5 to 2.0 hours – greatly reducing ion-milling artifacts and significantly increasing the area viewable by TEM. The process is equally effective for all classes of samples: Silicon devices, ceramics or metals – in either cross-section or planar views.

A new method of preparing bicrystal substrates of NaCl with a common tilt zone axis has been developed. Upon a lateral overgrowth of NaCl, bridging the two mechanically polished and oriented crystals, very thin films can then be vapor deposited. Au bicrystals of ∼ 75Å thickness and b.c.c. Cr films of similar thickness with grain boundaries have been fabricated.

A technique for preparing thin sections in CdTe samples for transmission electron microscopy by a method of mechanical dimpling combined with chemical etching has been investigated. The dimpling rates and surface morphologies of dimpled (100) CdTe samples as a function of pressure, abrasive size and viscosity are presented. This technique produces dimpled samples of well controlled geometries and surface morphologies and offers the advantage of a high dimpling rate and the precise determination of the dimple position. The disadvantage of this technique is that a final application of chemical etching or atom milling is still required to produce electron thin sections.

A brief review of possible causes of artefacts in ceramic TEM specimens is illustrated with examples from oxide, silicate and titanate ceramics.

The particulate produced by many of the methods of rapid solidification, such as atomized powder, is of order 50 microns in diameter and is thus much too small to form the 3mm diameter disc conventionally used for thin-foil microscopy. 50 microns is, however, much too thick for direct TEM study on a support film and grid. A technique is described in detail that produces a composite wafer where atomized metal powder is sandwiched between two layers of electroplated nickel. This wafer is about 25 mm in diameter and about 250 microns thick. 3mm diameter TEM discs can be punched from the wafer and thinned by combinations of grinding, dimpling, jet-polishing, and ion milling. Depending on the composition and structure of the powder under study, the composite nature of the wafer can sometimes promote undesirable galvanic effects during jet polishing and differential thinning rates during ionmilling. Typical results are presented and discussion of the benefits and shortcomings of this technique is made. The method should be applicable to a variety of materials and geometries.

In-situ strain experiments with the electron microscope have contributed substantially to our understanding of deformation in metals and ceramics. However, physical characteristics of rock-forming minerals limit the direct application of experimental procedures developed for metals. The minerals muscovite (KAl2(Si3Al)O10(OH,F)2) and biotite (K(Mg0.6–1.8 Fe2.4–1.2) (Si3Al)O10 (OH,F)2) are chosen to develop techniques for preliminary deformation experiments. The present communication describes modifications of sample preparation techniques for micas. The standard tensile straining configuration is altered to a simple shear geometry by means of an intermediary specimen cage to allow the use of a more favorable sample orientation. The extension of the shearing geometry to the in-situ deformation of other rock-forming minerals is discussed.

Mechanical abrasion has been used by the authors to prepare a variety of materials, mainly ceramics, which have been thinned to electron transparency. The basic premise of this technique is the rotation of a spherically shaped wood tool at right angles to a rotating 3mm specimen disk (∼100 μm thick). A slurry of 1/2 μm diamond powder in a glycerin vehicle thins the specimen and carries away the abraded matter. In addition to the wood tool other materials such as brass, teflon and polyethylene have been tried without success. Abrasion “marks” left on the thin specimen surface can be ignored in some situations or removed by a touch up ion milling at 3 keV for ∼1/2 hr. Recently, attempts to thin N+ implanted Al from the un-implanted side using a wood tool were found to be extremely time consuming, i.e. 60 hr or more. It was found that a spherical stainless steel tool produced a suitably thin transmission electron microscopy (TEM) specimen using glycerin as the vehicle and no diamond powder. Depending upon the pressure applied to the tool these specimens could be thinned in as little as 3 hr. The turning marks left by the lathe tool proved to be sufficient to thin the soft aluminum. From this result It appears that soft tools will thin hard materials and hard tools can be used to thin soft materials efficiently. A number of other specimens recently prepared using mechanical microthinning will also be presented.

The preparation of transverse section TEM foils from thin (0.2 mm to 1.5 mm) aluminum sheet would usually be accomplished by a combination of dimpling and ion milling. Both of these techniques are time consuming. A technique has been developed which allows these transverse section foils to be prepared by electropolishing, which greatly reduces the time required for specimen preparation. This technique also produces far more thin area for examination than a comparable foil which has been dimpled and ion milled, and eliminates artifacts produced by ion milling.

Ultramicrotomy is a technique for cutting cross-sections of material which was originally used by biologists for soft tissue analysis. With only a few changes to accommodate the hard dielectric coatings and substrates, the technique may be used to prepare specimens of optical multilayer devices for cross-sectional transmission electron microscopy (XTEM).

The ultramicrotome, mounted on a vibration damped table, is capable of cutting uniform 40 nm thick cross-sections of materials with a diamond knife. An epoxy embedded sample is cycled past the knife at a controlled rate and advanced by a precise, preset distance on each pass. As each section is cut, it comes off the knife edge to a reservoir of water where, while floating, it can be picked up on a TEM grid.

Artifacts generated by this mechanical technique for preparing thin cross-sections are readily apparent yet easy to disregard. TEM analysis of these cross-sections provides direct imaging of real samples for accurate feature and thickness measurement and direct chemical and crystalline structure analysis.

Cu-Nb in situ composites attain anomolous increases in strength upon mechanical deformation. The unique filamentary microstructures that evolve during processing (cold rolling and/or wire drawing) are the source of the strengthening. Results from transmission electron microscopy characterization studies have played a key role in the understanding of the relationships between structure and properties. However, the fabrication of reliable TEM samples has been extremely challenging for the following reasons: (1) traditional electrochemical techniques are not suitable for the two-phase microstructure, (2) preparation of longitudinal and transverse sections of fine (∼150 μm diameter wires) and thin (∼60 μm thick) sheet is tedious, and (3) it is necessary to avoid excessive heat (< 30°C) during sample preparation to preserve the metastable structural arrangements. This paper will review the procedures used to prepare TEM specimens from bulk wire and sheet samples as well as from extracted Nb filaments. Proper techniques for plating, mounting, sectioning, polishing, and ion-thinning will be discussed.

This paper discusses a rapid and simple specimen preparation technique which was originally developed for plan view TEM investigation of processed silicon, but which afterwards was modified for the study of GaAs, Al/Al2O3 and Silicon-On-Insulator (SOI) structures. The major advantage of this poor man's method is that no specialised nor expensive equipment is needed.

A second technique is also described which is used in the case of unseeded SOI structures where the analysis of the top silicon layer is important.

A simple and rapid specimen preparation technique for the cross section TEM investigation of layered structures is discussed. Its wide applicability is illustrated for the investigation of processed silicon, compound semiconductors, silicon on quartz and also for metal/metal oxide interfaces.

Cross-sectional samples for Transmission Electron Microscopy (TEM) have been made without the use of mechanical polishing and ion beam milling. Instead of traditional methods, we have used a combination of electron beam (e-beam) lithography for metal lift-off and reactive ion etching (RIE) to produce TEM samples of selected areas. The sample integrity for handling, dropping and ease of use is excellent, and the large amount of transparent area available for study is nearly 2 orders of magnitude larger than that given by traditional methods. The thickness of the samples is somewhat extreme, on the order of 0.50–1.0μm, but efforts are being made to reduce this dimension in order to make the method applicable to the whole range of materials used in silicon technology.

Microstructural characterization of plutonium utilizing Transmission Electron Microscopy (TEN) has previously been difficult because of the extreme toxicity and high oxidation rate of plutonium metal. Recent developments in plutonium sample preparation have shown that foils of both alpha and delta phases of plutonium may be prepared for TEN without the use of inert atmospheric systems or complex preparation devices. Samples may be produced, using standard electropolishing techniques, that yield important microstructural data on plutonium and plutonium alloys.

Transmission electron microscopy (TEM) is an important technique for studies of extended defects and other microstructural features in semiconductor materials. An efficient, plan-view thinning technique is always desirable for these TEM studies. The problems associated with wet chemical thinning of silicon are often surface residues, pitting and rapid breakthrough. A controlled method for obtaining thin, plan-view TEM silicon samples by chemical thinning was developed and the method is described in this paper. Results indicate that the method minimizes the above cited problems and has several other advantages over previously reported thinning methods.