A method of preparing transmission electron microscopy (TEM) specimens of coated ceramic fibers has been developed that produces large areas containing many electron transparent fibers, due to the minimal preferential milling of the epoxy matrix. Multiple individual fibers or tows are impregnated with a high-temperature epoxy and contained to assure a high fiber-to-epoxy volume ratio. The samples are then sectioned and mechanically thinned either parallel or normal to the fiber axes using a wedge polisher on diamond lapping films to achieve a thickness of less than 5 μm. The thinned sample is then ion-milled to electron transparency in less than 30 min, giving representative specimens of the coating, fiber, and coating-fiber interface. This technique is also well suited to preparing extremely flat specimens for both light microscopy and scanning electron microscopy analysis of thin coatings.

A site specific technique for cross-section transmission electron microscopy specimen preparation of difficult materials is presented. Focused ion beams are used to slice an electron transparent sliver of the specimen from a specific area of interest. Micromanipulation lift-out procedures are then used to transport the electron transparent specimen to a carbon coated copper grid for subsequent TEM analysis. The experimental procedures are described in detail and an example of the lift-out technique is presented.

The cross-sectional transmission electron microscopy (TEM) specimens of Pt/Ti/SiO2/Si, RuO2/SiO2/Si, W/TiN/SiO2/Si, (Pb,La)TiO3/Pt/MgO, Bi4Ti3O12/Lal-xCaxMnO3/MgO, and GaN/Al2O3 were successfully made by the rocking-angle ion-milling technique. The differential thinning problems could be effectively mitigated when the rocking-angle and the ion-beam incidence angle were optimized for each heterostructure. It was found that the sputtering yield ratio between the layer milled most quickly and the layer milled most slowly is one of the important factors which determine the optimum rocking-angle ion-milling condition. The atomic force microscopy study on the surface topography of the cross-sectional Pt/Ti/SiO2/Si TEM sample after ion-milling provided quantitative information about the effects of the rocking-angle variation. A parameter which is the ratio between the layer with a minimum electron transparency and the layer with a maximum electron transparency was suggested.

Focused Ion Beam (FIB) systems have been steadily gaining acceptance as specimen preparation tools in the semiconductor industry. This is largely due to the fact that such instruments are relatively commonplace as failure analysis tools in semiconductor houses, and are commonly used in the preparation of cross-sections for imaging under the ion beam or using an electron beam in an SEM. Additionally, the ease with which cross-sectional TEM specimens of semiconductor devices can be prepared using FIB systems has been well demonstrated. However, this technology is largely unknown outside the semiconductor industry. Relatively few references exist in the literature on the preparation of cross-sectional TEM specimens of non-semiconductor materials by FIB. This paper discusses a specific use of FIB technology in the preparation of cross-sectional TEM specimens of non-semiconductor samples that are difficult to prepare by conventional means. One example of such materials is commercial galvannealed steel sheet that is used to form corrosion resistant auto-bodies for the automobile industry. Cross-sectional TEM specimens of this material have proved difficult and time-intensive to prepare by standard polishing and ion milling techniques due to galvanneal's inherent flaking and powdering difficulties, as well as the different sputtering rates of the various Fe-Zn intermetallic phases present in the galvannealed coatings. TEM results from cross-sectional samples of commercial galvannealed steel coatings prepared by conventional ion milling and FIB techniques are compared to assess image quality, the size of the electron-transparent thin regions that can be readily prepared and the quality of samples produced by both techniques. Specimen preparation times for both techniques are reported.

With the advent of the modem analytical electron microscope with its ultrahigh vacuum conditions, extremely high current density in a very small probe, and its light element analysis capability, it is imperative that contamination of the TEM sample, particularly by hydrocarbons, is eliminated. The degree of cleanliness required for analysis using surface sensitive techniques is also much greater than for other forms of analysis. Contamination of samples can occur (a) prior to analysis, due to the way samples are prepared or handled, or (b) during analysis. Examples of surface contamination prior to analysis and during analysis will be given, in order to illustrate their effect on an analysis.Polished Si, Ni, and Ti bulk samples and pre-thinned TEM Ni and Ti samples were intentionally contaminated by two methods. One set of samples was put on a liquid nitrogen cooled stage for one hour in a diffusion pumped Gatan Duomill in which the liquid nitrogen cold trap above the diffusion pump was intentionally left warm. The other set was contaminated by dipping them into a 100 ml solution of acetone containing 0.04 g of an acetone-soluble low temperature wax. Two commercially available plasma cleaners, specifically designed for eliminating hydrocarbon contamination, were used to clean the samples. The bulk samples were examined with x-ray photoelectron spectroscopy and the TEM samples were examined in a 200 keV analytical TEM. The results from these experiments will be discussed.

Various small-angle wedge two-view samples have been prepared by a small-angle cleavage technique using hand tools and examined by transmission electron microscopy. Cleaved wedges from the same material are mounted both as plan-view and cross-sectional samples on the same TEM specimen grid allowing convenient examination in both views. Samples of Si3N4, Zr, Co and TiN/CN/TiN films deposited on Si, and He ion implanted Si prepared by this technique are shown to be suitable for analysis in the TEM.

We present a sample preparation technique for using transmission electron microscopy (TEM) to profile the dopant in a specified doped region of a very large scale integrated (VLSI) devices. This technique is based on preferential etching of the doped region in silicon. Because the rate at which silicon is etched depends on the dopant concentration, the dopant distribution can be inferred by observing the thickness fringe. Using two-beam approximation and information on the dependence of the etching rate on the concentration, we calculated the intensity of the transmitted electron beam and found that the results agreed well with the observed fringes. In addition, by using a focused ion beam (FIB), we could also observe the dopant distribution in a specified source region of a VLSI device.

XTEM investigations are an important tool to characterize the geometry, structure and microchemical composition of semiconductor devices. Over the last 25 years, several thinning procedures have been used, based on Ar ions at about 5 kV. Common to all of them is that the thinning takes several hours, or the ion thinning has to be combined with awkward mechanical preparation steps, like dimpling.

The technique described below uses Ar ions up to 15 keV and with a total ion current of up to 0.2 mA. A maximum sputtering rate of 25 μm/h for Si is reached at an incidence angle of 6°. A low energy thinning step at 3.5 keV is used at the end to reduce the amorphization and heating of the thinnest regions. The combination of this fast ion thinning with simpler mechanical steps requiring only a final lapping step, without the need for dimpling and polishing, results in a yield of nearly 100% and a preparation time of about 3h.

A novel design of test sample for X-TEM specimen preparation is presented. The test sample is particurlarly suited for surface coatings on hardened steel (heat treated materials). The technique for cutting and preparation of a specimen from the test sample is given in some detail and a few hints about ion thinning and X-TEM analysis are included.

Although many publications have discussed focused ion beam (FIB) preparation of TEM samples, few have presented a detailed, step-by-step milling procedure. This is a summary of techniques that evolved over the past 3 years in our laboratory. In addition to describing more traditional mechanical pre-thinning techniques, we introduce a method to pre-thin samples down to thicknesses of the order of 20 μm within 1 hour using a wafer dicing saw. We then discuss different ways to handle mechanically difficult samples such as those prone to delaminate. Our approach to FIB milling is designed to minimize the effects of ion-beam spreading which is responsible for most of the failures to prepare good FIBTEM samples. The technique is presented in a step-by-step fashion including a simple yet reliable method to terminate FIB milling. Examples are shown to illustrate applications to different types of problems including - precision cross-sectioning of integrated circuit (IC) devices, cross-sectioning of samples prone to delamination, and cross-sectioning of specific defect sites. Finally, we discuss the effect of artifacts in the quality of TEM samples.

The complex materials systems in VLSI devices require specialized preparation techniques for TEM microstructural analysis. For this purpose, it is desirable to obtain electron transparency in all material layers from the oxides used in dielectrics to refractory metals such as tungsten. The primary advantage of dimpling these materials is that ideal specimens are obtained for low angle ion milling. By dimpling both sides of the cross section with a padded flatting tool, a thicker specimen of 130μm at the outer rim of the 3mm disc is produced that narrows to the 125nm thickness fringes in the center. These samples do not require a copper support grid, thereby allowing for a lower milling angle of 2.5 degrees on both sides of the specimen. This technique provides a cross section that is electron transparent in all layers without the loss of oxides due to differential thinning rates of various materials at higher milling angles.

It is generally thought that precision thinning through a submicron feature is not possible on the dimpler. However, a simple step-by-step procedure for this technique will be demonstrated and discussed.

The generation and usage of a reactive gas plasma for a wide range of applications has been cited since the early 1970's. More recently, the use of a plasma generating system has been applied to analytical transmission electron microscopy to minimize and, in some cases, eliminate the problems associated with various contamination sources, including the specimen holder and the specimen itself. Although the technology is well known, no definitive characterization of process parameters has been developed for specimen and specimen holder cleaning applications. An investigation of the effects that power levels and gas mixtures have upon contamination rates and removal were done using a Philips CM30T. Measurements of contamination rates both prior to and following plasma cleaning were done to characterize the effects of various parameter changes. Results of different process parameters and contamination rates will be reported.

During conventional ion milling of carbon thin films on Si or SiC, the carbon has a much slower milling rate than the Si, SiC, and the epoxy resin. As a result, the substrates were thinned much more rapidly than the carbon films. A solution suggested by several subscribers to the Microscopy Society of America's Microscopy Listserver among others was to reactively ion mill the samples with a 20–25% oxygen-argon gas mixture. Is this the best inert gas to use? Neon has a mass that is between Si and C and therefore should impart a higher energy transfer to the C atoms than Ar. To determine whether the mass of the inert gas is important in balancing the milling rates, four gases were used to ion mill samples of a PLD DLC film with a nominal thickness of 0.5 μm. For improved adhesion of the films to the Si substrate, an initial 2 nm of Ti and a nominal 0.5 μm thick layer of TiC was grown using a combined PLD and magnetron sputtering technique prior to the PLD DLC.1,2 The gases were 100%Ar, 100%Ne, 75%Ar-25%O2, and 75%Ne-25%O2. Using the Tripod Polisher, the samples were polished flat using typical conditions and the surfaces examined by atomic force microscopy and compared. TEM samples prepared by single-sided dimpling prior to ion milling were prepared using the gas composition which gave the best results with respect to the AFM. A methodology is established for determining ion milling conditions for samples having layers of different compositions.

The Small Angle Cleavage Technique is a relatively simple and inexpensive method of producing superior cross sectional TEM specimens. For speed of preparation, it is unsurpassed. One limitation is that the technique does require the substrate material to cleave or fracture. For this reason, it has been applied almost exclusively to semiconductor materials. Recently, the technique has been extended to other substrates such as glass, silicon carbide, quartz, sapphire, and other hard materials. It is particularly well suited for rapidly examining coatings and thin films very soon after they are deposited. Several procedures have been added or modified to the original technique developed by McCaffrey to simplify the technique. The steps are presented in a detailed pictorial outline form. A method for mounting the cleaved samples utilizing a commercially available grid is presented. In addition, the advantages that the special geometry of the prepared samples have when mounted properly in a double-tilt holder are discussed with respect to the angular range of tilting experiments that are now possible in the TEM.

In this paper, different variations of a recently developed focused ion beam (FIB)-based TEM specimen preparation technique are studied conceptually and experimentally, compared, and evaluated. This procedure mainly consists of formation, removal, transport, and mounting of an electron transparent transverse membrane on a support grid for TEM study. Based on the experimental results obtained from this evaluation, some modifications have been conceived and implemented. These details as well as other critical information have been presented and discussed.

A new and improved commercial version of a tool designed originally for angle-lapping to electron-transparency has been presented in this paper. The new tool commercially known as precision angle lapper (PALTM) was originally developed and introduced in 1995. The improvements incorporated in the PAL design were conceived and implemented mainly as a result of a systematic analysis of the original tool design, the shortcomings and complications encountered during the routine hands-on use of it, requirements for major auxiliary equipment in conjunction with application of the tool and, finally, the input from other users of the tool. The basis for each added and/or improved feature of the PAL has been individually discussed and the resulting advantages have been reviewed.

Combining substantial pre-thinning of semiconductor device specimens via tripod polishing, followed by multiple, selective material removal steps with a focussed ion beam (FIB) tool, offers some unique possibilities with regard to preparing plan-view specimens at precise locations in the material below, and in the interconnect layers above, the semiconductor surface. Extension of these methods to other types of specimens in different configurations allows for the fabrication of multiple specimens on the same TEM grid that may not be possible by any other means.

A tripod polisher method that extends the use of the tool to the preparation of difficult particulate and fiber specimens, sufficiently thin to permit direct TEM examination with minimal or no ion milling, is detailed. The specimen is surrounded with Si in order to take advantage of the colour changes displayed by thin Si to assess the thickness of the specimen during preparation.

TEM of semiconductors containing tungsten interconnects is hampered by the problem of tungsten being intrinsically opaque to the electron beam, and at the same time typically being much thicker than the rest of the specimen. This work describes a technique which can predictably and reproducibly thin tungsten to electron transparency using chemical mechanical polishing (CMP). Chemically-assisted ion beam etching (CAIBE) techniques were also investigated, but found to be of little benefit. The key to development and evaluation of these methods was the AFM.

A rapid and precise sample preparation method using focused ion beam (FIB) etching was developed for cross-sectional transmission electron microscopy (X-TEM) analysis of a thin-film transistor (TFT) fabricated on a glass substrate. Gallium (Ga) ions accelerated at 30 kV and at various incident beam angles were applied during FIB etching to create a uniform thin wall. We successfully prepared X-TEM specimens of long and fragile aluminum (Al) whiskers formed on thin Al films in TFT metallization, where a strong charge is built up during FIB etching. The effect of ion-beam-assisted tungsten deposition prior to FIB etching is discussed. A whisker having a length not exceeding approximately 10 #x00B5;m can be successfully etched to a thickness of 200 nm while keeping its original shape. The performance of this technique is demonstrated in applications to etching at other fragile locations related to TFTs.