Simulation of front-end processing is a critical component of integrated-circuit (IC) technology development. Today's electronics are so small that characterization of their material parameters is very difficult and expensive. Simulation is often the only effective tool for exploring the lateral and vertical doping profiles of a modern device at the level of detail required for optimization. Additionally, the cost of fabrication and test lots increases with each technology generation; for this reason, simulation becomes especially costeffective, if it can be made accurate. Increasingly, process simulation is being performed by harnessing a hierarchy of tools. Ab initio and molecular-dynamics (MD) codes are used to generate insight into the physics of individual particle reactions in the silicon lattice. This information can be fed to kinetic Monte Carlo (MC) codes to establish the dominant, critical mechanisms. Finally, traditional continuum codes can make use of this information and couple with the other process steps to simulate the entire process flow. Both MC and continuum codes can be compared with experiment in order to validate the calculations.

Fracture dynamics remains a challenging research topic in materials science, mechanical engineering, mathematics, and nonequilibrium physics. Despite nearly a century of intense investigation, several basic problems remain unsolved. In particular, there is still no fundamental understanding of the distinction between brittle and ductile failure; there is still no definitive explanation of how breaking stresses can be transmitted through plastic zones near crack tips, nor is there an adequate understanding of why the energy-release rate even in brittle fracture is often orders of magnitude larger than the rate at which surface energy is created. These difficulties seem to stem primarily from the lack of an adequate theory of deformation near crack tips, where stresses and strain rates are large.

Metal oxides are important materials in industry. For example, there are many kinds of functional oxides: dielectric oxides such as BaTiO3 (perovskite), semiconductor oxides such as ZnO, ionic conductors such as Bi2O3, magnetic oxides such as Fe3−xMxO4 (spinel), and so on. These oxide materials must be prepared as films, nanodots, and layered films to increase their functionality for a wide variety of applications.

The safety of today' novel foods and food materials, especially those produced by means of genetic modification, has been in the news in recent times. However, the major safety problems in the food chain come from much more long-standing causes. The principal risk remains the health threat from pathogenic bacteria. Other risks include the food chain as a vector for certain serious viral infections such as hepatitis A. Food as a source of significant(and, in extremis, fatal) allergenic reactions is also a growing concern. Another significant food-safety problem is the contamination of food by potentially harmful foreign substances (pesticides, plasticizers, heavy metals, fungal micotoxins, etc.)

Magnets are widely used in a large number of applications, and their market is larger than that of semiconductors. Information storage is certainly one of the most important uses of magnets, and the lower limit to the size of the memory elements is provided by the superparamagnetic size, below which information cannot be permanently stored because the magnetization freely fluctuates. This occurs at room temperature for particles in the range of 10–100 nm, owing to the nature of the material. However, even smaller particles can in principle be used either by working at lower temperatures or by taking advantage of the onset of quantum size effects, which can make nanomagnets candidates for the construction of quantum computers.

In the manufacture of solid-oxide fuel cells (SOFCs), thermal-plasma technology, especially plasma spraying, offers several advantages, the most important of which is the ability to achieve considerably higher deposition rates than those that can be obtained with such approaches as physical or chemical vapor deposition (PVD or CVD). This article describes an international collaborative research project partially funded by NEDO (New Energy and Industrial Technology Development Organization, Japan) and carried out at five research laboratories around the world: at the University of Tokyo and National Institute for Research in Inorganic Materials (NIRIM) in Japan, the University of Minnesota in the United States, the University of Sherbrooke in Canada, and DLR—Stuttgart in Germany. The objective of the project was to conduct a comparative study on the possible use of four thermal-plasma spraying techniques for the integrated fabrication of SOFCs.

Transparent, electrically conductive films have been prepared from a wide variety of materials. These include semiconducting oxides of tin, indium, zinc, and cadmium, and metals such as silver, gold, and titanium nitride. In this article, the physical properties of these materials are reviewed and compared.

Mixed conductors show significant mobility of both electronic and ionic species and were the subject of an earlier review in MRS Bulletin.1 The current review is restricted to those mixed conductors of interest for use in lithium batteries, with an emphasis on commercialization. The first lithium batteries were primary cells using pure lithium anodes and carbon monofluoride or manganese oxide as the cathode. Both were developed in Japan, the former for use in fishing floats and the latter for calculators and similar small devices. Such primary cells based mainly on MnO2 or FeS2 cathodes are still extensively used in watches, cameras, and so on. Lithium primary cells are also the main power source for many medical devices, such as pacemakers. In some of these applications, silver vanadate is the cathode.

The passage of ions through a crystalline material can be affected by the regular and repeating arrangement of atoms within the crystal structure; this is called ion channeling. Channeling occurs when an ion beam is aligned with a planar or axial direction of a crystal lattice. The particles are shepherded through the crystal by the gentle steering effects of the atomic rows and planes so that they travel in the regions of reduced electron density between the atoms. This leads to a significantly reduced energy-loss rate compared with nonchanneled (or “random”) ions: MeV protons channeled in the {111} and {110} planes of silicon suffer an average energy-loss rate of 45% and 60% of the nonchanneled value, respectively. Channeling also lowers the close-encounter probability between the channeled ions and the crystal's atoms, reducing the rate of ion backscattering and ion-induced x-ray production. Comparison of the yields of these signals between channeled and nonchanneled alignment gives information on crystal quality, epitaxy, and the lattice position of interstitial elements.

Table I gives some useful parameters for 3-MeV protons channeled along axial and planar directions of silicon. The channeling critical angle ψ is a measure of how close in angle a channeled ion must be to an axial or planar direction in order for it to become channeled. This is of the order of 0.3° for ⟨110⟩ directions and 0.1° for the planar directions. Even when an ion beam is aligned to within the critical angle of a channeling direction, not every ion becomes channeled, as some are scattered by close interactions with the first few monolayers of the crystal. The fraction of non-channeled ions is given by the minimum yield Xmin and this is ~30% for planar directions and a few percent for axes. Those ions that become channeled eventually leave their privileged trajectories and revert to nonchanneled paths through the crystal. This dechanneling occurs naturally, due to scattering from electrons within the channel and perturbations from the atoms of the channel walls. For planar channeling directions, the fraction of ions remaining channeled decreases exponentially with depth into the crystal and is described by a half-thickness z1/2, the depth within the crystal at which 50% of the initially channeled ions have become dechanneled. This is of the order of 5 μm for 3-MeV protons channeled in the major planes of silicon. Finally, the energy-loss ratio shows the reduction in energy loss for a channeled ion compared with that of a random ion.

The increasing demands of miniaturization in the microelectronics industry has forced continual improvement in the materials that are used in the fabrication of semiconductor devices. Advances in photoresists for microlithographic applications have reduced the feature size to 0.25 µm and below, and this drive to eversmaller features, coupled with the introduction of copper, has placed increasing demands on the dielectric material. Materials with lower dielectric constants (depicted in dark gray in Figure 1) are therefore required to more efficiently insulate these submicron features, such as the copper interconnect lines used to connect the transistors and memory cells in these advanced multilevel devices (Figure 1). This allows the minimization of crosstalk, signal delays, and power consumption. While vapor-deposited silicon dioxide and other derivatives are currently being employed, they suffer from unacceptably high dielectric constants (ε > 3.6) and are unacceptable for future generations of microelectronic devices.

In spite of the success of surgical implants such as artificial hip joints, the materials used to make them are not always quite up to the job. Even stainless steel and titanium alloys can break under the enormous stress on load-bearing joints and corrode in the salty environment of the body. Deposits of inorganic salts can scratch weight-bearing surfaces, making artificial joints stiff and awkward. As a result, the lifetime of an implant is, at most, 10–15 years.

Metallurgists and engineers often treat the surfaces of metal parts to improve their properties. The use of advanced surface-treatment techniques such as glow-discharge ion implantation, plasma deposition, and plasma coating can significantly improve the strength, hardness, and corrosion resistance of metal implants. At the same time, these methods should also improve the biocompati-bility of the implanted devices.

Cobalt-based alloys are widely used for joint replacements. However, other compounds, such as titanium alloys, have excellent potential biocompatibility and interesting but imperfect mechanical properties. Stainless steel, namely 316L, has a good price-to-mechanical-properties ratio, but has the lowest corrosion resistance of the most commonly used metallic biomaterials.

This article describes a new technique for nuclear microprobes that has been developed to produce angle-resolved channeling information from small areas of crystalline material without any rotation or translation of the sample. This “beam rocking” system, with a focused MeV ion beam, has been used to detect and quantify small interface rotation angles in strained Si1−xGex/Si samples with 0.015 < x ξ 0.175, as well as samples with graded germanium composition. By eliminating possible rotation errors caused by translation of the sample stage or backlash in the gears of a goniometer, smaller rotation angles can be measured than with standard ion-channeling analysis.

Channeling is frequently used in ion-beam analysis to characterize crystalline materials (see the previous article by King). If the crystal is positioned near axial or planar alignment and then tilted incrementally with respect to the beam, as the sample is brought into channeling alignment, the yield of interactions with the host lattice will be reduced as the ions become channeled, since they are less likely to interact closely with atomic nuclei. Angular scans can be used to measure strain in heteroepitaxial layers by measuring the rotation of off-normal axes using this process.

Ceramic thermal-barrier coatings (TBCs) have received increasing attention for gasturbine engine applications. The advantages of using TBCs include increased fuel efficiency by allowing higher gas temperatures and improved durability and reliability from lower component temperatures. As illustrated in Figure 1, TBCs can provide effective heat insulation to engine components, thus allowing higher operating temperatures and reduced cooling requirements. Atypical two-layer TBC system consists of a porous ZrO2-Y2O3 ceramic top coat and an oxidation-resistant metallic bond coat. These TBC systems can be applied to the metal substrate either by plasma spray or by electron-beam physical vapor deposition (EB-PVD) techniques.

“Ferrite plating” is a typical “soft solution processing” (SSP) application; it enables the formation of oxide ferromagnetic films from an aqueous solution at T 24−100°C under atmospheric pressure. Using ferrite plating, we can grow crystallized ferrite films of spinel-type (MFe)3O4 (where M = Fe, Co, Ni, Zn, Al, Cr, etc.) in one step, requiring no heat treatment. This opens the door to fabricating novel ferritefilm devices using substrates of such nonheat-resistant materials as plastics and GaAs integrated circuits; conventional ferrite-film preparation techniques, such as sputtering, vacuum evaporation, molecularbeam epitaxy, liquid-phase epitaxy, and so on, require high temperatures (>∼600°C) for the crystallization of ferrites, which deteriorates the non-heat-resistant substrates. Ferrite plating is a unique technique that allows us to synthesize ferrite “films” by means of a wet chemical process. There are many techniques, for synthesizing ferrite “particles” from aqueous solutions, but no technique, to our knowledge, enables ferrite-film synthesis by a wet chemical process.