Nanochemistry: synthesis in diminishing dimensions

slant angle of the normal at the respective observed points was proposed. The slope of a plastic aspherical lens was measured in terms of the normal of the profile. The results were illustrated as contour circles of equal slope. The difference between the neighboring radii of the circles for the slope varied at constant intervals and was not made equal due to the asphericity. A profile of the asphericity along the radial direction was obtained by integrating the slope. 12 Refs. 50. McCune, R. C.; Chase, R. E.; Cartwright, E. L. Methodology for adhesion characterization of microwave PECVD diamond films on SlAION tool Inserts. Surface & Coatings Technology. 1992 Sep 15; 53(2): 189-197. The silicon nitride / SiAION family of ceramic tool materials provides substrates with low thermal expansion coefficients for the deposition of continuous diamond films for prospective metal-cutting applications. Adhesion of diamond films grown by processes such as microwave plasma-enhanced chemical vapor deposition (MPECVD) to these ceramics can, however, be erratic. The characteristics of the diamond-ceramic interface which evolves during the deposition process are thus significant in the understanding of film adhesion. In this study, Auger electron spectroscopy (AES) and scanning electron microscopy were used to elucidate the nature of this interface, revealed by indentation fractures that produced interfacial cracks between diamond films and SiAION substrates. The films were prepared with comparable methane-hydrogen feedstocks, but in two different microwave plasma deposition systems. AES showed, in some cases, apparent carburization of the SiAION surface, rendering it less insulating and thus amenable to characterization by electron spectroscopy and scanning microscopy. Improved adhesion of the diamond films was observed when carbon enrichment of the SiAION surface was apparently achieved during the growth process. 15 Refs. 51. Farooqui, M. M.; Evans, A. G. R.; Stedman, M.; Haycocks, J. Micromachined silicon sensors for atomic force microscopy. Nanotechnology. 1992 Apr; The lateral resolution obtainable in atomic force microscopes is determined to a large extent by the sharpness of the sensing tip and its profile. Single-crystal silicon with its excellent mechanical properties is an eminently suitable material not only for the fabrication of the sensing cantilever, but for the tip as well. A new process for IC compatible batch fabrication of boron-doped single-crystal cantilevers with integral sensing tips is described. The cantilever thickness of less than a micrometer and tip radii of a few nanometers with profiles ranging from pyramidal to highly cusped have been obtained routinely. In comparative trials with commercially available devices, higher resolution has been obtained with the sensors described here. 52. Ozin, G, A. Nanochemistry: synthesis in diminishing dimensions. Advanced Materials. 1992 Oct; Atomic and molecular size devices are the ultimate goal of those working on, for example, nanoscale patterning and templating techniques. The various approaches to nanophase materials with stringent requirements of size, shape, and dimensionality are discussed, recent highlights are described, and the advantages to be gained by working on this scale with zeolites, LB films, fullerenes, organic polymer hosts, semiconductor clusters, porous silicon, STM technology and much more are reviewed. 53. Louskinovich, P. N.; Nikishin, V. I.; Ryzhikow, I. A.; Wuorinen, J. H. Nanoelectronics based on scanning tunneling microscopy. 39th International Solid-State Circuits Conference; 1992 Feb. 19; San Francisco, CA. New York, NY: IEEE; 1992. 144-5, 268, 319. Nanotechnology focuses on research and development of recording devices with bit densities on the order of 1014 b/cm 2 and on quantum ICs with delay times on the order of 10"12 s. The possible field interactions down to plasmon states using the complex precise control instrumentation of nanotechnology are sketched. Reversible decomposition and atom tunneling are possible. Different technological modules of nanotechnology permit operation in air, gas, liquids, and ultrahigh vacuum. Nanotechnology requires complex probe-tip control mechanisms. The basis elements of the technology system are the probe tip as the source of particles, coarse and fine positioning control of manipulators, an electronic control system, and the control of technological parameters. 54. Kern, D. P.; Lee, K. Y.; Rishton, S. A.; Wind, S. J. Nanofabrication of quantum devices. Japanese Journal of Applied Physics, Part 1 - 5th (4th International) MicroProcess Conference (MPC '92); 1992 Jul 13; Kawasaki, Japan. 1992 Dec. 4496-500. Fabrication of structures for investigation of quantum effects frequently involves the use of MBE / CVD type growth processes to achieve control on an atomic scale in vertical direction and a wide range of combinations of lithography and pattern transfer techniques for control in lateral directions. The challenges ahead lie in the degree of lateral control with which the lithography can be performed, i.e. resolution and placement accuracy, but also in the throughput of the lithography equipment once technological applications are considered. Electron beam resolution can certainly extend to the 1 nm regime, in the case of the STM even to 0.1 nm, appropriate resist materials have to be found, however. Parallelism may be introduced into nanolithography through contact printing with X-rays, electron, ion, or X-ray projection, or arrays of miniaturized scanning electron or ion columns. Pattern transfer relies on a broad spectrum of subtractive and additive processes ranging from wet and dry etching to selective growth techniques. Pattern fidelity and damage to the material are the key issues. 55. Iwatsuki, M.; Kitamura, S.; Sato, T.; Sueyoshi, T. Nano-fabrication on silicon at high temperature in a UHVSTM. Nanotechnology- International Workshop on Atoms and Clusters (WAC-92); 1992 Jan 8; Atami, Japan. 1992 Jul. 13741. The microscopic manipulation of atoms at high temperature has been attempted. A UHV-STM is designed to facilitate sample heating up to 1,300 °C after sample introduction. The UHV-STM employs stacked piezoelectric elements to control the three-dimensional drive of the tip. Nano-fabrication utilizes this fine positioning mechanism and the imaging capability of the STM for ultrafine fabrication of the surface. The technique for nano-fabrication usually changes the bias voltage between the tip and sample during pattern writing while maintaining the tip-sample distance. This method is applied to a high-temperature silicon sample in which atoms on the sample surface are migrated towards the tip. As a result, a pyramid or a crater is formed on the sample. The authors succeeded in creating a hexagonal pyramid and crater on an Si(111) surface and a quadrangular

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JULY 1993 VOL 15 NO 3