Several mechanisms can extend the equilibrium domain of a liquid phase into the solid region of the normal phase diagram. The causes of premelting, which include surface melting, interface curvature and substrate disorder, occur in all types of substances, including H2O. In the case of H2O, premelting can have important environmental consequences, among which are the heaving of frozen ground, breakdown of rock and concrete, sintering of snow, flow of glaciers, scavenging of atmospheric trace gases by snow and ice, and the electrification of thunderclouds. The article reviews the basic mechanisms of premelting and discusses their roles in the environmental phenomena. The principal results of numerous studies are reviewed, and trends in current research are outlined.

http://iopscience.iop.org/article/10.1088/0034-4885/58/1/003/pdf

The premelting of ice and its environmental consequences

The technology of high‐resolution focused ion beams has advanced dramatically in the past 15 years as focusing systems have evolved from laboratory instruments producing minuscule current densities to high current density tools which have sparked an important new process: direct micromachining at the micrometer level. This development has been due primarily to the exploitation of field emission ion sources and in particular the liquid‐metal ion source. Originally developed in the early 1960’s as a byproduct of the development of electrostatic rocket engines, the liquid‐metal ion source was adapted for focused beam work in the late 1970’s, when it was demonstrated that submicrometer focused ion beams could be produced with current densities greater than 1 A cm−2. Ions can be produced with liquid‐metal ion sources from elements including Al, As, Au, B, Be, Bi, Cs, Cu, Ga, Ge, Fe, In, Li, P, Pb, Pd, Si, Sn, and Zn. In the past decade, focused ion beam systems with liquid‐metal ion sources have had a signific...

High‐resolution focused ion beams

A direct, accurate and convenient procedure for calibrating the spring constants of probes used for force microscopy/spectroscopy is described. It amounts to deflecting an 'unknown' cantilever with a 'standard' lever, where the standard lever has been precalibrated. The absolute and relative accuracies of the procedure are ±20-30% and ±10-20%, respectively; the former is limited by uncertainties in the determination of the spring constant for the 'standard' lever, as well as that for the 'unknown'. The method differs from others of the static deflection variety by its exploitation of the routine features of current instruments. The technique is compared with other static and dynamic methods currently being used.

https://iopscience.iop.org/article/10.1088/0957-4484/7/3/014/pdf

Determination of the spring constants of probes for force microscopy/spectroscopy

A sample fabricating method of irradiating a sample with a focused ion beam at an incident angle less than 90 degrees with respect to the surface of the sample, eliminating the peripheral area of a micro sample as a target, turning a specimen stage around a line segment perpendicular to the sample surface as a turn axis, irradiating the sample with the focused ion beam while the incident angle on the sample surface is fixed, and separating the micro sample or preparing the micro sample to be separated. A sample fabricating apparatus for forming a sample section in a sample held on a specimen stage by scanning and deflecting an ion beam, wherein an angle between an optical axis of the ion beam and the surface of the specimen stage is fixed and formation of a sample section is controlled by turning the specimen stage.

Method and apparatus for specimen fabrication

The behavior of electromigration‐induced voids in narrow, unpassivated aluminum interconnects is examined, using scanning electron microscopy. Some electromigration tests were interrupted several times in order to observe void nucleation, void growth, and finally the failure of the conductor line. It is found that voids which opened the line have a specific asymmetric shape with respect to the electron flow direction. Besides void nucleation and void growth, void shape changes can consume a major part of the lifetime of the conductor line. A first attempt to model these processes on the basis of diffusion along the void surface shows that voids with a noncircular initial shape tend to produce the fatal asymmetry due to electron wind effects, with the anisotropy of surface energy possibly playing only a minor role.

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Electromigration failure by shape change of voids in bamboo lines

Focused ion beam (FIB) technique applications to very large scale integration (VLSI) failure analysis are reviewed. Three examples of microscopic cross sectioning and in situ observation on a VLSI chip are presented. One is a cross section of an electromigration‐induced open circuit. Another shows a pinhole in the SiO2 layer between the metal layer and the substrate. The third shows an open circuit, caused by process anomalies. Five preparation methods for further failure analysis are presented: cutting and connecting metal lines, making holes at insulation layer for electron beam probing, probing pad formation for mechanical and electron beam probing, microscopic cross sectioning for secondary electron miscroscopy observation, and marking for transmission electron spectroscopy observation. FIB was shown to be useful, as an aluminum microstructure observation tool, not only for qualitative observation of aluminum grains, but also for quantitative measurement of aluminum grain orientation. Each example is ...

K. Nikawa

Papers

Applications of focused ion beam technique to failure analysis of very large scale integrations: A review