The application of focused ion beam (FIB) technology in microfabrication has become increasingly popular. Its use in microfabrication has advantages over contemporary photolithography or other micromachining technologies, such as small feature resolution, the ability to process without masks and being accommodating for a variety of materials and geometries. An overview of the recent development in FIB microfabrication technology is given. The emphasis will be on direct milling, or maskless techniques, and this can distinguish the FIB technology from the contemporary photolithography process and provide a vital alternative to it. After an introduction to the technology and its FIB principles, the recent developments in using milling techniques for making various high-quality devices and high-precision components at the micrometer scale are examined and discussed. Finally, conclusions are presented to summarize the reviewed work and to suggest the areas for improving the FIB milling technology and for future research.

https://iopscience.iop.org/article/10.1088/0960-1317/14/4/R01/pdf

Recent developments in micromilling using focused ion beam technology

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

Applications of focused ion beam microscopy to materials science specimens

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

Patterning of diamond and amorphous carbon films using focused ion beams

Focused ion beam machine technology is generally divided into two distinct categories according to the intended applications. These are: (1) low-energy (10–30 keV) heavy-ion beam (usually Ga) systems used in sputtering and ion-induced material deposition and (2) high-energy (50–200 keV) systems with generally more complex ion optics for implantation and lithography applications. State-of-the-art focused ion beam systems are capable of minimum beam diameters (FWHM) on the order of 500 A with a chromatic aberration-limited current density of about 1 A/cm 2 . While continuing progress in ion optics and the computer automation of both these types of focused ion beam systems has enabled them to emerge from the laboratory and into limited production uses, some new approaches are also on the horizon. These new approaches include the use of achromatic quadrupole lenses to improve the maximum achievable beam current density perhaps by a factor of 10, and the use of immersion lenses for producing finely focused beams at very low (100 eV or less) energy to minimize substrate damage during processing. This paper will review some of the recent developments in focused ion beam machine technology in the context of existing and emerging processing techniques.

L.R. Harriott

Papers

The technology of finely focused ion beams