High Current Focused Ion Beam Research Articles

Probe Optimization studies For High current Focused Ion Beam Instruments

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High brightness inductively coupled plasma source for high current focused ion beam applications

A high brightness plasma ion source has been developed to address focused ion beam (FIB) applications not satisfied by the liquid metal ion source (LMIS) based FIB. The plasma FIB described here is capable of satisfying applications requiring high mill rates (>100μm3∕s) with non-gallium ions and has demonstrated imaging capabilities with sub- 100-nm resolution. The virtual source size, angular intensity, mass spectra, and energy spread of the source have been determined with argon and xenon. This magnetically enhanced, inductively coupled plasma source has exhibited a reduced brightness (βr) of 5.4×103Am−2sr−1V−1, with a full width half maximum axial energy spread (ΔE) of 10eV when operated with argon. With xenon, βr=9.1×103Am−2sr−1V−1 and ΔE=7eV. With these source parameters, an optical column with sufficient demagnification is capable of forming a sub-25-nm spot size at 30keV and 1pA. The angular intensity of this source is nominally three orders of magnitude greater than a LMIS making the source more amenable to creating high current focused beams, in the regime where spherical aberration dominates the LMIS-FIB. The source has been operated on a two lens ion column and has demonstrated a current density that exceeds that of the LMIS-FIB for current greater than 50nA. Source lifetime and current stability are excellent with inert and reactive gases. Additionally, it should be possible to improve both the brightness and energy spread of this source, such that the (βr∕ΔE2) figure-of-merit could be within an order of magnitude of a LMIS.

CoSi2 microstructures by means of a high current focused ion beam

The Rossendorf focused ion beam IMSA-100 was constructed and used for writing implantation of cobalt to form CoSi2-submicron structures on silicon by ion beam synthesis. Two types of cobalt containing liquid alloy ion sources were developed with Co–Nd and Co–Ge alloys. The fabrication of CoSi2 structures by stoichiometric implantation of Co+ (E=30–35 keV, Iion=1.3 nA) and Co2+ ions (E=60 keV, Iion=0.6 nA) at doses between 0.3 and 5×1017 cm−2 and a subsequent two step annealing (600 °C, 60 min; 1000 °C, 30 min in N2) is demonstrated. The dose dependence as well as the influence of the substrate temperature between room temperature and 400 °C during ion implantation on the ion beam synthesis process were studied. The quality of the silicide submicron structures was investigated by scanning electron microscopy, energy dispersive x-ray analysis, and electrical measurements. While the room temperature implantation and subsequent annealing generate an inhomogeneous CoSi2 film, 400 °C substrate heating during implantation leads to a continuous film with a resistivity below 20 μΩ cm, comparable with broad beam implantation.

High current FIB system for micromechanics application

A high current Focused Ion Beam (FIB) system, designed to achieve current densities above 10 A/cm 2 is presented. The system parameters and properties are discussed and first applications in the field of micromechanics are shown.