Investigation of Boron Liquid Metal Alloy Ion Sources for Focused Ion Beam Applications

Focused Ion Beam (FIB) processing is established as a well-suited and promising technique in R&D in nearly all fields of nanotechnology for patterning and prototyping on the μm-scale and below. Liquid Metal Alloy Ion Sources (LMAIS) represent an alternative to expand the FIB application fields beside all other source concepts [1]. Due to the interest on light elements, especially boron, various alloys were investigated and characterized. In this contribution we will describe Co31Nd64B5 as the most promising alloy in more detail. The mass spectrum of such a source was obtained in a VELION FIB-SEM system (Raith GmbH) [2]. The source operation life time was longer than 600 μAh and a first imaging characterization showed a lateral resolution of (30 ± 5) nm so far. This LMAIS is suited for several mass-filtered FIB applications like implantation, high rate sputtering, surface patterning or ion lithography [3]. The switching between the certain ion species. B – very light, suitable for ion lithography or writing p-type doping. Co – medium mass for applications in the field of nano-magnetics or CoSi2 for ion beam synthesis of conductive nano-structures on Si. Finally Nd as double charged heavy ion for ion sputtering. The change between ion species can be done in seconds and leads to remarkable expansion of the application spectrum of FIB technology.
[1] L. Bischoff, P. Mazarov, L. Bruchhaus, and J. Gierak, Liquid Metal Alloy Ion Sources - An Alternative for Focused Ion Beam Technology; Appl. Phys. Rev. 3 (2016) 021101.
[2] L. Bischoff, N. Klingner, P. Mazarov, W. Pilz, and F. Meyer, Boron Liquid Metal Alloy Ion Sources for special FIB applications, JVST B 38 (2020) 042801.
[3] L. Bruchhaus, P. Mazarov, L. Bischoff, J. Gierak, A. D. Wieck, and H. Hövel, Comparison of Technologies for Nano Device Prototyping with a Special Focus on Ion Beams – A Review,
Appl. Phys. Rev. 4 (2017), 011302.