Imaging and milling resolution of light ion beams in modern FIBs

Light ions are of increasing interest by application of focused ion beam (FIB) techniques due to the available high beam resolution in the nanometer range and their special chemical and physical behavior in the substrate [1, 2]. We compare helium and neon ion beams from a helium ion microscope with ion beams such as lithium, boron, and silicon, obtained from a mass-separated FIB using a liquid metal alloy ion source (LMAIS) with respect to the imaging and milling resolution, as well as the current stability [3]. While He+ offers, experimentally and in simulations, the smallest minimum trench width, light ion species such as Li+ from a LMAIS [4] offer higher milling rates and ion currents while outperforming the milling resolution of Ne+ from a gas field ion source. The comparison allows one to select the best possible ion species for the specific demands in terms of resolution, beam current, and volume and time for milling.

References
[1] L. Bischoff et al., Appl. Phys. Rev. 3 021101 (2016).
[2] P. Mazarov et al., Phys. Usp. 63 1219–1255 (2020).
[3] N. Klingner et al., Beilstein J. Nanotechnol. 11 1742–1749 (2020).
[4] W. Pilz et al., JVSTB 37 021802 (2019).