Speaker
Description
Gas Field Ion Sources (GFIS) have already demonstrated their efficiency in nano imaging and patterning due to their high brightness, high current density and superior spatial resolution [1]. This type of ion source typically employs light noble gases such as helium and neon. In the first case, negligible sputtering and fast diffusion enables image resolution as low as 0.5nm, while the latter allows high resolution milling of small nanostructures with resolutions milling of small nanostructures with resolutions better than conventional Liquid Metal Ion Source (LMIS). GFIS suffers from limitation in terms of material removal rate due to low current. Another limitation comes from the light ion species used, as well as bubble formation due to deep implantation making GFIS less efficient than LMIS for larger volume or high aspect ratio milling application with only shallow end of range defects. To overcome those limitations, we investigated GFIS performance in a Focused Ion Beam (FIB) using heavier noble gases, namely argon and xenon.
In addition, we consider an alternative emitter configuration. Historically, GFIS emitters are based on single-crystal tungsten tips while, we employed an iridium coated tungsten tip. Among noble metals, iridium confers the strongest bond with tungsten [2]. That particularity would allow the overall tip structure to withstand higher electric field than with any other noble metal coating. As a result, iridium coated tip enable higher beam currents without endangering the emitter stability. We also work with a single emission point opposed to the typically trimer configuration traditionally used in Helium Ion Microscope (HIM).
In this work we will present the first FIB evaluation and performances of this particular emitter using argon and xenon. Comparison to helium and neon based GFIS used in the HIM will also be covered.
[1] Höflich, K.; et al. Roadmap for focused ion beam technologies. Applied Physics Reviews 2023
[2] Oshima, C.; Tomitori, M.; Shimoda, T.; Yasaka, A.; Asai, H.; Rokuta, E. Thermal Stability of Single-Atom Termination at a Pyramidal Apex of an Ir-W Tip. Surface Science and Nanotechnology 2018