A Compact Nuclear Microprobe With a Liquid Metal Ion Source and a Toroidal Analyzer

A nondestructive three-dimensional RBS/channeling analysis system with an atomic resolution has been designed and is being constructed in Osaka University for analysis of nanostructured surfaces and interfaces. An ultra high-vacuum sample-chamber with a three-axis goniometer and a toroidal electrostatic analyzer for medium energy ion scattering (MEIS) was combined with a short acceleration column for a focused ion beam. A liquid metal ion source (LMIS) for light metal ions such as Li+ or Be+ was mounted on the short column. A minimum beam spot-size of about 10 nm with a current of 10 pA is estimated by optical property calculation for 200 keV Li+ LMIS. An energy resolution of 4 × 10−3 (ΔE/E) for the toroidal analyzer gives rise to atomic resolution in RBS spectra for Si and GaAs. This system seems feasible for atomic level analysis of localized crystalline/disorder structures and surfaces.