Design of a 200 kV Focused Ion Beam Surface Analysis System

A nanometer nondestructive three-dimensional Rutherford back scattering (RBS) and medium energy ion scattering (MEIS) analysis system with a compact 200 kV focused ion beam (FIB) column has been designed. A high-vacuum sample chamber with a six-axis goniometer and an electrostatic toroidal analyzer for channeling and RBS analysis are connected to the acceleration column. A minimum beam spot size of less than 50 nm with a current of 50 pA is estimated by calculation for a 400 keV Be++ ion beam. As compared with MeV proton or helium ion microprobes, this compact system can produce about 10 times finer microprobes, 900-1600 times larger scattering cross section and higher depth resolution.