Nuclear microprobe for integrated circuit process inspection

Abstract

A nuclear microprobe with a minimum beam-spot diameter of less than 100 nm, intended for application to IC (integrated circuit) process inspection, has been designed and installed at Osaka University. An ultra high-vacuum sample-chamber with a three-axis goniometer stage 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 80 nm with a current of 30 pA was obtained for 400 keV Be++ LMIS. An energy resolution of 4 x 10-3 (ΔE/E) for the toroidal analyzer gives ri..