Secondary Ion Mass Spectrometry (SIMS) has unique features that makes this technique a very attractive candidate for sub-micron analysis: high elemental sensitivity (ppm or better) if reactive primary ions are used ; isotopic analysis capability ; possible insulator analysis ; no sample preparation needed ; small probed depth (a few run) and small interaction volume (cascade collision dia. < 10 nm).
Similar to a SEM microscope, a beam of Cs+ or O− primary ions is focused and rastered on the surface of the sample. The ions sputtered by this primary beam are collected, and this secondary ion beam is shaped in order to be mass filtered by a magnetic sector mass analyzer. Five mass selected images can be simultaneously recorded, originating from the exact same sputtered volume, ensuring reliable isotopic ratio and perfect image registration.
Based on Pr. Slodzian and al. [1, 2] original design, the commercial version of the NANOSIMS 50 ion microprobe incorporates several new developments in order to improve performances: