HIGH-RESOLUTION CHEMICAL IMAGING WITH SCANNING ION PROBE SIMS

Scanning ion microprobes, in conjunction with secondary ion mass spect rometry (SIMS) provide, at high spatial resolution, chemical, isotopic and morphological information about materials. A powerful analytical microscopy technique, scanning probe SIMS offers, in the best cases, 2 0 nm spatial resolution, with nanometer-scale depth resolution and par ts per billion concentration sensitivity. By employing different measu rement strategies, either the uppermost monolayer, the top few monolay ers, or the bulk of a solid can be studied. It is well known that, bec ause of trade-offs imposed by the finite volume of matter being studie d, it is impossible to combine high spatial resolution with ultimate s pectrometric sensitivity. In this paper, we briefly review the history of the scanning probe SIMS technique. Then we describe several recent developments in the field: improvements conceived to improve simultan eously spatial resolution and sensitivity. The technique has found app lications in many diverse areas, from biology to semiconductors, from cosmochemistry to superconductors. Highlighting. these applications, w e present results from the study of dynamic processes on the surface o f liquids, and the analysis of engineered ceramics and photoemulsion m icrocrystals.