Advances in source technology for focused ion beam instruments

Owing to the development of new ion source technology, users of focused ion beams (FIBs) have access to superior performance when compared with the industry standard Ga+ liquid metal ion source. FIBs equipped with an inductively coupled plasma (ICP) ion source are better able to carry out large volume milling applications by providing up to 2 mu A of Xe+ ions focused into a sub-5 mu m spot. However, ICP FIBs are presently limited to 25 nm imaging resolution at 1 pA.The gas field ionization source (GFIS) relies upon an ion source that is the size of a single atom and correspondingly gains high brightness through its very small source size. The high brightness allows the GFIS to produce a very small focused probe size (<0.35 nm for helium), but with comparatively small beam currents (less than 2 pA). The Cs+ low temperature ion source, still being developed, has a projected sub-nm focal spot size at 1 pA, a maximum current of several nanoamps, and has the potential to offer integrated secondary ion mass spectrometry capabilities.