Focused-Ion-Beam System
A focused ion beam (FIB) system mills, images, and deposits material using a focused beam of ions — traditionally gallium — rather than electrons, giving it a capability SEM alone doesn't have: it can physically cut into and remove material with nanometer precision, not just image a surface. Plasma FIB replaces the traditional gallium liquid-metal ion source with a plasma ion source (commonly xenon), trading some beam precision for dramatically higher milling rates on larger volumes.
Plasma FIB exists specifically because conventional gallium FIB's milling rate becomes impractically slow once a job needs to remove a large volume of material. Gallium liquid-metal ion sources are excellent at fine, precise milling but are current-limited in a way that makes removing a large cross-section — the kind of job that used to take hours — genuinely impractical for routine use. A plasma source can deliver far higher beam current, milling that same large volume dramatically faster, at the cost of a somewhat larger, less precisely focused beam spot — a direct speed-for-precision tradeoff that makes plasma FIB the right choice specifically for large-volume milling jobs, while gallium FIB remains the choice for the finest precision work.
Circuit editing is a capability unique to FIB-class tools that plain SEM or imaging-only microscopy fundamentally can't provide. Because FIB can both deposit conductive material and mill away existing material with sub-micron precision, failure-analysis and process-development engineers use it to physically cut an existing metal line, deposit a new connection between two points that weren't previously wired together, or probe an internal node directly — effectively rewiring a chip at the physical level for debug purposes, something no purely imaging-based tool can do.
FIB and plasma FIB both bring the same core capability — precise, controllable material removal and deposition at a microscopic scale — and the choice between a gallium and a plasma ion source comes down to whether the job needs the finest achievable precision or the fastest practical milling rate for the volume of material involved.