Applications of Focused Ion Beams

The liquid metal ion source, once just a laboratory curiosity, is now the basis of focused ion beam systems that use a variety of heavy metal ions (with currents of lpA-3OnA)which can be focused into diameters smaller than 10nm with current densities of several A/cm2. The predominate use of these systems has been in various aspects of IC fabrication. The two main features of the FIB tool that are most important are the capability to remove material from the sample by sputtering (micro-machining) and to add materials to the sample by ion induced reactions (deposition) at sub-micron dimensions. In this role, the FIB tool is used in failure analysis, defect characterization, design modification, and process control in a variety of industries. The use of FIB falls into three major categories: 1) IC review and modification, where sputtering is used to create cross sections or modifications to the sample where cutting is desired, as well as the deposition of either metallic or insulating materials to either modify existing or to create new structures. The FIB tool can be used in several different environments. Laboratory tools are generally found in a research environment, while off-line tools are not used in the fab, as are on-line tools: in-line tools are in the fab, used in the actual fabrication process.