Nanofabrication by Focused Ion Beam

Focused ion beam (FIB) is the most versatile tool in nanofabrication. Due to the heavy mass of ions, FIB can remove materials by scanning over a sample surface without a mask and resist pattern transfer. The chapter first introduces three types of ion sources currently employed in FIB, i.e., liquid metal ion source, plasma ion source, and gas field ion source, each of which has its own advantages and disadvantages. As charged particles, ions can scatter in solid materials like electrons but with much small angles than electrons; particularly there exists channeling effect in crystalline materials. The key properties for FIB to be used as a nanofabrication tool are sputtering removal and gas-assisted deposition of materials. The principles of both features are explained and four typical usages of FIB are presented, including FIB inspecting and editing integrated circuits, repairing photomasks, preparing TEM/STEM samples, and nanostructuring for scientific research.