Focused ion beam (FIB) provides strong capability and tremendous flexibility of nano-fabrication. Based on physical reaction, FIB milling can be applied to majority of materials.  The ion beam (usually Ga⁺ ions) scans through a desired location and mills a very small area around the region of interest, without causing damages to other areas. FIB provides a way for maskless and resistless processing. It is also a precise instrument that can be applied to the fabrication of microelectronic and optoelectronic devices, such as direct-write lithography, circuit modification, failure analysis of ICs, TEM sample preparation, maskless implantation, and ion beam assisted etching and micromachining. 

FIB 200 TEM system of FEI Company provides better performance on overall operations of fabrication of micro optical devices by Ga⁺ ion beam micromachining.  This system is an advanced tool for rapid, precise micromachining and deposition of submicron features in various substrates and materials.  It is also a superb general purpose tool for SEM/TEM specimen cross section preparation, high contrast imaging, grain structure analysis, high aspect ratio probe drilling, fabrication of MEMS structures, and other related applications.  The major system specifications include that its accelerating energy range between 5 - 30 keV. Beam current range from 1 pA - 20 nA for 12 apertures. Beam diameter is 6 - 500 nm. Secondary electron image resolution is 7 nm. Stage movement accuracy is 0.5 mm. Maximum stage movement is up to 15 mm.  Primary ion species are Ga and In. It can handle up to 3 inches wafer. Two gas injection systems are equipped.  I₂ is used for enhanced etch and XeF₂ for insulator enhanced etch. Other functions include an in-situ optical microscope, real time milling monitor, auto FIB programmable milling, and selective etch.