FIB is used to observe surface structure by detecting electrons generated upon ion beam irradiation and process the surface of a sample to an arbitrary shape by the use of focused ion beam. Since the ion beam can arbitrarily scan on a sample, FIB is widely used for site-specific cross section preparation for SEM observation and lamella preparation for TEM observation. FIB-SEM incorporates both FIB and SEM in a single system, and allows in-situ SEM observation of FIB-prepared cross section. By repeating FIB milling and SEM observation, serial cross-sectional SEM images can be collected and reconstructed for further three-dimensional structural analysis of the sample.