[en] This paper reports the basic results obtained from an investigation of the microstructure of lithium niobate (LiNbO₃) crystals fabricated by using the focused ion beam (FIB) sputtering method. The morphology characterization of the microstructure is explained in terms of scanning electron microscopy observations based on the geometrical integrity, surface smoothness, cross-sectional area, aspect ratio, etc. The optimized micro-fabrication conditions and the sample morphology characterization are presented, and the sputtering rate of Ga ions for a 30-keV energy milling of the LiNbO₃ crystal is calculated, which is lower than the theoretical one gained from 'The Stopping and Range of Ions in Matter' (SRIM) sputtering simulation due to the redeposition effect being enhanced with increasing milling depth.