The use of focused ion beam (FIB) gas assisted etching (GAE) for photolithography mask repair was investigated. The atomic force microscopy (AFM) was used for analyzing the sputtered depth and surface topography. The secondary ion and electron signals, and the ion image were also recorded for each repair. It was observed that the FIB GAE with bromine enhanced the etching rate of the chrome mask that resulted in 193 nm optical transparency of ∼60%. It was also found that the gas mixtures, NH 3/Br 2 and CO 2/Br 2, reduced the amount of residue and enhanced the chromium mask etching rate compared to the Br 2-only etching.