Three-dimensional diamond-like carbon mold fabricated by focused-ion-beam chemical vapor deposition (FIB-CVD) using a precursor of phenanthrene has been applied to a nanoimprint lithography (NIL) process. The mold has a very smooth surface, which is one of the advantages for the fabrication of optical devices. FIB-CVD uses a Ga+ beam control system which convert three-dimensional computer aided design data into the scanning signal and is capable of fabricating any shape of optical device mold surface such as a microlens. The microlens molds have been replicated onto poly (methylmethacrylate) (PMMA) and hydrogen silsequioxane using NIL. A microlens of polydimenthyl siloxane has been fabricated by replication using the PMMA reversal mold fabricated by NIL using the FIB-CVD mold. (C) 2004 American Vacuum Society.