Using a helium-metastable atom beam and an octanethiol (OT) self-assembled monolayer (SAM), we carried out atom lithography to the gold film on muscovite mica having a flat surface. A large intact area and a clear pattern with a nanoscale width similar to80-100 nm of the etched step was obtained. The, gold surface, as well as the surface of the, mica substrate, was flat. From the analysis of the roughness, appreciable gold islands were not detected in. the area exposed to the He* atom beam. This finding demonstrates that the OT SAMs on atomically flat surfaces can be used as a resist for exposure to metastable-atom beams. (C) 2003 American Vacuum Society.