Flattening performance is evaluated on the atomic scale of Si (111) surfaces finished by a precise surface-preparation method utilizing fine SiO2 particles mixed with ultrapure water. An atomically flat Si(111) surface with periodic steps, which is obtained by dipping into an NH4F solution, is processed by the surfacing method. The low-energy electron diffraction image of the processed surface exhibits a 1 x 1 pattern. Atomic force microscopy observations show that the periodic steps formed by the NH4F treatment are completely removed, and highly resolved scanning tunneling microscopy images reveal that the processed surface is composed of nanometer-scaled small terraces. From these results, it is speculated that fine powder particles in ultrapure water remove microbumps and apparent steps to flatten work surfaces, although they can etch some surface atoms inside a terrace. (C) 2006 The Electrochemical Society.