We present a novel Si nanofabrication method based on an atomic force microscope (AFM) field-enhanced oxidation and an anisotropic wet chemical etching using SlMOX (separation by implanted oxygen) wafer. A newly developed AFM system enables this fabrication method to be fully compatible with a conventional VLSI process. Using this technique, Si quantum wire with a feature size of 60 nm has been successfully fabricated within the intended area. Moreover, by means of a structural analysis by cross-sectional transmission electron microscopy, it is confirmed that the AFM-field-enhanced oxide film has a similar excellent structure as thermally grown oxide.