Si(100) surfaces have been successfully oxidized at nanometer scale using an atomic force microscope working in tapping mode (TMAFM). To modify the surface, gold coated tips and chromium-gold coated tips have been used in order to apply a positive voltage to the sample against the grounded tip. A silicon oxide line of similar to 10 nm lateral dimensions can be routinely grown on Si(100) surfaces by TMAFM, at a tip velocity as high as 0.1 mm/s. pattern dimensions have been measured for different tip velocities and applied voltages and a tip velocity of up to 10 mm/s has been predicted. The patterns have been successfully used as a lithographic mask for a wet chemical etching.