Nanometer-scale structures were fabricated using electric field enhanced oxidation using an atomic force microscope with a conducting probe. The dependencies of thicknesses and widths of oxide stripes on applied voltage and time during which voltage is applied, were investigated. Also, the dependencies of depths of trenches, which are fabricated on the silicon surface by removing oxide stripes, on applied voltage and time during which voltage is applied, were investigated. The oxidation mechanism is discussed based on these investigations.