LITHOGRAPHY BY TAPPING-MODE ATOMIC-FORCE MICROSCOPY WITH ELECTROSTATIC FORCE MODULATION

The tapping-mode operation of the atomic force microscope (AFM) with a n electrostatic force modulation was characterized by analyzing amplit ude versus distance and amplitude versus frequency curves. This techni que was applied to the modification of silicon surfaces on the nanomet er scale and imaging the modified surface for the first time. Lines of different width and height were formed on a hydrogen-passivated Si su rface by the oxidation process caused by a bias voltage between tip an d sample. The pattern etched in aqueous KOH solution (1 mol/l) at 60 d egrees C showed a good pattern transfer. A distortion of the pattern w as observed when the writing direction was changed. A minimum line wid th of about 10 nm was obtained, which is close to that achieved by a c ontact-mode AFM.