Linewidth determination in local oxidation nanolithography of silicon surfaces

We measure the linewidth of structures fabricated by local oxidation lithography on silicon surfaces. Two different structures, isolated and arrays of parallel lines have been generated. The oxide structures have been fabricated in the proximity of sexithiophene islands whose size is comparable to the oxide motives. The comparison between local oxides and sexithiophene islands reveals that atomic force microscopy (AFM) images faithfully reproduce the size and shape of local silicon oxides. The oxide lines have a trapezoidal shape with a flat section at the top. AFM images of the oxide structures show rather small slopes ∼0.05–0.15 which imply angles with the horizontal between 3° and 8°. The shallow angles imply a minimum feature size of 14 nm at the base for an oxide thickness of 1 nm. Linewidths of 7 nm and 20 nm at the top and base, respectively, have been fabricated. We have also demonstrated the ability to pack structures with a periodicity of 13 nm.