Direct nanolithography of organic polysilane films using carbon nanotube tips

Polysilane is well known as a new type of polymer which is applicable to optoelectronic nanodevices because of attractive characteristics such as photoconductivity with high hole mobility, large nonlinear optical effects, and efficient light emission due to one-dimensional exciton. Polysilanes are also photochemically labile in a ultraviolet region and have been used as photoresist. Recently, nanolithography of polymer resist films have succeeded by means of low energetic electrons from a scanning probe microscope (SPM) tip as an alternative to conventional high voltage electron beams. The advantages of the SPM lithography technique are the higher resolution and no radiation damage in the substrate to be patterned. One can expect that a carbon nanotube (CNT) SPM tip realizes extraordinarily fine lithography. This is because of its high aspect ratio and small radius of curvature at the tip end. Recently, we have reported preliminary results on nanolithography about polysilane films in air performed using an atomic force microscope (AFM) with nanotube tips and found the possibility of fine direct lithography. In this work, we have investigated the finer direct lithography of polysilane films using nanotube tips.