Field-assisted nanopatterning

A new atomic force microscopy (AFM)-based lithography method called field-assisted nanopatterning (FAN) has been demonstrated. Through the use of a conventional atomic force microscope with no alterations, FAN controllably patterns solid or liquid organic and inorganic molecules in the air under ambient conditions. In this manner, patterns can be produced with feature sizes that range from tens of microns to sub-20 nm. Examples include the high-resolution FAN of [60]fullerene, N-methylpyrrole, naphthalene, poly-3-octylthiophene, polyaniline, meso-tetraphenylporphyrin, and gold. These molecules have been patterned onto highly ordered pyrolytic graphite, indium-tin oxide, Au, and passivated Au. The molecules are first coated on a standard AFM tip and then are deposited onto the substrate when a threshold tip bias is achieved. The deposition process is a field-assisted transfer of the molecules from the tip to the substrate. Patterning is turned on or off by controlling tip bias, and the same tip is used for both patterning and imaging. Pattern dimensions are controlled by varying tip bias and fabrication (tip) speed.