Nanoscale deposition of solid inks via thermal dip pen nanolithography

We demonstrate that nanolithography can be performed using a heated atomic force microscope (AFM) cantilever tip to control the deposition of a solid organic "ink." The ink, octadecylphosphonic acid (OPA), has a melting temperature near 100degreesC and can self-assemble on mica. Postdeposition analysis shows that deposition occurs only when the cantilever tip is heated above OPA's melting temperature, that the deposited structure does not spread significantly while cooling, and that a cool tip coated with OPA does not contaminate the substrate during subsequent imaging. Single lines were written with a width of 100 nm. This approach greatly expands the potential of dip pen nanolithography, allowing local control of deposition and deposition of materials typically immobile at room temperature, while avoiding potential problems arising from inadvertent deposition and postdeposition diffusion. (C) 2004 American Institute of Physics.