Super-Precise Nanolithography Using Multilayer of Self-Assembled Monolayers
Tanaka, H.; Anderson, M.E.; Tan, L.P.; Mihok, M.; Horn, M.W.; Weiss, P.S. Super-Precise Nanolithography using Multilayer of Self-Assembled Monolayers. J. Surf. Sci. Soc. Jpn.2004,25, 650-655.
The combination of self-, directed and positional assembly techniques, i. e., “bottom up” fabrication, is demonstrated in this work because they will be essential for patterning and connecting future nanodevices. An array of polystyrene spheres was used instead of conventional lithographic techniques to make “parent” structures. A close-packed monolayer of polystyrene spheres (diameter∼400 nm) was used as a hard mask. Gold was vapor deposited through this mask and lift-off of the spheres produced arrays of triangular gold dots, which were used as “parent” structures. Multilayers of 16-mercaptohexadecanoic acid and Cu2+ ions were selectively deposited as a molecular resist onto these gold dots followed by chromium deposition creating a daughter structure on the substrate. After lift-off of the molecular resist, uniform spacings between “parent” and “daughter” structures are observed using a scanning electron microscope. Nanometer-scale spacing can be controlled around the nanostructures by simply changing the number of layers in the molecular resist or by using molecules of different lengths. In the near future, many applications using this method are expected to impact nanofabrication, such as nanoelectronic devices and micromachines.