Combination of nanolithography and wet chemical etching including the
fabrication of nanoarrays of sub-50 nm gold dots and line structures with
deliberately designed approximately 12-100 nm gaps. These structures were
made by initially using direct write nanolithography to pattern the etch
resist, 16-mercaptohexadecanoic acid (MHA), on Au/Ti/SiO.sub.x/Si
substrates and then wet chemical etching to remove the exposed gold.
These are the smallest Au structures prepared by a wet chemical etching
strategy. Also, Dip-Pen Nanolithography (DPN) has been used to generate
resist layers on Au, Ag, and Pd that when combined with wet chemical
etching can lead to nanostructures with deliberately designed shapes and
sizes. Monolayers of mercaptohexadecanoic acid (MHA) or octadecanethiol
(ODT), patterned by DPN, were explored as etch resists. They work
comparably well on Au and Ag, but ODT is the superior material for Pd.
MHA seems to attract the FeCl.sub.3 etchant and results in nonuniform
etching of the underlying Pd substrate. Dots, lines, triangles and
circles, ranging in size from sub-100 to several hundred nm have been
fabricated on these substrates. These results show how one can use DPN as
an alternative to more complex and costly procedures like electron beam
lithography to generate nanostructures from inorganic materials.