Patterned self-assembled monolayers for the fabrication of micro- and nanostructures

This thesis describes the use of self-assembled monolayers (SAMs) for the fabrication of structures with dimensions ranging from 100 m m to <100 nm. By controlling the properties of the surface on which they assemble, SAMs and in particular patterned SAMs, can act as resists against etching, or as templates on which selective adsorption or nucleation can occur. Two methods for patterning SAMs are discussed. Microcontact printing, and a new method that patterns regions of disorder in SAMs at abrupt changes in the topography of metal substrates that support them.; Chapter 1 describes the fabrication of two layer structures of electrically isolated wires---crossed wire structures and a surface coil inductor. The fabrication process utilizes the tools of soft lithography and is based on two levels of self-assembly; (i) formation of patterned SAMs by m CP (using molecular scale self-assembly), followed by (ii) preferential wetting of a prepolymer on the hydrophilic regions of the monolayer (using meso- or macroscopic self-assembly). The use of microcontact printing and patterned self-assembly of liquid polymers removes the need for registration in two steps that would, with conventional techniques, require registration.; Chapter 2 describes the development of a new methodology for patterning SAMs that intentionally generates highly localized regions of disorder in SAMs at the edges of evaporated metal structures. We used this methodology (which we have named "topographically directed etching" or TODE) to fabricate 50 nm trenches specifically at the edges of topographically patterned films of Ag supporting SAMs of alkanethiols. The features generated by TODE are an order of magnitude smaller than those patterned originally in the material. Several variations of the basic methodology are described, the results of which include the fabrication of 100 nm trenches in SiO2/Si and Al2O3/Al, 100 nm lines of silver, asymmetric structures in aluminum and silver, and 30 nm features in curved silver surfaces. Although the techniques can be combined with photolithography, the pattern transfer step is chemical, and is not limited therefore by diffraction or depth of focus.; Chapter 3 describes the use of two new techniques---topographically directed etching (TODE) and photolithography in the near-field---to make structures having 100--300 nm feature sizes, and the use of these structures as masters against which to mold poly(dimethylsiloxane) (PDMS) to prepare stamps for microcontact printing ( m CP). Printing with these stamps can routinely produce positive and negative structures with 100--300 nm dimensions in silver. These procedures are limited in the generality of the patterns they can produce: they cannot, in general, make closely spaced features, and distortions and sagging in the mask place other types of limitations on the patterns that can be made. They do, however, provide ready access to a range of useful patterns without requiring access to high-resolution pattern-generating systems.