The creation of three-dimensional nanostructured materials is crucial to the development of nanoelectronics, optical devices, drug delivery agent, biosensors and many other nanometre-scale systems. However, the development of practical methods capable of generating nanostructures and building up into the third dimension represents a major task, and is one of the greatest technical challenges now facing nanofabrication. Perhaps of the most interest for the future is the possibility of creating functional nanostructures by combining bottom-up self-organisation of self-assembled nanoentities, which occur in solution, with top-down lithographic approaches such as UV, X-ray and electron-beam lithography. The integration of top-down approaches and bottom-up self-assembly processes - what might be termed precision chemical engineering1 - suggests that materials and subsequent devices could have multiple length scales, from the micron to the atom. The term precision chemical engineering encapsulates the precision engineering of writing to surfaces in a spatially controlled fashion to direct the surface chemistry, coupled with the engineering that is involved in fabricating three-dimensional architectures from the surface from molecular and condensed phase entities. Another aspect that is encapsulated by this term is the fact that the three-dimensional structures are not only engineered, but are held together by both mechanical and chemical interactions. Thus, the stability of the three dimensional structures will be dominated by thermodynamics as well as mechanics. This integration of the two methodologies is representing a new paradigm for creating nanostructured surfaces, and will involve close collaboration between scientists and engineers.
The lecture will highlight our methodologies for creating three dimensional nanostructures using lithographic techniques based upon e-beam2 (Figure a) and scanning near field optical3 lithographies (Figure b).