ORC Seminars 2011

“Photolithographic Fabrication of Molecular Nanostructures”

Speaker: Graham Leggett, Department of Chemistry, University of Sheffield

Date: Wednesday 9th February

Time: 1.30pm

Venue: L/T C Building 46

Abstract:

The integration of top-down (lithographic) and bottom-up (synthetic) methodologies remains one of the most important unsolved problems in molecular nanoscience. Photochemistry is an attractive solution, because there is such a large catalogue of photochemical synthetic reactions to draw upon. The problem is to integrate this with nanometre scale spatial control of reactivity. We have addressed this with near-field optical techniques. Using a scanning near-field optical microscope attached to a UV laser, we have fabricated structures as small as 9 nm in self-assembled monolayers of alkanethiols on gold. Subsequently, we have developed a variety of routes that enable the nanometre scale patterning of molecules on silicon, aluminium and titanium substrates, employing photochemical reactions in monolayers of silanes, phosphonic acids, polymers, fullerenes and metal nanoparticles. We have adapted photochemical protecting group strategies from oligonucleotide synthesis, and for the first time integrated conventional synthetic chemical methodology into a nanofabrication system. The fabrication of molecular nanostructures over large areas has been addressed by blending near-field approaches with the concept of parallelism embodied in IBM’s Millipede. In a new device we call the “Snomipede”, parallel near-field probe arrays are excited using either a liquid crystal spatial light modulator or a Brewster angle zone plate array combined with a digital mirror device, providing individual control of writing by up to sixteen probes in parallel. The Snomipede can write molecular patterns with a line width of 125 nm over an area more than 1 mm wide in monolayers of aminosilanes, and has achieved features sizes of 70 nm in photoresist while operating with the entire probe array immersed under water, pointing the way to a future “reactive nanolithography”.

Biography

Graham Leggett is Professor of Chemistry at the University of Sheffield, UK. He received his B.Sc. (1987) and Ph.D. (1990) from the University of Manchester Institute of Science and Technology, and carried out postdoctoral work at the Universities of Washington and Nottingham. Prior to moving to Sheffield in 2002, he held academic positions in Nottingham and Manchester. His research has centered on the surface chemistry and analysis of organic, polymeric and biological materials. Currently, three themes are of special interest: the development of near-field optical techniques for molecular n anofabrication, the application of nanofabrication techniques to the assembly of biological structures, and the nanotribology of organic and polymeric films (in particular, studies by friction force microscopy).

Copyright University of Southampton 2006