Sub-Micron 3D Holographic Lithography.

The miniaturization of measurement systems has been an outstanding technological success for many decades enabling some of mankind's most spectacular achievements. For example: extra terrestrial space landings on the large scale and in-vivo intensive care instrumentation on a small scale. In-situ measurement is fundamental to progress and will remain so for the discoveries to come. Connecting together and assembling these micro- and nano- systems has been achieved to date with essentially planar solutions. Photographically defined wires on flat silicon chips have suited the mass manufacture market well and avoided time consuming writing in three dimensions of one wire at a time. Our research programme addresses this problem, to enable the creation of three dimensional measuring devices on the nanometric scale produced as we manufacture computer chips at present. When component size gets very small, the molecular world is rarely flat and our project in Holographic Lithography is intended to pioneer some of the approaches needed to engineer and build this new small world. The construction of the silicon age has required as many sophisticated tools as the building of previous stone, steam or space ages . One technique above all others stands out as we live through the information revolution: that of lithography. Akin to photography, the creation of micro circuits by developing overlaid pictures of the components and interconnections required has reached incredible precision. But like all photographs, photocopiers or printers, they freeze the action on a two dimensional plane. Attempts to move into the three-dimensional, sub-micron world leave us with out of focus and coarse structures requiring individual attention and wire-by-wire assembly. However, holograms give us the means to store and reproduce three-dimensional images as they ought to be. We can use holograms as a pair of spectacles in our lithography system to enable us to create the correct patterns in three-dimensions.Our research is aimed at extending two-dimensional photolithography, which has already achieved deep sub micron resolutions of better than 50 nanometres, to three-dimensional holographic lithography. The potential applications occur wherever the small active measurement system has to connect to the real world. Miniature gyroscpes or microphones, aerials and test tubes are all 3D real objects able to work more effectively if not constrained to flat world restrictions. In terms of connection alone, the ability to wire and stack existing 2D computer chips with a 3D wire lattice between layers will enable a greater information processing density for new computer technology.Potential benefits can now be extrapolated. An age comes to an end for the researchers when every last ounce of performance is squeezed from the technology. Expanding information processing into the third dimension is an inevitable but tricky step to accomplish. We believe our work in sub-micron Holographic Lithography will enable one of the required tools and will thus bring many direct and indirect benefits both to the scientific and wider community.