Sep 1 2010
Demand for ever-smaller electronic devices, whether are for information storage, high-definition displays or sensor arrays, is driving demand for nanofabrication techniques that can define ever-smaller features on circuit boards — on scales smaller than micrometers, or even nanometers, in diameter.
Electron beam and X-ray lithography are well-established techniques for nanofabrication, but both have disadvantages, especially in terms of cost and flexibility. On the contrary, optical lithography is generally cheap and adaptable, but it does not allow the fabrication of features smaller than a few hundred nanometers. This limitation can be overcome by applying a technique known as near-field enhanced laser irradiation, whereby the light of optical beams is concentrated in a spatial region much smaller than the wavelength when it scatters on a nanostructure. The degree of improvement is determined by the dimensions of the nanostructures and the distance from its surface.
Using optical lithography, Xincai Wang from A*STAR’s Singapore Institute of Manufacturing Technology and co-workers have now fabricated arrays of ‘nanobumps’ surrounded by ring-shaped trenches on a silicon substrate.
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