What is nanopantography?
If you don't know the answer, I cannot blame you. After all, a query for 'nanopantography' on Google returns only 43 results as I'm typing this. But researchers from the University of Houston say that nanopantography can create billions of nanotech devices in hours. The idea behind the technology is surprisingly simple: it uses microlenses placed on a substrate (the surface that is being written upon) to divide a single ion beam into billions of smaller beams, each of which writes a feature on the substrate for nanotech device production. The scientists think that when this technology is ready for mass-production -- in about 10 years -- all our liquid crystal display (LCD) televisions will be replaced by field emission display (FED) ones which will have much higher resolutions.
This technique has originally been developed by Vincent Donnelly, Demetre Economou and Paul Ruchhoeft of the Cullen College of Engineering at the University of Houston. The diagram above describes the nanopantography method. "As the wafer is tilted about two orthogonal axes, the intersection of the wafer normal with an imaginary plane at far field traces a pattern that is written simultaneously at the bottoms of a large number of holes." (Credit: University of Houston)
You can see above another diagram showing the nanopantography setup for Ni deposition (Credit: Nader Sadeghi and University of Houston). This figure has been picked from a 28-slide presentation given by the researchers listed above and by Nader Sadeghi of the Laboratoire de Spectrométrie Physique, University Joseph Fourier-Grenoble and CNRS, France. Here is a link to this presentation, "Nickel ICP Nickel Plasma for Deposition of Nanodots using Nanopantography," given at the IMP Plastics conference (Tehran, Iran, 2006). Don't miss the last slide to discover the next-generation nanopantography system. [Caution: I have no problem accessing this file with Internet Explorer, but I cannot read it with Firefox 2.0.]
Now, let's return to the University of Houston news release to discover how these arrays of ion-focusing micro-lenses are used. "'These lenses act as focusing elements,' Donnelly said. 'They focus the beamlets to fabricate a hole 100 times smaller than the lens size.' A beam of ions is then directed at the substrate. When the wafer is tilted, the desired pattern is replicated simultaneously in billions of many closely spaced holes over an area, limited only by the size of the ion beam. 'The nanostructures that you can form out of that focusing can be written simultaneously over the whole wafer in predetermined positions,' Economou said. 'Without our technique, nanotech devices can be made with electron-beam writing or with a scanning tunneling microscope. However, the throughput, or fabrication speed, is extremely slow and is not suitable for mass production or for producing nanostructures of any desired shape and material.'"
A previous University of Houston news release, "New Technique Could Speed Mass Production of Nanotech Devices " (January 25, 2007), provides other details. "A standard lithography technique that can create lenses measuring 100 nanometers wide could therefore be used to draw features just one nanometer wide if combined with nanopantography. In addition to allowing for the creation of much smaller features, nanopantography has huge advantages of scale over other nanotech fabrication approaches. Direct writing can craft nanofeatures the same size as nanopantography. However these features must be written just a few at a time, as most. This approach would require an extremely long time to process one standard silicon wafer measuring 12-inches in diameter, compared with the potential parallel writing speed that should be possible with nanopantography."
The first paper describing nanopantography was published by Nano Letters under the name "Nanopantography: A New Method for Massively Parallel Nanopatterning over Large Areas" (Volume 5, Number 12, Pages 2563-2568, December 2005). Here are some quotes from the abstract. "We report a radically different approach to the versatile fabrication of nanometer-scale preselected patterns over large areas. [...] We expect nanopantography to become a viable method for overcoming one of the main obstacles in practical nanoscale fabrication: rapid, large-scale fabrication of virtually any shape and material nanostructure. Unlike all other focused ion or electron beam writing techniques, this self-aligned method is virtually unaffected by vibrations, thermal expansion, and other alignment problems that usually plague standard nanofabrication methods. This is because the ion focusing optics are built on the wafer." Here is a link to the full paper (PDF format, 6 pages, 255 KB) from which the illustration on the top of this post has been picked.
A more recent paper was published on the subject by the Journal of Applied Physics under the name "Nickel atom and ion densities in an inductively coupled plasma with an internal coil" (Volume 101, Article 013304, January 1, 2007). It says that "an inductively coupled argon plasma with a powered internal Ni coil was used to create a nickel-containing discharge with potential applications in ionized physical vapor deposition and nanopantography." Here are two links to the abstract and to this technical paper (PDF format, 9 pages, 228 KB).
Now, if you've followed me up to the end of this post, you don't have any excuses to ignore what nanopantography means.
Sources: University of Houston news release, September 4, 2007; and various websites
You'll find related stories by following the links below.