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| Schematic illustration of the pattern-writing process using an optically controlled microbubble on a plasmonic substrate and the logo of “UT-AUSTIN” written with 60 nm polystyrene beads. Courtesy: M Yogeesh |
A new “bubble-pen” lithography technique can be used to pattern colloidal and biological particles on solid-state substrates according to researchers at the University of Texas at Austin. The technique, which works by using laser-controlled microbubbles to create the patterns, will find a wide range of applications in microelectronics, nanophotonics and nanomedicine.
Photolithography is one of the main techniques available today to make micro- and nano-scale components for semiconductor devices. However, the problem is that these methods have inherent disadvantages. “Far-field" optical lithography, for example, is limited by the so-called diffraction limit of light, which means that it is extremely difficult to create features smaller than several hundred nanometres across. Techniques based on "near-field" scanning optical microscopy can overcome the diffraction limit by bringing the light source very near to the surface, but they are low-throughput and can only scan small areas at a time. Electron-beam lithography, although able to produce much smaller features, is also limited by the choice of working materials and substrates that can survive exposure to an electron beam.
The new bubble-pen lithography technique invented by Yuebing Zheng's team in collaboration with Deji Akinwande's and Andrew Dunn's groups in Texas uses a single low-power laser beam to generate a microbubble at the interface of a colloidal suspension of nanoparticles and a plasmonic substrate containing a network of metallic nanoparticles that interact strongly with light via localized surface plasmons (collective oscillations of electrons on a metal's surface). These metal particles act as efficient optical nanoantennas and can focus light to wavelengths dramatically below the diffraction limit. The microbubble produced captures and immobilizes the colloidal particles on the substrate and by directing the laser beam to move the bubble, the researchers can create different patterns from the colloidal particles with varying sizes and architectures.
Nanotechweb: Bubble-pen lithography patterns nanodevices, Belle Dumé
Excellent Work! Whats the smallest resolution can be achieved?
ReplyDeleteThanks! Currently, we can capture 6 nm QDs and pattern them as clusters. For the patterning of the individual particles, the particle size is a couple of hundred nanometers. The resolution is limited by bubble size, which we are pushing to nanoscale via substrate and wavefront engineering.
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