A new fabrication technique could lead to smaller chips
Source: “Flying Plasmonic Lens in the Near Field for High-Speed Nanolithography”
Xiang Zhang et al.
Nature Nanotechnology online, October 12, 2008
Results: Researchers developed, and demonstrated precise control of, a lens that converts ultraviolet light into a type of wave called a plasmon, which could be used to etch features as narrow as five to ten nanometers into semiconductor materials.
Why it matters: Photolithography–the technique used to manufacture microchips–is limited by the physics of conventional optical systems: it can’t produce features smaller than about 30 nanometers. The new lens produces surface plasmons, which are like waves passing through electrons on the surface of a metal. Since plasmons can concentrate light energy more narrowly than conventional optics can, the plasmonic lens could carve out ultrasmall patterns, enabling higher-capacity DVDs and faster microprocessors.
Methods: The researchers created a lens that consists of concentric circles patterned onto a thin film of silver. When the circles are illuminated with an ultraviolet laser, the electrons on their surfaces oscillate at a frequency that corresponds to the circles’ size, creating plasmons; the radiation produced by the plasmons extends about 100 nanometers from the lens. The researchers created a novel system that floats the plasmonic-lens arrays about 20 nanometers above a substrate. The substrate spins rapidly, creating an air flow along the bottom surface of the lenses, which regulates the nanoscale gap between the lenses and the substrate.
Next steps: So far, the researchers have used their invention to produce only relatively thick, 80-nanometer-wide lines, since they were focused on demonstrating the concept of the floating plasmonic lens. They are now conducting experiments to verify the possible resolution of the lens.