Because the light from plasmons decays less than 100 nanometers from the metal surface, the photoresist material must be placed very close to the lens. To accommodate this limitation, the researchers designed an air bearing that uses the aerodynamic lift force created by the spinning to help keep the two surfaces a mere 20 nanometers apart.
Air bearings are used to create magnetic tapes and disk drives, but this is the first application for a plasmonic lens.
With this innovative setup, the engineers demonstrated scanning speeds of 4 to 12 meters per second.
"The speed and distances we're talking about here are equivalent to a Boeing 747 flying 2 millimeters above the ground," added Zhang. "Moreover, this distance is kept constant, even when the surface is not perfectly flat."
The researchers pointed out that a typical photolithography tool used for chip manufacturing costs $20 million, and a set of lithography masks can run $1 million. One of the reasons for the great expense is the use of shorter light wavelengths to create higher resolution circuitry. Shorter wavelengths require nontraditional and costly mirrors and lenses.
The system described by the UC Berkeley engineers uses surface plasmons that have much shorter wavelengths than light, yet are excitable by typical ultraviolet light sources with much longer wavelengths. The researchers estimate that a lithography tool based upon their design could be developed at a small fraction of the cost of current lithography tools.
Other alternatives have been developed that can achieve hi
|Contact: Sarah Yang|
University of California - Berkeley