Lobsters Serve as Inspiration for X-Ray Lithography Technology

Kathleen G. Tatterson

STURBRIDGE, Mass. -- A new lens design originally created for applications in astronomy, and based on the eye structure of a lobster, holds promise in the etching of ultrasmall electronic components on a chip.

Nova Scientific Inc. and a team from the University of Leicester, UK, invented the microchannel plate, or "lobster-eye" lens, and hope to use it to make electronic components much smaller than 0.18 µm -- the smallest that has been produced using x-rays -- for a fraction of the cost of current x-ray technology. In traditional photolithography, a collimated beam of visible light shines through a stencil-like mask onto a semiconductor substrate. The light beams change the properties of the substrate so that when it is etched with acid, exposed portions are not disturbed, but when the light is diffracted, it casts a shadow off the edge of the mask onto the substrate. Therefore, 0.25 µm is usually the smallest component size that can be created.

The lens is being used in point-source proximity x-ray lithography with a laser-induced plasma source. The curved lens reformats the resulting beams into a parallel beam, which it focuses down to a point. The collimator is necessary because the laser-induced plasma source is weaker and more divergent than a synchrotron, which is currently the primary source of x-ray technology. The advantage of the multichannel lens is cost. A synchrotron can run upward of $40 million to $60 million, whereas the easily reproducible lens system is estimated to cost less than $1 million.

The silver-dollar-size lens comprises an array of tubes -- each between 10 and 200 µm across -- encased in a 36-mm glass plate measuring 6 mm deep. The novel round-channel design creates a uniform output from a divergent beam, according to W. Bruce Feller, vice president and chief scientist at Nova Scientific.

The research is sponsored by the Defense Advanced Research Projects Agency, the National Science Foundation, the US Department of Commerce and the Naval Research Laboratory. Though the lens is still in development, further applications are being considered in medical imaging, nondestructive testing and scientific analysis.