Researchers at Harvard University have developed a lithography technique that uses an array of microscopic lenses to shrink patterns more than 1000 times and repeat them across a surface.
The technique could be used to produce cheap optical filters and change some of the processes involved in IC manufacture.
The technique uses white light instead of UV lasers, shining the light through overhead transparencies made with a desktop printer. The approach is similar to conventional projection photolithography, but the microlenses that produce the reduction are positioned within 10µm of the photoresist.
The microlens array used in the technique uses a 'fly's eye' configuration that produces a common pattern and projects it repeatedly across a surface.
Dr Ming-Hsien Wu, a graduate student at Harvard and researcher on the project, has used transparent microspheres and convex microlenses. The microspheres generate uniform patterns over an area of about 2sq cm, using a mask with an area of 25X25cm, illuminated with a white light source.
"We have used polystyrene spheres as small as 1.5µm to generate arrays of simple patterns with 1.5µm pitch, such as hexagonal arrays of microscale crosses," said Dr Wu. "The technique provides the route for simple, low-cost desktop nanolithography."
But he says the technique will not be well suited to conventional IC production: "It would really be suited to applications like frequency-selective devices, such as optical filters, optical gratings, beam splitters and photonic crystals. It has limited IC applications, such as memory and flat panel displays, because of its repetitive nature."
Dr Wu has managed to produce features as narrow as 100nm. He estimates that, if only technological issues were considered, practical applications would be possible in two to five years.
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