Aug 9 2010
A research team led by Chad Mirkin of Northwestern University, Illinois, has joined conventional photolithography with near-field scanning optical microscopy to pattern large silicon areas in an economic way.
The team had already developed a polymer pen lithography technique to create small plastic tips, which are shaped like an inverted pyramid. The plastic tips write the features on a surface by using ink.
The new technique, which is known as beam-pen lithography, uses same type of plastic tips that are made of transparent polymer. The researchers used a layer of gold to coat the pyramids, except the tips. When light is shined on the base of the pyramids array, it goes through the polymer, comes out of the tips, and falls onto the photosensitive layer, which is on top of the silicon surface.
The team used 15,000 tips for patterning 15,000 copies of Chicago skyline. Each replica comprised 182 dots, with each dot measuring approximately 450nm in diameter. The beam-pen lithography technique can also be merged with photolithographic stencils to manufacture any kind of pattern. The team has also developed arrays of 11 million tips, after submitting the research paper.