NanoTech-Electronics

The demand for ever faster, cheaper electronics is pushing the lithography-based manufacturing techniques standard in the semiconductor industry to their limits. Now researchers report a cheap, fast lithography technique that uses arrays of flexible polymer nano pens to precisely pattern millions of complex structures in parallel. The technique, which the researchers have used to create an integrated circuit (and lilliputian versions of the Olympics logo), can be employed to make lines whose sizes range from a few nanometers to millimeters thick.

The technique, developed by Chad Mirkin, a chemist at Northwestern University and director of the International Institute for Nanotechnology, uses arrays of pyramid-shaped polymer pens whose tips are dipped in solutions of chemicals that may feature almost any molecule, including proteins and acids; the pens are then traced over a surface by a mechanical arm to create millions of structures in parallel. The width of the lines drawn by each pen can be carefully controlled by varying the force exerted on the flexible pen tips. Because Mirkin's pens trace out designs programmed by computer software, they can quickly switch between complicated designs, making possible the creation of complex patterns whose features are very close together.

Polymer-pen lithography is an improvement over dip-pen lithography, a technique that Mirkin has been developing since 1999. Dip-pen lithography uses arrays of sharp, stiff cantilevered probes--the same ones used for atomic force microscopy. Mirkin created a company, NanoInk, to commercialize the technology. But, he acknowledges, "its ultimate utility has been limited by problems with throughput, cost, and complexity." The size of its molecular strokes has been restricted to a relatively narrow range, the cantilevers are prone to breaking, and the number of structures that can be made in parallel is limited.

More information here.