A MINUSCULE ACCOMPLISHMENT

NANOTECH

DIP PEN nanolithography (DPN) is the etching of nanoscale patterns on various surfaces. It's accomplished by the dipping of an Atomic Force Microscope's tip, or cantilever, in a special liquid ink. But the technology has limitations that make it useless for manufacturing semiconductors. For one thing, DPN doesn't work in a vacuum because the ink evaporates. Another drawback: Once the ink starts flowing, it can't be turned off and back on, which limits the kinds of patterns it can make.

But now researchers at the Georgia Institute of Technology and the Naval Research Laboratory have developed what they call tDPN -thermal dip pen nanolithography-which uses a heated cantilever and a solid ink that liquefies when warmed. The result is a DPN method that can be turned on and off. It also works in a vacuum (because the solid-to-liquid ink immediately bonds to the surface). The tDPN has other features that make it ideal for chip fabrication. The tip "can touch a surface without contaminating it, allowing in-situ metrology," says William P. King, an assistant professor of mechanical engineering at Georgia Tech who is heading the research.

The tDPN is also proving to be a much finer tool than its predecessors. Most DPN patterns are around the 100 nanometer level; the tDPN has already produced patterns at 65 nanometers, and King is certain he'll attain 50 nanometers by this summer- a level that's considered the "magic number" for semiconductors. Ultimately, researchers think tDPN is capable of producing patterns at the 10 nanometer level. To put that in perspective, a human hair is about 50,000 nanometers wide. -TG

Copyright American Society for Engineering Education Summer 2005
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