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Cover of the Spring 2010 issue




Here’s a tip:
Technique yields durable diamond probes

Nano-foundry technique

Nano-foundry technique. Image courtesy of IBM Research-Zurich. view larger image

When a team of university and industry researchers tried a novel, foundry-style mold-filling technique to make nanoscale devices, they realized they had discovered a gem: They used their process to fabricate ultra-hard, wear-resistant nanoprobes out of a material much like diamond.

On a larger scale, materials that look smooth still abrade because of slight irregularities and defects on their surfaces. Now zoom in: At the nanoscale, atoms rub off one at a time, challenging researchers who build devices just tens of atoms wide. Silicon-containing diamondlike carbon, or Si-DLC, could solve this problem.

Kumar  Sridharan, Ph.D.

Kumar Sridharan, Ph.D. view larger image

Engineering Physics Distinguished Research Professor Kumar Sridharan developed the “nano foundry” technique. He started with an IBM silicon-on-insulator wafer previously etched with sharp, pyramid-shaped “molds.” Then, he used plasma immersion ion implantation and deposition, a room-temperature deposition process, to fill the molds.

The technique works somewhat like the way in which a snowfall blankets the ground. In this case, the “snow” is ionized hexamethyl disiloxane, a liquid precursor to Si-DLC that gasifies in the plasma chamber and packs neatly into the molds. Fabricated on standard silicon microcantilivers, the ultrasharp tips in wear tests were 3,000 times more wear-resistant than silicon tips.

The team, which also included researchers from the University of Pennsylvania and IBM Research-Zurich, published details of its research January 31 in the advance online edition of Nature Nanotechnology.

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