Can Carbon Put Copper Down for the Count?

In the nano realm, copper vertical interconnects won't cut it

3 min read

Copper interconnects carry current in today's integrated circuits, but in the nanometer-size future, the metal just won't do the job. At this month's IEEE 2010 International Electron Devices Meeting, in San Francisco, European researchers plan to announce that they're one step closer to a replacement. Nanotubes made of carbon, if grown in dense bundles, can transport large quantities of charge through tiny channels reliably. As part of the European ViaCarbon project, a team led by Jean Dijon, the head of nanotube research at the French government research organization CEA LITEN in Grenoble, says they've grown the densest bundles yet, packing 2.5 trillion carbon nanotubes per square centimeter. The density of their interconnects is within an order of magnitude of what's needed for replacing copper. In the future, such bundles have the potential to exceed copper's current-carrying capabilities by a factor of 100.

Copper needs a replacement particularly in the narrow pegs, called vias, that connect the silicon surface to the chips' wiring and connect one layer of wiring to another. According to the 2009 International Technology Roadmap for Semiconductors, engineers predict that as the features on chips shrink, not only will copper vias be more difficult to manufacture and suffer from more resistance, but by 2015 they may not work at all.

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The Ultimate Transistor Timeline

The transistor’s amazing evolution from point contacts to quantum tunnels

1 min read
A chart showing the timeline of when a transistor was invented and when it was commercialized.

Even as the initial sales receipts for the first transistors to hit the market were being tallied up in 1948, the next generation of transistors had already been invented (see “The First Transistor and How it Worked.”) Since then, engineers have reinvented the transistor over and over again, raiding condensed-matter physics for anything that might offer even the possibility of turning a small signal into a larger one.

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