IBM puts vacuum spaces in chips

Nothing insulates like a vacuum. Big Blue says its Airgap technique will increase chip speed and reduce power consumption. Images: IBM's vaccuum techique Video: Building chips with Airgap

IBM is putting nothing into its chips, and that's a big deal.

Researchers at Big Blue have come up with a way to create vacuum spaces between copper wires in semiconductors, an insulating technique that will allow these chips to increase in speed and performance and reduce power consumption. Early indications show that chip performance can be increased by up to 35 percent, power consumption can be cut by 15 percent, or some combination of increased performance and power savings can be achieved.

Here's an animated video produced by IBM to explain how chips with vacuum technique called Airgap will be built.

The vacuum technique, called Airgap, will be introduced to IBM's manufacturing process with the 32-nanometer generation of microprocessors, said IBM fellow Dan Edelstein, who led the project. These chips will start rolling out in 2009. IBM's semiconductor partners--including Advanced Micro Devices, Toshiba, Sony "and soon to be others"-- will be able to adopt the technology for their own chips, he added.

Nothing insulates like a vacuum, which is space devoid of matter (including air). Chipmakers for years have used insulators to inhibit unintended transmission and chatter between wires, but the relentless march of Moore's Law has made the search for new insulating materials a difficult task. Shrinking the size of chips, after all, means that the copper wires inside chips are getting closer all the time and smaller.

Scientists have been working on porous materials that are relatively vacuum-like. Unfortunately, these porous materials are generally fragile and can break down under heat and other stresses found inside microchips.

"We think these other materials will fall by the wayside," Edelstein said.

The manufacturing technique for inserting the vacuum gaps was derived from research on self-assembling molecules, called diblock copolymers, conducted by IBM researcher Chuck Black.

A diblock copolymer consists of two types of molecules that, in ordinary circumstances, would repel each other. By designing the molecules in a particular way and controlling how they interact, they create intricate patterns through chemical repulsion.

"This is a synthetic way of trying to imitate certain processes in nature," Edelstein said. "It's similar to how seashells or snowflakes grow molecule by molecule."

Others are looking at ways of exploiting microbe proteins to guide self-assembly.

With Airgap, IBM first creates copper wires on a chip and then deposits insulators between the wires. The diblock copolymer is then applied. The self-assembly process results in an evenly spaced matrix of dots, with each dot having a 20-nanometer diameter.

The dots essentially create a template for the next step: The dots are chemically etched away and become holes.

"One polymer becomes the hole and one becomes the material between the holes," according to Edelstein's description.

The insulating material is removed through more etching, and the void is capped to create a vacuum.

The self-assembly techniques and the research on finding better insulators actually were somewhat independent. Edelstein, however, read Black's published papers and "put two and two together," he said.

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