Computer chips take a leap forward.

IBM introduced a new technology this week that can more than triple the speed of computer chips, paving the way for improved electronic devices. The company announced that it has found a practical way to make connections on integrated circuits with copper instead of aluminum. Copper connections will allow circuits to be packed together more densely, leading to smaller and faster chips.

"This is a very advanced technology," says Harry T. Weaver, manager of microelectronics fabrication at Sandia National Laboratories in Albuquerque, N.M.

In the most advanced chips now available commercially, the aluminum wires connecting various features can be as little as 0.35 micrometer ([micro]m) wide. The electrical resistance of aluminum prevents those features from becoming much smaller, however.

Copper conducts electricity much better than aluminum, making wires as thin as 0.2 [micro]m possible. "There's nothing on the market like that," says Weaver. "It's more than a generation beyond what you can buy today."

The advance should keep chip technology in step with an empirical rule, according to which the capacity of integrated circuits doubles roughly every 18 months, says Weaver.

Despite its superior electrical properties, copper has several features that have prevented it from being used in silicon computer chips until now. Most troubling was copper's tendency to diffuse into silicon, "poisoning" features that had already been deposited, says William O'Leary, spokesperson for the IBM Microelectronics Division in Hopewell Junction, MY To overcome this obstacle, IBM inserted a barrier between the copper and silicon.

The company is patenting several parts of the manufacturing process and keeping others as trade secrets, O'Leary says.

An advantage of the technology, he adds, is that "it can be introduced rather painlessly into existing [fabrication] facilities." What's more, the new chips will probably cost only 70 to 80 percent as much to make, even though copper is a more expensive material. Making chips with copper requires fewer processing steps, which translates into lower cost.

Other research teams have been trying to deposit copper on silicon wafers, and a few have succeeded. However, those techniques still remain experimental, while IBM is already manufacturing chips in limited quantities. "IBM has always been a leader in taking advanced concepts and converting them into a process," Weaver says.

The first products to run on the new chips will probably be high-end computers, like those used as Internet servers. IBM also plans to work with companies that need custom-made chips.

The new chips demand less power than those currently available, which opens the door to more efficient electronic devices. A laptop computer that's less power-hungry, for example, could run longer between recharging or require a smaller, lighter battery. The chips should find their way into consumer electronics by next year, says O'Leary.

The technology is expected eventually to move integrated circuits into the giga-hertz speed range-well beyond the 300 megahertz in today's top-of-the-line personal computers. O'Leary says the technology should keep engineers productively occupied for the next 10 to 15 years.