September 9, 2002 6:54 AM PDT

IBM chip fights power leaks

IBM's labs have produced a chip with double-gate transistors, a significant milestone in the raging semiconductor space race.

Scientists at the Armonk, N.Y.-based company revealed that they have manufactured a working static RAM chip out of so-called Fin-Fet transistors, which feature two gates, rather than a single one, for conducting electricity. To date, IBM has said little publicly about double-gate transistors. At a technical conference in December, the company will provide details about the memory chip and also talk about other research on transistors.

"The problem with double gates is figuring out how to manufacture them," said Jeff Welser, a senior chip design manager at IBM Microelectronics. "We certainly don't have Fin-Fets on our product road maps yet, but this makes it more real...This shows more and more that these are useful structures."

Later this week, rival Intel will discuss its plans for multigate transistors at its developer conference in San Jose, Calif.

Double-gate transistors like the Fin-Fet have emerged as one of the technologies that could help engineers ward off technical limitations over the course of the next decade and make faster, more powerful chips.

Gates essentially function as conduits for electricity inside transistors, the building blocks of chips. By doubling the number of gates, engineers can pump more electricity through a transistor and thereby increase chip performance.

"You probably get a 50 percent performance improvement instead of the full factor of two," Welser said.

Even more important, using two gates allows engineers to cut down on leakage, or the unintentional dissipation of electricity, because the average amount of electricity flowing through each gate can be lowered. Leakage wasn't a significant problem a few years ago, but it has become acute now that transistor gates and other chip components measure only a few atoms thick.

In chips produced with the 90-nanometer process, approximately half of the electricity will be lost through leakage, Welser said. Such chips are expected to come out next year.

In a notebook, leakage means terrible battery life. In a server, it means higher power bills. Not only does the server require more energy, but also ambient cooling systems have to be beefed up because of the excess heat created by the excess electrical flow.

Welser likens the way these transistors lower leakage to stopping the flow of water through a garden hose. If you press down with one hand, the water flow can be stopped, but with difficulty. "But if you grip it on both sides, it is easier," he said.

In December, IBM will also publish technical papers on adding metallic layers to Fin-Fet transistors and other, related subjects.

The chip race
IBM's achievement will further charge the increasingly competitive atmosphere in the semiconductor universe as companies race to find a creative solution to the industry's looming problems. For years, semiconductor manufacturers improved the performance of their products by doubling the number of transistors on their chips every two years, in keeping with Moore's Law. More and smaller transistors lead to higher clock speeds and greater integration of functions into silicon.

This process, though, has had unsavory and unintended consequences. The heat produced by microprocessors, which now can contain over 200 million transistors, is becoming extremely difficult to dissipate. Meanwhile, the cost of designing and manufacturing chips with this vast number of microelements has grown astronomically. Except for Intel, most companies will join forces to build and operate factories, and even pool design efforts, because of the financial risks involved.

In this race, IBM and Intel are bitter rivals. For its part, IBM can claim a number of firsts. It was the first to produce chips with copper, rather than aluminum, wires. The company also developed silicon-on-insulator, a technology for improving performance and reducing heat, that has been licensed to Advanced Micro Devices, among others.

IBM has also been at the forefront of strained silicon and carbon nanotubes, other technologies that will one day likely be used to make chips.

Intel, though, can boast of research breakthroughs of its own, as well as far higher sales volumes. Despite the downturn in the PC industry, Intel remains the largest semiconductor manufacturer in the world.

The two companies aren't alone in the race. Hewlett-Packard has actively pursued research in molecular computing, creating circuits out of chains of atoms.


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