IBM Transistor Gets Smaller, Speedier

But some say obstacles remain for faster chips.

IBM last week became the latest major chip maker to announce a new transistor design for microprocessors that will boost performance and reduce power consumption.

The disclosure came less than a week after Intel Corp. revealed a similar research effort aimed at overcoming potential obstacles to building ever-faster and more energy-efficient computer components. The two leading chip manufacturers touted their separate initiatives last week at the International Electron Devices Meeting in Washington.

IBM researchers said their "double-gate" transistor—a microscopic on/off switch that forms the heart of integrated circuits—will be smaller and twice as fast as todays conventional transistors.

Shrinking the size of a transistor is one key to building faster processors, with chip makers packing tens of millions of the electronic switches onto a single die. But as transistors are shrunk to once-unimaginable sizes, already as tiny as 0.06 microns—a human hair is about 50 microns wide—chip makers are nearing the physical limits of conventional designs.

"Other than getting smaller, the basic transistor has largely gone unchanged for decades," said Bijan Davari, vice president of semiconductor development at IBM Microelectronics, in East Fishkill, N.Y. "It has now been shrunk nearly to a point where it will cease to function."

Despite the latest advances touted by IBM and Intel, one analyst said several challenges still lie ahead for the development of faster chips.

"As you get to smaller geometries, theres always the danger of whats called punch-through, and thats where if the voltage is too high, you just fry the insulating material," said Tony Massimini, an analyst with Semico Research Corp., in Phoenix. In addition, by adding insulating material, Massimini said, "youve got a whole other chemistry to deal with, and youre changing the electrical parameters and characteristics of the chip," which may cause further problems.

A major obstacle in designing smaller transistors is how to prevent electricity from seeping out of components, which becomes a bigger problem as the parts are made smaller. Energy leakage causes processors to consume more power and heat. Using present designs, processors in a few years would run so hot they would melt metal.

To address that issue, IBM is using new materials, such as SOI (silicon on insulator), which it already uses in its chips, to shield components and reduce energy leakage. In a transistor, an element called a gate controls the electrical flow through the transistor. As transistors shrink, it becomes more difficult for a single gate to effectively control switching.

In IBMs double-gate transistor, the channel is surrounded by two gates, which gives it twice the control over the current and enables significantly smaller, faster and lower-power circuits.