December 2, 2001 9:00 PM PST
IBM: New transistor to boost chip speed
In a presentation at the International Electron Devices meeting that starts Monday in Washington, D.C., Big Blue will show off what it calls a Double Gate transistor. Transistors, which are microscopic on-off switches inside semiconductors, channel electronic signals that eventually get orchestrated into higher commands.
Double Gate transistors improve on existing designs, according to IBM, because they effectively double the electrical current that can be sent through a given transistor, or, alternatively, lower the amount of electricity running through a given gate for better power management.
"These are suited for very high-performance (processors) or for very low power," said Bijan Davari, vice president of semiconductor development at IBM Microelectronics. IBM has already made samples of Double Gate transistors, he added, which will likely start to appear in chips by 2006.
Meanwhile, Advanced Micro Devices is using this week's forum to announce a new 15 nanometer transistor, a prototype for the transistors it will use in future chips.
IBM's presentation underscores two of the major trends in the semiconductor world:
The ever-growing number of transistors on chips is creating a power crisis and forcing designers to revamp chips so they run on less electricity and/or produce less heat.
The need to come up with creative solutions to manage power is pushing research, development and technology licensing to the competitive forefront. As a result, companies with sophisticated labs and ranks of material scientists with Ph.D.s are going to use those resources to gain market share.
"Because the industry is going through one of these bends in the road, if you don't use (new power management technologies), you will be left behind," Davari said.
In the early 1990s, IBM would often release its advances to the industry somewhat liberally. Now, the company is getting "a lot more rigorous" about how it licenses technological developments and about how they come to market, Davari noted. "Technological leadership is a critical cornerstone of our business."
The competition of ideas is sprouting up all over. At the same conference this week, Intel will be presenting a paper--though no samples--on its "Terahertz" processor, which Intel says will cut power and improve performance in the next decade's chips.
IBM is also competing with Hewlett-Packard over nanotechnology, a proposed method for building chips out of self-aligning strands of carbon molecules. Although IBM asserts that nanotechnology may not hit the market in a significant way for another 20 years, HP researchers believe elements of it will reach commercial production within five to 10 years in hybrid silicon-nano chips, said Stan Williams, an HP fellow.
The Moore the merrier?
The processor space race largely comes as a function of Moore's Law. Under Moore's Law, the number of transistors on a chip doubles roughly every 18 to 24 months through, among other factors, shrinking the transistors. The transistor explosion has allowed computers to experience continual improvements in performance.
But smaller, faster transistors in greater numbers mean that chips need more electricity, which creates a host of problems. Designers have to come up with ways to deliver jolts of energy simultaneously to different parts of the chip.
At the same time, excess energy can lead to signal interference. In addition, more energy means more heat. Without any structural changes, for instance, future power-hungry chips will exude more heat, proportionally speaking, than the sun.
"Physics was once our friend," said Nathan Brookwood, an analyst at Insight 64. "Now it is our enemy."
With Double Gate, IBM is fiddling with the basic structural elements of transistors.
Transistors generally consist of three basic elements: a source, a gate and a drain. When the gate is charged, current passes from the source to the drain, and the completed circuit goes from a "0" state to a "1" state. The gate sits atop and at an equal distance from the source and drain--sort of like the top stone of a ziggurat. The source and drain, meanwhile, sit on top of silicon and--in IBM's case--on top of a layer called Silicon on Insulator (SOI).
In Double Gate transistors, the gate, rather than merely sitting on top of the source and drain, wraps around the source-drain connection like a clamp. The whole structure then lays flat on the SOI layer. By shifting the ziggurat from a standing pose to its side, all three elements touch the SOI layer, further insulating the chip.
SOI is one of the crucial elements of the new design, Davari said. A form of SOI is also critical to Intel's upcoming "Terahertz" transistor, which Davari finds ironic because Intel has criticized it for years.
"They've been bashing it at all the technical conferences," Davari said. IBM has promoted SOI since 1998 and incorporated the technology in several chips. Although Intel executives admit that the company has criticized SOI, researchers there claim that their version of SOI, due out toward 2005, is better.
IBM will use Double Gate transistors in its own chips and license it to its foundry clients, Davari said.