IBM adds zip to PowerPC chips

IBM is ready to enter production with a new performance-enhancing microprocessor technology, called "silicon-on-insulator," the company announced Monday.

IBM claims the addition of silicon-on-insulator, or SOI, can increase a processor's performance by between 20 and 30 percent.

For the past five years IBM has been developing SOI technology, which adds a layer of insulation underneath a transistor inside of the processor. The resulting manufacturing technique embeds an insulating layer of oxide between the transistor and the silicon bed on which it rests.

This insulator "reduces the drag of the substrate on transistor performance" said IBM Fellow Russ Lange, chief technologist of IBM's Microelectronics Division.

By reducing this drag -- known to chip designers as parasitic capacitance -- SOI also increases transistor performance. It does this by limiting the amount of electrical current absorbed by the silicon substrate as the current passes from one transistor to another inside the chip. Thus the chip pushes greater amounts of current, an important improvement because, Lange said, "The more current you put into the next stage of a computation, the faster it will move."

The first product to utilise SOI will be IBM's AS400 processor, a server chip based on its PowerPC design. IBM's first production SOI chips will ship in the new AS/400e server, announced on Monday, and slated to ship in August. IBM will also ship SOI chips in its RS/6000 servers later in the year.

SOI technology holds significant promise for consumers. IBM plans to use the technology in PowerPC chips embedded in consumer devices. IBM, for example, plans to incorporate the technology into desktop PowerPC processors, like those used by Apple. IBM will also use SOI in new low-power processors for personal devices, such as mobile phones, and is also looking to apply SOI to its network processors for use in network infrastructure equipment.

SOI can be used in one of two ways. It can be used to create low-power chips. In this case, by keeping clock speed the same, SOI would reduce the power consumption of a chip by two to three times. And SOI can also work to increase clock speed frequency while maintaining the same level of power consumption, Lange said.

"We're first taking it to severs," Lange said, "because that allows us to introduce it where it's most valuable."

Server customers are also willing to bear the brunt of cost premiums, IBM argues. Although IBM has not disclosed pricing for the chips, processors using SOI will be priced higher than those not using the technology. IBM officials said they believe that its copper interconnect technology, combined with SOI, give it a two-year lead over competitors, such as Intel. This is because SOI chips, in the past, in the have been notoriously difficult to manufacturer in a cost-effective way.

"I think we're two years ahead of anybody that wants to put together this combination," Lange said.

IBM will also utilise SOI in its forthcoming Power4 processor. The company will manufacture SOI chips at its Burlington, Vermont, fabrication plant.

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