IBM touts chipmaking technology

The IBM chipmaking division is working to popularize its relatively new silicon-on-insulator (SOI) chipmaking technology, both through licensing and manufacturing agreements as well as by using it in its own chips.

Wide adoption of SOI technology, used to increase performance or lower the power consumption of a processor, would be a point of pride for IBM as it would prove detractors of the technology wrong. At the same time, licensing fees and contract manufacturing would help boost IBM Microeleclronics' bottom line.

To date, IBM Microelectronics has only one public SOI licensee, a joint venture between IBM, Sony and Toshiba, that will create Cell, a new Internet access chip. But executives say the company has others waiting in the wings.

One SOI adopter could be Advanced Micro Devices. An AMD spokesman confirmed that IBM and AMD entered into an agreement for IBM to provide design assistance with forthcoming AMD chips that will use SOI.

IBM has also been hired to manufacture Alpha processors for Compaq Computer and PA RISC chips for Hewlett-Packard, both using its SOI technology.

The company has already shipped high-end p680 Unix servers containing PowerPC chips using SOI. A company spokesman said IBM will begin releasing SOI over its remaining PowerPC, SRAM and custom ASIC product lines, starting in the third quarter of this year.

The SOI chipmaking method places an insulator between the transistor and the bed of silicon upon which it rests. The insulator helps reduce the amount of electrical energy absorbed from the transistor, making for a stronger signal between transistors.

When compared to a similar chip at the same clock speed, an SOI equipped chip can offer either increased performance or reduced power consumption. IBM says the method can boost performance by up to 30 percent or cut power consumption by more than half.

Because of its properties, IBM sees SOI as having particular benefits for chips used in servers and low-power handheld computers.

"We're getting a lot of demands from a lot of sides, including dense server configurations," said Bijan Davari, vice president of technology and emerging products for IBM Microelectronics. "Anywhere you have significant power constraints or the need for performance and battery life, SOI is becoming very attractive."

Low-power chipmaker Transmeta would be another obvious target for SOI.

"Transmeta, we have talked to them...and there are other server companies that are using our SOI for high performance applications," Davari said, declining to offer further details.

If there's a downside to SOI, it's the costs of the process. IBM says its method, which uses a layer of oxide between the transistor and silicon substrate, adds only about 10 percent to the cost of a finished wafer, before it is divided into individual chips.

"If you consider the cost of cooling technology, then SOI more than compensates," Davari said.

But for chipmakers dealing with already thin profit margins, even a modest increase in cost may be prohibitive against using SOI in high-volume chip manufacturing, such as mainstream desktop PC processors, analysts say.

"No doubt about it, take any bulk silicon-based circuit and convert it to SOI and there will be a performance gain," wrote Dan Hutcheson, president of LSI research, in a series of reports on SOI technology. "The real issues lie in whether the performance benefits are enough to outweigh the design hassles and the additional cost. This question can only be answered by first looking at the manufacturing prowess of the companies involved as well as the markets they engage in."

Intel says SOI is still too expensive. A spokesman argued that even a small amount of extra cost, multiplied by the 100 million or so chips Intel produces per year, makes SOI's cost prohibitive.

Intel has conducted research into SOI, and "what we came up with is that there is some performance increase," spokesman Manny Vara said. "The issue we have is that it adds complexity and cost. Therefore, for us, it makes no sense...because any performance increases would be negated by the added cost and complexity."

Analysts say it's unlikely SOI will show up in mainstream processors any time soon.

Hutcheson noted that IBM focuses on low-volume, high-performance custom chips, while Intel pumps out mainstream microprocessors by the bucket. "Thus, SOI makes much more sense for IBM than it does for Intel today," Hutcheson said in his SOI report.

"This is why (Intel) never implements a technology until it is ready for prime time," he wrote. "If and when SOI makes sense in volume manufacturing, you can bet Intel will be there.

"The key company to watch for in this transition is AMD," he continued. "They are also a high-volume manufacturer; they don't have to implement across multiple (factories) and they are particularly good at wringing the most out of new technologies."

AMD has announced that SOI will be incorporated in its Hammer family of processors, starting with the desktop-oriented ClawHammer, which will replace the current Athlon. AMD plans to provide ClawHammer samples to PC makers late this year. The company plans to ship it in volume in the first quarter of 2002.

Motorola is also targeting SOI for its next-generation G4 chip, code-named Apollo.