SAN MATEO, Calif. — The technology has been used for more than a decade in military applications. In recent years, it's been applied to high-speed commercial microprocessors. Now, silicon-on-insulator (SOI) is about to take a big leap into more mainstream applications as chip companies seek ways to bring it into their fabs for their own products or for companies willing to pay a premium.
Last week, Cypress Semiconductor Corp. (San Jose, Calif.) and startup American Semiconductor Inc. (Boise, Idaho) were the latest companies to disclose plans to manufacture semiconductors using SOI, which adds a thin sheath of glasslike insulating material just beneath a chip's transistors as a way to reduce capacitance and boost transistor speed. The two decisions could pave the way for more off-the-shelf chips that are beyond the realm of conventional CMOS, such as high-density memory devices or ultralow-power wireless ICs.
"You can get up to 80 percent savings on active power, so you get a choice of using it for more performance or spending it all on power savings," said Chris Seams, executive vice president of technology and manufacturing at Cypress.
Both Cypress and American Semiconductor have a strong link to military electronics, which for years have taken advantage of SOI to protect gear against radiation. Cypress tapped Honeywell Inc. for its SOI expertise, honed for more than 10 years. Honeywell, in turn, will be able to build SOI-based devices at Cypress' SOI-enabled fabrication facility under a foundry arrangement.
"We exploit the commercial market and they exploit the military market," said Cypress president and chief executive officer T.J. Rodgers at a Lehman Brothers investment conference in San Francisco, where he disclosed the deal.
The two companies described their partnership deal, which was a year in the making, as a technology exchange. Honeywell, which has been making SOI-based chips for military electronics for more than a decade, needed access to a process technology finer than 0.25 micron, Seams said.
At the same time, Cypress wanted to keep pace with other IC makers that have adopted SOI, including Advanced Micro Devices, IBM and Intel. But it did not want to spend $40 million to develop the transistor technology internally, Rodgers said.
Under a five-year agreement, the two companies are co-developing a 0.13-micron process technology based on SOI. The companies are developing circuit libraries for the SOI process and expect to produce their first test chip next month. The process should be ready for volume production at Cypress' fabrication facility in Bloomington, Minn., by the second half of 2003, said Seams.
American Semiconductor, meanwhile, said it obtained funding for its proprietary, low-power SOI process from the Department of Defense. Under the plan, the Missile Defense Agency has awarded the IC company a contract under which it will show the feasibility of its SOI process, dubbed FlexFET SOI. The contracts calls for the chip maker to process low-power, rad-hard devices based on the SOI process.
Startup outlines plans
Yet American Semiconductor's ambitions go beyond the military market. "We plan to take the [SOI] technology beyond defense," said Douglas Hackler, president and chief executive officer of the year-old startup.
Established by former managers of M/A-Com Inc., Micron Technology Inc., Zilog Inc. and other chip makers, American Semiconductor calls itself a foundry. The company does not have its own fab facility, but rather outsources its wafer production to Zilog's 5-inch wafer plant in Boise.
Long term, American Semiconductor plans to build its own fab, said Hackler, who was previously director of manufacturing for M/A-Com, a gallium-arsenide device specialist. The company counts Honeywell and X-Fab Semiconductor Foundries AG among its chief competitors.
Possible applications
Cypress said it has several products that would be a good fit for SOI technology. In data communications, the company is considering applying SOI to its quad-port digital switching devices. SOI could also be used to make capacitorless DRAMs with exceptionally high bit densities, Seams said.
Other candidates include Bluetooth and wireless universal serial bus (USB) devices, which would benefit from the low-power consumption and low-noise characteristics conferred by SOI. Rodgers noted in his presentation that the lowest-power Bluetooth radio ever reported, from startup Silicon Wave Inc., uses SOI technology.
While more chip companies are adopting SOI, it still has a long way to go before it is considered mainstream technology. Seams said producing SOI-based devices will cost 30 percent to 35 percent more than standard CMOS, which means SOI's appeal will be limited in the short term. "Eventually, over a 10-year horizon, everything will be on some form of SOI," he said.
Cypress' decision to bring SOI technology in-house is consistent with its desire to manufacture most of its chips internally. Unlike many chip companies that own fabs, Cypress has resisted farming out large portions of its chip manufacturing to external foundries. The company produces 85 percent to 90 percent of its chips in-house, and Seams said the company can still make a "plain-vanilla" CMOS at a lower cost than foundries.
Indeed, Rodgers said, the gross margins on Cypress' USB devices have suffered because many of them were made by foundries. "Wafers from foundries cost twice as much as those made internally by Cypress," he said.
"Until we get those things inside . . . we're going to have low gross margins in the personal communications group," Rodgers said.
