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Rad-Hard To Volume MPU Ready IBM moves SOI from military to mainstream devices East Fishkill, N.Y. -- IBM continues to be full of surprises. Last year, Big Blue made national headlines with the revelation that the computer giant was close to producing copper-based chips in volume production (EN, Sept. 29, 1997). On Monday, August 3, IBM dropped another bomb when the company confirmed speculation that it would soon roll out chips using silicon-on-insulator (SOI) technology (EN, March 23). What took many by surprise, even within the SOI research community, was just how widespread IBM's use of SOI would be. Long relegated to radiation-hardened circuits for military and space environments -- a small niche market, SOI's role in IBM chipmaking plans are pervasive. The company will incorporate SOI technology into its merchant market custom chip (systems-on-a-chip) products, standard products like the PowerPC microprocessor and in chips used in its S/390, AS/400 and RS/6000 line of servers. IBM, which already was producing SOI-based chips in its East Fishkill, N.Y., pilot production line, will introduce the technology on its high-volume Burlington, Vt., manufacturing lines in the first half of 1999. Some handwriting was on the wall as early as February. In an investment analysts' briefing on Feb. 24, IBM outlined its roadmap to bring gigahertz-level microprocessors to market. The company ticked off three key technologies under development that it felt were critical to the GHz MPUs. IBM said copper offered 40 percent better conductivity than aluminum. Second, IBM forecast SOI would offer a 20 percent performance improvement due to reduced capacitance, a by-product of having a thin oxide layer under the transistors. Third, the company mentioned advanced lithography. SOI may have proved far more valuable to IBM's chipmaking plans than it indicated in February. "We believe SOI, with its high-performance and low-power characteristics, is a significant breakthrough in chip technology," said Mike Attardo, GM, IBM Microelectronics division in a statement. On Monday, the company disclosed that IBM engineers have manufactured SOI chips that improve performance by up to 35 percent. Big Blue used the example of a microprocessor designed to operate at 400MHz to demonstrate what the company believes will be the technology's impact. IBM said the same 400MHz-designed microprocessor could instead be built using SOI and achieve speeds in excess of 500MHz. "At the same time, if performance levels are held constant, SOI chips can require as little as one-third the power of today's microchips," the computer giant said. IBM believes the low-power aspects of SOI technology will be key to the creation of multifunction, handheld "information appliances" of the future. The technology behind SOI has been explored for some time, yet technical hurdles made it difficult and expensive to apply in high-volume, mainstream chip making. IBM claims its approach allows SOI to be used in mainstream semiconductor manufacturing with few changes or additions to existing fabrication lines and at little additional cost. The new process represents the culmination of more than 15 years of collaboration between IBM Research and the company's manufacturing and development teams. IBM made two major changes to bring about this development, according to Bijan Davari, IBM fellow and director of advanced logic technology development for IBM Microelectronics. On the substrate itself, IBM optimized the implant and anneal steps to get the lowest defect per density. Then, on the devices, Big Blue optimized the device design and the process in order to fabricate "partially depleted" SOI devices, "where the undesirable effects such as the floating body affect can be dealt with," says Mr. Davari. He feels IBM is a year or two ahead of its competitors in this space. However, IBM is not alone in development work on SOI for semiconductor applications. Several companies including Honeywell, Mitsubishi Electric and Peregrine Semiconductor, among others, have been making devices using SOI. None have targeted mainstream product applications and widespread use prior to IBM's entry. In terms of development work, Motorola is said to be using the material at some level for wireless communication chips in pilot scale operations, sources said. The company is already home to at least one Ibis implanter. They could be moving SOI into production sometime in the near future. In addition, South Korean juggernaut Hyundai and Europe's Philips have been investigating SOI for device applications. In Japan, Mitsubishi, which has a close relationship with Ibis, and Sharp are said to be doing SOI research work, according to industry sources. Both Boeing and Lucent are working with Sematech in a program at The Massachusetts Institute of Technology's Lincoln Labs. DEC may be a wildcard as well. The company had "quite an active program," one source said, before the settlement with Intel. |