Fab Trends: Are Europe and Asia leading the way?
03/01/2000
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Robert Haavind
Editor in Chief,
[email protected]
Not too long ago, most semiconductor fabricating plants made a family of standard chips or discretes. In a captive fab, these would be used in the company's products, or in merchant fabs, sold directly to a few major OEMs and to smaller customers mainly through distributors. As more and more functionality was put onto each board, the PC board houses installed workstations to check interconnect designs, which were often faulty. Some customers just let their board suppliers work out the PCB wiring for them. The next step for the electronics OEM was to let a contract manufacturer put the components onto the boards. Then it could focus on its real business — trying to keep ahead of a fast-paced electronics marketplace.
There still are fabs making standard DRAMs or microprocessors by the millions. But there is a variety of new types of fabs arising, and they may be more indicative of the future.
Europe has virtually abandoned fabs for standard memory chips or PC processors. Instead, many European fabs combine analog with digital circuitry on the same chip to make semi-custom parts for telecom and embedded system applications. More and more interconnect is being put onto a complex integrated circuit instead of a board, and European fabs are learning how to do this efficiently, along with mixing intellectual property (IP) cores on the same chip. At STMicroelectronics in Crolles, France, for example, chip designers now work at workstations right in the fab (reminiscent of the workstations moving into PC board houses in the past). Right next to the STM facility, Soitec has built a modern wafer fab making silicon-on-insulator (SOI) wafers that offer important advantages for cutting down current leakage in analog/digital chips. Special process steps also may be needed for semi-custom parts, such as wafer-thinning for smart cards.
Asian foundries go even further, with a single fab serving a score or more of customers, making a wide variety of chips. Many of these designs are from fabless firms that must speed chips to fast-changing markets. When the industry goes to 300mm wafers, some orders from fabless shops may be for as few as three wafers a month! Yet these chips may demand top performance. To meet such needs, the foundries are already close to the technology level of the top fabs of integrated device manufacturers (IDMs). A fab capable of dealing flexibly and economically with such orders will be very different from a mass-production factory.
For larger volumes of a semi-custom chip, the Japanese have moved to the mini-fab concept. Sony and Toshiba are making 128-bit microprocessors for the Sony PlayStation2 in a dedicated sector within a bigger fab. They are seeking other embedded applications for this processor, to expand its markets and extend its market life.
Putting more circuitry onto the same chip will make it harder to tailor standard ICs to fill a wide range of needs. Performance is certainly better if a dedicated ASIC is feasible, but the design cost and the time needed for verification of an intricate, multicore chip have dictated against this solution without huge volumes. Few chips can qualify.
If the newer fab models can be combined with faster, more efficient methods for semi-customizing complex ICs, this will bring profound changes. Fabs doing this kind of work will need very close links to customers. Packing more of the system on a chip rather than a board will save space, weight, and assembly costs. Today it is difficult to do this because of limitations in the design/verification process for complex, multi-core chips. Packaging with hundreds of pins is also a problem, and even with test pins it may be a severe challenge to test internal operations adequately.
These problems are being intensively addressed, however, and solutions will emerge. It will lead to a different world, with new economics, new kinds of tools, and new challenges. Prepare for it.