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Absolutely Fab-ulous: Changes in CPU Manufacturing November 13, 2002 Bigger Wafers, Smaller Dies, New Technologies Some PC users view a desktop or notebook as a mysterious black box. Some know a good deal about the processor inside, or even picked out a particular brand and model of CPU before buying or building the rest of the PC. But not many pay attention to how the CPU itself was built -- they may vaguely remember the old Intel commercials portraying dancing lab workers in clean-room "bunny suits," but tune out when techies talk about chipmakers' moving to 300mm wafers or SOI (silicon-on-insulator) technology. That's a shame -- not because PC shoppers need to know every detail of silicon engineering, but because they like to get faster, more affordable CPUs. And better performance and lower costs are the twin engines behind today's and tomorrow's changes in semiconductor manufacturing. Let's take a quick look at a few major trends. From Bigger Circles ... Perhaps the most fundamental transition facing chipmakers is the move from carving chips out of 200mm silicon wafers (about 8 inches in diameter) to using 300mm wafers (about 12 inches in diameter, yielding 2.25 times as much surface area per wafer). The logic behind this move is simple: The bigger the wafer, the more chips that can be made from it, and the lower the cost of producing a single chip -- roughly 30 percent lower, according to Intel. So if 300mm wafers are such a good idea, why is the CPU industry just now getting around to using them? Intel opened a development facility in Oregon in 2001 and plans to have three high-volume 300mm "fabs" -- fabrication plants or chip factories -- by 2004, while AMD has partnered with United Microelectronics Corp. (UMC) to build a Singapore fab scheduled to open in 2005. The answer is that, apart from technological barriers, there's a huge economic one: According to Dick Deininger, director of manufacturing technology at AMD in Austin, Tex., a 300mm-wafer fab costs $2.5 billion to $3.5 billion to build, compared to $1.5 billion for a 200mm plant. If you're going to invest that much to produce twice as many chips from a wafer, you'd better be sure there's a market out there for them -- the reason Intel began building a 300mm fab in Ireland in June 2000, halted construction when the economy slumped, and restarted in April 2002. "People have been waiting for enough volume to support the very large investment in building, from the ground up, one of these large fabs," explains AMD vice president for process technology Craig Sander. "Economics is what has delayed 300mm more than anything else." These new facilities offer advantages beyond just making whopper wafers. They are likely to have lower "defect densities," meaning the number of imperfections per square inch of wafer, adds Peter Glaskowsky, editor in chief of the Microprocessor Report newsletter published by In-Stat/MDR in Scottsdale, Ariz. While 300mm wafers are the wave of the future, their benefits are eluding consumers today because there aren't enough 300mm fabs producing enough chips to have a serious impact on the market. It will take "a few years" before that will occur, Glaskowsky says. Nevertheless, the move to 300mm manufacturing is a very big deal. While Moore's Law rules that processing power doubles roughly every 18 months, incremental changes in wafer size can take as long as a decade. ...Come Smaller Squares You can think of the shift to 300mm wafers as analogous to feeding more people at a pizza party by making a bigger pizza (using a larger pan). Another way to feed more partygoers is to serve smaller slices. And within the past year, both AMD and Intel have done so by moving their respective Athlon XP and Pentium 4 CPUs from 0.18- to 0.13-micron process manufacturing -- referring to the average size of the circuits or elements etched onto chips. Besides letting manufacturers make more CPUs from each wafer, denser process manufacturing makes the CPUs themselves more efficient. The chip's transistors can switch faster; they require less energy; the chip runs cooler; and designers can pack more transistors onto the same size die. All these things boost performance. In the second half of 2003, Intel's "Prescott" Pentium 4 redesign will take the next step -- from 0.13-micron to 0.09-micron process technology, although it's not called that. Below a tenth of a micron (the size, Intel points out, of a typical virus), it's fair to say you've entered the realm of nanotechnology. So while technicians acquired the habit of saying "0.13-micron" instead of "130-nanometer," the next process plateau is referred to as 90-nanometer technology. After Prescott breaks the ice, AMD says 90-nanometer versions of its Opteron server/workstation and Athlon ClawHammer desktop/notebook CPUs will ship in the first half of 2004. Ultimately, the new technology promises chips that will run twice as fast and be half the size of their 0.13-micron predecessors.