Paul, this article talks about Intel migrating to copper in the not to distant future. I've been having one of my dangerous futuristic visions lately. What do you think of the possibility of Intel creating fiberoptic chips? Have you seen any work done in this area? And do you believe it's technologically feasible?
Thanks, Michael
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May 17, 1999
Computer Shopper : Although most chips today are made of aluminum, silicon manufacturers are increasingly drawn to copper-process CPUs. Copper conducts electricity up to 50 percent better than aluminum, and this characteristic enables the development of faster, smaller chips. While every chip manufacturer will presumably migrate to copper, some are doing so sooner than others.
Here's why. CPUs are comprised of a layer of transistors and several layers of interconnects. These interconnect layers essentially provide the wiring that connects the transistors. In the past, aluminum worked well as the interconnect metal, and using copper posed a serious problem: It tends to diffuse into the materials around it, which would cause shorts in a semiconductor device. But chip manufacturers have now found workable ways to contain the copper interconnects, so the threat of diffusion is no longer an issue.
Furthermore, as transistors shrink ever smaller and CPU speeds grow ever faster, the resistance of aluminum is rapidly becoming a limiting factor, in part because the smaller the cross-sectional area of a conductor, the greater the resistance. Thus, manufacturers are increasingly turning to copper.
In fact, the first copper CPU for a mass-market personal computer is IBM's 400MHz PowerPC 750, which can be found in the Apple Power Macintosh G3. Motorola will reportedly begin shipping a G4-class PowerPC this summer, and AMD is expected to ship the first x86 copper processor early next year--a 700MHz, 0.18-micron version of its K7 (following the scheduled release of a 0.18-micron version before the end of this year using aluminum interconnects).
At press time, Intel reported that it will move to copper when it migrates to a 0.13-micron process, but it declined to give a firm date. Sources say it could happen as early as the end of 2001 or as late as the beginning of 2003. In the meantime, Intel's forthcoming Coppermine version of the Pentium III will debut its 0.18-micron process with aluminum interconnects. Intel plans to continue ramping up the speed of its CPUs aggressively until it switches conductors. Copper or not, its CPUs are slated to reach speeds of 1GHz by late 2000
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