IBM finds gold in copper

IBM is making a good living from copper, and expanding its horizons.

Two years ago, IBM invested in performance-improving copper interconnect technology, and Thursday said it had shipped its one-millionth copper chip. The chips use copper instead of aluminium to bridge the gaps, or interconnects, between their transistors. An IBM spokesman said the company expects to ship another million copper chips by the end of this year.

The high volumes come even though the only major PC maker using processors based on the technology is Apple Computer. With just one big customer, it raises the question, what's so great about copper?

For one thing, it's faster. Because copper is a more efficient conductor than aluminium, electrons traveling down a copper wire move faster than they would if they were moving down an aluminium wire of similar length. That translates into increased performance inside a chip. Speeds can increase by ten percent. That doesn't sound like much, but it translates into a bump in clock speeds. It's like going from 450MHz to 500MHz, according to Nathan Brockwood, principal analyst at Insight 64.

IBM took advantage of that improvement in its new PowerPC 440 core, a processor core based on copper technology. The core, which will run at speeds of up to 550MHz, will be used mostly in communications applications. IBM does offer other PowerPC chips, notably the PowerPC 750, with copper.

It also can mean lower power consumption, useful for notebook computers and other portable devices. "If it is more efficient at carrying voltage... you can drive performance up or you could also drop down power," said Bill O'Leary, director of communications at IBM's Microelectronics Division.

But even with IBM's latest copper chip, and Apple Computer's use of the IBM PowerPC 750 and Motorola's G4 processor in its latest Macintosh desktops, "People are still questioning copper," O'Leary said. "A lot of people still pooh pooh it. But that's because they don't have it."

That's true. Sort of, said Brockwood. "Motorola is now shipping the G4 product, but not in any significant volume, much to Apple's dismay," he said. Apple fingered Motorola and a shortage of G4 chips in its earnings shortfall, announced earlier this week.

Intel and Advanced Micro Devices (AMD) also plan to adopt copper technology, eventually. AMD recently announced that it had produced prototype K6 processors with copper interconnects in its Dresden, Germany, fabrication plant. Brockwood said AMD claims it will ship an Athlon chip with copper before the middle of next year.

Intel will be last to the party, with copper being used in its 860 process technology, due in mid-2001, Brockwood said. Intel's 860 process will utilise copper with .13 micron interconnects. The interconnect is the width of the wire between transistors inside a chip.

Intel has said that it can achieve good performance with its current aluminium technology and therefore, could not justify moving to copper. That is evidenced by Intel's forthcoming introduction of Pentium IIIs that use its Coppermine technology (despite the Coppermine code name, the chip uses aluminium interconnects). Chips based on the technology will run at speeds in excess of 700MHz.

Meanwhile, IBM intends is looking ahead to new technologies. It plans to bring its silicon germanium manufacturing technology to the PowerPC chip later this year. The process allows transistors to be placed directly on to the silicon surface of the chip, using a layer of insulation. The technology should make for a more efficient chip, which can again result either in higher performance or lower power.

IBM will aim for low power at first, likely using the chips in portable applications, such as cellular phones.