Copper supercharges supercomputers

Deep Blue? Meet Deep Copper. IBM will unveil a new generation of supercomputers it says offers a major performance increase by using IBM Power3 processors with copper interconnect technology.

Called RS/6000 SP, the new supercomputer will offer up to 20 percent greater performance than its predecessor, according to IBM. IBM's supercomputers, which are generally very large and very expensive, tackle computing tasks that require enormous amounts of data by breaking up the data into smaller pieces and processing it in parallel on a number of nodes. The new RS/6000 SP will have up to 144 nodes and 1,152 375MHz Power3-II chips. Each node will cost about $46,000 (£28,000).

While consumers won't purchase the new supercomputers, which will be used by researchers in health care or by scientists working to predict weather patterns, they may benefit from them indirectly.

Homer Walker, a professor and head of Worcester Polytechnic Institute's Mathematical Sciences department, says the college is going to use an RS/6000 SP to study topics as diverse as highway safety, arterial blood flow in humans and combustion.

Walker, as part of a joint project between WPI, the University of Utah and the Centre for Simulation of Accidental Fires and Explosions, a US Department of Energy-funded organisation, will use the machine to model combustion. The RS/6000 SP will be used to look at "how (fires) proceed and how they may go to catastrophic stages," he said.

Not only will the copper technology used in the RS/6000 SP supercomputer benefit researchers, it's working its way into mainstream products that are available to consumers.

"The fundamental thing copper does ... is allow the (processor) to run at a much higher clock frequency," said Dean McCarron, principal analyst at Mercury Research. "Copper is no longer as exotic as it was, but it is still cutting-edge."

Copper-based PowerPC processors manufactured by IBM are used, for example, in Apple Computer's Macintosh computers and iBook portable. IBM officials said a copper-based PowerPC chip will also power a forthcoming game console from Nintendo.

Put simply, copper is a more efficient conductor than aluminum, making it useful in processors because it allows for smaller, thinner interconnects. Interconnects are tiny pieces of wire that connect transistors inside a processor. Smaller interconnects make for smaller, higher-performance chips because chip makers can pack more transistors into a smaller space. Copper's properties also make it more power-efficient than aluminum.

The metal, however, is difficult to use in the manufacturing of processors. It has a habit of contaminating the silicon of a chip. IBM developed a workaround for this.

Taking a page from a jeweller's handbook, IBM developed a manufacturing process for copper chips that it says is less expensive than the process used to create aluminium ones.

A jeweller, using a process called the Damascene Process, carves a design in a certain kind of metal, such as silver, and pounds in another kind of metal, such as gold. The gold is then polished off, revealing a silver and gold pattern. IBM uses this same process to create the copper interconnects on its chips.

Chips are manufactured in layers. IBM's manufacturing process digs tiny trenches into each oxide layer of the chip (an oxide is used as an insulator between layers of a chip) in the pattern in which interconnects are needed and then deposits a layer of copper. With the trenches filled, creating the interconnects, the rest of the copper is polished off and the process is repeated between three and seven times, depending on the kind of chip.

When aluminum chips are manufactured, a layer of oxide is put down, followed by a layer of aluminium, which is then etched to create interconnects.

For IBM, which has been working on copper technology since the mid-1980s, greater performance is the reward, along with lower power consumption, said Russell Lange, an IBM fellow and chief technologist of the company's Microelectronics Division, in East Fishkill, New York.

"The delay for sending signals across the chip was limited more by the metallurgy (aluminium interconnects) than by the (transistor) devices," he said. "That's like hooking a race car up to a very heavy trailer."

Consumers, in the end, need not worry whether there is copper inside the chip powering their game consoles as much as they should ask, "Is it faster and does it have more cool graphics?" McCarron said. However, "there is a market where that extra 10 percent of performance is worth the cost."

When it comes to designing faster processors, Advanced Micro Devices and Intel both have copper in their road maps. AMD, in fact, will move to copper shortly for its Athlon processor. The company demonstrated Tuesday a copper-based Athlon running at 1.1GHz.

Intel will move to copper in 2001, company officials have said. The company, in the meantime, will implement design optimisations in its Pentium III processor aimed at taking it up to 1GHz.

Transmeta's Crusoe chip, manufactured by IBM's Microelectronics Division in Burlington, Vermont, is also a copper chip, sources said.

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