September 2003

Reinventing the Transistor

Hewlett-Packard is betting that it can build computers whose functionality rests on the workings of individual molecules. It's blue-sky research, but if it works, it will push computing far beyond the limits of silicon.

By Claire Tristram

Every Friday afternoon at Hewlett-Packard Labs in Palo Alto, CA, R. Stanley Williams, one of the most respected thinkers in the field of molecular electronics, gets his group of 25 research scientists together to talk shop. One by one, they make their way to the conference room. Williams walks in exactly on time, sits down in front, and leans back, frowning, his hands steepled. He was hired by HP in 1995 to rethink the basics of computing and has handpicked the team inside this room to do just that. Williams likes to wear jeans, and his hair reaches halfway down his back, so he gives a first, fleeting impression of quietude and informality. But he apparently never smiles, and his people work 19-hour days to meet his deadlines. Williams waits a few minutes for the habitual latecomers, then stands up. He speaks in an efficient monotone.

"We're going to hear first from Gun-Young today," he says. "What he has accomplished is magnificent. Everyone here owes him a lunch because his hard work has paid for our salaries for the last several months."

Gun-Young Jung, a recent postdoc from South Korea, stands up and quietly describes his work on nano imprint lithography, a process that uses a physical mold to create features as small as six nanometers across on silicon wafers. That's more than an order of magnitude smaller than the finest features achievable using today's advanced photo-lithographic processes. Sometimes things stick to the mold, though. It's like cake batter sticking to a pan, he says. His presentation lasts about ten minutes and is followed by two others.

Listening to these speakers, one after another, gradually conveys a sense of the group's style. They enjoy self-deprecating humor and inject frequent expressions of bewilderment into their scientific explanations, like "I don't know" and "it's still a mystery" and "I still need to investigate," and even "I am still quite a novice." And despite their obvious expertise, this isn't false modesty.

Williams's group faces a monumental task: trying to make computers whose functionality rests on the workings of molecules. To do so will mean reinventing the transistor. While silicon and other inorganic semiconductors have always been the basic building blocks of microchips, it turns out that organic molecules can also have some potentially useful electrical properties. Indeed, over the last few years, researchers have learned to synthesize molecules that can function as electronic switches, holding binary 1s or 0s in memory or taking part in logical operations. And molecules have one significant advantage: they are really small.

Such work is critical to the future of computing, because conventional chip fabrication technology is on a collision course with economics. Today's best computer chips have silicon features as small as 90 nanometers. But the smaller the features, the more expensive the optical equipment needed to manufacture them. A state-of-the-art fabrication plant for silicon microchips now costs some $3 billion to build. A chip in which silicon transistors are replaced with molecular devices, on the other hand, could in principle be fabricated through a simple chemical process as inexpensive as making photographic film. A circuit with 10 billion switches could eventually fit on a grain of salt; that's a thousand times the density of the transistors in today's best computers. A computer built from such circuits could search billions of documents or thousands of hours of video in seconds, conduct highly accurate simulations and predictions of weather and other physical phenomena, and do a much better job of imitating human intelligence, perhaps even communicating with us through natural conversation.

But no matter how tempting in theory, it's speculative, blue-sky research, and investing in molecular electronics is a gamble few companies have been willing to make. HP's confidence in Williams is a big reason it's one of the exceptions, says Shane Robison, the company's executive vice president and chief strategy and technology officer. "In addition to his ability to put together a first-class team of cross-disciplinary experts and an emphasis on how to turn science and technology into real products, Stan's best quality is probably his eternal optimism," says Robison. Of course, there's also the lure of immense profits, should Williams's technology ever displace conventional silicon chips. "Projects this ambitious are always a long shot, but we wouldn't be doing it if we didn't think there was a good chance of succeeding," Robison says.