The phrase "on a wing and a prayer" got a more literal meaning recently among researchers at Tufts University who discovered that the structure of butterfly wings may show a better way to control temperature during the microprocessor-fabrication process.
The Tufts team, headed by assistant research professor of mechanical engineering Peter Wong and funded by the National Science Foundation, is currently studying how iridescent butterflies control heat with the millions of microscopic scales - called thin-film structures - clinging to their wings.
Insects like butterflies are cold-blooded and so must constantly regulate their body temperatures. By understanding how the biological thin-film structures work in butterflies, the researchers hope to apply a similar thin-film pattern to thermal processing of silicon manufacturing.
"As our team sat down and had lunch one day, we thought about the nice ways in which nature controls heat. We sent students to various departments and one found an interesting example in butterflies," explains Wong.
The cellular microstructures in iridescent butterflies are well known to biologists. Wong's team discovered, however, that little is understood about how butterflies reflect and absorb radiation - a phenomena that also happens to be key to thermoregulation in silicon manufacturing. So Wong and his team of engineers have undertaken the unusual task of studying an insect in the hopes of developing a technique for building similar thermoregulating structures in silicon.
"They're not perfectly analogous, but we're trying to study similarities in the optical phenomenon. It's interesting because we're progressing in two different ways, one biologically, and the other is in manufacturing," says Wong.
Controlling heat - inside computers, and in the production of chips - has become an increasingly important challenge for the semiconductor industry.
"I wouldn't say the problem is intractable, but it's getting more and more attention," says Linley Gwennap, a vice president at MicroDesign Resources, a publishing and consulting firm in Sebastopol, California. Gwennap points out a steady progression in the amount of heat generated by microprocessors: "Back in the 486 days, the processor dissipated maybe 5 watts, when you got into Pentium, you were talking about 10 or 15 watts, now with Pentium II you can get as much as 40 watts. So you can see from generation to generation the general increase in the amount of power and the amount of cooling required. I think there will probably be more increases and new technologies will be needed to address it."
The Tufts team hopes to see their research result in improved heat transfer techniques on the factory floor within the next chip-manufacturing cycle. "This will probably become useful for companies like Intel and Motorola in about two years," says Wong. For now, Wong is working with the R&D group at Digital Equipment Corp.
