Batallas En El Desierto

Transistors promise more powerful logic, more logical power
Research could affect U.S. manufacturing indirectly, by helping introduce products difficult to build elsewhere, and directly, by reducing production costs.
Larry Hardesty, MIT News Office
As the United States seeks to reinvigorate its job market and move past economic recession, MIT Newsexamines manufacturing’s role in the country’seconomic future through this series on work at the Institute around manufacturing.

Broadly speaking, the two major areas of research at MIT’s Microsystems Technology Laboratory (MTL) are electronics — transistors in particular — and microelectromechanical systems, or MEMS — tiny mechanical devices with moving parts. Both strains of research could have significant implications for manufacturingin the United States, but at least for the moment, the market for transistor innovation is far larger.

MTL’s Judy Hoyt is proof of the influence that academic research can have on that market. In the 1990s, she helped pioneer the use of “strained silicon” — silicon whose atoms have been pried apart slightly more than normal — to improve the performance of microchips. Intel, most of whose chipsare produced in the United States, was the first chipmaker to introduce strained silicon, in 2003. But by now, Hoyt says, the technology has percolated throughout the industry.

Hoyt, a professor of electrical engineering at MIT, argues that U.S. chipmakers have a commercial incentive to keep manufacturing at home. Innovative ideas that afford a competitive advantage often emerge from the veryprocess of building and operating a fabrication facility, Hoyt says. “In the course of doing the manufacturing, additional know-how gets generated,” she says. “If you do design here and do the actual fabrication and manufacturing elsewhere, it’ll work for a while, but in the long run, you can lose early access to the most advanced technologies.” Indeed, Intel — whose domination of themicroprocessor market depends in large part on always being a few steps ahead of its competition technologically — recently began building a massive new production facility in Arizona.

Hoyt continues to research chip technologies that are an even more radical departure from the norm than strained silicon was in the 1990s — and will thus require “additional know-how” to produce, she says. One approach isbuilding transistors from strained nanowires of silicon or germanium. In particular, Hoyt says, her group is investigating techniques for fabricating the nanowires that would make mass production viable. She’s also collaborating with several other MTL researchers on what she describes as “new concepts about how a digital switch might operate” — concepts that, for example, involve quantum tunneling, acounterintuitive physical phenomenon in which a subatomic particle seems to magically pass through a physical barrier.

Compound interest

MTL’s Jesus del Alamo, on the other hand, researches ways to keep the existing transistor design going as long as possible. That design hasn’t changed much in the last 50 years, but chipmakers are finally bumping up against the fundamental physical limitsof silicon. Del Alamo studies compound semiconductors — so called because they combine multiple elements, such as gallium, indium and arsenic — whose electrical properties offer advantages over silicon. If chipmakers can successfully introduce these exotic materials into their fabrication processes, they might be able to continue to improve chip performance without abandoning existing chipdesigns.

That’s a big “if,” however, as the chemicals and conditions required to create compound-semiconductor circuitry are incompatible with the processes currently used to produce silicon chips. The first chipmaker to reconcile the two could enjoy a pronounced competitive advantage.

“It was really Intel’s leadership about six, seven years ago that focused attention on the difficulties of...