As consumers come to expect that everything from cell phones to stuffed animals will pack significant computing power, manufacturers are under pressure to churn out ever faster and cheaper microchips. But making computer chips using photolithography-the standard manufacturing technique-is wildly expensive. A significant part of that cost is the stencil-like "masks" that filter the light beam used to pattern millions of transistors onto a chip. Indeed, making a single silicon chip can require as many as 30 masks costing more than a million dollars-and as the transistors on a chip continue to shrink, the cost of the masks only grows.

No wonder, then, researchers are racing to develop ways to do away with masks entirely. One of the most promising efforts, led by Henry Smith, director of MIT's NanoStructures Laboratory, uses an array of tiny mirrors, each just 16 micrometers across, to direct light through microscopic lenses; each lens focuses a beam of light to a spot on the silicon wafer, and the more powerful the lens, the smaller the spot. By tilting individual mirrors back and forth, a computer can turn individual beams on and off as the whole setup scans across the wafer. With as many as a million mirrors, the system could create the same complex pattern on the silicon chip that would normally require a series of masks.

So far, Smith's group has used the system to pattern chip features 350 nanometers wide-40 percent wider than those on today's best chips. But computer simulations predict the MIT technology can generate features as small or even smaller than those derived using conventional lithography by switching to shorter wavelengths of light.

At the University of California, Berkeley, a group led by electrical engineer William Oldham is taking a similar approach; but where the MIT group has focused on increasing the power of the lenses to make smaller features, the Berkeley researchers are reducing the size of the mirrors. Without increasing the power of the lenses, "to get smaller patterns you need smaller mirrors," says Yashesh Shroff, a graduate student in Oldham's lab.