Making the most of chip fabrication

For more than 40 years, the microelectronics industry has made ever-smaller, usually-cheaper, and more-powerful circuits using one set of basic manufacturing methods. Scientists now report that tweaks to a key optical process improve those methods. The advances may be enough to permit conventional manufacturing practices to meet the demand for the smaller-than-ever circuits for a decade or so.

In one step in the fabricating of chips’ transistors and other components, manufacturers project patterns of light onto silicon wafers. Defining the smallest components requires short-wavelength light. Currently, the industry uses 193-nanometer-wavelength laser radiation to make wires and other circuit parts as thin as 90 nm.

Shorter-wavelength radiations pose major challenges, so chip makers began exploiting a microscopy trick—putting a layer of water between a lens and the wafer. The water slows the 193-nm light and thereby shrinks its wavelength. However, this technique is only enough to meet demands for the next 7 years, industry forecasts indicate. By then, wire widths will have shrunk to 32 nm.

On Feb. 20, scientists from IBM Almaden Research Center in San Jose, Calif., and JSR Micro of Sunnyvale, Calif., presented an experimental pattern-making system that uses an unidentified light-slowing liquid instead of water. The system yielded wires an average of only 29.9 nm thick. Unveiled at a chip-technology conference, the findings suggest that even skinnier components lie ahead, the scientists say.

The liquid, developed by JSR Micro, slows light about 12 percent more than water does. A quartz prism—instead of a typical glass lens—also beefed up the pattern-making system, says IBM physicist Donald S. Bethune, who codeveloped the system.

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