MIT's Nanoruler Could Impact Space Physics

By Roland Piquepaille

Researchers from the Massachusetts Institute of Technology (MIT) have devised the world's most precise ruler, able to draw parallel lines separated by only a few hundred nanometers with a precision of under a nanometer. This has the potential to have a great influence on fields such as computer chips manufacturing as well as space physics. And, as says the MIT, this is a promising line of work.

The Nanoruler is 10 to 1,000 times faster and more precise than other methods for patterning parallel lines and spaces (known collectively as gratings) across large surfaces more than 12 inches in diameter. Such large surfaces are key to a number of applications involving gratings, such as larger wafers for the production of computer chips and higher-resolution space telescopes.

"Patterning gratings with precise control across large areas has bedeviled labs around the world for a long time, despite great efforts, said Mark L. Schattenburg, leader of the team

The Nanoruler can pattern gratings of lines and spaces separated by only a few hundred nanometers, or billionths of a meter, across a surface 300 millimeters in diameter. It does so with a precision of less than one nanometer. "That is the equivalent of shooting a target the size of a nickel in Manhattan all the way from San Francisco," said Carl G. Chen, one of Schattenburg's colleagues.

Here is a photo of a 400 nm-period grating written by the Nanoruler on a 300 mm-diameter silicon wafer (Photo Courtesy: Ralf Heilmann).

This area of research is not new, because gratings allow the analysis of light, which is key for such technological marvels as NASA's Chandra X-ray Observatory.

The High Energy Transmission Grating, also developed by Schattenburg's lab at MIT, spreads the X-rays from Chandra's mirrors into a spectrum that can then be "read" like a kind of cosmic bar code. From there, scientists can deduce the chemical composition and temperature of the source (such as the corona of a star).

But actually, the Nanoruler project started with another goal in mind, creating a better ruler for the semiconductor industry.

"Today's advanced computer chips are packed with millions of transistors," said Schattenburg. "Increasingly, however, it becomes a challenge to stuff more and more of these ever-shrinking features into an area no larger than a thumbnail."

What Schattenburg wanted, in essence, was an extremely well-made ruler whose ticks are spaced not millimeters but nanometers apart, and whose size was comparable to the largest commercial silicon wafers. "If such a ruler could be created, it would help chip makers do a much better job of laying down the Lilliputian circuitry," he said.

In a few words, the Nanoruler combines two well-known methods: mechanical ruling and interference lithography. For technical details, please read the news release.

And for even more details, you can read this report, "A Brief History of Gratings and the Making of the MIT Nanoruler" (PDF format, 10 pages, 116 KB).

You also can visit the Space Nanotechnology Laboratory, Home of the MIT Nanoruler.

Source: Massachusetts Institute of Technology news release, January 28, 2004