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Navigating Your Way Through Materials At The Nano Level

This panel compares the performance of the electron microscope without the aberration correction (left) and with the correction. More images and data
Yorktown Heights - August 8, 2002
IBM and Nion Co. researchers have developed innovative technology to peer deep inside materials and view atoms interacting in different environments at a resolution never before possible. With computer-chip features shrinking to atomic scales, this breakthrough addresses scientists' urgent need to see more clearly the details of materials used in manufacturing semiconductors.

As reported in the August 8 issue of the journal Nature, the new technique significantly extends the capabilities of the electron microscope -- a scientific instrument that uses magnetic lenses to focus electrons into very small beams to look at small, atomic-scale details in thin slices of materials.

"We can't fix what we can't see," said Dr. Philip Batson, the lead scientist on the project at IBM Research. "As the dimensions of computer chips shrink, scientists need new tools to explore the structures and properties of materials used in these chips. This breakthrough improves our ability to see and thoroughly explore properties of electronic materials."

For the past 50 years, electron optics engineers have sought to improve the precision of electron microscopes by counteracting the image-blurring effects of lens imperfections, or "aberrations."

The largest imperfection, "spherical aberration," cannot be fixed in a single lens. To fix the problem, the IBM and Nion scientists combined seven new sets of magnetic lenses with modern computers to actively correct the aberration in real-time.

After this correction, the microscope can make an electron beam that is only 75 thousandths of a nanometer (3 billionths of an inch), which is smaller than a single hydrogen atom. This is the smallest electron beam produced in an electron microscope to date.

Spying on Silicon for Smaller, Faster Computer Chips

Before the correction, the electron microscope yielded tantalizing but incomplete information about the atomic structure of important defects -- atomic level mistakes such as missing or extra atoms -- in semiconductor materials. Using this correction technique, scientists now can see those defects, and if necessary, find ways to fix them.

For example, by examining the interaction of silicon (a semiconductor) with silicon oxide (an insulator), scientists can look at how the silicon and oxygen atoms bond to each other and determine the quality of the insulator. If the insulator has any defects, scientists can suggest ways to fix them, such as setting the right conditions to optimize the growth of silicon and silicon oxide materials.

The breakthrough could also help scientists improve the properties of silicon through a better understanding of how the atoms inside of materials interact in certain environmental conditions.

Watching how atoms assemble, move around and interact with other atoms is fundamental to understanding the properties of materials and may lead to a better understanding of how to control environmental conditions so components of future computer chips could self-assemble.

The authors of the Nature report, entitled "Sub-angstrom Resolution Using Aberration Corrected Electron Optics," are Philip E. Batson of IBM's T.J. Watson Research Laboratory in Yorktown Heights, N.Y; and Niklas Dellby and Ondrej L. Krivanek of Nion Co. in Kirkland, Washington.

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Lining Them All Up In Quantum Land
Madison - Jul 26, 2002
Material scientists at the University of Wisconsin at Madison have built a semiconductor based device that can trap individual electrons and line them up, an advance that could bring quantum computing out of the gee-whiz world of scientific novelty and into the practical realm.