New microscope could focus nanotech dream

Forget megapixel count. A device being created by the Department of Energy will be able to show things smaller than hydrogen atoms. Photos: Nanotech visions

The U.S. Department of Energy is enlisting partners to develop a microscope that can capture images of particles measuring a half an angstrom, or half the size of a hydrogen atom, a necessary step in the nanotechnology evolution.

The $100 million project--known as TEAM, or Transmission Electron Aberration-corrected Microscope--is being conducted at five national laboratories. Hillsboro, Ore.-based FEI, which makes electron microscopes and other equipment necessary for observing or manipulating individual atoms and molecules, will also participate in the project, along with other companies.

The first TEAM microscope, which will be located at the Lawrence Berkeley National Laboratory in Berkeley, Calif., is expected to become operational by 2007 or 2008. The project began in 2000, but activity is mounting. The Energy Department announced FEI's involvement this week.

Microscopes, probes and other equipment are a crucial part of the foundation for a nanotech industry because they enable scientists to actually see what they are making. With a scanning electron microscope, scientists can "look" inside layers of silicon wafers to detect subsurface defects, an increasing problem in chipmaking.

A focused ion beam, meanwhile, works something like an atomic meat slicer, trimming off thin layers of material.

"You can also use it to deposit metals or insulators," Robert Sinclair, chairman of the materials science and engineering department at Stanford University, said earlier this month at a nanotechnology symposium.

How big will nanotech be? Many assert that it will become a huge industry. The U.S. government, the European Union and Japan will each spend around $900 million in 2004 on research, while companies like Intel and IBM say nanotech is already part of chipmaking. Others, such as venture capitalist Don Valentine, however, say it is overhyped.

The resolution level the TEAM project hopes to achieve is, well, small. An angstrom is one-tenth of a nanometer, which itself is a billionth of a meter. A human hair is about 1 million times thicker than an angstrom. At this level, polished samples of carbon atoms look like rows of ball bearings, while the different layers of atoms that make up silicon nanowires resemble the stratified geological layers of a canyon.

Earlier this year, FEI announced that it captured images with a resolution just below an angstrom (i.e., particles or features measuring a little less than an angstrom could still be identified). The company's machines were also used to create the first pictures of the SARS virus.

One of the principal challenges in getting below an angstrom lay in filtering out the impact of any aberrations in the microscope lenses and thereby improving the resolution of the captured image. Electron microscopes create images by shooting electrons at a specimen and then capturing the pattern created by the electrons after encountering the specimen through a series of magnetic or electric lenses. Technically, these aren't lenses in the conventional sense, but fields that focus or control electron behavior and ultimately the resulting image.

But, like glass optical lenses, it is the quality of the lens that determines the resolution of the image and, in the end, all lenses are defective. Aberration correction essentially tries to overcome these defects by using multiple lenses.

"By putting multiple elements together, you can arrange the aberration coefficient so that they cancel each other out," said Nestor Zaluzec, a scientist at Argonne National Laboratories. Argonne, along with Heidelberg, Germany-based CEOS, is creating for the TEAM what it calls the Ultracorrector, which will consist of 13 magnetic lenses. Argonne hopes to have a prototype of the Ultracorrector created in three years.

Some companies and institutions have recently said they have created images through aberration correction, but the use of the technique has just begun and is still somewhat basic. "We've known mathematically how do to this for 20 years, but the technology hasn't been there," Zaluzec said.

The TEAM microscope is a variation of a transmission electron microscope. In these systems, an electron beam is aimed at a thin sample that lies above a detector. An image is then created by measuring the number of electrons that pass through the systems, analogous to how a slide projector works. Earlier this year, scientists were able to capture images where particles as long as an angstrom could be clearly seen.

By contrast, a Scanning Electron Microscope captures images by measuring the deflection of electrons. It can capture images in the best circumstances down to a nanometer.

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