Magazine article Science News

Light Lens Precisely Guides Atom Beams

Magazine article Science News

Light Lens Precisely Guides Atom Beams

Article excerpt

Today's semiconductor manufacturers use photolithography to etch microscopic circuits onto computer chips: They shine light through a mask onto a photosensitive surface to create the circuit's pattern. But to make nanometer-size circuits--about 1,000 times finer than current ones--these companies may one day use light in a very different way.

To work, photolithography depends on atoms in a mask to block light from parts of its target surface. But in a new process developed by AT&T Bell Laboratories in Holmdel, N.J., light does the blocking for atoms. "Instead of using matter to control light, we're using light to control matter," says Bell Labs physicist Gregory Timp. "We built a light pattern and transferred [the pattern] onto the surface."

For this technique, the researchers use a beam of atoms to deposit a thin film on a surface. To place the atoms, they tune a laser to a wavelength close to that which causes a particular atom to resonate. Because of light's wave-like nature, its intensity periodically increases, then decreases, creating peaks and valleys of high and low energy along its path, Timp says.

As an atom approaches this wave, it senses these energy differences because of its dipole moment (the internal polarization that causes the atom to prefer a specific position), Timp explains. The atom shifts to where the light's energy is most compatible with this dipole moment. If the laser's frequency is slightly lower than the one that causes the atom to resonate, then the atom heads to the brightest spots, Timp says. …

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