Science / Medicine : Circuits Now Even Smaller

IBM researchers have used a new technique called X-ray lithography to manufacture the most densely packed integrated circuits yet produced. Denser circuits mean faster, more powerful and more economical computers.

Integrated circuits are now made by coating silicon with a light-sensitive material called a “resist” and shining light on the resist through a template of the desired circuit pattern. Resist struck by light is chemically changed so that it can be washed away, leaving the circuit pattern on the silicon surface. This unprotected silicon can then be etched away with an acid to form the circuit.

But researchers want to make circuit components that are smaller than the wavelength of light. To do this, they need radiation with very short wavelengths: X-rays.

The IBM researchers developed new resists that would work with X-rays and used the large synchrotron (particle accelerator) at the Brookhaven National Laboratory in Upton, N.Y., to produce the intense X-rays needed to create very sharp patterns of ultra-thin lines. The metal lines in the photo above, less than one-hundredth the width of a human hair, carry electrical signals to transistors buried beneath them.