From hand-held supercomputers to synthetic enzymes that repair damaged cells in the human body to self-assembling molecular-sized machines that clean up our environment, the future belongs to nanotechnology. A key to achieving this future is x-ray lithography, which can fabricate devices with features of about 100 nanometers, only a thousandth the thickness of a human hair.
"To build nanosized devices, you need microsized machines," says Keith Jackson, a physicist with Berkeley Lab's Materials Sciences Division and leader of the lithography programs at the Center for X-ray Optics. "These micromachines will be three-dimensional structures such as sensors, actuators, gears, and surgical tools, roughly ranging in size from 10 to 500 microns." (A micron is a millionth of a meter.)
One approach to making micromachines is through deep-etch lithography using light at x-ray wavelengths. With conventional lithography, a beam of light is used to transfer intricate patterns from a mask onto the surface of a material in order to make a device, such as an integrated circuit. With deep-etch lithography, the light beam sculpts out material several hundred microns below the surface. As a result, instead of producing two-dimensional devices such as computer chips, truly three-dimensional micromachines and parts can be fashioned.
"Using x-rays produced at synchrotrons such as the Advanced Light Source, we can get deep exposures into a target material," Jackson says. "If we then tilt the target through a series of such exposures, we can create highly complex structures."
Jackson is a rarity in the science world, holding undergraduate degrees in both physics and electrical engineering. Born and raised in Columbus, Ohio, he moved to Atlanta, where in May of 1976 he earned his B.S. in physics from Morehouse College, the same undergraduate school attended by Martin Luther King. One month later he earned his B.S. in electrical engineering from Georgia Tech.
Jackson's M.S. in 1979 and Ph.D. in 1982 were both in physics, from Stanford University. He came to Berkeley Lab in 1992 from the Rocketdyne division of Rockwell International, where he'd been developing diamond films and optical elements for synchrotrons and free electron lasers.
The focus of his research today is on a deep-etch lithography technique known as LIGA, from a German acronym for lithography electroplating molding. With LIGA, high-energy x-rays penetrate the transparent portion of a lithography mask, the exposed material is removed, and a metal is electroplated into the open space. This produces either a working 3-D device or a master mold.
AXSUN Technologies recently sponsored the construction of a new LIGA beamline at the Advanced Light Source, which will also be available for noncommercial research. Says Jackson, "It's like a free beamline for the scientific community."