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When the rubber hits the chip

Bell Labs has developed a high-tech rubber stamp that could be used to print features as fine as microchip circuits without some of the constraints of traditional chipmaking technology.

Stephen Shankland principal writer
Stephen Shankland has been a reporter at CNET since 1998 and writes about processors, digital photography, AI, quantum computing, computer science, materials science, supercomputers, drones, browsers, 3D printing, USB, and new computing technology in general. He has a soft spot in his heart for standards groups and I/O interfaces. His first big scoop was about radioactive cat poop.
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Stephen Shankland
3 min read
Bell Labs has developed a high-tech rubber stamp that could be used to print features as fine as microchip circuits without some of the constraints of traditional chipmaking technology.

The technique has its roots in traditional chip manufacturing methods, but enables people to put circuitry on unconventional materials such as glass or plastic, said John Rogers, a physical chemist at Bell Labs, the research arm of Lucent.

Possible uses of the new technology could be large flexible screens that could be unrolled and attached to a wall, or fiber optic cables that could be tuned to transmit just the right frequency of light, Rogers said.

The technique begins the same way as traditional chipmaking, where ultraviolet light is used to etch tiny patterns on silicon wafers. Next, a liquid silicone is poured across the silicon surface and solidified by baking it at a low temperature. The rubber then can be peeled off, coated with special ink, and used to stamp the pattern on other surfaces.

While the technique could be used to create ordinary chips, it's not realistic, at least in the short term, that the research technique could displace conventional silicon chip manufacturing methods, Rogers said.

The stamp itself, as well as the mold used to create it, can be used over and over, Rogers said.

Using Bell Labs' chipmaking equipment, features the size of 0.02 microns can be etched and reproduced accurately in the rubber stamp. However, because the ink used spreads some when the rubber stamp is used, the ultimate feature size is restricted to about 0.2 microns, Rogers said. In contrast, future editions of Intel's Pentium III chip due in August will have a feature size of 0.18 microns.

Using a kind of glue, the rubber stamp can be wrapped around a glass tube backing that can be used like printing presses to lay down features on flat surfaces, Rogers said.

One potential use for this approach would be to roll ink onto sheets of special electroluminescent plastic that could be used in flexible computer or television displays. Using a special treatment process, the inked surface can be converted into actual wire circuitry that controls which pixels are on or off, similar to an active matrix liquid crystal display used in today's laptops.

The technique wouldn't work with ordinary technologies, which use etching chemicals that would dissolve the plastic, Rogers said.

Another possible use of the technology would be to modify fiber optic lines so they can do a better job carrying data, he said. By rolling an optic fiber across an inked rubber stamp and treating the cable, a spiral of wires can be laid on the surface of the hair-thin filament.

Running electrical current through the wires heats them up, which can change the spacing of tiny parallel lines along the cable called "gratings." Gratings currently are used to reflect light inside the fiber so the light bounces down the fiber. But with the wire microcoil, the grating spacing can be changed to tune the frequency of light the optical fibers transmit, allowing the fibers to be tailored to different tasks.

Rogers will describe the technology Friday at a meeting of the American Physical Society.