|To enable processors to reach ever-higher clock speeds, microprocessor manufacturers are integrating millions of microscopic transistors onto each chip. For instance, Intel Corp.'s top performing Pentium III processor, built using 0.18 micron technology, currently features 27 million transistors.
But to fit increasingly larger numbers of transistors onto a chip, manufacturers have had to continually reduce component size. Now, with transistors heading toward 0.10 micron (1 micron equals about 1/25,000 of an inch) and smaller, manufacturers are nearing the limits on current lithography methods.
IBM Microelectronics Tuesday shed light on a new electron-beam lithography method they are developing in association with Nikon Corp. at a gathering here of the International Society for Optical Engineering.
Making it smaller
Called PREVAIL, for Projection Reduction Exposure With Variable Axis Immersion Lenses, the technology would not only allow the manufacture of much smaller components (potentially down to the atomic level) but also significantly improve the speed at which silicon chips can be processed, researchers said
"The technology that has been in the forefront of this for all these years has been optical lithography, using photons of visible light in the beginning, to today shorter wavelengths like UV and EUV," said Hans Pfeiffer, a researcher with IBM Microelectronics in East Fishkill, N.Y. "Now we're using electron beams because the wavelengths of electrons is five orders of magnitude shorter, so it is basically an open-ended resolution media that for all practical purposes is limitless."
While the use of electron beams is relatively commonplace today, with the most popular devices using the technology being TVs and computer video monitors, there's a vast difference between the number of pixels used to create a TV image and the pixels used to create processor components, Pfeiffer said.
"If you look at the average television screen, for example, even though the screens are very big, the number of pixels on a television screen is rather small -- less than 200,000 pixels," he said. "Now, in contrast, using the technique we have developed and we have demonstrated, you can actually image and resolve 10 million pixels in a 0.25 millimeter field."
The PREVAIL technology was developed in the early '90s, Pfeieffer said, but IBM Microelectronics and its partner Nikon, which will eventually serve as the vendor for the manufacturing method, only recently put the technology to the test by building a "proof-of-concept system."
"We built a proof-of-concept system primarily to convince Nikon that this idea can really be reduced to practice," Pfeiffer said.
The demonstration system was used to create components at 0.08 microns, or 80 nanometers. But Pfeiffer said the system could have been designed to produce even smaller components.
"We can extend the resolution downward," he said. "We don't really see a limit at 50 or 35 nanometers, which is many years away."
Nikon recently gave the green light to start building an alpha tool, or an early version of a production tool that could be used by early customers. The alpha tool probably won't be completed until the end of 2002, Pfeiffer said.