With existing lithography technologies moving rapidly toward obsolescence, Motorola Inc.'s Semiconductor Products Sector has demonstrated the capability of fabricating IC masks that meet requirements for next-generation electron-projection and extreme-ultraviolet (EUV) lithography.
Commercial use of the techniques are still five or six years away, but SPS believes current technology developments are crucial to scaling the impending lithography wall.
"We're rapidly approaching the kinds of dimensions where the evolutionary tweaks of traditional lithography will no longer provide sufficient resolution to keep us going," said Joe Mogab, manager of advanced process development for SPS in Austin, Texas. "We think this new technology will allow us to finally go below 0.1-micron-level processing," he said. "We also recognize that mask technology has to be developed concurrently with exposure tools and the other things that will be necessary."
Traditional lithography techniques employed for the better part of two decades use a projection step-and-repeat or step-and-scan technology to complete IC patterning. But the capabilities of these techniques will not be adequate as process geometries begin to scale below 0.1 micron and pattern resolution becomes increasingly difficult, according to Mogab.
Electron-projection and EUV lithography both provide methods of increasing patterning resolution at smaller geometries. However, projecting the patterns will require masks that are "radically different than those currently used in the industry," he said. SPS believes it is the first company to demonstrate a yielding full-field large-area mask capable of processing practical chip sizes for electron-projection technology.
The new mask consists of a membrane roughly 1,000 angstroms thick with an overlying patterned surface material capable of scattering electrons to create the pattern's image on the wafer. By adjusting the patterns on the mask, silicon wafers can be processed much like conventional methods such as step-and-scan, Mogab said.
SPS is working in parallel on EUV techniques, and is a member of the EUV LLC-a consortium that includes Intel Corp. and Advanced Micro Devices Inc.-which is working to develop masks for EUV technology.
SPS' first full-field microprocessor die mask pattern on an EUV mask and an electron-projection resolution test pattern over a 200-mm mask were both exhibited at the International Sematech Advanced Lithography Workshop in Chicago in June.
It's unclear which lithography technology the industry will adopt first, or which will ultimately prove most effective, Mogab said. However, "it's more likely that the industry will eventually gravitate to just one of these techniques," he added.
Meanwhile, SPS doesn't plan to become a commercial mask supplier. As next-generation masks are brought into full-scale production capability, along with the development of necessary ancillary equipment and processes, the company will either license or transfer the technology to mask suppliers, according to Mogab.
"We want to provide this kind of know-how to the mask suppliers, who could supply our needs and ultimately use their volumes to commercialize this," he said.