SANTA CLARA, Calif. Lithography vendors at the SPIE Microlithography conference here last week said they are getting their feet wet with a technology that could possibly be the industry's next breakthrough immersion lithography.
While chip makers are still evaluating immersion lithography for future IC production, advocates say the technology could turn the industry upside down. Immersion lithography could extend 193-nanometer tools down to 45-nm and possibly finer line widths, which could delay the need for 157-nm tools and extreme-ultraviolet lithography.
Nikon Corp. stunned the SPIE crowd by announcing that it saw "no showstoppers" preventing the development of 193-nm tools based on immersion techniques. The company claimed to have printed 65-nm lines based on the technology. Canon and ASML said they too are investigating immersion technology.
In immersion lithography, the space between the equipment's projection lens and the image-receiving wafer is filled with a liquid. For the 193-nm exposure wavelength, water is the preferred transparent medium. Immersion technology could offer better resolution enhancement than conventional projection lithography because, when it is in contact with a liquid, the lens can have a numerical aperture higher than 1.0. Thus, it is able to produce smaller images.
Chip maker consortium International Sematech Inc. recently held a workshop on immersion lithography and started a six-month feasibility study. As part of the workshop, researchers drew up a top-10 list of challenges facing the technology.
Sematech will report its initial finding in mid-2003, but some believe the technology is still an R&D curiosity. It may take until 2008 or 2009 to prove the technology is even viable, if indeed it is, said Peter Silverman, an Intel fellow and director of Intel Corp.'s lithography capital equipment operations. "The technology is more than not ready," he said.
The total available market for lithography tools is projected to reach $230 million in 2005, according to The Information Network, a market research company in New Tripoli, Pa.
"Currently and in the near future, immersion lithography will be used in niche applications where contact and proximity printers, 1x steppers and direct-write e-beam tools are currently used," said Robert N. Castellano, president of The Information Network. "That market was $120 million in 2002 and will grow to $230 million in 2005.
"After 2005, immersion tools will have matured to a point whereby they could ostensibly be used as the next-generation tool beyond 193-nm DUV deep-ultraviolet lithography for semi-onductor applications, competing with ASML, Canon and Nikon," Castellano added.
Those companies are investigating the technology. ASML Holding NV, along with Sematech and the Semiconductor Research Corp., is funding immersion technology development at the Rochester Institute of Technology.
For its part, Canon Inc. says it has formed an internal task force to investigate the feasibility of immersion lithography. Like ASML and Nikon, Canon is also working with Sematech on the technology.
Mark LaPedus is editor of Semiconductor Business News, an EE Times Network Web site.