SBN reporter's notebook:
By Jack Robertson, Semiconductor Business News
Jul 17, 2000 (11:25 AM)
URL: semibiznews.com
SAN FRANCISCO -- So you thought only 157-nm F2 optical, or extreme UV, or even electron-beam projection (EPL) technologies were the most likely lithography candidates for the 0.07-micron (70-nm) process node? Well, guess again. Last year's Next-Generation Lithography Workshop, sponsored by International Sematech, selected 157-nm as the "preferred" tool for 0.07-micron processing. Two other Next-Generation Lithography contenders -- EUV and EPL -- were pushed back to the 50-nm (0.05-micron) node, but these technologies were still expected to see some early action, competing with other 157-nm tools.
However, Charles Sparkes, associate director of technology for Nikon Precision Inc. in Belmont, Calif., told last week's Semicon West technical symposium that 193-nm argon fluoride tools with hard phase shift masks and numerical aperture lens of 0.7 could be expected to reach 80-nm processing. Like other vendors, Japan's Nikon is covering its bets at very low resolutions.
During the session in San Francisco, Sparkes said the firm is also developing 157-nm for the 70-nm node, but alternating phase shift masks might extend this tool into the 50-nm node, where Nikon is also working on EUV and EPL systems for that generation of lithography.
Canon Inc.'s Semiconductor Equipment division is also working on all those advanced lithography systems for the sub-100-nm nodes. But Akiyoshi Suzuki, general manager of Canon Research Center, said the Japanese vendor is also developing two other lithography concepts -- multiple e-beam direct write (MEBDW) and also a point source proximity X-ray lithography tool.
Canon's MEBDW technique uses a correction lens array between the electron source and optics to generate multiple images, and then compensates for detected field curvature and distortion. Canon touted the new technique as "maskless" e-beam lithography for 70-nm mode with a throughput of 200-mm wafers at 50 substrates per hour.
And Canon's proximity X-ray point source could be developed on a faster time schedule than other Next Generation Lithography candidates, said Suzuki during a Semicon West seminar. The Japanese ASET (Association of Super-Advanced Electronic Technology) consortium is testing Canon's PXL with an expected feasibility demonstration this year. Susuki said PXL shows potential of operating at the 50-nm mode.
A radical contact printing maskless sub-100-nm lithography -- called "step-and-flash imprint lithography (SFIL) -- was described by Grant Willson, microlithography researcher and professor at the University of Texas in Austin. The novel approach uses a phase shift photomask to make a quartz template, which is then pressed into the surface of the silicon wafer.
Willson said initial tests show that a precise imprint with resolution as fine as the photomask pattern results on the wafer. SFIL works at room temperature, with no lens or environment control needed.
The University of Texas professor said fears that contamination on the template could be a problem proved unfounded. "The tool cleans itself in operation," he said. "The best way to clean the tool is just to print with it."
The bevy of 70-nm mode exposure tool candidates compounds industry's dilemma, according to exhibitors at Semicon West last week. However, Doug Dunn, president and chief executive officer of ASM Lithography, said picking a tool is only part of the problem.
"The industry has to develop an extensive infrastructure around whatever tool is selected," noted the CEO of ASML, based in the Netherlands. "Ideally, you might like to have several different technologies in tools. But I'm not sure you can build a viable infrastructure for each."
Dunn is narrowing his bets for NGL (Next-Generation Lithography) to either EUV or EPL. Although ASML is working in a European consortium developing ion beam projection as a potential NGL choice, Dunn said he thought that technology "is now a distant third in the race." |
