INDUSTRY NEWS

SPIE MICROLITHOGRAPHY 99

Technical meeting to shed more light on postoptical lithographic technologies

Alternative lithographic methods, the semiconductor industry's equivalent of baseball's "wait-til-next-year" teams, may finally have their day in the sun. Several novel techniques standing ready to pinch-hit for optical lithography will be in the spotlight during a three-day conference at the 24th Annual International Symposium on Microlithography. Sponsored by SPIE, the international optical engineering society, the symposium and exhibition will take place March 14—19 at the convention center and adjoining Westin Hotel in Santa Clara, CA.

"The IC manufacturing business in the last year or so has been heavily concerned with what technology will replace optical lithography," says Victor Pol, the symposium's chairman. "Today, the mainstream lithography is optical. That is the topic of one of the four conferences during the symposium and probably the one that generally receives the most attention."

Intense industry concern about the capabilities of optical techniques for printing smaller linewidths has pushed nonoptical alternatives under the noses of chipmakers. This is happening despite the fact that nonoptical alternatives have, as Pol puts it, "been on the outs" for years and have approached the status of a running joke. "They're always five years in the future," says Pol, who is section manager of advanced lithography at Motorola's advanced products R&D labs in Austin, TX.

The future is now, however. The symposium chairman notes that optical lithography "will take us down to 200 nm [linewidths] probably" and will most likely reach the limits of its capabilities at 100-nm geometries. This will usher in the need for much-scrutinized alternatives, such as proximity x-ray and EUV lithography.

In addition to these technologies, other leading candidates which have emerged as postoptical alternatives include electron projection and ion projection technology, says Pol. Scalpel, an E-beam projection lithography system developed by Lucent, and EUV will receive the most attention during the session on emerging technologies, he notes. The session on E-beam techniques will showcase papers on the manufacturing of Scalpel mask blanks and stress mapping techniques for Scalpel masks. A morning session devoted to a Scalpel high-throughput system will feature papers covering resist characteristics, writing strategy, and alignment mark detection. That session will take place on Tuesday, March 16.

Late last year reports emerged that International Sematech had been urged to fund only two postoptical technologies, EUV and Scalpel, following a meeting of Sematech's next-generation lithography workshop. Pol notes that the nonoptical technologies present chipmakers with some yield questions. "We have a lot of problems in the alternative technologies...coming up with ways to measure defects. Defect inspection, classification, and, of course, reduction are critical to some of our technologies."

Despite the increased attention to the alternatives, the industry continues to take optical lithography further along the roadmap than expected, Pol points out. "The interesting thing that has come up this year is the advent of 157 nm as a real potential technology," he says. "One year ago, we thought optical's [capabilities] would stop at 193 nm."

The exhibition will take place March 16—17 and will feature more than 150 companies. The technical program includes 470 presentations and 25 short courses. Plenary speakers Sam Harrell, KLA-Tencor's senior vice president of strategic business development, and Bill Arnold, ASM Lithography's executive scientist, will discuss the selection of equipment during a time of uncertainty. The topic has become crucial as the costs of steppers and related components rise rapidly while the industry debates which postoptical technology it needs to back.

The four conferences at the symposium are emerging lithographic technologies III; metrology, inspection, and process control for microlithography XIII; advances in resist technology and processing XVI; and optical microlithography XII.

Pol points out that the annual SPIE gathering has a reputation as "a users' conference" that has had to withstand criticism because the technical submissions are not peer reviewed. Nevertheless, the chairman says, "I have a personal bias toward the SPIE conference. I think it's the most valuable conference for someone involved in present and near-term developments, and by that I mean in the next five years."

Adds Pol: "It's probably an important conference for those doing very future-oriented work. They can get the attention of those doing near-term development." With that benefit in mind, participants may come a few nanometers closer this year to determining which postoptical technique is ready to step up to the plate.

Information on Microlithography 99 is available from SPIE at 360/676-3290; fax, 360/647-1445. The society's URL is http://www.spie.org.

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