Chirodoc and all, Interesting article...Lucent Vows to put Scalpel system in fabs by 2003 -- Lucent nabs allies for next-gen lithography
December 30, 1997
Electronic Engineering Times via Individual Inc. : Washington - Lucent Technologies is quietly forming a 10-company partnership aimed at taking its Scalpel scanning e-beam lithography system out of Bell Labs and into the marketplace, EE Times has learned. The goal is to deliver a working Scalpel system by 2003 for high-throughput 0.13-micron lithography on 300-mm wafers, capable of at least 50 wafers per hour.
Lucent's move is the latest in a fierce competition to rally IC makers around one of many next-generation lithography tools, which will be needed in only five years. That timetable has technologists worried about which of various options will be production-worthy by then. Maintaining the rate of progress in lithography seen over the last two decades is considered key for building giga- scale memories and processors.
"The prospects for post-optical lithography center on the productivity issue," said Tim Brunner, in charge of the lithography and metrology development effort at IBM Corp. But at some point, there is no longer any doubt that Moore's Law will be revised to a slower rate of integration increases, mainly because of slowing progress in lithography.
"We simply are not going to be printing 1-nanometer lines, so [the question of Moore's Law being broken] is not a matter of if, but when," Brunner said in a keynote address at the 1997 International Electron Devices Meeting (IEDM) here. If optical systems can take the industry to the 100-nm range, the next- generation lithography systems now being considered may work down to about 50 nm, he said.
Though IBM is the furthest along in developing a production-worthy system capable of 10th-micron and 0.07-micron production, Lucent is moving quickly to establish a place for Scalpel. One advantage over X-ray lithography is that Scalpel does not require a synchrotron orbital radiation (SOR) ring.
David Boulin, a veteran Bell Labs researcher now in charge of business development for Scalpel, said Lucent is in the process of sending out contracts to 10 prospective partners, including two non-U.S. semiconductor companies.
NEC Corp. executive vice president Hajime Sasaki said last month that NEC was interested in joining the Scalpel consortium.
Lucent has contracted with Integrated Solutions Inc. (Austin, Texas) to build a second Scalpel system. The first demonstration unit was built within Bell Labs and shown to participants at a Sematech-sponsored lithography workshop in October at Murray Hill, N.J.
"We wanted to show 'proof of lithography' at Murray Hill," Boulin said. "We showed that we could stitch a centimeter-by-centimeter [1 cm2] field, with stripes that matched end to end and side to side, at 50-nm resolution."
Lucent will now take orders for Scalpel at $8 million per system. Noting that X-ray lithography requires an SOR ring with multiple steppers, Boulin said that Scalpel has "none of the granularity issues associated with X-ray. For Scalpel, if you need to add another stepper, just buy one for another $8 million."
Unlikely endorsement
At a panel discussion on next-generation lithography at IEDM, praise for Scalpel came from an unlikely source: competitors. When asked to name the best option for next-generation lithography, proponents of the other major solutions all supported their own racehorse: IBM choosing X-ray, Lawrence Livermore Labs picking extreme ultraviolet (EUV) and so on. But asked to give a second choice, each of the panelists chose Scalpel.
To drum up support, Mark Pinto, chief technology officer at Lucent Microelectronics, and Lloyd Harriott, in charge of the Scalpel project, met at IEDM with technology officers from the largest semiconductor companies worldwide to explain Scalpel's current status.
As in X-ray, the largest hurdle is to develop the masks. While X-ray lithography requires 1:1 proximity masks, which present a major challenge to the mask-writing tools, both EUV and Scalpel use 4:1 reduction masks. Boulin said the Scalpel scanning e-beam has an advantage in that little heat is created in the membrane of the scattering-type mask, which cuts down on distortion at the wafer.
A company that specializes in micromachine structures, MNCC (Mems North Carolina Corp.), is capable of making up to 30,000 of the nitride-membrane blanks per year. Boulin said Lucent is in discussions with a volume mask manufacturer he declined to name. Also, he said that Olin Chemical Corp. has developed both positive and negative resist for use with Scalpel.
"In terms of the beam, Scalpel can do picometers if you want to. The challenge is always the mask, how to keep it clean and how to repair it," Boulin said.
"We have to create struts, long rectangles on which the membrane is supported. Keeping the membrane clean, and developing ways to repair it, are other issues."
The initial Scalpel system built at Bell Labs did not have a movable stage and worked with 150-mm (6-inch) wafers. By July, the 30-member development group had obtained the resist chemistry and printed wafers. The system that ISI will build next year will have a 200-mm movable stage.
For its part, Lucent is increasing the manpower devoted to Scalpel from about 30 now to 50 next year and, eventually, to 75. Boulin said Lucent wants to involve one of the major lithography manufacturers in the project, so that commercial sales of high-throughput machines will be ready by 2003 for second- generation 0.13-micron devices.
Argon fluoride-based excimer-laser steppers, with a 193-nm wavelength beam, are expected to be ready for production use by 2001. They provide a relatively good 28 percent improvement over the krypton-fluoride, 248-nm steppers now coming into widespread use on 0.25-micron production lines.
The five-year plan
At IEDM, several participants said they believe ArF-based lithographic tools will be extended to 100-A (0.1-micron) design rules by means of various optical enhancement techniques.
"All of the next-generation lithography systems want to be ready by 2003, " said Roc Blumenthal, a process-engineering manager at Motorola Inc.'s advanced products research and development laboratory (Austin). "People in the industry are starting to realize that, all of a sudden, that is only five years away."
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Regards, Michael
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