EETimes.com – Point/Counterpoint: Whats the right path for litho?

EETimes.com – Point/Counterpoint: Whats the right path for litho?.

Back in 1997, Intel led the formation of EUV LLC, a consortium that planned to commercialize extreme ultraviolet lithography by 2005. Advanced Micro Devices, IBM, Infineon and Micron were among the companies that signed on to the effort.

EUV was supposed to have replaced conventional optical lithography by now. But optical lithography is still driving the semiconductor engine, while EUV now is targeted for early production in 2012-or perhaps 2015 or 2016, depending on who’s offering the estimate. Some say it may never work.

Others are pushing for nanoimprint, maskless lithography or an emerging technology called self-assembly. And there are those who hope to extend today’s optical lithography indefinitely.

Was EUV the wrong bet for the industry? If so, what should it be working on instead? And who will benefit in the long run?

During the recent SPIE Advanced Lithography conference and other events, EE Times posed these questions to lithography experts and executives. Here are their responses.

Yan BorodovskyYan Borodovsky Intel Corp. senior fellow and director of advanced lithography at Intel’s Technology and Manufacturing Group

(Though it originally pushed for EUV, Intel is now weighing a mix-and-match lithography strategy.)

“I think complementary lithography is the right direction [for future IC designs]. . . . 193-nm lithography is the most capable and most mature technology that can meet both fidelity and cost-of-ownership requirements, but it has a weakness in terms of resolution. Complementing 193 nm with a new technology might be the best cost-of-ownership, performance and fidelity solution. The complementary technology could be either EUV or e-beam lithography.

“I think introducing EUV as a complementary technology has its challenges for high-volume manufacturing. Introducing multibeam e-beam as a complementary technology [also has its challenges].

“NAND flash makers have a much higher probability of introducing something like EUV before we do. Logic actually has more degrees of freedom in terms of layout, design rules and restrictions. So I can see why Samsung will be more aggressive to deploy EUV. They have no choice but to go to smaller wavelengths, higher NA [numerical apertures] and a K1 of 0.25.”

Dan HutchesonG. Dan Hutcheson CEO of market research firm VLSI Technology Inc.

“I think the industry is going in the right direction. It’s a lot better in this decade than in the last decade. I remember in the 1990s, when everything was on the [next-generation lithography] road map and no one would pull anything off.

“Meanwhile, we have an ongoing business that allocates so many dollars for R&D every year. And if you look out there for future nodes, you need to have two to three alternatives over your existing technology to make sure you can go down Moore’s Law.

“As a last resort, e-beam will always write fine geometries. The downside is that it violates Moore’s Law. Imprint is a very interesting technology; the technology needs to be developed. EUV, too.

“Then we have the existing technology, which is double patterning. But [if I’m a chip maker] I am going to spend a lot of money on [double patterning], because now my litho tool productivity is basically cut in half. So my cost per wafer doubles. And I am going to need twice as many tools, which is great for the equipment industry.”

Burn LinBurn Lin Senior director of the micropatterning division at Taiwan Semiconductor Manufacturing Co. Ltd.

“The industry is betting too much on one horse. I think it’s dangerous to bet on one horse. A lot of people know that.”

Chris MackChris Mack Consultant and “gentleman scientist”

“It’s always risky to bet on one technology that is high risk and not pursue others simultaneously. And I think it’s been a little bit out of whack that we’ve invested too much in trying to make EUV successful and getting too emotionally attached when you say, ‘We’ve got to make sure we’re not distracted by these other technologies, so we’re going to make sure that only EUV is the one we focus on.’ I don’t have a lot of complaints that EUV got a lot of funding. What I’ve got a complaint about is when people try to limit the other options that are the competitors.

“I am an ‘optical forever’ guy. I am a big proponent of doing more [research] on line-edge roughness. I think longer-term research on subassembly is something we should be doing. It was very premature to give up on some of the high-index materials development. If we have stayed the course, I think those high-index materials would have been there to extend double patterning another generation.”

Hans PfeifferHans Pfeiffer Proprietor of HCP Consulting Services

“If you remember, there have been quite a number of alternatives in lithography. One of them was X-ray, a large program that was supposed to extend lithographic capability beyond optical lithography. But optical lithography never fell off the cliff. And that’s the case today. However, I think we’re seeing the cliff a little bit closer now, and that’s what mobilizes all of these additional resources to finally come up with a practical alternative or solution.

“There are sure no winners right now. That’s the reason why many different technologies are being pursued. The top priority is still to further work on 193 nm and extend that to the absolute. This provides some time for EUV, which is the next major contender.

“But are we headed in the wrong direction? There are many different directions being pursued, but none has really so far exceeded EUV. Most large semiconductor companies are pretty much counting on EUV to be there.

“EUV always looked like the impossible dream. But there are tremendous resources behind it. Is EUV late? Yes. Everyone understands that lateness is not only inconvenient, but it’s also expensive.

“Maskless lithography is struggling to regain a certain level of interest in the industry. E-beam had a very successful period and then basically went under. It did not keep up with Moore’s Law.”

Kurt RonseKurt Ronse Director of the lithography department at IMEC

“I think we’re going in the right direction because there are not many alternatives at this moment; [we] either stop scaling or continue to push EUV.

“A lot of progress has been made on EUV. It’s not a done deal; there is a lot of work to be done. [But] in my opinion, the gap between EUV and the alternatives has increased during the last year. All of the other alternatives did not make much progress. They also had difficulties in getting funds. For the alternatives, it will be very challenging to hit their targets. The alternatives have to focus on 16 or 11 nm, because they have some ways to go. If they keep focusing on 32 nm or maybe 22 nm, they will miss their targets.”

Wally RhinesWalden Rhines Chairman and chief executive of Mentor Graphics

“Computational lithography [including OPC and other resolution enhancement techniques] is what will save us from the [soaring costs] of steppers. Computational lithography represents the biggest TAM [total available market] for EDA in the last decade.”

Dan RubinDan Rubin Venture capitalist with Alloy Ventures

“It is increasingly apparent that EUV is not able to leverage the conventional optical lithography infrastructure. The novel innovation required across an unestablished supply chain for EUV sources and reflective masks, and defect inspection continues to require herculean efforts, significant funding and schedule adjustments. If a complete technical solution is assembled in time, the suggested costs will make EUV unaffordable for advanced memory device adoption.

“I [am] a believer in imprint lithography for the memory market. The progress Molecular Imprints has made on less than a $100 million total investment is incredible, and the pace of performance improvements continues unabated. The usability of their CMOS tools and the throughput of their hard drive tools are technically impressive. If they had received a fraction of the dollars and industry attention that have been spent on EUV, they would have sub-32-nm CMOS production tools today.”

Mark Mmelliar-SmithMark Melliar-Smith CEO of nanoimprint lithography vendor Molecular Imprints Inc.

“The industry [has] restricted its vision. It is focusing much, much more on a single solution. I think that’s bad. “If MII had a month’s worth of EUV funding in the past year, we could have moved a long way to solving our remaining issues in the semiconductor market and been ready for production in 12 to 18 months.”

Kazuo UshidaKazuo Ushida President of the Precision Equipment Co. at Nikon Corp.

“For small-volume production, EUV looks very promising. But . . . EUV will be late for the 22-nm half-pitch road map. EUV will appear later, maybe by 16 nm. We have no metrology tools. It will take two years to develop the mask tools.”

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