Competing Lithography Technologies Share Heartaches
Aaron Hand, Executive Editor, Electronic Media -- Semiconductor International, 5/21/2008 11:35:00 AM
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Listen to a podcast of the Litho Forum panel in full (Runtime: 47:00)
An important part of the Litho Forum is, after two days of presentations about the readiness of the various technologies, attendees take a survey to assess industry perception on the readiness and feasibility. Preliminary lithography survey results show EUV lithography taking over the lead position around the 2012 timeframe, with it really taking off by 2016. Program chair Bernie Roman will present the full Litho Forum survey results in a webcast on June 3.
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| Preliminary Litho Forum survey results show EUV lithography figuring prominently beyond 2012. Full results will be webcast by Semiconductor International on June 3. (Source: Bernie Roman) |
A key recurring theme throughout the panel, which was moderated by Mike Lercel, Sematech’s director of lithography, was the difficulty to obtain the results needed in many of the leading-edge lithography technologies without more available resources. As posed in the first question to the panelists, leading-edge lithography tool suppliers are typically large, well capitalized companies; given the huge development costs, what business models are needed to enable innovative lithography technologies?
Players in the nanoimprint lithography space, as well as high-index immersion and maskless development, have repeatedly complained about the minuscule amounts of money coming their way for development — particularly in relation to the amount that has been poured into EUV. But rather than make that well-known complaint again, S.V. Sreenivasan, founder and CTO of nanoimprint toolmaker Molecular Imprints Inc. (MII), made reference to the help they’re getting from customers such as Toshiba, which has presented results on MII’s behalf. “We’re also looking at programs with Sematech, and so on,” he said. “That really helps on developing processes, getting data on defects, things like that that’s very hard for us to do ourselves.”
From a tool development perspective, Sreenivasan said, MII is also looking into an approach in which his company would simply supply modules to a larger integrator — like a lens maker supplying lenses to a stepper integrator. “And then we could depend on somebody who already knows what they’re doing in these other areas like stages and temperature control and interferometry — the things that we don’t have too much expertise in.”
Janice Golda, director of lithography capital equipment at Intel Corp., agreed, noting that the arrangement Sreenivasan spoke of would help to enable new platforms. “We heard a number of presentations [at the Litho Forum]; people with innovative ideas for [e-beam] direct write, which I’d like to see end up in a mask writer,” she said. “But getting those technologies mated with the platform capabilities is key to bringing those to market.”
The key issue for developing any technology is whether there’s enough profit to be made; whether it’s worthwhile to cover the development costs of the technology, said TSMC’s Burn Lin. “Take nanoimprint or maskless or whatever. If it’s a good NGL, it will take over the entire generation, and that’s a huge market.” He added that just one chipmaker adopting a technology could provide a market of almost 2 billion euros ($3.13B) based on a need of 60 tools. “A few companies together is a huge business case.”
Freescale’s Will Conley pointed to the benefit of working together and sharing costs, such as efforts going on at Albany NanoTech and IMEC. “I can speak on behalf of Freescale, where the amount of money we’re paying into it is quite small, and the benefit is quite large,” he said. “And so that benefit is not just large to us as a user, but it also can be very large to the equipment companies in general.”
Although some of the innovative technologies face technical challenges of their own — such as source power for EUV lithography or high-index lens material development for the next generation of immersion lithography — panelists noted also how much they share in the way of infrastructure concerns. A key concern for double patterning, for example, is overlay, noted IBM’s David Medeiros. “And that’s certainly an infrastructure element that’s going to affect all of the technologies,” he said. “So we really need a lot of focus on all of the contributors to the overlay budget — not just the tooling contributions, but also the mask image placement and the process residuals.”
Another key focus area for double patterning, Medeiros added, is in data prep volumes and the handling of that data for mask creation. Golda added, “I think mask infrastructure is the one that crosses just about everything here except maskless — in terms of the data prep, data volumes, getting high-productivity writers…” Data volume is less of a concern at this point for EUV lithography, she said, but other pieces of the infrastructure — including mask inspection, overlay, resists and LER — are common to most of the technologies.
Imprint is looking at the pellicle-less mask handling infrastructure, according to Sreenivasan. “We’re looking into what’s been done for EUV. That certainly will help us; there’s some synergy there between what’s been done there and what we would need,” he said. “But for us to really get down to the defect levels that people would desire, I think really understanding how you would protect your mask through the entire cycle of its usage is very important for us.”
Medeiros added, “I think there’s also a good opportunity with the advent of nanoimprint and the focus on 1× template making to maybe beef up the infrastructure resources towards photomask making in general — a historically underfunded business.”
For high-index immersion lithography, however, “it’s all about the LuAG,” Conley said. Currently, the uncertainty of the feasibility of LuAG materials for use in high-index lens elements is seen as something of a showstopper, but getting the funding needed to make progress quickly has been difficult. “Well, first thing, you can’t have a supplier cancelling the program,” Conley quipped, making reference to the announcement made earlier in the day that Nikon was discontinuing its high-index immersion program. “The presentation from [Nikon’s Soichi] Owa-san is quite telling in LuAG development. So if LuAG development is improved, or the timeline is improved, then its applicability is much more viable.” Conley also made reference to comments made at the last Immersion Symposium, in which Schott’s Peter Krüll said that an investment of about $5M could give LuAG the accelerated learning that it needs. “I think that’s one EUV mask, maybe?” Conley said.
Earlier in the forum, toolmakers ASML, Nikon and Canon all gave their assessments of the feasibility of high-index immersion. As lithography expert Chris Mack pointed out, all three said basically the same thing: It’s going to remain a science project until customers commit and say that they want a tool with numerical aperture (NA) of 1.55.
In response, Conley repeated what he’d said earlier as high-index session chair, which is that high-index immersion is a “technology of attrition.” He explained, “I think what will happen is that it’s something that we will continue to work on, go ahead with. And when we have nothing else that works, when nothing else works, then that’s a possibility for us to take the existing infrastructure that we have and move forward with it.”
Comments were also made about the relatively minuscule size of investment in maskless e-beam technology compared with photon-based technologies. One question was raised about what it would take to see a significant boost in that funding.
“First of all, people have to have peace of mind in the feasibility of the technology,” Lin said. “They want to make sure there’s no showstopper. So I think the e-beam developers would have to work very diligently to show that there’s no showstopper. And whatever the concept is, it’s workable, and can be scaled up to the economical potential. And the other thing definitely is for people to realize that this is not the old e-beam; this is a new era for e-beam. And indeed, if it’s applicable, it can be an economic solution, so it’s cost and feasibility. I think if the cost potential and the feasibility can be demonstrated, that will trigger a lot of support.”
Bryan Rice, immersion lithography program manager at Sematech, pointed to what he saw as a fundamental breakdown in the funding of innovative technologies: “Do you think that the failure of the semiconductor industry as a whole to provide available and affordable solutions is an indictment of the current research environment?” he asked. Although semiconductor revenue is larger than ever, he said, the industry is seeing repeated requests for additional funding “to make relatively modest investments that might potentially make significant improvements.” He added, “I’m wondering if we can draw a correlation between the lack of available and affordable solutions and our current strategy as an industry to invest in new technologies.”
Medeiros conceded that it was a valid point. “As Will pointed out earlier, there’s a lot of consolidation for doing research,” he said. “A lot of companies are just not willing to put the money behind the research, so they’re joining together via consortia. And I think you raise a very valid point.”
Others, however, pointed to the bifurcation of the industry (in fact, Conley often brings up the “quatrification” of the industry) as a complication to the investment strategy. “There seem to be a lot more requirements coming in,” Sreenivasan said. Conley added to that point: “We saw a very nice presentation from Toshiba, where they’re talking about a 32 nm half-pitch process. For Freescale, as a low-power logic supplier, I can’t even spell 32 nm half-pitch right now. You have this huge divergence that’s going on between the two.”
