Selete Symposium 2002: Progress in e-beam, 157nm
08/01/2002
E-beam seems to look a lot better from the Japanese side of the Pacific. The approach shared attention with 157nm technology at Selete Symposium 2002, the consortium's annual update on the progress of its research programs.
While there is still an alarming divergence of opinion about the future direction of next-generation lithography (NGL), Matsushita Process Technology Center's Masaru Sasago's survey of Japanese NGL plans found nearly as much support for e-beam projection as for F2 technology for the 65nm node (see figure). The survey also found considerable hope still for the extension of ArF technology.
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Sasago's overview of lithography trends figured e-beam direct write and e-beam projection technology would be needed on critical layers to meet roadmap targets for both 157nm and extreme ultraviolet production. Because of 157nm's limited depth of focus, he concluded, "EPL is the main candidate for NGL contact holes."
Selete's report on its own work with TEL, using Nikon's 4x electron beam projection lithography (EPL) tool, claimed significant progress in preventing pattern collapse by slowing rotation speed during rinsing and adding a surfactant, and by a supercritical drying process developed with Kobelco and Nikon. Masaki Yamabe, of Selete's Research Department 2, said they were getting high resolution with good CD control and figured cost of ownership would be low, especially for system-on-chip (SOC) applications.
The target is an R&D tool with 100-70nm resolution in 2003 and a 45nm production tool in 2005. Still, throughput is expected to only be 4-8 wafers/hr next year, and only 10-20wph by 2005. (Full handouts from this and many of the rest of the symposium presentations are available online at www.selete.co.jp.)
Selete's F2 lithography group, however, has already printed 55nm lines. Toshiro Itani reported the 0.85 NA microstepper developed with Exitech, using a Lambda Physik light source, was working well, though it has only a 0.5mm2 field. Their fluoropolymer resist appeared to be sufficiently (>60%) optically transparent, resistant to dry etching, and soluble in alkaline developer. He said both attenuated and alternating phase-shift masks looked like they would work with enough exposure latitude for production of 70nm lines and spaces.
Joint development with suppliers of better maskmaking tools to bring down mask costs is also proceeding.
Nobuyuki Yoshioka, of Selete's optical lithography photomask program, said the 100nm-node inspection tool developed with NEC can now detect defects down to 60-75nm, depending on the type of defect. They are working on a new platform for the 70nm tool with NEC and Toshiba. The 100nm defect repair tool developed with Seiko Instruments can repair down to its target accuracy of 15nm at 3σ, and they are working on a new platform for the 70nm model that targets 7nm accuracy. It uses Ga FIB and e-beam to repair clear defects with carbon patches and opaque defects with gas etching. The mask writer being developed with Hitachi High Tech, JEOL, and Toshiba Machine uses shaped e-beam and a standard data format.
Selete's goal is practical, cost-effective 70nm process technology, particularly for SOC devices, by September 2004.
— Paula Doe, Contributing Editor
Future chip market may look familiar
While the US is waiting for the rebound in corporate IT spending to jumpstart PC demand and get the chip market hopping again, the keynote speaker at Selete's Symposium 2002 does not think that is going to happen. TEK Consulting president Tsuyoshi Kawanishi figures the consumer, automotive, and enhanced broadband communications applications currently driving chip demand are just what is going to continue to drive the market through the next decade. The former Toshiba Semiconductor executive, who is also one of the founding forces behind SMIC, figures the personal computer market will average only 10% annual growth for the five-year period through 2003, while the cellular phone and PDA market averages 40% growth, and that for digital consumer appliances sees 50% annual increases.
While the rest of the world may be writing off Japan's semiconductor industry, Kawanishi thinks Japan could be well-positioned for a strong recovery in this new era, provided its chipmakers can make the necessary management reforms.
The growth in consumer and broadband communication products plays to Japan's lead in technologies ranging from advanced-generation internet phones and digital broadcasting to displays and batteries. Also, any move toward faster time-to-market, smaller production lots, and shorter product life cycles plays to the country's lead in the development of quick-turnaround minifabs.— P.D.