Cymer Is ASML’s Source Supplier for Volume EUV Scanners
David Lammers, News Editor -- Semiconductor International, 7/20/2007
Cymer Inc. (San Diego) announced at SEMICON West 2007 in San Francisco this week that it will be the source supplier for ASML's (Veldhoven, Netherlands) extreme ultraviolet (EUV) lithography tools, a critical step toward bringing EUV lithography to high-volume manufacturing.
Cymer and ASML signed a multi-year, multi-unit EUV source agreement, with late 2008 as the target for the first shipment of its laser-produced plasma (LPP) sources. Bob Akins, CEO of Cymer, said that the company achieved a 50 W power level in June, and is “on track” to the higher levels of source performance required for sub-32 nm exposure tools.
Cymer employs an LPP system based on a multi-staged carbon dioxide (CO2) laser and droplets of tin as the target, an approach that has been in operation at Cymer for more than a year. While tin has a higher conversion efficiency than other source targets such as xenon, the downside is that tin produces more debris, which, if uncontrolled, can damage the expensive collector optics. Early this year, Cymer said it had developed a debris mitigation technology that will extend the lifetime of the multi-layer-mirror (MLM) collector.
ASML last year shipped EUV alpha demonstration tools to IMEC (Leuven, Belgium) and the Albany College of Nanoscale Science and Engineering (Albany, N.Y.). Operation was delayed somewhat until an improved debris mitigation subsystem could be installed. Dense patterns and contact holes were exposed at 32 nm in March at the research consortia.
At SEMICON West, IMEC executive vice president Ludo Deferm said the discharge-produced plasma (DPP) source used on the EUV alpha demonstration scanner at IMEC results in only 0.2 wph of throughput. “Already, our lithography program partners are asking us to speed things up, but we are limited by the source,” said Deferm, who is in charge of business development at IMEC. “Fortunately, we also have an interferometer-based EUV system that we can also use for resist development, but we need the alpha scanner for masks and other types of EUV development.” Both IMEC and Albany Nanotech use a DPP source provided by Philips.
For volume production, experts believe ~180 W of source power will be needed to reach the throughput targets required for volume manufacturing. Even that target depends on the quality of the reflective optics, as well as resist dose, which determines in part the power of the light on the wafer.
“We are confident that Cymer will help us make production-worthy EUV lithography a reality,” said Martin van den Brink, executive vice president of marketing and technology at ASML. “The sources delivered to ASML have the potential to expose 100 wph, which is required for cost-effective EUV chip manufacturing.”
