EUV Sources and Engineering the Impossible
“The difficult we do immediately, the impossible takes longer” is a quote ascribed to different individuals in history. The sentiment is surely felt in the hearts of the valiant engineers working overtime to create vital new manufacturing technologies for IC production. Of all the new engineering challenges, few push the boundaries of the possible like creating extreme ultra-violet (EUV) sources for high-volume manufacturing (HVM).
EUV lithography requires the entire infrastructure of exposure tools, masks, sources, and resist. Ron Kool directs product marketing for EUV tool developer ASML, and we had a brief chance to chat during SEMICON West about the engineering challenges of EUV source hardware. There are two ways that tin (Sn) is used to create a beam of electro-magnetic energy for EUV steppers: laser pulsed plasma (LPP) and electrical-Discharge Produced Plasma (DPP). In both, a liquid Sn plasma is pulsed with energy so that electron decay emits a pulse of ~13.5nm wavelength EUV. The source sub-systems must balance material flows, laser beams, energy pulses, and cooling at incredibly high speeds.
Kool acknowledged that these source technologies look dauntingly complex, but no more so than the water immersion 193nm (193i) steppers that are the current industry work-horses. If we remember back to the first pilot line work on 193i, the engineering challenges appeared nearly impossible: reduced throughput, uncontrolled yield losses, and serious resist issues. All those problems were solved.
During the week of SEMICON West this year, Gigaphoton announced that its original technology for mitigating debris with magnetic fields for laser-produced plasma (LPP) sources is successfully removing 92% of Sn debris. Scheduled to be shipped in the beginning of 2012, this announcement verifies that Gigaphoton has proven its technology a number of times. Details of Gigaphoton’s plans to reach 250W output power, along with the most recent results for the Cymer and Xtreme EUV sources, were reported on earlier this year by M. David Levenson at BetaSights. No worries, the industry is once again engineering the impossible.