The availability of EUV light sources, measurement tools, and integrated test systems is of major importance for the development of EUVL to be used in high-volume chip manufacturing, which is expected to start in 2009. For economic use of EUVL, a throughput of 100 wafers per hour will be necessary, as estimated from the cost of an EUV exposure tool in combination with sophisticated throughput models. This means that light sources will be necessary that deliver an EUV output power of 115 W at 13.5 nm at the entrance of the illuminator system. The choice of the wavelength is derived from a general convention to use Mo∕Si-based reflection coatings on the near-normal-incidence mirrors of the lithography system. The power specification in combination with the required lifetimes of source components and collector optics makes the source technology the most critical issue in developing EUVL. LPPs as sources for EUV radiation are a promising technical approach because of their physical principle, which allows one to manage the thermal load of source components to provide sufficient component lifetimes. As a result, the EUV output power seems to be scalable to high-volume manufacturing (HVM) requirements.
At XTREME technologies GmbH—a joint venture of Lambda Physik AG, Göttingen, and Jenoptik LOS GmbH, Jena, Germany—EUV sources based on the generation of a plasma by an electrical gas discharge and by laser excitation have been investigated and developed since 2001. This chapter gives an overview of the basics of LPP EUV sources and their technology, the development roadmap, and the current state of the art of these light sources at XTREME technologies. An overview of GDPP EUV sources at XTREME technologies is contained in Chapter 14.
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