The timely availability of EUV light sources, measurement tools, and integrated test systems is of major importance during the development phase of EUVL for use in high-volume chip manufacturing, which is expected to start in 2009. The cost estimates of an EUV exposure tool in combination with sophisticated throughput models lead to a throughput requirement of 80–120 wafers (300-mm diameter) per hour for economic use of EUVL. The projection for the necessary EUV output power from the light source is 115 W at a 13.5-nm wavelength at the entrance of the illuminator system for an estimated resist dose of 5 mJ∕cm2. The EUV power requirement, in combination with the necessary lifetimes of source components and collector optics, has made source technology one of the most critical issues in developing EUVL.
Gas-discharge-produced plasma (GDPP) EUV sources that are based on socalled Z-pinch arrangements are a promising technological approach to critical technical issues in EUV sources. GDPP Z-pinch sources have been proven to possess a high intrinsic efficiency and very good stability as well as low complexity. Since 2001 the EUV output power of Z-pinch sources at XTREME technologies GmbH has been increased by two orders of magnitude to 400 W in 2π sr in continuous operation (see Fig. 14.1). Thus Z-pinch sources are currently the most powerful EUV sources for lithography development. Their EUV output power is likely scalable to high-volume manufacturing (HVM) requirements. Moreover, with appropriate electrode design, the lifetime requirements of source components also seem to be reachable.
This chapter gives an overview of GDPP Z-pinch source basics and an update of the development status of these EUV light sources at XTREME technologies GmbH, operating in Jena and Göttingen, Germany, including some recent achievements (early 2005). Opportunities, challenges, and risks in developing Z-pinch GDPP sources to HVM lithography specifications are discussed as well.
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