Based on several years of development work, multiple source vendors and research institutions dealing with EUV lithography are demonstrating a strong rise in performance of EUV sources. One of the EUV source types, namely Discharge Produced Plasma (DPP) source, powers the installed EUV ASML scanners. One of the critical aspects of the integrated source performance proved to be lifetime of the collector optics in the source-collector assembly. The factor which determines this life time is ion sputtering of the material at the surface of the collector. The ions are in turn being generated by the DPP itself. This research focuses on the characterization of the fast ionic debris in the range up to 100 keV with extreme sputtering efficiencies. The ion beam emitted from the DPP is analyzed using different time-of-flight techniques while the discharge was monitored by a current probe and gated MCP imaging. By varying the ignition parameters the maximum kinetic energy of the emitted fast ions could be reduced and thus the lifetime of the collector can be increased with a factor of 5-10x.
|Title of host publication||Proceedings of the International Symposium on Extreme Ultraviolet Lithography 2008 (2008 EUV Symposium), 28 September-1 October 2008, Lake Tahoe, USA|
|Publication status||Published - 2008|