Sn film and ignition control for performance enhancement of laser-triggered DPP source

A laser-triggered DPP source is being developed and showing considerable progress toward HVM. Performance, in terms of power and lifetime, of DPP sources has been proven by long-term usage in lithography development fields. Since high-performance debris-mitigation tools are used in DPP sources, collector lifetime is not an issue. However, it is worth developing the technology to enhance overall lifetime of the collector module. In order to suppress both neutral and ionic debris, two technologies, which can be simultaneously used in a DPP source, have been developed. First, a discharge ignition by using two lasers was developed. It was able to reduce the amount and energy of fast ions which could sputter a collector by a factor of 5. In addition to fast ion reduction, CE enhancement of 60 % was obtained. Second, an active control of liquid tin layer, which acts as a fuel material, electrode protection and cooling medium, could reduce particle debris and lower the load of a debris-mitigation tool. Implementing these technologies is considered to provide enhancement of the lifetime of the collector module and support HVM readiness.