Debris-free high-brightness light source based on LPP for actinic EUV microscopy and metrology applications

The progress of EUVL and the introduction of HVM scanners demands advanced actinic metrology especially for the EUV mask supply chain. For stand alone field use reliable metrology sources for EUV inband emission around 13.5 nm are critically needed. For nanometer resolution the effective “inband brightness” is extremely important. Laser produced EUV sources (LPP) are cost effective with efficient energy use thus providing a reliable approach for real-life industrial applications. However, apart from the Cymer/ASML LPP scanner source no such source is available. One reason is that realizing a reliable tin droplet target is beyond the technical and financial scope of a metrology source. In this paper, we propose a path to make industrial laser produced plasma based EUV sources reliable and with easy renewable targets a reality.