While the exact cost crossover point between EUVL and multiple-patterning 193i varies by product (such as DRAM and logic), WPH of should be a fair metric for gauging the success of EUVL in HVM. In the past few years, EUV source suppliers have made substantial progress through hard work, investment, and innovation. However, clean EUV power currently supports less than 10 WPH. In order to sustain Moore’s law, speedy progress in EUV source technology in the next 24 months is crucial. In addition, metrology tools for EUV masks have different requirements for EUV sources, including high brightness and low average power. Since the cost of metrology is part of the overall cost of EUVL, the throughput of metrology tools must be equally scrutinized, which again brings us to needing continuous progress in using EUV sources for metrology.