Extreme ultraviolet light source with cold cathode electron beam using silicon solid target

Abstract We report on the significant enhancement of extreme ultraviolet (EUV) light power with a cold cathode electron-beam by substituting the conventional tin (Sn) excitation anode with a solid silicon (Si) target. Conventionally, a solid anode for EUV generation would be very difficult to apply the high input power for EUV generation due to debris generation. The industry has developed a very small droplet of solid Sn to generate EUV light with a high power laser irradiation technique. However, mitigating Sn debris remains a significant technical challenge. Thus, we developed novel debris-free EUV light with a cold cathode electron beam (C-beam) with a solid Si anode target. While Sn provides high conversion efficiency, its application in solid-target systems has limitations to operate with the high input power of the electron beam, laser and discharge due to its low melting point, limiting the maximum allowable input power with a solid target. To obtain higher EUV power, we should consider the anode power thermal load to enhance EUV photon power. Consequently, we achieved a 4-fold increase in the absolute EUV photon current compared to the maximum output obtainable from the solid Sn target. This result suggests the possibility of Si based EUV light sources as next generation high power EUV inspection tools.