Development of a cold electron-beam-driven compact EUV source for next-generation inspection tools. Part I: design, fabrication, and evaluation of long-lifetime and reproducibility of source

BackgroundStable and reproducible extreme ultraviolet (EUV) light generation is essential for advanced semiconductor lithography and actinic inspection. Conventional plasma-based EUV sources, such as laser-produced plasma and discharge-produced plasma, provide high output power but suffer from high power consumption, mirror contamination, electrode erosion, plasma instabilities, rapid optics degradation, and system complexity.AimWe (part I) focus on the design, long-term reliability, reproducibility, and operational stability of a vertically aligned carbon nanotube (CNT)-based cold electron-beam (C-beam)-driven EUV light source. The physical emission mechanism and source efficiency analysis are presented in the companion paper (part II).ApproachWe demonstrate a CNT cold cathode electron-beam (C-beam)-irradiated EUV source based on surface-excitation-driven EUV emission. The system operates at an optimized irradiation condition using a tin anode mounted on a copper jig, enabling controlled EUV generation while suppressing anode melting and cathode degradation.ResultsCompared with our previous lab measurements, the proposed C-beam EUV source exhibits a significant improvement in temporal stability. Short-term stability improved from 2.0% to 0.6%, whereas long-term stability improved from 4.0% to 2.5%. The source demonstrates durable and reproducible EUV emission without observable degradation of either the cathode or anode.ConclusionsThe CNT-based C-beam EUV source offers a compact form factor, low operating power, debris-free operation, and high temporal stability. These characteristics make it a promising candidate for actinic metrology and semiconductor inspection systems that require highly reproducible EUV emission and long operational lifetimes.