Carbon Nanotube-Based Cold Electron Beam (C-Beam) EUV Source for CNT Membrane Inspection

Extreme ultraviolet (EUV) lithography continues to drive progress in semiconductor fabrication by enabling patterning of structures smaller than 7 nm. However, contamination and debris during EUV exposure remain a significant challenge. To enhance production efficiency and device yield, it is essential to maintain clean patterning conditions. A crucial element in achieving this is the implementation of high-transmission pellicles, which serve to prevent contaminating particles from reaching the focal plane. By doing so, these pellicles significantly reduce the risk of imaging defects caused by particle interference. In this work, we present a novel debris-free EUV light source based on carbon nanotube (CNT) cold cathode electron beam emission designed specifically for pellicle inspection applications. The system generates EUV radiation by directing electron beams onto a tin (Sn) anode, achieving high-intensity, narrowband EUV light output without plasma generation or particle contamination. This compact and low-power EUV system enables reliable, high-precision measurement of pellicle transmission characteristics, even for ultrathin membranes. Three CNT-based pellicle samples were systematically evaluated under consistent operating conditions. Among these, Sample H demonstrated the highest transmittance of 94.25%$\pm ~0.40$% confirming the method’s suitability for precise performance evaluation of ultrathin EUV pellicles. These experimental results confirm the utility of the cold cathode-based electron beam (C-beam) source for quantitative EUV pellicle characterization. This work offers a scalable pathway for laboratory-scale, high-resolution EUV metrology essential to next-generation lithography.