Characterization of CNT pellicles in an EUV scanner environment and strategies to extend pellicle durability

EUV pellicles must achieve high transmission, mechanical strength, thermal stability above 1000 °C, and resistance to hydrogen-radical etching in high-power scanners. Carbon nanotube (CNT) membranes are strong candidates due to their robustness and ability to form uniform, free-standing films. We investigated CNT pellicle etching in hydrogen-radical plasma up to ~1000 °C. The etch rate showed a non-monotonic trend, peaking near 400–500 °C and becoming negligible above 800 °C, consistent with the balance of hydrogen radical adsorption, reaction, and desorption. Raman spectroscopy confirmed that elevated temperatures suppress defect formation and can enhance CNT structural order. Structural strategies, including capping and dual-density reinforcement, extended pellicle lifetime by up to eightfold compared with standard membranes. The dual-density design was demonstrated at full scale, combining improved durability with mechanical robustness. Benchmarking against industry specifications demonstrated that the CNT pellicles developed in this work meet or exceed targets for transmission, scattering, mechanical deflection, and source power capability, confirming their suitability for integration into next-generation EUV lithography systems.