<p>This study explores the use of ultra-thin Mo and Mo₂C films as protective capping layers for graphene-based EUV pellicles, which are essential for next-generation lithography. As semiconductor miniaturization progresses, EUV lithography utilizing materials with high transmittance and mechanical strength, such as graphene, becomes increasingly critical. However, graphene’s vulnerability to hydrogen radicals generated in EUV environments presents a significant challenge. In this research, films less than 5&#xa0;nm thick of Mo and Mo₂C were deposited on ozone-treated and untreated graphene films using electron-beam evaporation and flip-sputtering methods, respectively. The results reveal that Mo films deposited by e-beam evaporation are prone to etching and cause severe damage to the underlying graphene due to chemical reactions with hydrogen radicals, although Mo films deposited on ozone-treated graphene exhibited higher resistance. Conversely, for amorphous Mo₂C films deposited via sputtering, atomic defects in the graphene increased with prolonged hydrogen exposure, indicating radical penetration through the film. These findings suggest that while Mo offers limited protection, Mo₂C has the potential to serve as an effective capping material for graphene EUV pellicles, provided its resistance to hydrogen radicals can be further enhanced through crystallization. Consequently, strategies to improve the stability and adhesion of Mo₂C are proposed, aiming to develop high-performance, durable pellicle materials for future EUV lithography applications.</p> Graphical Abstract <p></p>