Composition-dependent properties of ultra-thin MoSi<i> _x </i> based extreme ultraviolet pellicle

Extreme ultraviolet (EUV) pellicle is essential for protecting photomask from external contamination in EUV lithography (EUVL), a critical technology for nanometer-scale photolithography. However, achieving high optical transmittance, thermal stability, and mechanical robustness in pellicle for high-power EUVL processes remains challenging. This study fabricated EUV pellicles using multilayer MoSi<i>_x</i>thin films with varying Mo-to-Si ratios and protective capping layers. As Mo content increased, mechanical and thermal properties improved, while optical transmittance decreased. MoSi₂(<i>x</i>= 2) exhibited the highest tensile strength and >90% fabrication yield. In contrast, MoSi₃.₄(<i>x</i>= 3.4) showed enhanced optical properties, and MoSi₂.₃(<i>x</i>= 2.3) offered superior thermal performance. These results highlight the composition-dependent trade-offs in optimizing pellicle performance for EUVL applications. In contrast to previous studies, which investigated a single MoSi₂composition, this study systematically explores a broad compositional range of MoSi<i>_x</i>(<i>x</i>= 1.6-3.4). A distinct contribution of this work is the quantitative linkage established between mechanical performance, particularly ultimate tensile strength, and fabrication yield. The results reveal that no single composition optimizes all critical properties simultaneously, highlighting the necessity of trade-off-based material selection for application-specific requirements in EUVL. This study offers a guideline for optimizing EUV pellicle design, contributing to higher wafer throughput, improved equipment utilization, and reduced operational costs in high-volume lithography.