Porous pellicle engineering: extending the limits of thin-film EUV pellicle technology

As extreme ultraviolet (EUV) lithography advances toward higher source power, EUV pellicles must simultaneously meet demanding requirements in optical transmittance, mechanical and thermal stability. In this study, a porous pellicle platform is proposed based on SiN_x and MoSi₂/SiN_x composite structures. Porous membranes with nanometer-scale hole arrays were fabricated using triangular and square patterns, and the resultant structural parameters were confirmed. EUV transmittance measurements showed significant improvements up to 95.5% for thinned SiNx_x pellicles and 93.4% for MoSi₂/SiN_x porous pellicles. Bulge testing confirmed the pressure-relief behavior of the porous architecture, which prevented rupture under differential pressure by facilitating flow through the holes. Additionally, under low-vacuum heat load conditions approximating scanner environments, porous pellicles exhibited reduced peak temperatures, attributed to enhanced convective cooling through the patterned openings. These findings highlight the feasibility of porous architecture as an effective design strategy for next-generation EUV pellicles, offering a balanced enhancement across optical, mechanical, and thermal performance metrics.