Mo/Multilayer graphene/SiN composite membranes with high EUV transmittance and mechanical robustness for EUV pellicles.

Abstract

Multilayer graphene (MLG) is a promising membrane material for extreme ultraviolet (EUV) pellicles because it combines high optical transparency with outstanding mechanical properties. However, practical implementation requires precise control of graphene thickness and uniformity while maintaining sufficient mechanical robustness. In this work, we demonstrate the controlled synthesis of few-layer MLG by chemical vapor deposition (CVD) using Ni and NiCu alloy catalysts and its integration into freestanding Mo/MLG/SiN composite membranes for EUV pellicle applications. The graphene thickness and uniformity were systematically tailored through catalyst composition and growth-condition optimization. Increasing the Cu content reduced the average graphene thickness from approximately eight to four layers while improving large-area thickness uniformity to below 5%, as confirmed by optical-contrast mapping and Raman spectroscopy. Transfer-matrix modeling predicted that a multilayer structure comprising an approximately 5 nm-thick MLG layer with ultrathin Mo and SiN capping layers can achieve an EUV transmittance exceeding 90% at a wavelength of 13.5 nm.Based on this design, freestanding Mo/MLG/SiN composite membranes were fabricated and evaluated by bulge testing. Increasing the MLG thickness enhanced the rupture pressure, rupture deflection, and ultimate tensile strength, while the Mo capping layer further improved fracture tolerance and overall mechanical reliability. These findings establish a practical design strategy for realizing mechanically robust and highly transparent EUV pellicles through precise control of graphene growth and multilayer membrane architecture.

Abstract as supplied by the indexing source. © the authors / publisher.