To boost the productivity of extreme ultraviolet (EUV) lithography, the development of an EUV pellicle that not only has excellent optical properties such as high EUV transmittance and low reflectance but also can withstand
high-power EUV light sources is in progress. In this paper, zirconium silicide (ZrSi2)-based pellicles were fabricated and optical, mechanical, and thermal properties were evaluated to verify their applicability to EUV pellicle materials.
ZrSi2 composite pellicle was fabricated by depositing ZrSi2 on a silicon nitride (SiNx) free-standing membrane. The heat load test that emulates EUV exposure conditions was performed to evaluate the thermal properties. The optical and mechanical properties were evaluated by an EUV microscope and bulge test, respectively.
As a result of the thermal load test, the emissivity of ZrSi2 was measured to be 0.18-0.29 at a ZrSi2 thickness of 10-40 nm, and the emissivity increased as the thickness increased. The ZrSi2-based pellicle of Si/ZrSi2/SiNx structure meets optical requirements with EUV transmittance and EUV reflectance of 92.7% and 0.04% or less, respectively. In addition, the ultimate tensile strength (UTS) of this composite pellicle was measured to be about 3.5 GPa. From these results, it is expected that ZrSi2 can be used as an EUV pellicle material.
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