Infrared Emissivity–Resistivity Correlation of RU Thin Films for EUV Pellicle Applications.

A high-infrared (IR) emissivity is required to dissipate heat effectively from high-temperature surfaces even in a near-vacuum environment. This radiative cooling capability is essential for the emissive layer of EUV pellicles operating under high vacuum conditions with increasing EUV source powers to ensure thermomechanical stability. We compute the IR emissivity of metal films by combining the classical oscillator model and DFT calculations. Based on the calculations, we predict a positive correlation between the electrical resistivity and IR emissivity of metal films, which is consistent with a recent experiment on Ru thin films. Our findings can provide a practical indicator for achieving high IR emissivity of metallic thin films based on electrical measurements. This emissivity–resistivity correlation can provide an effective way to search a large material space, and choose and synthesize a highly emissive layer of EUV pellicles. In this study, we computed the infrared absorbance of Ru thin films through the integration of the classical Drude-Lorentz oscillator model and DFT calculations. According to the Kirchhoff's law of thermal radiation, the IR absorbance is equal to the IR emittance. Based on the calculated results, we propose a positive correlation between IR emissivity and electrical resistivity. [ABSTRACT FROM AUTHOR]