Tetsuya Tomofuji

Factors Affecting Extreme Ultraviolet Reflectivity of Mo/Si Multilayer Films Synthesized by Superconducting Magnetron Sputtering

We first tried to determine the thickness of both Si-on-Mo and Mo-on-Si interdiffusion layers inherent in the Mo/Si multilayer films by taking high angle angular dark-field-scanning transmission electron microscopy (HAADF-STEM) images. Secondly, the origin of 2–5% shortage of the measured extreme ultraviolet (EUV) reflectivity relative to that expected from the Fresnel equation has been investigated from two possible viewpoints: one, the presence of residual Xe gas atoms incorporated into the film during deposition in the reduced Xe gas atmosphere, and the other, a gradual shift of the layer periodicity over an entire cycle of repeated depositions. By analyzing the grazing incident X-ray reflectivity (GIXR) spectra for the 50-layer films, we were able to demonstrate that the latter is responsible for lowering the EUV reflectivity.