Influence of Ru protecting layer and thermal annealing on the microstructure, surface morphology and optical properties of Mo/Si multilayer films for extreme ultraviolet lithography
Chao-Te Lee1*, Hung-Pin Chen1, Po-Kai Chiu1, Donyau Chiang1, Bo-Heng Liu1, Chien-Nan Hsiao1
1Instrument Technology Research Center, Hsinchu, Taiwan
* presenting author:Chao-Te Lee,
In this work, the Mo and Si materials with various complex refractive index were been used to design the Mo/Si periodic films application in high-reflectivity extreme ultraviolet (EUV) mirror. The Mo/Si multilayer films were deposited on Si substrate at room temperature by RF magnetron sputtering with Mo, and Si targets. The Ru protecting layer was deposited on the Mo/Si multilayers by plasma-enhanced atomic layer deposition (PEALD) using Ru(EtCp)2 precursor and H2 plasma. The effects of substrate temperature, and RF power of Ru film growth by PEALD and thermal annealing (400~600 °C) on the microstructure, roughness and EUV reflectance of Mo/Si periodic films were investigated by field emission scanning electron microscopy, X-ray diffraction, atomic force microscopy, high resolution transmission electron microscope, X-ray photoelectron spectroscopy (XPS), and EUV spectrometer. The possibility of Mo/B4C/Si/B4C…/Ru films with high reflectance and thermal stable application for EUVL mask blank was also investigated.

Keywords: extreme ultraviolet lithography, plasma-enhanced atomic layer deposition, precursor, mask blank