Improvement of the Crystal Orientation and Surface Roughness of Ru Thin Films by Introducing Oxygen during Sputtering

Abstract

Thin films of noble metals are considered to be important materials for microelectronics applications. In this study, Ru thin films were deposited on SiO2/Si substrates by RF magnetron sputtering using a mixture of Ar and O2 gases, and the effects of O2 flow ratio, substrate temperature and film thickness on the crystal orientation and surface roughness of the films were studied. Single orientation (001) Ru thin films were formed under appropriate conditions, such as O2 flow ratios lower than that required for RuO2 formation and high substrate temperatures. A minimum full-width at half-maximum of 1.2° was obtained for the rocking curve of the Ru (002) X-ray diffraction peak. The average surface roughness (Ra) of the single orientation films was estimated to be approximately 1 nm by atomic force microscopy. The oxygen introduced during sputtering was thought to play a role as a surfactant.