Physical and electrical analysis of Rux Yy alloys for gate electrode applications

Abstract

This letter describes Rux Yy as a potential candidate for dual metal complementary metal-oxide-semiconductor applications. The characterization of RuY alloys indicate that the effective work function can be controlled from 3.9 to 5.0 eV as the yttrium composition in the Rux Yy is decreased in film for both PMOS and NMOS application. From x-ray photoelectron spectroscopy analysis, it was found that the Ru 3d peaks do not change as the Y composition is changed, indicating the Ru-Y bonding is very weak or undetectable in Rux Yy film. However, it was also found that Y reacts with the underlying Si O2 to form yttrium silicate. In addition, in situ x-ray diffraction results did not detect the presence of Ru-Y compound in the Rux Yy films. Capacitance-voltage (C-V) characterization indicated that the oxide thickness decreased as the Y composition increased. We extracted the effective barrier height of Rux Yy at the metal-oxide interface via Fowler-Nordheim current analysis. The barrier height decreases as the Y composition increased. This agrees with the change of Rux Yy work function which was extracted from the C-V analysis. © 2005 American Institute of Physics.