Preparation and characterization of ruthenium films via an electroless deposition route

Abstract

A metallic Ru film was prepared by an electroless deposition method, followed by hydrogen reduction treatment. The electroless deposition formulation produced a solid film on a Cu-coated Si substrate at 40 degrees C preactivated by PdCl(2) solution. Chemicals including K(2)RuCl(5)center dot xH(2)O, NaNO(2), NaOH, and NaClO were mixed in a proper ratio that enabled heterogeneous nucleation and film growth. Results from X-ray photoelectron spectroscopy (XPS) on the as-deposited films confirmed the presence of RuO(x) and Ru, while X-ray diffraction (XRD) pattern suggested an amorphous nature. Planar images from a scanning electron microscope revealed a rather smooth surface at thickness less than 250 nm. Above that formation of surface crack and partial detachment from the substrate were observed. After hydrogen reduction at 200 degrees C for 2 h, we obtained a metallic Ru film, as confirmed by XPS and XRD. In addition, the surface roughness was increased due to the formation of pinholes that was caused by the volume contraction associated with RuO(x) reduction to Ru. (C) 2010 Elsevier B.V. All rights reserved.