The failure mode and Cu barrier properties of a 5 nm thick boron and carbon added Ru (Ru-B-C) film deposited on Si substrate have been investigated. Results from X-ray diffraction (XRD) and Fourier-transformed electron diffraction patterns indicate that the Ru-B-C film is amorphous up to 700 degrees C. Unlike pure Ru film, the Ru in the Ru-B-C film recrystallized at 750 degrees C instead of reacting with Si at the interface to form Ru2Si3. The sheet resistance and XRD results show that the 5 nm Ru-B-C barrier is thermally stable up to 750 degrees C, whereas the 5 and 10 nm Ru are only stable below 550 and 600 degrees C, respectively. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3442753] All rights reserved.