Characterization of Ruthenium Thin Film on Tantalum by Electrochemical Deposition: Rutherford Backscattering Spectroscopy

The electrochemical deposition (ECD) of ruthenium (Ru) thin layer on tantalum (Ta) substrate as copper (Cu) diffusion barrier was investigated. The electron beam deposited Ta layer on Si substrates was used for the electrochemical deposition of Ru barrier layer. The smoothness and the uniformity of Ru barrier layer were increased with the increase of the deposition time at the constant current of 20 mA. The X-rays diffraction patterns of Ta substrate were remained unchanged after the ECD of Ru barrier layer which might due to the intermingling of Ta (100) and Ru (100) phase. The XPS studies demonstrated the presence of pure metallic Ru on the Ta substrate after ECD. Rutherford Backscattering Spectrometry (RBS) studies revealed that the deposited Ru barrier layer achieved an optimum thickness of 7.4 nm after 30 s of ECD and served as efficient barrier layer for the ECD of Cu thin layer. The Ta substrate and the Ru/Ta bilayer were found stable in the acid bath solution during the ECD of Cu.