Interfacial adhesion energies of Ru-Mn direct plateable diffusion barriers prepared by atomic layer deposition for advanced Cu interconnects

Abstract

The effects of Mn addition and post-annealing on the interfacial decohesion energies of Ru direct plateable diffusion barrier layer prepared by atomic layer deposited (ALD) for advanced Cu interconnect applications were systematically evaluated using a four-point bending test. The interfacial decohesion energy increased with the addition of Mn to the Ru thin films and further increased after post-annealing at 500 degrees C for 30 min in a hydrogen atmosphere, and the interfacial decohesion energies were 3.63, 6.74, and 20.09 J/m(2) for the as-deposited Cu/Ru/SiO2, as-deposited Cu/Ru-4.2 at.%Mn/SiO2, and annealed Cu/Ru-4.2 at.%Mn/SiO2, respectively. The scanning transmission electron microscopy (STEM) and energy dispersive spectroscopy (EDS) analysis results clearly indicated that the Mn in the annealed ALD Ru-Mn film diffused toward a Ru/SiO2 interface and Mn silicate was formed at the Ru/SiO2 interface. Additionally, the results of the X-ray photoelectron spectroscopy (XPS) analysis clearly showed that MnSiO3 and MnSi were formed at the Ru/SiO2 interface. Consequently, the findings of the XPS and STEM/EDS study revealed that there was an adequate correlation between the interfacial decohesion energy and the MnSi and MnSiO3 bond formed at the Ru-Mn /SiO2 interface. Therefore, a properly annealed ALD Ru-4.2Mn thin film appears to be a hopeful diffusion barrier layer candidate with strong interfacial reliability for advanced Cu interconnects.