Atom beam sputtered Mo2C films as a diffusion barrier for copper metallization

The saddle field fast atom beam sputtered (ABS) 50 nm thick molybdenum carbide (Mo2C) films as a diffusion barrier for copper metallization were investigated. To study the diffusion barrier properties of Mo2C films, the as-deposited and annealed samples were characterized using four probes, X-ray diffraction, field enhanced scanning electron microscopy, energy dispersive X-ray analysis, atomic force microscopy and Rutherford back scattering techniques. The amorphous structure of the barrier films along with presence of carbon atoms at the molybdenum carbide-silicon interface is understood to reduce effective grain boundaries and responsible for increased thermal stability of Cu/Mo2C/Si structure. The lowest resistivity of the as-deposited molybdenum carbide barrier films was similar to 29 mu Omega cm. The low carbon containing molybdenum carbide was found thermally stable up to 700 degrees C, therefore can potentially be used as a diffusion barrier for copper metallization. (C) 2008 Elsevier B.V. All rights reserved.