Comparative Study of Cu Diffusion in Ru and Ru-C Films for Cu Metallization.

In this paper, the diffusivities of copper in 15 nm thick Ru and Ru-C barrier layers are determined experimentally by using sheet resistance and X-ray diffraction measurements with the Cu/barrier/Si samples. By fitting the dependence of diffusivities on temperature, the activation energy for Cu diffusion in Ru-C film is 1.11 eV, which is substantially higher than that n Ru film (0.54 eV). Microstructural analysis by transmission electron microscopy combined with energy-dispersive X-ray suggests that the higher activation energy for Cu diffusion Ru-C is associated with the stuffing of added carbon atoms on the grain boundaries of the Ru matrix and consequently leading to the superior diffusion barrier performance of the Ru-C film. [ABSTRACT FROM AUTHOR]