Diffusion barrier effects of transition metals for Cu/M/Si multilayers (M=Cr, Ti, Nb, Mo, Ta, W)

In order to find appropriate diffusion barrier materials for Cu, the diffusion of Cu into Si through various barrier metals M (M=Cr, Ti, Nb, Mo, Ta, W) was investigated. The behavior of Cu in Cu/M/Si multilayers was measured after annealing using x‐ray diffraction analysis, secondary ion mass spectroscopy, Rutherford backscattering spectroscopy, and electric resistance change. Only Cu/Ta/Si and Cu/W/Si multilayers retained their multilayer structures after annealing at 600 °C×1 h in H2 without resistivity increases. Multilayers of the other metals did not retain their structures after the same annealing condition. This difference in the barrier properties of the transition metals appeared to be related to the metal‐Cu binary phase diagrams and their self‐diffusion coefficients.

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