10-nm-thick quinary (AlCrTaTiZr)N film as effective diffusion barrier for Cu interconnects at 900 °C

In this study, an ultrathin quinary nitride film (AlCrTaTiZr)N of only 10 nm thick has been developed as a diffusion barrier layer for Cu interconnects. The (AlCrTaTiZr)N nanocomposite film was constructed of nanocrystallites embedded in an amorphous matrix. At an extremely high temperature of 900 °C, the Si/(AlCrTaTiZr)N/Cu film stack remained thermally stable. Neither interdiffusion between Si and Cu through the (AlCrTaTiZr)N layer nor formation of any silicides occurred. The nanocomposite structure and severe lattice distortions attributed to the addition of multiple elements were expected as the dominant factors for the superior diffusion resistance of the (AlCrTaTiZr)N film.