Evaluation of the thermal stability of reactively sputtered (Ti, Zr)Nx nano-thin films as diffusion barriers between Cu and Silicon

Refractory binary metal nitride films, (Ti, Zr)Nx, were prepared by direct current reactive magnetron sputtering from a Ti-5 at.% Zr alloy target in N2 / Ar gas mixtures and then used as diffusion barriers between Cu and Si substrates. In order to investigate the thermal stability of Cu (60 nm) / (Ti, Zr)Nx (6 nm) / Si contact systems, sheet resistance measurement, X-ray diffraction, scanning electron microscopy, cross-section transmission electron microscopy, and X-ray photoelectron spectroscopy depth profile were performed. Experimental results indicate that the barrier performance are significantly affected by the chemical composition of (Ti, Zr)Nx films, N / (Ti, Zr) atomic ratio. Besides, our results also suggest that the refractory binary metal nitride film, (Ti, Zr)Nx, can be used as a superior diffusion barrier for Cu metallization as compared to the well-known TaN film.