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A weakly Ti-doped copper nitride (Cu3N) film was prepared by cylindrical magnetron sputtering. The XPS results indicate that Ti atoms do not substitute for the Cu atoms but probably locate at the grain boundaries. The columnar grains size is about half of that of the undoped Cu3N film and the surface is smoother. For weakly Ti-doped Cu3N films, a dense layer appears on top of the columnar crystals. The RMS of the Cu film formed by annealing of the weakly Ti-doped Cu3N film is more than twice larger than that of the film before annealing. Compared with the undoped Cu3N film, it possesses fine thermal stability both in vacuum and in atmosphere.

Fe-doped Cu3N films were prepared by cylindrical magnetron sputtering equipment at room temperature. The doping of Fe with the proper concentration results in a change in the preferred growth orientation from the Cu-rich plane (1 1 1) to the N-rich plane (1 0 0), which relates to the evolution of the surface grain shape from pyramid to sphere. Excessive doping of Fe is not favourable for the crystallization of Cu3N films. The cross-sections of the doped films with preferred growth orientations of [1 0 0] exhibit regular columnar grains. The variation between the lattice constant and the XPS results reveals that Fe probably replaces the position of Cu atoms in the lattice or is segregated in the grain boundaries. Weaker bonding of Cu–N results in a reduction of thermal stability for Fe-doped Cu3N films. And the incorporation of Fe can effectively modify the energy gap. According to the variations in the mean grain size, the peak of N1s and the energy gap, it is inferred that a doping limitation exists around 2.0 at%.