Low energy IBAD: correlation between process parameters and film properties for ion beam assisted evaporation and sputter deposition

Binary nitride films with Al, Cr and Ti as metal components have been deposited with ion beam assisted evaporation and sputtering (IBAD), and the film properties are investigated in terms of the individual deposition parameters. In the case of ion beam assisted evaporation the flux ratio between the film forming metal atoms and the nitrogen ions from the ion source was shown to enable a quantitative control of the composition and the chemical phases of the films. Detailed studies for TiN reveal the possibilities to manipulate texture and stress, the average grain size and the morphology of the films. Such results are discussed with an extended structure zone model, introducing the energy input per film forming particle as the relevant parameter. Also, the structural film properties and the deposition parameters are quantitatively correlated with the hardness and the adhesion of the films. A dynamic process control during the beginning of TIN deposition on stainless steel resulted in distinctly improved adhesion properties. For the deposition of TiN with a dual ion beam arrangement in which one ion beam bundle was directed onto a Ti-target and another onto the substrate with the growing film, a strong influence of the particle energies and the incidence angles on the film texture and its directional orientation was found. Such effects are quantitatively related to the minimization of the free energy of the films and the influence of preferential re-sputtering effects. For ion beam sputter deposition without simultaneous ion bombardment of the growing film, the texture and the film stress are found to be controlled by energetic particles resulting from elastic backscattering at the target surface.