Effect of ferromagnetic substrates on the film growth in magnetized plasma systems

We found substantial differences in TiN films on austenite (non-ferromagnetic) and martensite (ferromagnetic) steel substrates. The films were grown by the reactive PVD in a magnetized M–M (Magnets-in-Motion) linear hollow cathode plasma as well as in a hybrid M–M hollow cathode and microwave ECR plasma system. The martensite steel substrates can, depending on their position and shape, deform the magnetic field of the plasma PVD source and create a certain kind of “bypass” channel for magnetic field lines causing acceleration of charged particles towards the substrate surface. This leads to a considerable enhancement of the particle bombardment of the surface of the martensite steel substrates as compared to non-ferromagnetic substrates already at ground potential. The ion bombardment affects texture and morphology of the growing TiN film. It was found that the substrate bias can control the particle bombardment and compensate the effect of substrate in the film growth at considerable extent. We have also found that, although the observed effect is of particular importance for very high-density plasmas generated by the magnetized hollow cathodes, it also affects the film growth even in conventional closed-field magnetron sputtering systems.