Transition metal nitrides thin films deposition using a dynamically controlled magnetron sputtering apparatus

Abstract

Transition metal nitrides thin films are normally used as coatings to protect mechanical tools, e.g., bits and drills, to provide biocompatibility for common materials like steel and as decorative layers. Among these nitrides, TiN is the most usual coating deposited as a single film or multilayered with other materials deposited preferentially by magnetron sputtering. The film properties such as adhesion, intrinsic stress and hardness can be controlled and improved by means of a bias potential applied to the substrates. The problem of stoichiometry oscillation during the deposition process was resolved using the dynamic partial pressure control to maintain the argon to nitrogen ratio and the working pressure constant by means of a computer controlled interface. In this work the argon to nitrogen ratio was changed in order to obtain one stoichiometric nitride for the transition metals of group IV and group V. Film characterization was performed using Rutherford backscattering, nuclear reaction analysis and energy dispersive spectroscopy for elemental composition and stoichiometry; X-ray diffraction to study the crystal phase formation and scanning electron microscopy to determine the thin film thickness and microstructure. The corrosion protection ability and microhardness of the samples are also presented in view of the applicability potential of the coatings. The results shows that formation mechanisms of the studied nitrides are similar showing an optimal argon to nitrogen pressure ratio to obtain the stoichiometric phase.