Structural studies of TiN/ZrN multilayer coating deposited by physical vapour deposition

Multilayer coatings have been produced using unbalanced magnetron physical vapour deposition in which discrete layers of TiN and ZrN were co-deposited. It has been shown that the multilayers exhibited two-fold periodicity having values of 13 and 2.8 nm. This periodicity, measured both by cross-sectional transmission electron microscopy and low-angle X-ray diffraction, has been precisely related to the process parameters used. Analysis has shown that a third, previously unreported, phase existed within the coating having a lattice parameter comparable to that of TiN and a well-defined orientation relationship with the primary phases. The existence of this phase has been explained in terms of variations in the stoichometry of the coating due to non-uniform metal to nitrogen deposition rates within the chamber. Textural studies revealed that preferred orientation existed in the coating; the degree of which was greater in the ZrN layers than the TiN layers.