Phase Composition Stability of ZrN/SiNх Multilayered Coatings under Air Annealing: the Role of the Thicknesses Ratio of the Elementary Layers

Abstract

In the present work the phase composition stability and oxidation resistance of ~300 nm thick ZrN/SiNx nanoscale multilayers at the air annealing procedure were studied. Coatings were prepared by reactive magnetron sputter-deposition on Si wafers under Ar+N2 plasma discharges. ZrN/SiNx multilayers with ZrN and SiNx layer thickness varying from 2 to 10 nm were synthesized by sequential sputtering from elemental Zr and Si3N4 targets at T dep =300 °C. According to X-ray diffraction (XRD) analysis the multilayered films consist of nanocrystalline (002)-oriented ZrN and amorphous SiNx layers. The oxidation resistance under air was studied using in situ XRD in the temperature range from 400 to 950 °C, as well as by scanning electron microscopy (SEM) and wavelength dispersive X-ray spectrometry (WDS) after air annealing procedure. While the reference ZrN film starts to oxidize at Tox. = 550 °C, a much higher oxidation resistance is found for multilayered films, till Tox. = 860–950 °C for ZrN/SiNx coatings with the elementary layer thickness ratio of 5 nm/10 nm and 2 nm/5 nm.