Structure and mechanical properties of delta-NbN/SiNx and delta '-NbN/SiNx nano-multilayer films deposited by reactive magnetron sputtering

摘要

We deposit cubic 8-NbN/SiNx and hexagonal delta'-NbN/SiNx nano-multilayer films using reactive magnetron sputtering in discharge of a mixture of Ar and N-2 gas, and explore the effects of SiNx. layer thickness on the microstructure and mechanical properties for both cubic 8-NbN/SiNx. and hexagonal delta'-NbN/SiNx multilayer films by virtue of X-ray diffraction, electron diffraction, high-resolution transmission electron microscope, and nanoindentation measurements. We find that the structure for NbN layers is a critical factor in determining the hardness of NbN/SiNx. multilayer films. For cubic 8-NbN/SiNx. nano-multilayer films, as SiNx layer thickness is smaller than or equal to 0.4 nm, the cubic delta-NbN layers force SiNx layers to crystallize, accompanied with a remarkable increase in hardness with maximum hardness of 32 GPa. With an increase in thickness, SiN. layers become amorphous, and correspondingly the hardness decreases. For hexagonal delta'-NbN/SiN. nano-multilayer films, both the stress and hardness decrease with increasing the SiN. layer thickness and the nano-multilayer films do not show any enhancement in hardness, compared to delta'-NbN single layer film.