The texture and electrical properties of Zr and ZrN_x thin films deposited by DC sputtering

Zr and ZrN_x thin films are grown on Si(001) by DC magnetron sputtering. The detailed microstructure evolution and its corresponding electrical properties are systematically studied with various processing parameters including applied power, N₂/Ar ratio, substrate bias and substrate temperature by 4-point probe, EPMA and XRD. It is found that while the negative substrate bias can decrease the resistivity of both Zr and ZrN_x thin films, the texture microstructure of each thin film in the series is changed differently. As increasing N₂/Ar ratio, the resistivity decreases in the beginning and then increases rapidly, which results from the variations of compositions and phases, while this minimum resistivity point shifts to a higher N₂/Ar ratio for the films sputtered under higher applied power. The substrate temperature not only decreases the ZrN_x film resistivity, but also increases the (002) preferred orientations most efficiently. The cause of each phenomenon is briefly discussed. Finally, two samples showing different degrees of (002) to (111) textures are annealed to investigate the diffusion barrier properties from a sandwich structure of Cu/ZrN_x/Si(001). Results from 4-point probe reveal that the film with higher degree of (111) textures has a superior thermal stability.