Effect of Substrate Bias on Microstructures of Zirconia Thin Films Deposited by Cathodic Vacuum Arc

Zirconium oxide (ZrO₂) thin films are deposited at room temperature by cathodic arc at substrate biases of 0V, -60V and -120V, respectively. The crystal structure, composition, morphology, and deposition rate of the as-deposited thin films are systematically investigated by x-ray diffraction, x-ray photoelectron spectroscopy (XPS) as well as scanning electron microscopy. The results show that the crystal structure, morphology and deposition rate of the films all are dependant on substrate bias. With the increase of bias voltage from 0V to -120V, the zirconium oxide thin film grown on silicon wafer first exhibits monoclinic lattice and tetragonal lattice, further evolves monoclinic phase with the preferred orientation along the (-111) and (-222) directions at -60V and finally along nearly one observed preferred (002) direction under -120V. In addition, the variations of morphology with bias voltage are correlated to changes of the film structure. The results of XPS demonstrate that Zr elements are almost oxidized completely in the films achieved under -120V bias.