Structure and Surface Morphology of Cr-Zr-N Thin Films Deposited by Reactive DC Magnetron Sputtering

AbstractIn this study, chromium zirconium nitride (Cr-Zr-N) thin films have been prepared by reactive dc closed field unbalanced magnetron co-sputtering on Si (100) wafers and glass slides for 60min without substrate heating and biasing voltage in gas mixture of Ar and N2 with flow rates kept constant at 3.0sccm and 6.0sccm, respectively. The sputtering currents applied to Zr target were varied from 0.2 A to 0.8 A, whereas the current of Cr target was kept at 0.8 A. To investigate films structure and surface morphology as a function of Zr content, the as-deposited films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDX). The results suggested that increasing in current applied to Zr target enhanced the deposition rate and also increased Zr content in the films ranging from 6.0 to 31.2 at %. The films formed a solid solution (Cr, Zr)N where Zr atoms substitute Cr atoms in the CrN lattice. The lattice parameters increased from 0.4207nm to 0.4357nm, whereas the grain sizes decreased from 11.27nm to 7.412 nm. The film structure developed with the coexistence of (111) and (200) crystallographic orientation into a mixture of nanocrystalline grains as the sputtering currents of Zr target exceeded 0.2 A. The AFM images showed smoothing surface morphology with the roughness decreased from 9.471nm to 2.437nm. Cross-sectional micrographs exhibited the microstructure evolution corresponding to the grain refinement as a result of increasing Zr discharge current