CrN/CNx nano-scale multilayered films have been grown on both Si(1 0 0) and high speed steel substrates (HSS) by closed-field unbalanced magnetron sputtering. Designed experimental parameters enabled an evaluation of the effects of negative substrate bias voltage (Vb), and bi-layer thickness λ (by changing substrate rotation rate) during deposition on the structural and mechanical properties of reactively sputtered CrN/CNx multilayer thin films. In all cases, the CNx layers prepared at OEM = 55% were amorphous independent of Vb, while the microstructures of the CrN layers were dependent primarily on Vb. The CrN layers showed a mixed structure phase consisting of CrN, Cr2N, and Cr at Vb = -(40-120) V. At higher Vb values (-140 V or above), the Cr2N phase was dominant along with low CrN phase content. AFM measurements revealed that the root-mean-square (rms) surface roughness of the CrN/CNx film was 2.5 nm at Vb = -200 V whereas the rms values were about 9.5-3.3 2 nm for lower Vb values of -(40-180 V). By nanoindentation measurements, a maximum hardness of ∼36 GPa was observed in a film prepared at Vb = -140 V. The improved mechanical properties of the CrN/CNx multilayer films are correlated to the phase formation during deposition.
- A. CrN/CN layered structures
- B. Mechanical properties
- D. Photoelectron spectroscopy (XPS)
- D. Transmission electron microscopy (TEM)
- D. X-ray diffraction (XRD)