Abstract
Nanocrystalline Zr(N,O) thin films were deposited on P-type (100) Si wafers using unbalanced magnetron sputtering (UBMS) system with reactive gases consisting of nitrogen and oxygen. Oxygen with different flow rate was introduced into the optimized nitride-deposited process to deposit the Zr(N,O) thin films. The purpose of this study was to investigate the phase transition due to changing oxygen flow rate and the variation of related structure and properties of the thin films. As the oxygen flow rate increases, the oxygen content of films determined using X-ray Photoelectron Spectroscopy (XPS) increased significantly. The major phases observed from X-ray Diffraction (XRD) were in an order of fcc-ZrN, c-Zr2ON2, t-ZrO2 and m-ZrO2 with increasing oxygen content. The characteristics of the films could be categorized into three zones respectively predominated by ZrN (zone I), Zr2ON2 (zone II) and ZrO2 (zone III). The properties of the films including electrical resistivity, mechanical and optical properties were substantially affected by the oxygen content in the film and the predominant phase in the three zones. The residual stresses of ZrN, t-ZrO2 and m-ZrO2 phases were measured separately using XRD modified sin2ψ method. The residual stress in ZrN was relieved with increasing oxygen content. High residual stress in the t-ZrO2 may be ascribed to the lattice distortion due to the insertion of excess interstitial anions. Zr2ON2 and m-ZrO2 were found to be low stress phases, and might relieve the residual stress of the films. Experimental results indicated that t-ZrO2 could be stabilized at room temperature by the nitrogen interstitials in the octahedral sites along the c-axis. The increase of nitrogen content in ZrO2 phase resulted in the increase of refractive index, the decrease of band gap and the varying color from lemon green to pink.